278	----	Trinity Site: 1945-1995. A National Historic Landmark White Sands Missile Range, New Mexico Contents: Radiation at Trinity Site. How to Get to Trinity Site. Trinity Site National Historic Landmark. The Manhattan Project. The Theory. Building a test site. Jumbo. Bomb Assembly. The test. After the explosion. It's the Schmidt house. Afterwards. White Sands Missile Range. Reading List. "The effects could well be called unprecedented, magnificent, beautiful, stupendous, and terrifying. No man-made phenomenon of such tremendous power had ever occurred before. The lighting effects beggared description. The whole country was lighted by a searing light with the intensity many times that of the midday sun." Brig. Gen. Thomas Farrell Radiation at Trinity Site In deciding whether to visit ground zero at Trinity Site, the following information may prove helpful to you. Radiation levels in the fenced, ground zero area are low. On an average the levels are only 10 times greater than the region's natural background radiation. A one-hour visit to the inner fenced area will result in a whole body exposure of one-half to one milliroentgen. To put this in perspective, a U.S. adult receives an average exposure of 90 milliroentgens every year from natural and medical sources. For instance, the Department of Energy says we receive between 35 and 50 milliroentgens every year from the sun and from 20 to 35 milliroentgens every year from our food. Living in a brick house adds 50 milliroentgens of exposure every year compared to living in a frame house. Finally, flying coast to coast in a jet airliner gives an exposure of between three and five milliroentgens on each trip. Although radiation levels are low, some feel any extra exposure should be avoided. The decision is yours. It should be noted that small children and pregnant women are potentially more at risk than the rest of the population and are generally considered groups who should only receive exposure in conjunction with medical diagnosis and treatment. Again, the choice is yours. At ground zero, Trinitite, the green, glassy substance found in the area, is still radioactive and must not be picked up. Typical radiation exposures for Americans Per The National Council on Radiation Protection On hour at ground zero = 1/2 mrem Cosmic rays from space = 40 mrem at sea level per year Radioactive minerals in rocks and soil = 55 mrems per year Radioactivity from air, water, and food = anywhere from 20 to 400 mrem per year About 22 mrem per chest X-ray and 900 mrem for whole-mouth dental X- rays Smoking one pack of cigarettes a day for one year = 40 mrem Miscellaneous such as watch dials and smoke detectors = 2 mrem per year How to Get to Trinity Site Trinity Site, where the world's first atomic bomb was exploded in 1945, is normally open to the public twice a year--on the first Saturday in April and October. Trinity is located on the northern end of the 3,200-square-mile White Sands Missile Range, N.M., between the towns of Carrizozo and Socorro, N.M. There are two ways of entering the restricted missile range on tour days. Visitors can enter through the range's Stallion Range Center which is five miles south of Highway 380. The turnoff is 12 miles east of San Antonio, N.M., and 53 miles west of Carrizozo, N.M. The Stallion gate will be open 8 a.m. to 2 p.m. Visitors arriving at the gate between those hours will receive handouts and will be allowed to drive unescorted the 17 miles to Trinity Site. The road is paved and marked. The other way of entering the missile range is by travelling with a caravan sponsored by the Alamogordo (N.M.) Chamber of Commerce. The caravan forms at the Otero County Fairgrounds in Alamogordo and leaves at 8 a.m. Visitors entering this way will travel as an escorted group with military police to and from Trinity Site. The drive is 170 miles round trip. There are no service station facilities on the missile range. The caravan is scheduled to leave Trinity Site at 12:30 p.m. for the return to Alamogordo. The caravan may leave later if there is a large number of vehicles in the returning caravan. In 1995, an additional open house will be conducted on July 16, the 50th anniversary of the Trinity test. Visitors may enter the missile range through the Stallion Range Center gate from 5 to 11 a.m. There will be no caravan leaving from Alamogordo, N.M., for this event. The early hours will allow visitors to be on-site at 5:29:45 a.m., the time the Trinity Site detonation occurred, and should help visitors avoid the 100-plus degree afternoon temperatures common here in July. Included on the Trinity Site tour is Ground Zero where the atomic bomb was placed on a 100-foot steel tower and exploded on July 16, 1945. A small monument now marks the spot. Visitors also see the McDonald ranch house where the world's first plutonium core for a bomb was assembled. The missile range provides historical photographs and a Fat Man bomb casing for display. There are no ceremonies or speakers. Portable toilet facilities are available on site. Hot dogs and sodas are sold at the parking lot. Cameras are allowed at Trinity Site, but their use is strictly prohibited anywhere else on White Sands Missile Range. For more information, contact the White Sands Missile Range Public Affairs Office at (505) 678-1134/1700. Trinity Site National Historic Landmark Trinity Site is where the first atomic bomb was tested at 5:29:45 a.m. Mountain War Time on July 16, 1945. The 19 kiloton explosion not only led to a quick end to the war in the Pacific but also ushered the world into the atomic age. All life on Earth has been touched by the event which took place here. The 51,500-acre area was declared a national historic landmark in 1975. The landmark includes base camp, where the scientists and support group lived; ground zero, where the bomb was placed for the explosion; and the McDonald ranch house, where the plutonium core to the bomb was assembled. On your visit to Trinity Site you will be able to see ground zero and the McDonald ranch house. In addition, on your drive into the Trinity Site area you will pass one of the old instrumentation bunkers which is beside the road just west of ground zero. The Manhattan Project The story of Trinity Site begins with the formation of the Manhattan Project in June 1942. The project was given overall responsibility of designing and building an atomic bomb. At the time it was a race to beat the Germans who, according to intelligence reports, were building their own atomic bomb. Under the Manhattan Project three large facilities were constructed. At Oak Ridge, Tenn., huge gas diffusion and electromagnetic process plants were built to separate uranium 235 from its more common form, uranium 238. Hanford, Wash. became the home for nuclear reactors which produced a new element called plutonium. Both uranium 235 and plutonium are fissionable and can be used to produce an atomic explosion. Los Alamos was established in northern New Mexico to design and build the bomb. At Los Alamos many of the greatest scientific minds of the day labored over the theory and actual construction of the device. The group was led by Dr. J. Robert Oppenheimer who is credited with being the driving force behind building a workable bomb by the end of the war. The Theory Los Alamos scientists devised two designs for an atomic bomb--one using the uranium and another using the plutonium. The uranium bomb was a simple design and scientists were confident it would work without testing. The plutonium bomb worked by compressing the plutonium into a critical mass which sustains a chain reaction. The compression of the plutonium ball was to be accomplished by surrounding it with lens-shaped charges of conventional explosives. They were designed to all explode at the same instant. The force is directed inward, thus smashing the plutonium from all sides. In an atomic explosion, a chain reaction picks up speed as atoms split, releasing neutrons plus great amounts of energy. The escaping neutrons strike and split more atoms, thus releasing still more neutrons and energy. In a nuclear explosion this all occurs in a millionth of a second with billions of atoms being split. Project leaders decided a test of the plutonium bomb was essential before it could be used as a weapon of war. From a list of eight sites in California, Texas, New Mexico and Colorado, Trinity Site was chosen as the test site. The area already was controlled by the government because it was part of the Alamogordo Bombing and Gunnery Range which was established in 1942. The secluded Jornado del Muerto was perfect as it provided isolation for secrecy and safety, but was still close to Los Alamos. Building a test site In the fall of 1944 soldiers started arriving at Trinity Site to prepare for the test. Marvin Davis and his military police unit arrived from Los Alamos at the site on Dec. 30, 1944. The unit set up security checkpoints around the area and had plans to use horses to ride patrol. According to Davis the distances were too great and they resorted to jeeps and trucks for transportation. The horses were sometimes used for polo, however. Davis said that Capt. Bush, base camp commander, somehow got the soldiers real polo equipment to play with but they preferred brooms and a soccer ball. Other recreation at the site included volleyball and hunting. Davis said Capt. Bush allowed the soldiers with experience to use the Army rifles to hunt deer and pronghorn. The meat was then cooked up in the mess hall. Leftovers went into soups which Davis said were excellent. Of course, some of the soldiers were from cities and unfamiliar with being outdoors a lot. Davis said he went to relieve a guard at the Mockingbird Gap post and the soldier told Davis he was surprised by the number of "crawdads" in the area considering it was so dry. Davis gave the young man a quick lesson on scorpions and warned him not to touch. Throughout 1945 other personnel arrived at Trinity Site to help prepare for the test. Carl Rudder was inducted into the Army on Jan. 26, 1945. He said he passed through four camps, took basic for two days and arrived at Trinity Site on Feb. 17. On arriving he was put in charge of what he called the "East Jesus and Socorro Light and Water Company." It was a one-man operation--himself. He was responsible for maintaining generators, wells, pumps and doing the power line work. A friend of Rudder's, Loren Bourg, had a similar experience. He was a fireman in civil life and ended up trained as a fireman for the Army. He worked as the station sergeant at Los Alamos before being sent to Trinity Site in April 1945. In a letter Bourg said, "I was sent down here to take over the fire prevention and fire department. Upon arrival I found I was the fire department, period." As the soldiers at Trinity Site settled in they became familiar with Socorro. They tried to use the water out of the ranch wells but found it so alkaline they couldn't drink it. In fact, they used Navy salt-water soap for bathing. They hauled drinking water from the fire house in Socorro. Gasoline and diesel was purchased from the Standard bulk plant in Socorro. According to Davis, they established a post office box, number 632, in Socorro so getting their mail was more convenient. The trips into town also offered them the chance to get their hair cut in a real barbershop. If they didn't use the shop, Sgt. Greyshock used horse clippers to trim their hair. Jumbo The bomb design to be used at Trinity Site actually involved two explosions. First there would be a conventional explosion involving the TNT and then, a fraction of a second later, the nuclear explosion, if a chain reaction was maintained. The scientists were sure the TNT would explode, but were initially unsure of the plutonium. If the chain reaction failed to occur, the TNT would blow the very rare and dangerous plutonium all over the countryside. Because of this possibility, Jumbo was designed and built. Originally it was 25 feet long, 10 feet in diameter and weighed 214 tons. Scientists were planning to put the bomb in this huge steel jug because it could contain the TNT explosion if the chain reaction failed to materialize. This would prevent the plutonium from being lost. If the explosion occurred as planned, Jumbo would be vaporized. Jumbo was brought to Pope, N.M., by rail and unloaded. A specially built trailer with 64 wheels was used to move Jumbo the 25 miles to Trinity Site. As confidence in the plutonium bomb design grew it was decided not to use Jumbo. Instead, it was placed in a steel tower about 800 yards from ground zero. The blast destroyed the tower, but Jumbo survived intact. Today Jumbo rests at the entrance to ground zero so all can see it. The ends are missing because, in 1946, the Army detonated eight 500-pound bombs inside it. Because Jumbo was standing on end, the bombs were stacked in the bottom and the asymmetry of the explosion blew the ends off. To calibrate the instruments which would be measuring the atomic explosion and to practice a countdown, the Manhattan scientists ran a simulated blast on May 7. They stacked 100 tons of TNT onto a 20-foot wooden platform just southeast of ground zero. Louis Hemplemann inserted a small amount of radioactive material from Hanford into tubes running through the stack of crates. The scientists hoped to get a feel for how the radiation might spread in the real test by analyzing this test. The explosion destroyed the platform, leaving a small crater with trace amounts of radiation in it. Bomb Assembly On July 12 the two hemispheres of plutonium were carried to the George McDonald ranch house just two miles from ground zero. At the house, Brig. Gen. Thomas Farrell, deputy to Maj. Gen. Leslie Groves, was asked to sign a receipt for the plutonium. Farrell later said, "I recall that I asked them if I was going to sign for it shouldn't I take it and handle it. So I took this heavy ball in my hand and I felt it growing warm, I got a certain sense of its hidden power. It wasn't a cold piece of metal, but it was really a piece of metal that seemed to be working inside. Then maybe for the first time I began to believe some of the fantastic tales the scientists had told about this nuclear power." At the McDonald ranch house the master bedroom had been turned into a clean room for the assembly of the bomb core. According to Robert Bacher, a member of the assembly team, they tried to use only tools and materials from a special kit. Several of these kits existed and some were already on their way to Tinian, the island in the Pacific which was the base for the bombers. The idea was to test the procedures and tools at Trinity as well as the bomb itself. At one minute past midnight on Friday, July 13, the explosive assembly left Los Alamos for Trinity Site. Later in the morning, assembly of the plutonium core began. According to Raemer Schreiber, Robert Bacher was the advisor and Marshall Holloway and Philip Morrison had overall responsibility. Louis Slotin, Boyce McDaniel and Cyril Smith were responsible for the mechanical assembly in the ranch house. Later Holloway was responsible for the mechanical assembly at the tower. In the afternoon of the 13th the core was taken to ground zero for insertion into the bomb mechanism. The bomb was assembled under the tower on July 13. The plutonium core was inserted into the device with some difficulty. On the first try it stuck. After letting the temperatures of the plutonium and casing equalize the core slid smoothly into place. Once the assembly was complete many of the men took a welcome relief and went swimming in the water tank east of the McDonald ranch house. The next morning the entire bomb was raised to the top of the 100 foot steel tower and placed in a small shelter. A crew then attached all the detonators and by 5 p.m. it was complete. The test Three observation points were established at 10,000 yards from ground zero. These were wooden shelters protected by concrete and earth. The south bunker served as the control center for the test. The automatic firing device was triggered from there as key men such as Dr. Robert Oppenheimer, head of Los Alamos, watched. None of the manned bunkers are left. Many scientists and support personnel, including Gen. Leslie Groves, head of the Manhattan Project, watched the explosion from base camp which was ten miles southwest of ground zero. All the buildings at base camp were removed after the test. Most visiting VIPs watched from Compania Hill, 20 miles northwest of ground zero. The test was scheduled for 4 a.m. July 16, but rain and lightning early that morning caused it to be postponed. The device could not be exploded under rainy conditions because rain and winds would increase the danger from radioactive fallout and interfere with observation of the test. At 4:45 a.m. the crucial weather report came through announcing calm to light winds with broken clouds for the following two hours. At 5:10 the countdown started and at 5:29:45 the device exploded successfully. To most observers the brilliance of the light from the explosion--watched through dark glasses--overshadowed the shock wave and sound that arrived later. Hans Bethe, one of the contributing scientists, wrote "it looked like a giant magnesium flare which kept on for what seemed a whole minute but was actually one or two seconds. The white ball grew and after a few seconds became clouded with dust whipped up by the explosion from the ground and rose and left behind a black trail of dust particles." Joe McKibben, another scientist, said, "We had a lot of flood lights on for taking movies of the control panel. When the bomb went off, the lights were drowned out by the big light coming in through the open door in the back." Others were impressed by the heat they immediately felt. Military policeman Davis said, "The heat was like opening up an oven door, even at 10 miles." Dr. Phillip Morrison said, "Suddenly, not only was there a bright light but where we were, 10 miles away, there was the heat of the sun on our faces....Then, only minutes later, the real sun rose and again you felt the same heat to the face from the sunrise. So we saw two sunrises." After the explosion Although no information on the test was released until after the atomic bomb was used as a weapon against Japan, people in New Mexico knew something had happened. The shock broke windows 120 miles away and was felt by many at least 160 miles away. Army officials simply stated that a munitions storage area had accidentally exploded at the Alamogordo Bombing Range. The explosion did not make much of a crater. Most eyewitnesses describe the area as more of a small depression instead of a crater. The heat of the blast did melt the desert sand and turn it into a green glassy substance. It was called Trinitite and can still be seen in the area. At one time Trinitite completely covered the depression made by the explosion. Afterwards the depression was filled and much of the Trinitite was taken away by the Nuclear Energy Commission. To the west of the monument is a low structure which is protecting an original portion of the crater area. Trinitite is visible through openings in the roof. It's the Schmidt house The George McDonald ranch house sits within an 85'x85' low stone wall. The house was built in 1913 by Franz Schmidt, a German immigrant, and an addition was constructed on the north side in the 1930's by the McDonalds. There is a display about the Schmidt family in the house during each open house. The ranch house is a one-story, 1,750 square-foot building. It is built of adobe which was plastered and painted. An ice house is located on the west side along with an underground cistern which stored rain water running off the roof. At one time the north addition contained a toilet and bathtub which drained into a septic tank northwest of the house. There is a large, divided water storage tank and a Chicago Aeromotor windmill east of the house. The scientists and support people used the north tank as a swimming pool during the long hot summer of 1945. South of the windmill are the remains of a bunkhouse and a barn which was part garage. Further to the east are corrals and holding pens. The buildings and fixtures east of the house have been stabilized to prevent further deterioration. The ranch was abandoned in 1942 when the Alamogordo Bombing and Gunnery Range took over the land to use in training World War II bombing crews. The house stood empty until the Manhattan Project support personnel arrived in early 1945. Inside the house the northeast room (the master bedroom) was designated the assembly room. Work benches and tables were installed. To keep dust and sand out of instruments and tools, the windows were covered with plastic. Tape was used to fasten the edges of the plastic and to seal doors and cracks in the walls. The explosion, only two miles away, did not significantly damage the house. Most of the windows were blown out, but the main structure was intact. Years of rain water dripping through holes in the roof did much more damage. The barn did not do as well. During the Trinity test the roof was bowed inward and some of the roofing was blown away. The roof has since collapsed. The house stood empty and deteriorating until 1982 when the U.S. Army stabilized the house to prevent any further damage. Shortly after, the Department of Energy and U.S. Army provided the funds for the National Park Service to completely restore the house. The work was done in 1984. All efforts were directed at making the house appear as it did on July 12, 1945. Afterwards The story of what happened at Trinity Site did not come to light until after the second atomic bomb was exploded over Hiroshima, Japan, on August 6. President Truman made the announcement that day. Three days later, August 9, the third atomic bomb devastated the city of Nagasaki, and on August 14 the Japanese surrendered. Trinity Site became part of what was then White Sands Proving Ground. The proving ground was established on July 9, 1945, as a test facility to investigate the new rocket technology emerging from World War II. The land, including Trinity Site and the old Alamogordo Bombing Range, came under the control of the new rocket and missile testing facility. Interest in Trinity Site was immediate. In September 1945 press tours to the site started. One of the famous photos of ground zero shows Robert Oppenheimer and General Leslie Groves surrounded by a small group of reporters as they examine one of the footings to the 100 foot tower on which the bomb was placed. That picture was taken Sept. 11. The exposed footing is still visible at ground zero. On Sept. 15-17, George Cremeens, a young radio reporter from KRNT in Des Moines, visited the site with soundman Frank Lagouri. They flew over the crater and interviewed Dr. Kenneth Bainbridge, Trinity test director, and Capt. Howard Bush, base camp commander. Back in Iowa, Cremeens created four 15-minute reports on his visit which aired Sept. 24, 26, 27 and 29. A 15-minute composite was made and aired on the ABC Radio Network. For his work Cremeens received a local Peabody Award for "Outstanding Reporting and Interpretation of the News." At first Trinity Site was encircled with a fence and radiation warning signs were posted. The site remained off-limits to military and civilian personnel of the proving ground and closed to the public. In 1952 the Atomic Energy Commission let a contract to clean up the site. Much of the Trinitite was scraped up and buried. In September 1953 about 650 people attended the first Trinity Site open house. A few years later a small group from Tularosa visited the site on an anniversary of the explosion to conduct a religious service and prayers for peace. Similar visits have been made annually in recent years on the first Saturday in October. In 1967 the inner oblong fence was added. In 1972 the corridor barbed wire fence which connects the outer fence to the inner one was completed. Jumbo was moved to the parking lot in 1979. Visits to the site are now made in April and October because it is generally so hot in July on the Jornada del Muerto. White Sands Missile Range White Sands Missile Range has developed from a simple desert testing site for the V-2 into one of the most sophisticated test facilities in the world. The mission of White Sands Missile Range begins with a customer--a service developer, or another federal agency, which is ready to find out if engineers and scientists have built something which will perform according to job specifications. It ends when an exhaustive series of tests has been completed and a data report has been delivered to the customer. Between the beginning and the end of the test program, be it the Army Tactical Missile System or newly designed automobiles, range employees are involved in every operation connected with the customer and his product. The range can and does provide everything from rat traps to telephones, from equipment hoists and flight safety to microsecond timing. We shake, rattle and roll the product, roast it, freeze it, subject it to nuclear radiation, dip it in salt water and roll it in the mud. We test its paint, bend its frame and find out what effect its propulsion material has on flora and fauna. In the end, if it's a missile, we fire it, record its performance and bring back the pieces for post mortem examination. All test data is reduced and the customer receives a full report. For more information on Trinity Site or White Sands Missile Range contact: Public Affairs Office (STEWS-PA) White Sands Missile Range White Sands Missile Range, N.M. 88002-5047 Reading List The Day the Sun Rose Twice, by Ferenc Szasz, University of New Mexico Press, 1984. Manhattan: The Army and the Atomic Bomb, by Vincent Jones, Center of Military History, U. S. Army. Trinity, by Kenneth Bainbridge, Los Alamos publication (LA-6300-H). The Making of the Atomic Bomb, by Richard Rhodes, Simon and Schuster, 1986. Now It Can Be Told, by General Leslie Groves, Da Capo Press, 1975. Day One, By Peter Wyden, Simon and Schuster, 1984. City of Fire: Los Alamos and the Atomic Age, 1943-1945, by James Kunetka, University of New Mexico Press, 1978. Los Alamos 1943-1945: The Beginning of an Era, Los Alamos Publication (LASL-79-78). Day of Trinity, by Lansing Lamont, Atheneum. Radiological Survey and Evaluation of the Fallout Area from the Trinity Test: Chupadera Mesa and White Sands Missile Range, N. M., Los Alamos publication (LA-10256-MS). Life Magazine, August 20 and September 24, 1945. Time Magazine, August 13 and 20, 1945. 
279	----	Photos and Maps of Trinity (Atomic Test) Site The picture files are courtesy of U.S. Army White Sands Missile Range Public Affairs Office: basecamp.gif -- Base camp for Trinity site workers. blast.gif -- Trinity test blast at 10 seconds. crater.gif -- Oppenheimer and Groves examine tower piling in crater. gadget1.gif -- Lifting the "gadget" into the 100-foot tower. gadget2.gif -- Norris Bradbury with the "gadget". jumbo.gif -- Unloading Jumbo. mcdonald.gif -- McDonald-Schmidt ranch house, where plutonium core was assembled. patch.gif -- Patch issued to Manhattan Project military participants. tr_map1.gif -- Map of roads to Trinity Site and visitors' site map. whitsand.gif -- Emblem of the U.S. Army White Sands Missile Range. 
277	----	TRINITY SITE by the U.S. Department of Energy National Atomic Museum, Albuquerque, New Mexico Contents: The First Atomic Test. Jumbo. Schmidt-McDonald Ranch House. Notes. Bibliography. The National Atomic Museum. THE FIRST ATOMIC TEST On Monday morning July 16, 1945, the world was changed forever when the first atomic bomb was tested in an isolated area of the New Mexico desert. Conducted in the final month of World War II by the top-secret Manhattan Engineer District, this test was code named Trinity. The Trinity test took place on the Alamogordo Bombing and Gunnery Range, about 230 miles south of the Manhattan Project's headquarters at Los Alamos, New Mexico. Today this 3,200 square mile range, partly located in the desolate Jornada del Muerto Valley, is named the White Sands Missile Range and is actively used for non-nuclear weapons testing. Before the war the range was mostly public and private grazing land that had always been sparsely populated. During the war it was even more lonely and deserted because the ranchers had agreed to vacate their homes in January 1942. They left because the War Department wanted the land to use as an artillery and bombing practice area. In September 1944, a remote 18 by 24 square mile portion of the north-east corner of the Bombing Range was set aside for the Manhattan Project and the Trinity test by the military. The selection of this remote location in the Jornada del Muerto Valley for the Trinity test was from an initial list of eight possible test sites. Besides the Jornada, three of the other seven sites were also located in New Mexico: the Tularosa Basin near Alamogordo, the lava beds (now the El Malpais National Monument) south of Grants, and an area southwest of Cuba and north of Thoreau. Other possible sites not located in New Mexico were: an Army training area north of Blythe, California, in the Mojave Desert; San Nicolas Island (one of the Channel Islands) off the coast of Southern California; and on Padre Island south of Corpus Christi, Texas, in the Gulf of Mexico. The last choice for the test was in the beautiful San Luis Valley of south-central Colorado, near today's Great Sand Dunes National Monument. Based on a number of criteria that included availability, distance from Los Alamos, good weather, few or no settlements, and that no Indian land would be used, the choices for the test site were narrowed down to two in the summer of 1944. First choice was the military training area in southern California. The second choice, was the Jornada del Muerto Valley in New Mexico. The final site selection was made in late August 1944 by Major General Leslie R. Groves, the military head of the Manhattan Project. When General Groves discovered that in order to use the California location he would need the permission of its commander, General George Patton, Groves quickly decided on the second choice, the Jornada del Muerto. This was because General Groves did not want anything to do with the flamboyant Patton, who Groves had once described as "the most disagreeable man I had ever met."[1] Despite being second choice the remote Jornada was a good location for the test, because it provided isolation for secrecy and safety, was only 230 miles south of Los Alamos, and was already under military control. Plus, the Jornada enjoyed relatively good weather. The history of the Jornada is in itself quite fascinating, since it was given its name by the Spanish conquerors of New Mexico. The Jornada was a short cut on the Camino Real, the King's Highway that linked old Mexico to Santa Fe, the capital of New Mexico. The Camino Real went north from Mexico City till it joined the Rio Grande near present day El Paso, Texas. Then the trail followed the river valley further north to a point where the river curved to the west, and its valley narrowed and became impassable for the supply wagons. To avoid this obstacle, the wagons took the dubious detour north across the Jornada del Muerto. Sixty miles of desert, very little water, and numerous hostile Apaches. Hence the name Jornada del Muerto, which is often translated as the journey of death or as the route of the dead man. It is also interesting to note that in the late 16th century, the Spanish considered their province of New Mexico to include most of North America west of the Mississippi! The origin of the code name Trinity for the test site is also interesting, but the true source is unknown. One popular account attributes the name to J. Robert Oppenheimer, the scientific head of the Manhattan Project. According to this version, the well read Oppenheimer based the name Trinity on the fourteenth Holy Sonnet by John Donne, a 16th century English poet and sermon writer. The sonnet started, "Batter my heart, three-personed God."[2] Another version of the name's origin comes from University of New Mexico historian Ferenc M. Szasz. In his 1984 book, The Day the Sun Rose Twice, Szasz quotes Robert W. Henderson head of the Engineering Group in the Explosives Division of the Manhattan Project. Henderson told Szasz that the name Trinity came from Major W. A. (Lex) Stevens. According to Henderson, he and Stevens were at the test site discussing the best way to haul Jumbo (see below) the thirty miles from the closest railway siding to the test site. "A devout Roman Catholic, Stevens observed that the railroad siding was called 'Pope's Siding.' He [then] remarked that the Pope had special access to the Trinity, and that the scientists would need all the help they could get to move the 214 ton Jumbo to its proper spot."[3] The Trinity test was originally set for July 4, 1945. However, final preparations for the test, which included the assembly of the bomb's plutonium core, did not begin in earnest until Thursday, July 12. The abandoned George McDonald ranch house located two miles south of the test site served as the assembly point for the device's core. After assembly, the plutonium core was transported to Trinity Site to be inserted into the thing or gadget as the atomic device was called. But, on the first attempt to insert the core it stuck! After letting the temperatures of the core and the gadget equalize, the core fit perfectly to the great relief of all present. The completed device was raised to the top of a 100-foot steel tower on Saturday, July 14. During this process workers piled up mattresses beneath the gadget to cushion a possible fall. When the bomb reached the top of the tower without mishap, installation of the explosive detonators began. The 100-foot tower (a surplus Forest Service fire-watch tower) was designated Point Zero. Ground Zero was at the base of the tower. As a result of all the anxiety surrounding the possibility of a failure of the test, a verse by an unknown author circulated around Los Alamos. It read: From this crude lab that spawned a dud. Their necks to Truman's ax uncurled Lo, the embattled savants stood, and fired the flop heard round the world.[4] A betting pool was also started by scientists at Los Alamos on the possible yield of the Trinity test. Yields from 45,000 tons of TNT to zero were selected by the various bettors. The Nobel Prize-winning (1938) physicist Enrico Fermi was willing to bet anyone that the test would wipe out all life on Earth, with special odds on the mere destruction of the entire State of New Mexico! Meanwhile back at the test site, technicians installed seismographic and photographic equipment at varying distances from the tower. Other instruments were set up for recording radioactivity, temperature, air pressure, and similar data needed by the project scientists. According to Lansing Lamont in his 1965 book Day of Trinity, life at Trinity could at times be very exciting. One afternoon while scientists were busily setting up test instruments in the desert, the tail gunner of a low flying B-29 bomber spotted some grazing antelopes and opened up with his twin.50-caliber machine guns. "A dozen scientists,... under the plane and out of the gunner's line of vision, dropped their instruments and hugged the ground in terror as the bullets thudded about them."[5] Later a number of these scientists threatened to quit the project. Workers built three observation points 5.68 miles (10,000 yards), north, south, and west of Ground Zero. Code named Able, Baker, and Pittsburgh, these heavily-built wooden bunkers were reinforced with concrete, and covered with earth. The bunker designated Baker or South 10,000 served as the control center for the test. This is where head scientist J. Robert Oppenheimer would be for the test. A fourth observation point was the test's Base Camp, (the abandoned Dave McDonald ranch) located about ten miles southwest of Ground Zero. The primary observation point was on Compania Hill, located about 20 miles to the northwest of Trinity near today's Stallion Range Gate, off NM 380. The test was originally scheduled for 4 a.m., Monday July 16, but was postponed to 5:30 due to a severe thunderstorm that would have increased the amount of radioactive fallout, and have interfered with the test results. The rain finally stopped and at 5:29:45 a.m. Mountain War Time, the device exploded successfully and the Atomic Age was born. The nuclear blast created a flash of light brighter than a dozen suns. The light was seen over the entire state of New Mexico and in parts of Arizona, Texas, and Mexico. The resultant mushroom cloud rose to over 38,000 feet within minutes, and the heat of the explosion was 10,000 times hotter than the surface of the sun! At ten miles away, this heat was described as like standing directly in front of a roaring fireplace. Every living thing within a mile of the tower was obliterated. The power of the bomb was estimated to be equal to 20,000 tons of TNT, or equivalent to the bomb load of 2,000 B-29, Superfortresses! After witnessing the awesome blast, Oppenheimer quoted a line from a sacred Hindu text, the Bhagavad-Gita: He said: "I am become death, the shatterer of worlds."[6] In Los Alamos 230 miles to the north, a group of scientists' wives who had stayed up all night for the not so secret test, saw the light and heard the distant sound. One wife, Jane Wilson, described it this way, "Then it came. The blinding light [no] one had ever seen. The trees, illuminated, leaping out. The mountains flashing into life. Later, the long slow rumble. Something had happened, all right, for good or ill."[7] General Groves' deputy commander, Brigadier General T. F. Farrell, described the explosion in great detail: "The effects could well be called unprecedented, magnificent, beautiful, stupendous, and terrifying. No man-made phenomenon of such tremendous power had ever occurred before. The lighting effects beggared description. The whole country was lighted by a searing light with the intensity many times that of the midday sun. It was golden, purple, violet, gray, and blue. It lighted every peak, crevasse and ridge of the nearby mountain range with a clarity and beauty that cannot be described but must be seen to be imagined..."[8] Immediately after the test a Sherman M-4 tank, equipped with its own air supply, and lined with two inches of lead went out to explore the site. The lead lining added 12 tons to the tank's weight, but was necessary to protect its occupants from the radiation levels at ground zero. The tank's passengers found that the 100-foot steel tower had virtually disappeared, with only the metal and concrete stumps of its four legs remaining. Surrounding ground zero was a crater almost 2,400 feet across and about ten feet deep in places. Desert sand around the tower had been fused by the intense heat of the blast into a jade colored glass. This atomic glass was given the name Atomsite, but the name was later changed to Trinitite. Due to the intense secrecy surrounding the test, no accurate information of what happened was released to the public until after the second atomic bomb had been dropped on Japan. However, many people in New Mexico were well aware that something extraordinary had happened the morning of July 16, 1945. The blinding flash of light, followed by the shock wave had made a vivid impression on people who lived within a radius of 160 miles of ground zero. Windows were shattered 120 miles away in Silver City, and residents of Albuquerque saw the bright light of the explosion on the southern horizon and felt the tremor of the shock waves moments later. The true story of the Trinity test first became known to the public on August 6, 1945. This is when the world's second nuclear bomb, nicknamed Little Boy, exploded 1,850 feet over Hiroshima, Japan, destroying a large portion of the city and killing an estimated 70,000 to 130,000 of its inhabitants. Three days later on August 9, a third atomic bomb devastated the city of Nagasaki and killed approximately 45,000 more Japanese. The Nagasaki weapon was a plutonium bomb, similar to the Trinity device, and it was nicknamed Fat Man. On Tuesday August 14, at 7 p.m. Eastern War Time, President Truman made a brief formal announcement that Japan had finally surrendered and World War II was over after almost six years and 60 million deaths! On Sunday, September 9, 1945, Trinity Site was opened to the press for the first time. This was mainly to dispel rumors of lingering high radiation levels there, as well as in Hiroshima and Nagasaki. Led by General Groves and Oppenheimer, this widely publicized visit made Trinity front page news all over the country. Trinity Site was later encircled with more than a mile of chain link fencing and posted with signs warning of radioactivity. In the early 1950s most of the remaining Trinitite in the crater was bulldozed into a underground concrete bunker near Trinity. Also at this time the crater was back filled with new soil. In 1963 the Trinitite was removed from the bunker, packed into 55-gallon drums, and loaded into trucks belonging to the Atomic Energy Commission (the successor of the Manhattan Project). Trinity site remained off-limits to military and civilian personnel of the range and closed to the public for many years, despite attempts immediately after the war to turn Trinity into a national monument. In 1953 about 700 people attended the first Trinity Site open house sponsored by the Alamogordo Chamber of Commerce and the Missile Range. Two years later, a small group from Tularosa, NM visited the site on the 10th anniversary of the explosion to conduct a religious service and pray for peace. Regular visits have been made annually in recent years on the first Saturday in October instead of the anniversary date of July 16, to avoid the desert heat. Later Trinity Site was opened one additional day on the first Saturday in April. The Site remains closed to the public except for these two days, because it lies within the impact areas for missiles fired into the northern part of the Range. In 1965, Range officials erected a modest monument at Ground Zero. Built of black lava rock, this monument serves as a permanent marker for the site and as a reminder of the momentous event that occurred there. On the monument is a plain metal plaque with this simple inscription: "Trinity Site Where the World's First Nuclear Device Was Exploded on July 16, 1945." During the annual tour in 1975, a second plaque was added below the first by The National Park Service, designating Trinity Site a National Historic Landmark. This plaque reads, "This site possesses national significance in commemorating the history of the U.S.A." JUMBO Lying next to the entrance of the chain link fence that still surrounds Trinity Site are the rusty remains of Jumbo. Jumbo was the code name for the 214-ton Thermos shaped steel and concrete container designed to hold the precious plutonium core of the Trinity device in case of a nuclear mis-fire. Built by the Babcock and Wilcox Company of Barberton, Ohio, Jumbo was 28 feet long, 12 feet, 8 inches in diameter, and with steel walls up to 16 inches thick. The idea of using some kind of container for the Trinity device was based on the fact that plutonium was extremely expensive and very difficult to produce. So, much thought went into a way of containing the 15 lb. plutonium core of the bomb, in case the 5,300 lbs. of conventional high explosives surrounding the core exploded without setting off a nuclear blast, and in the process scattering the costly plutonium (about 250 million dollars worth) across the dessert. After extensive research and testing of other potential containment ideas, the concept of Jumbo was decided on in the late summer of 1944. However, by the spring of 1945, after Jumbo had already been built and transported (with great difficulty) to the Trinity Site by the Eichleay Corporation of Pittsburgh, it was decided not to explode the Trinity device inside of Jumbo after all. There were several reasons for this new decision: first, plutonium had become more readily (relatively) available; second, the Project scientists decided that the Trinity device would probably work as planned; and last, the scientists realized that if Jumbo were used it would adversely affect the test results, and add 214 tons of highly radioactive material to the atmosphere. Not knowing what else to do with the massive 12 million dollar Jumbo, it was decided to suspend it from a steel tower 800 yards from Ground Zero to see how it would withstand the Trinity test. Jumbo survived the approximately 20 kiloton Trinity blast undamaged, but its supporting 70-foot tall steel tower was flattened. Two years later, in an attempt to destroy the unused Jumbo before it and its 12 million dollar cost came to the attention of a congressional investigating committee, Manhattan Project Director General Groves ordered two junior officers from the Special Weapons Division at Sandia Army Base in Albuquerque to test Jumbo. The Army officers placed eight 500-pound conventional bombs in the bottom of Jumbo. Since the bombs were on the bottom of Jumbo, and not the center (the correct position), the resultant explosion blew both ends off Jumbo. Unable to totally destroy Jumbo, the Army then buried it in the desert near Trinity Site. It was not until the early 1970s that the impressive remains of Jumbo, still weighing over 180 tons, were moved to their present location. SCHMIDT-McDONALD RANCH HOUSE The Schmidt-McDonald ranch house is located two miles south of Ground Zero. The property encompasses about three acres and consists of the main house and assorted outbuildings. The house, surrounded by a low stone wall, was built in 1913 by Franz Schmidt, a German immigrant and homesteader. In the 1920s Schmidt sold the ranch to George McDonald and moved to Florida. The ranch house is a one-story, 1,750 square-foot adobe (mud bricks) building. An ice house is located on the west side along with an 9'-4" deep underground cistern. A 14 by 18.5 foot stone addition, which included a modern bathroom, was added onto the north side in the 1930s. East of the house there is a large, divided concrete water storage tank and a windmill. South of the windmill are the remains of a bunkhouse, and a barn which also served as a garage. Further to the east are corrals and holding pens for livestock. The McDonalds vacated their ranch house and their thousands of acres of marginal range land in early 1942 when it became part of the Alamogordo Bombing and Gunnery Range. The old house remained empty until Manhattan Project personnel arrived in 1945. Then a spacious room in the northeast corner of the house was selected by the Project personnel for the assembly of the plutonium core of the Trinity device. Workmen installed work benches, tables, and other equipment in this large room. To keep the desert dust and sand out, the room's windows and cracks were covered with plastic and sealed with tape. The core of the bomb consisted of two hemispheres of plutonium, (Pu-239), and an initiator. According to reports, while scientists assembled the initiator and the Pu-239 hemispheres, jeeps were positioned outside with their engines running for a quick getaway if needed. Detection devices were used to monitor radiation levels in the room, and when fully assembled the core was warm to the touch. The completed core was later transported the two miles to Ground Zero, inserted into the bomb assembly, and raised to the top of the tower. The Trinity explosion on Monday morning, July 16, did not significantly damage the McDonald house. Even though most of the windows were blown out, and the chimney was blown over, the main structure survived intact. Years of rain water dripping through holes in the metal roof did much more damage to the mud brick walls than the bomb did. The nearby barn did not fare as well. The Trinity test blew part of its roof off, and the roof has since totally collapsed. The ranch house stood empty and deteriorating for 37 years until 1982 when the US Army stabilized it to prevent any further damage. The next year, the Department of Energy and the Army provided funds for the National Park Service to completely restore the house to the way it appeared in July, 1945. When the work was completed, the house with many photo displays on Trinity was opened to the public for the first time in October 1984 during the semi-annual tour. The Schmidt-McDonald ranch house is part of the Trinity National Historic Landmark. FOOTNOTES [Footnote 1: Szasz, Ferenc. The Day the Sun Rose Twice. Albuquerque: University of New Mexico Press, 1984. p. 28.] [Footnote 2: Hayward, John, ed. John Donne: Complete Poetry and Selected Prose. New York: Random House, Inc., 1949. p. 285.] [Footnote 3: Szasz, The Day the Sun Rose Twice, p. 40.] [Footnote 4: Wyden, Peter. Day One: Before Hiroshima and After. New York: Simon and Schuster, 1984. p. 204.] [Footnote 5: Lamont, Lansing. Day of Trinity. New York: Atheneum, 1965. p. 123-124.] [Footnote 6: Kunetka, James W. City of Fire: Los Alamos and the Atomic Age, 1943-1945. Albuquerque: University of New Mexico Press, 1978. p. 170.] [Footnote 7: Wilson, Jane S. and Charlotte Serber, eds. Standing By and Making Do: Women in Wartime Los Alamos. Los Alamos: Los Alamos Historical Society, 1988. p. x, xi.] [Footnote 8: Brown, Anthony Cave, and Charles B. MacDonald. The Secret History of the Atomic Bomb. New York: Dell, 1977. p. 516.] BIBLIOGRAPHY Bainbridge, Kenneth T. Trinity. Los Alamos: Los Alamos Scientific Laboratory, (La-6300-H), 1946. Brown, Anthony Cave, and Charles B. MacDonald. The Secret History of the Atomic Bomb. New York: Dell, 1977. Compton, Arthur Holly. Atomic Quest: A Personal Quest. New York: Oxford University Press, 1956. Fanton, Jonathan F., Stoff, Michael B. and Williams, R. Hal editors. The Manhattan Project: A Documentary Introduction to the Atomic Age. Philadelphia: Temple University Press, 1991. Feis, Herbert. Japan Subdued: The Atomic Bomb and the End of the War in the Pacific. Princeton: Princeton University Press, 1961. Groves, Leslie R. Now it Can be Told: The Story of the Manhattan Project. New York: Da Capo Press, 1975. Hersey, John. Hiroshima. New York: Alfred A. Knopf, 1946. Jette, Eleanor. Inside Box 1663. Los Alamos: Los Alamos Historical Society, 1977. Kunetka, James W. City of Fire: Los Alamos and the Atomic Age, 1943-1945. Albuquerque; University of New Mexico Press, 1978. Lamont, Lansing. Day of Trinity. New York: Athenaeum, 1965. Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon and Schuster, 1986. Skates, John Ray. The Invasion of Japan: Alternative to the Bomb. Columbia; University of South Carolina Press, 1994. Smyth, Henry DeWolf. Atomic Energy for Military Purposes. Princeton: Princeton University Press, 1948. Szasz, Ferenc. The Day the Sun Rose Twice. Albuquerque: University of New Mexico Press, 1984. Tibbets, Paul W. Flight of the Enola Gay. Reynoldsburg, Ohio: Buckeye Aviation Book Company, 1989. Williams, Robert C. Klaus Fuchs, Atom Spy. Cambridge, Massachusetts: Harvard University Press, 1987. Wilson, Jane S. and Serber, Charlotte, eds. Standing By and Making Do: Women in Wartime Los Alamos. Los Alamos: Los Alamos Historical Society, 1988. Wyden, Peter. Day One: Before Hiroshima and After. New York: Simon and Schuster, 1984. THE NATIONAL ATOMIC MUSEUM, Kirtland Air Force Base, Albuquerque, New Mexico Since its opening in 1969, the objective of the National Atomic museum has been to provide a readily accessible repository of educational materials, and information on the Atomic Age. In addition, the museum's goal is to preserve, interpret, and exhibit to the public memorabilia of this Age. In late 1991 the museum was chartered by Congress as the United States' only official Atomic museum. Prominently featured in the museum's high bay is the story of the Manhattan Engineer District, the unprecedented 2.2 billion dollar scientific-engineering project that was centered in New Mexico during World War II. The Manhattan Project as it was more commonly called, developed, built, and tested the world's first Atomic bomb in New Mexico. This display also includes casings similar to the only Atomic bombs ever used in warfare. Dropped on the Japanese cities of Hiroshima and Nagasaki, these two bombs helped bring World War II to an end in mid-August 1945. The story of the Manhattan Project's three secret cities, Hanford, Washington, Los Alamos, New Mexico, and Oak Ridge, Tennessee, is also presented in this area. A portion of the museum, the low bay, is devoted to exhibits on the research, development, and use of various forms of nuclear energy. Historical and other traveling exhibits are also displayed in this area. Also found in the low bay is the museum's store, which is operated by the museum's foundation. Adjacent to the low bay is the theater. The featured film is David Wolpers classic 1963 production, Ten Seconds That Shook The World. This excellent film is a 53-minute documentary on the Manhattan Project. Other films relating to the history of the Atomic Age are available for viewing and checkout from the library. Next to the theater is the library/Department of Energy public reading room, containing government documents that are available to the public for in-library research. The library also has many nuclear related books available for reference and checkout. Located around the outside of the museum are a number of large exhibits. These include the Boeing B-52B jet bomber that dropped the United States' last air burst H-bomb in 1962, and a 280-mm (11 inches) Atomic cannon, once America's most powerful field artillery. Also found in this area is a Navy TA-7C (a modified A-7B) Corsair II fighter-bomber, a veteran of the Vietnam War. Many other nuclear weapons systems, rockets, and missiles are found in this area. In front of the museum are a pair of Navy Terrier missiles. The Terrier was the Navy's first operational surface to air missile. To the south of the museum, next to the visitors parking lot, is a Republic F-105D Thunderchief fighter-bomber. Further south is a World War II Boeing B-29 Superfortress. This plane is similar to the B-29's, Enola Gay and Bockscar that dropped the Atomic bombs on Japan. The National Atomic Museum, is open 9 a.m. to 5 p.m. daily, except for New Years Day, Easter, Thanksgiving, and Christmas. The museum is located at 20358 Wyoming Blvd. SE, on Kirtland Air Force Base, Albuquerque, New Mexico. Guided tours for groups are available by calling (505)845-4636 in advance. Admission and tours are free, and cameras are always welcome! 
685	----	For an HTML version of this document and additional public domain documents on nuclear history, visit Trinity Atomic Web Site: http://www.envirolink.org/issues/nuketesting/ THE ATOMIC BOMBINGS OF HIROSHIMA AND NAGASAKI by The Manhattan Engineer District, June 29, 1946. Index FOREWORD INTRODUCTION THE MANHATTAN PROJECT INVESTIGATING GROUP PROPAGANDA SUMMARY OF DAMAGES AND INJURIES MAIN CONCLUSIONS THE SELECTION OF THE TARGET DESCRIPTION OF THE CITIES BEFORE THE BOMBINGS Hiroshima Nagasaki THE ATTACKS Hiroshima Nagasaki GENERAL COMPARISON OF HIROSHIMA AND NAGASAKI GENERAL DESCRIPTION OF DAMAGE CAUSED BY THE ATOMIC EXPLOSIONS TOTAL CASUALTIES THE NATURE OF AN ATOMIC EXPLOSION CHARACTERISTICS OF THE DAMAGE CAUSED BY THE ATOMIC BOMBS CALCULATIONS OF THE PEAK PRESSURE OF THE BLAST WAVE LONG RANGE BLAST DAMAGE GROUND SHOCK SHIELDING, OR SCREENING, FROM THE BLAST FLASH BURN CHARACTERISTICS OF INJURIES TO PERSONS BURNS MECHANICAL INJURIES BLAST INJURIES RADIATION INJURIES SHIELDING FROM RADIATION EFFECTS OF THE ATOMIC BOMBINGS ON THE INHABITANTS OF THE CITIES APPENDIX: Father Siemes' eyewitness account FOREWORD This report describes the effects of the atomic bombs which were dropped on the Japanese cities of Hiroshima and Nagasaki on August 6 and 9, 1945, respectively. It summarizes all the authentic information that is available on damage to structures, injuries to personnel, morale effect, etc., which can be released at this time without prejudicing the security of the United States. This report has been compiled by the Manhattan Engineer District of the United States Army under the direction of Major General Leslie R. Groves. Special acknowledgement to those whose work contributed largely to this report is made to: The Special Manhattan Engineer District Investigating Group, The United States Strategic Bombing Survey, The British Mission to Japan, and The Joint Atomic Bomb Investigating Group (Medical). and particularly to the following individuals: Col. Stafford L. Warren, Medical Corps, United States Army, for his evaluation of medical data, Capt. Henry L. Barnett, Medical Corps, United States Army, for his evaluation of medical data, Dr. R. Serber, for his comments on flash burn, Dr. Hans Bethe, Cornell University, for his information of the nature of atomic explosions, Majors Noland Varley and Walter C. Youngs, Corps of Engineers, United States Army, for their evaluation of physical damage to structures, J. 0. Hirschfelder, J. L. Magee, M. Hull, and S. T. Cohen, of the Los Alamos Laboratory, for their data on nuclear explosions, Lieut. Col. David B. Parker, Corps of Engineers, United States Army, for editing this report. INTRODUCTION Statement by the President of the United States: "Sixteen hours ago an American airplane dropped one bomb on Hiroshima, Japan, and destroyed its usefulness to the enemy. That bomb had more power than 20,000 tons of T.N.T. It had more than two thousand times the blast power of the British Grand Slam, which is the largest bomb ever yet used in the history of warfare". These fateful words of the President on August 6th, 1945, marked the first public announcement of the greatest scientific achievement in history. The atomic bomb, first tested in New Mexico on July 16, 1945, had just been used against a military target. On August 6th, 1945, at 8:15 A.M., Japanese time, a B-29 heavy bomber flying at high altitude dropped the first atomic bomb on Hiroshima. More than 4 square miles of the city were instantly and completely devastated. 66,000 people were killed, and 69,000 injured. On August 9th, three days later, at 11:02 A.M., another B-29 dropped the second bomb on the industrial section of the city of Nagasaki, totally destroying 1 1/2 square miles of the city, killing 39,000 persons, and injuring 25,000 more. On August 10, the day after the atomic bombing of Nagasaki, the Japanese government requested that it be permitted to surrender under the terms of the Potsdam declaration of July 26th which it had previously ignored. THE MANHATTAN PROJECT ATOMIC BOMB INVESTIGATING GROUP On August 11th, 1945, two days after the bombing of Nagasaki, a message was dispatched from Major General Leslie R. Groves to Brigadier General Thomas F. Farrell, who was his deputy in atomic bomb work and was representing him in operations in the Pacific, directing him to organize a special Manhattan Project Atomic Bomb Investigating Group. This Group was to secure scientific, technical and medical intelligence in the atomic bomb field from within Japan as soon as possible after the cessation of hostilities. The mission was to consist of three groups: 1. Group for Hiroshima. 2. Group for Nagasaki. 3. Group to secure information concerning general Japanese activities in the field of atomic bombs. The first two groups were organized to accompany the first American troops into Hiroshima and Nagasaki. The primary purposes of the mission were as follows, in order of importance: 1. To make certain that no unusual hazards were present in the bombed cities. 2. To secure all possible information concerning the effects of the bombs, both usual and unusual, and particularly with regard to radioactive effects, if any, on the targets or elsewhere. General Groves further stated that all available specialist personnel and instruments would be sent from the United States, and that the Supreme Allied Commander in the Pacific would be informed about the organization of the mission. On the same day, 11 August, the special personnel who formed the part of the investigating group to be sent from the United States were selected and ordered to California with instructions to proceed overseas at once to accomplish the purposes set forth in the message to General Farrell. The main party departed from Hamilton Field, California on the morning of 13 August and arrived in the Marianas on 15 August. On 12 August the Chief of Staff sent the Theater Commander the following message: "FOR MACARTHUR, SIGNED MARSHALL: "GROVES HAS ORDERED FARRELL AT TINIAN TO ORGANIZE A SCIENTIFIC GROUP OF THREE SECTIONS FOR POTENTIAL USE IN JAPAN IF SUCH USE SHOULD BE DESIRED. THE FIRST GROUP IS FOR HIROSHIMA, THE SECOND FOR NAGASAKI, AND THE THIRD FOR THE PURPOSE OF SECURING INFORMATION CONCERNING GENERAL JAPANESE ACTIVITIES IN THE FIELD OF ATOMIC WEAPONS. THE GROUPS FOR HIROSHIMA AND NAGASAKI SHOULD ENTER THOSE CITIES WITH THE FIRST AMERICAN TROOPS IN ORDER THAT THESE TROOPS SHALL NOT BE SUBJECTED TO ANY POSSIBLE TOXIC EFFECTS ALTHOUGH WE HAVE NO REASON TO BELIEVE THAT ANY SUCH EFFECTS ACTUALLY EXIST. FARRELL AND HIS ORGANIZATION HAVE ALL AVAILABLE INFORMATION ON THIS SUBJECT." General Farrell arrived in Yokohama on 30 August, with the Commanding General of the 8th Army; Colonel Warren, who was Chief of the Radiological Division of the District, arrived on 7 September. The main body of the investigating group followed later. Preliminary inspections of Hiroshima and Nagasaki were made on 8-9 and 13-14 September, respectively. Members of the press had been enabled to precede General Farrell to Hiroshima. The special groups spent 16 days in Nagasaki and 4 days in Hiroshima, during which time they collected as much information as was possible under their directives which called for a prompt report. After General Farrell returned to the U.S. to make his preliminary report, the groups were headed by Brigadier General J. B. Newman, Jr. More extensive surveys have been made since that time by other agencies who had more time and personnel available for the purpose, and much of their additional data has thrown further light on the effects of the bombings. This data has been duly considered in the making of this report. PROPAGANDA On the day after the Hiroshima strike, General Farrell received instructions from the War Department to engage in a propaganda campaign against the Japanese Empire in connection with the new weapon and its use against Hiroshima. The campaign was to include leaflets and any other propaganda considered appropriate. With the fullest cooperation from CINCPAC of the Navy and the United States Strategic Air Forces, he initiated promptly a campaign which included the preparation and distribution of leaflets, broadcasting via short wave every 15 minutes over radio Saipan and the printing at Saipan and distribution over the Empire of a Japanese language newspaper which included the description and photographs of the Hiroshima strike. The campaign proposed: 1. Dropping 16,000,000 leaflets in a period of 9 days on 47 Japanese cities with population of over 100,000. These cities represented more than 40% of the total population. 2. Broadcast of propaganda at regular intervals over radio Saipan. 3. Distribution of 500,000 Japanese language newspapers containing stories and pictures of the atomic bomb attacks. The campaign continued until the Japanese began their surrender negotiations. At that time some 6,000,000 leaflets and a large number of newspapers had been dropped. The radio broadcasts in Japanese had been carried out at regular 15 minute intervals. SUMMARY OF DAMAGES AND INJURIES Both the Hiroshima and the Nagasaki atomic bombs exhibited similar effects. The damages to man-made structures and other inanimate objects was the result in both cities of the following effects of the explosions: A. Blast, or pressure wave, similar to that of normal explosions. B. Primary fires, i.e., those fires started instantaneously by the heat radiated from the atomic explosion. C. Secondary fires, i.e., those fires resulting from the collapse of buildings, damage to electrical systems, overturning of stoves, and other primary effects of the blast. D. Spread of the original fires (B and C) to other structures. The casualties sustained by the inhabitants of both cities were due to: A. "Flash" burns, caused directly by the almost instantaneous radiation of heat and light at the moment of the explosion. B. Burns resulting from the fires caused by the explosion. C. Mechanical injuries caused by collapse of buildings, flying debris, and forceable hurling--about of persons struck by the blast pressure waves. D. Radiation injuries caused by the instantaneous penetrating radiation (in many respects similar to excessive X-ray exposure) from the nuclear explosion; all of these effective radiations occurred during the first minute after initiation of the explosion, and nearly all occurred during the first second of the explosion. No casualties were suffered as a result of any persistent radioactivity of fission products of the bomb, or any induced radioactivity of objects near the explosion. The gamma radiations emitted by the nuclear explosion did not, of course, inflict any damage on structures. The number of casualties which resulted from the pure blast effect alone (i.e., because of simple pressure) was probably negligible in comparison to that caused by other effects. The central portions of the cities underneath the explosions suffered almost complete destruction. The only surviving objects were the frames of a small number of strong reinforced concrete buildings which were not collapsed by the blast; most of these buildings suffered extensive damage from interior fires, had their windows, doors, and partitions knocked out, and all other fixtures which were not integral parts of the reinforced concrete frames burned or blown away; the casualties in such buildings near the center of explosion were almost 100%. In Hiroshima fires sprang up simultaneously all over the wide flat central area of the city; these fires soon combined in an immense "fire storm" (high winds blowing inwards toward the center of a large conflagration) similar to those caused by ordinary mass incendiary raids; the resulting terrific conflagration burned out almost everything which had not already been destroyed by the blast in a roughly circular area of 4.4 square miles around the point directly under the explosion (this point will hereafter in this report be referred to as X). Similar fires broke out in Nagasaki, but no devastating fire storm resulted as in Hiroshima because of the irregular shape of the city. In both cities the blast totally destroyed everything within a radius of 1 mile from the center of explosion, except for certain reinforced concrete frames as noted above. The atomic explosion almost completely destroyed Hiroshima's identity as a city. Over a fourth of the population was killed in one stroke and an additional fourth seriously injured, so that even if there had been no damage to structures and installations the normal city life would still have been completely shattered. Nearly everything was heavily damaged up to a radius of 3 miles from the blast, and beyond this distance damage, although comparatively light, extended for several more miles. Glass was broken up to 12 miles. In Nagasaki, a smaller area of the city was actually destroyed than in Hiroshima, because the hills which enclosed the target area restricted the spread of the great blast; but careful examination of the effects of the explosion gave evidence of even greater blast effects than in Hiroshima. Total destruction spread over an area of about 3 square miles. Over a third of the 50,000 buildings in the target area of Nagasaki were destroyed or seriously damaged. The complete destruction of the huge steel works and the torpedo plant was especially impressive. The steel frames of all buildings within a mile of the explosion were pushed away, as by a giant hand, from the point of detonation. The badly burned area extended for 3 miles in length. The hillsides up to a radius of 8,000 feet were scorched, giving them an autumnal appearance. MAIN CONCLUSIONS The following are the main conclusions which were reached after thorough examination of the effects of the bombs dropped on Hiroshima and Nagasaki: 1. No harmful amounts of persistent radioactivity were present after the explosions as determined by: A. Measurements of the intensity of radioactivity at the time of the investigation; and B. Failure to find any clinical evidence of persons harmed by persistent radioactivity. The effects of the atomic bombs on human beings were of three main types: A. Burns, remarkable for (1) the great ground area over which they were inflicted and (2) the prevalence of "flash" burns caused by the instantaneous heat radiation. B. Mechanical injuries, also remarkable for the wide area in which suffered. C. Effects resulting from penetrating gamma radiation. The effects from radiation were due to instantaneous discharge of radiation at the moment of explosion and not to persistent radioactivity (of either fission products or other substances whose radioactivity might have been induced by proximity to the explosions). The effects of the atomic bombs on structures and installations were of two types: A. Destruction caused by the great pressure from the blast; and B. Destruction caused by the fires, either started directly by the great heat radiation, or indirectly through the collapse of buildings, wiring, etc. 4. The actual tonnage of T.N.T. which would have caused the same blast damage was approximately of the order of 20,000 tons. 5. In respect to their height of burst, the bombs performed exactly according to design. 6. The bombs were placed in such positions that they could not have done more damage from any alternative bursting point in either city. 7. The heights of burst were correctly chosen having regard to the type of destruction it was desired to cause. 8. The information collected would enable a reasonably accurate prediction to be made of the blast damage likely to be caused in any city where an atomic explosion could be effected. THE SELECTION OF THE TARGET Some of the most frequent queries concerning the atomic bombs are those dealing with the selection of the targets and the decision as to when the bombs would be used. The approximate date for the first use of the bomb was set in the fall of 1942 after the Army had taken over the direction of and responsibility for the atomic bomb project. At that time, under the scientific assumptions which turned out to be correct, the summer of 1945 was named as the most likely date when sufficient production would have been achieved to make it possible actually to construct and utilize an atomic bomb. It was essential before this time to develop the technique of constructing and detonating the bomb and to make an almost infinite number of scientific and engineering developments and tests. Between the fall of 1942 and June 1945, the estimated probabilities of success had risen from about 60% to above 90%; however, not until July 16, 1945, when the first full-scale test took place in New Mexico, was it conclusively proven that the theories, calculations, and engineering were correct and that the bomb would be successful. The test in New Mexico was held 6 days after sufficient material had become available for the first bomb. The Hiroshima bomb was ready awaiting suitable weather on July 31st, and the Nagasaki bomb was used as soon after the Hiroshima bomb as it was practicable to operate the second mission. The work on the actual selection of targets for the atomic bomb was begun in the spring of 1945. This was done in close cooperation with the Commanding General, Army Air Forces, and his Headquarters. A number of experts in various fields assisted in the study. These included mathematicians, theoretical physicists, experts on the blast effects of bombs, weather consultants, and various other specialists. Some of the important considerations were: A. The range of the aircraft which would carry the bomb. B. The desirability of visual bombing in order to insure the most effective use of the bomb. C. Probable weather conditions in the target areas. D. Importance of having one primary and two secondary targets for each mission, so that if weather conditions prohibited bombing the target there would be at least two alternates. E. Selection of targets to produce the greatest military effect on the Japanese people and thereby most effectively shorten the war. F. The morale effect upon the enemy. These led in turn to the following: A. Since the atomic bomb was expected to produce its greatest amount of damage by primary blast effect, and next greatest by fires, the targets should contain a large percentage of closely-built frame buildings and other construction that would be most susceptible to damage by blast and fire. B. The maximum blast effect of the bomb was calculated to extend over an area of approximately 1 mile in radius; therefore the selected targets should contain a densely built-up area of at least this size. C. The selected targets should have a high military strategic value. D. The first target should be relatively untouched by previous bombing, in order that the effect of a single atomic bomb could be determined. The weather records showed that for five years there had never been two successive good visual bombing days over Tokyo, indicating what might be expected over other targets in the home islands. The worst month of the year for visual bombing was believed to be June, after which the weather should improve slightly during July and August and then become worse again during September. Since good bombing conditions would occur rarely, the most intense plans and preparations were necessary in order to secure accurate weather forecasts and to arrange for full utilization of whatever good weather might occur. It was also very desirable to start the raids before September. DESCRIPTION OF THE CITIES BEFORE THE BOMBINGS Hiroshima The city of Hiroshima is located on the broad, flat delta of the Ota River, which has 7 channel outlets dividing the city into six islands which project into Hiroshima Bay. The city is almost entirely flat and only slightly above sea level; to the northwest and northeast of the city some hills rise to 700 feet. A single hill in the eastern part of the city proper about 1/2 mile long and 221 feet in height interrupted to some extent the spreading of the blast damage; otherwise the city was fully exposed to the bomb. Of a city area of over 26 square miles, only 7 square miles were completely built-up. There was no marked separation of commercial, industrial, and residential zones. 75% of the population was concentrated in the densely built-up area in the center of the city. Hiroshima was a city of considerable military importance. It contained the 2nd Army Headquarters, which commanded the defense of all of southern Japan. The city was a communications center, a storage point, and an assembly area for troops. To quote a Japanese report, "Probably more than a thousand times since the beginning of the war did the Hiroshima citizens see off with cries of 'Banzai' the troops leaving from the harbor." The center of the city contained a number of reinforced concrete buildings as well as lighter structures. Outside the center, the area was congested by a dense collection of small wooden workshops set among Japanese houses; a few larger industrial plants lay near the outskirts of the city. The houses were of wooden construction with tile roofs. Many of the industrial buildings also were of wood frame construction. The city as a whole was highly susceptible to fire damage. Some of the reinforced concrete buildings were of a far stronger construction than is required by normal standards in America, because of the earthquake danger in Japan. This exceptionally strong construction undoubtedly accounted for the fact that the framework of some of the buildings which were fairly close to the center of damage in the city did not collapse. The population of Hiroshima had reached a peak of over 380,000 earlier in the war but prior to the atomic bombing the population had steadily decreased because of a systematic evacuation ordered by the Japanese government. At the time of the attack the population was approximately 255,000. This figure is based on the registered population, used by the Japanese in computing ration quantities, and the estimates of additional workers and troops who were brought into the city may not be highly accurate. Hiroshima thus had approximately the same number of people as the city of Providence, R.I., or Dallas, Tex. Nagasaki Nagasaki lies at the head of a long bay which forms the best natural harbor on the southern Japanese home island of Kyushu. The main commercial and residential area of the city lies on a small plain near the end of the bay. Two rivers divided by a mountain spur form the two main valleys in which the city lies. This mountain spur and the irregular lay-out of the city tremendously reduced the area of destruction, so that at first glance Nagasaki appeared to have been less devastated than Hiroshima. The heavily build-up area of the city is confined by the terrain to less than 4 square miles out of a total of about 35 square miles in the city as a whole. The city of Nagasaki had been one of the largest sea ports in southern Japan and was of great war-time importance because of its many and varied industries, including the production of ordnance, ships, military equipment, and other war materials. The narrow long strip attacked was of particular importance because of its industries. In contrast to many modern aspects of Nagasaki, the residences almost without exception were of flimsy, typical Japanese construction, consisting of wood or wood-frame buildings, with wood walls with or without plaster, and tile roofs. Many of the smaller industries and business establishments were also housed in wooden buildings or flimsily built masonry buildings. Nagasaki had been permitted to grow for many years without conforming to any definite city zoning plan and therefore residences were constructed adjacent to factory buildings and to each other almost as close as it was possible to build them throughout the entire industrial valley. THE ATTACKS Hiroshima Hiroshima was the primary target of the first atomic bomb mission. The mission went smoothly in every respect. The weather was good, and the crew and equipment functioned perfectly. In every detail, the attack was carried out exactly as planned, and the bomb performed exactly as expected. The bomb exploded over Hiroshima at 8:15 on the morning of August 6, 1945. About an hour previously, the Japanese early warning radar net had detected the approach of some American aircraft headed for the southern part of Japan. The alert had been given and radio broadcasting stopped in many cities, among them Hiroshima. The planes approached the coast at a very high altitude. At nearly 8:00 A.M., the radar operator in Hiroshima determined that the number of planes coming in was very small--probably not more than three--and the air raid alert was lifted. The normal radio broadcast warning was given to the people that it might be advisable to go to shelter if B-29's were actually sighted, but no raid was expected beyond some sort of reconnaissance. At 8:15 A.M., the bomb exploded with a blinding flash in the sky, and a great rush of air and a loud rumble of noise extended for many miles around the city; the first blast was soon followed by the sounds of falling buildings and of growing fires, and a great cloud of dust and smoke began to cast a pall of darkness over the city. At 8:16 A.M., the Tokyo control operator of the Japanese Broadcasting Corporation noticed that the Hiroshima station had gone off the air. He tried to use another telephone line to reestablish his program, but it too had failed. About twenty minutes later the Tokyo railroad telegraph center realized that the main line telegraph had stopped working just north of Hiroshima. From some small railway stops within ten miles of the city there came unofficial and confused reports of a terrible explosion in Hiroshima. All these reports were transmitted to the Headquarters of the Japanese General Staff. Military headquarters repeatedly tried to call the Army Control Station in Hiroshima. The complete silence from that city puzzled the men at Headquarters; they knew that no large enemy raid could have occurred, and they knew that no sizeable store of explosives was in Hiroshima at that time. A young officer of the Japanese General Staff was instructed to fly immediately to Hiroshima, to land, survey the damage, and return to Tokyo with reliable information for the staff. It was generally felt at Headquarters that nothing serious had taken place, that it was all a terrible rumor starting from a few sparks of truth. The staff officer went to the airport and took off for the southwest. After flying for about three hours, while still nearly 100 miles from Hiroshima, he and his pilot saw a great cloud of smoke from the bomb. In the bright afternoon, the remains of Hiroshima were burning. Their plane soon reached the city, around which they circled in disbelief. A great scar on the land, still burning, and covered by a heavy cloud of smoke, was all that was left of a great city. They landed south of the city, and the staff officer immediately began to organize relief measures, after reporting to Tokyo. Tokyo's first knowledge of what had really caused the disaster came from the White House public announcement in Washington sixteen hours after Hiroshima had been hit by the atomic bomb. Nagasaki Nagasaki had never been subjected to large scale bombing prior to the explosion of the atomic bomb there. On August 1st, 1945, however, a number of high explosive bombs were dropped on the city. A few of these bombs hit in the shipyards and dock areas in the southwest portion of the city. Several of the bombs hit the Mitsubishi Steel and Arms Works and six bombs landed at the Nagasaki Medical School and Hospital, with three direct hits on buildings there. While the damage from these few bombs were relatively small, it created considerable concern in Nagasaki and a number of people, principally school children, were evacuated to rural areas for safety, thus reducing the population in the city at the time of the atomic attack. On the morning of August 9th, 1945, at about 7:50 A.M., Japanese time, an air raid alert was sounded in Nagasaki, but the "All clear" signal was given at 8:30. When only two B-29 superfortresses were sighted at 10:53 the Japanese apparently assumed that the planes were only on reconnaissance and no further alarm was given. A few moments later, at 11:00 o'clock, the observation B-29 dropped instruments attached to three parachutes and at 11:02 the other plane released the atomic bomb. The bomb exploded high over the industrial valley of Nagasaki, almost midway between the Mitsubishi Steel and Arms Works, in the south, and the Mitsubishi-Urakami Ordnance Works (Torpedo Works), in the north, the two principal targets of the city. Despite its extreme importance, the first bombing mission on Hiroshima had been almost routine. The second mission was not so uneventful. Again the crew was specially trained and selected; but bad weather introduced some momentous complications. These complications are best described in the brief account of the mission's weaponeer, Comdr., now Capt., F. L. Ashworth, U.S.N., who was in technical command of the bomb and was charged with the responsibility of insuring that the bomb was successfully dropped at the proper time and on the designated target. His narrative runs as follows: "The night of our take-off was one of tropical rain squalls, and flashes of lightning stabbed into the darkness with disconcerting regularity. The weather forecast told us of storms all the way from the Marianas to the Empire. Our rendezvous was to be off the southeast coast of Kyushu, some 1500 miles away. There we were to join with our two companion observation B-29's that took off a few minutes behind us. Skillful piloting and expert navigation brought us to the rendezvous without incident. "About five minutes after our arrival, we were joined by the first of our B-29's. The second, however, failed to arrive, having apparently been thrown off its course by storms during the night. We waited 30 minutes and then proceeded without the second plane toward the target area. "During the approach to the target the special instruments installed in the plane told us that the bomb was ready to function. We were prepared to drop the second atomic bomb on Japan. But fate was against us, for the target was completely obscured by smoke and haze. Three times we attempted bombing runs, but without success. Then with anti-aircraft fire bursting around us and with a number of enemy fighters coming up after us, we headed for our secondary target, Nagasaki. "The bomb burst with a blinding flash and a huge column of black smoke swirled up toward us. Out of this column of smoke there boiled a great swirling mushroom of gray smoke, luminous with red, flashing flame, that reached to 40,000 feet in less than 8 minutes. Below through the clouds we could see the pall of black smoke ringed with fire that covered what had been the industrial area of Nagasaki. "By this time our fuel supply was dangerously low, so after one quick circle of Nagasaki, we headed direct for Okinawa for an emergency landing and refueling". GENERAL COMPARISON OF HIROSHIMA AND NAGASAKI It was not at first apparent to even trained observers visiting the two Japanese cities which of the two bombs had been the most effective. In some respects, Hiroshima looked worse than Nagasaki. The fire damage in Hiroshima was much more complete; the center of the city was hit and everything but the reinforced concrete buildings had virtually disappeared. A desert of clear-swept, charred remains, with only a few strong building frames left standing was a terrifying sight. At Nagasaki there were no buildings just underneath the center of explosion. The damage to the Mitsubishi Arms Works and the Torpedo Works was spectacular, but not overwhelming. There was something left to see, and the main contours of some of the buildings were still normal. An observer could stand in the center of Hiroshima and get a view of the most of the city; the hills prevented a similar overall view in Nagasaki. Hiroshima impressed itself on one's mind as a vast expanse of desolation; but nothing as vivid was left in one's memory of Nagasaki. When the observers began to note details, however, striking differences appeared. Trees were down in both cities, but the large trees which fell in Hiroshima were uprooted, while those in Nagasaki were actually snapped off. A few reinforced concrete buildings were smashed at the center in Hiroshima, but in Nagasaki equally heavy damage could be found 2,300 feet from X. In the study of objects which gave definite clues to the blast pressure, such as squashed tin cans, dished metal plates, bent or snapped poles and like, it was soon evident that the Nagasaki bomb had been much more effective than the Hiroshima bomb. In the description of damage which follows, it will be noted that the radius for the amount of damage was greater in Nagasaki than Hiroshima. GENERAL DESCRIPTION OF DAMAGE CAUSED BY THE ATOMIC EXPLOSIONS In considering the devastation in the two cities, it should be remembered that the cities' differences in shape and topography resulted in great differences in the damages. Hiroshima was all on low, flat ground, and was roughly circular in shape; Nagasaki was much cut up by hills and mountain spurs, with no regularity to its shape. In Hiroshima almost everything up to about one mile from X was completely destroyed, except for a small number (about 50) of heavily reinforced concrete buildings, most of which were specially designed to withstand earthquake shock, which were not collapsed by the blast; most of these buildings had their interiors completely gutted, and all windows, doors, sashes, and frames ripped out. In Nagasaki, nearly everything within 1/2 mile of the explosion was destroyed, including heavy structures. All Japanese homes were destroyed within 1 1/2 miles from X. Underground air raid shelters with earth cover roofs immediately below the explosion had their roofs caved in; but beyond 1/2 mile from X they suffered no damage. In Nagasaki, 1500 feet from X high quality steel frame buildings were not completely collapsed, but the entire buildings suffered mass distortion and all panels and roofs were blown in. In Nagasaki, 2,000 feet from X, reinforced concrete buildings with 10" walls and 6" floors were collapsed; reinforced concrete buildings with 4" walls and roofs were standing but were badly damaged. At 2,000 feet some 9" concrete walls were completely destroyed. In Nagasaki, 3,500 feet from X, church buildings with 18" brick walls were completely destroyed. 12" brick walls were severely cracked as far as 5,000 feet. In Hiroshima, 4,400 feet from X, multi-story brick buildings were completely demolished. In Nagasaki, similar buildings were destroyed to 5,300 feet. In Hiroshima, roof tiles were bubbled (melted) by the flash heat out to 4,000 feet from X; in Nagasaki, the same effect was observed to 6,500 feet. In Hiroshima, steel frame buildings were destroyed 4,200 feet from X, and to 4,800 feet in Nagasaki. In both cities, the mass distortion of large steel buildings was observed out to 4,500 feet from X. In Nagasaki, reinforced concrete smoke stacks with 8" walls, specially designed to withstand earthquake shocks, were overturned up to 4,000 feet from X. In Hiroshima, steel frame buildings suffered severe structural damage up to 5,700 feet from X, and in Nagasaki the same damage was sustained as far as 6,000 feet. In Nagasaki, 9" brick walls were heavily cracked to 5,000 feet, were moderately cracked to 6,000 feet, and slightly cracked to 8,000 feet. In both cities, light concrete buildings collapsed out to 4,700 feet. In Hiroshima, multi-story brick buildings suffered structural damage up to 6,600 feet, and in Nagasaki up to 6,500 feet from X. In both cities overhead electric installations were destroyed up to 5,500 feet; and trolley cars were destroyed up to 5,500 feet, and damaged to 10,500 feet. Flash ignition of dry, combustible material was observed as far as 6,400 feet from X in Hiroshima, and in Nagasaki as far as 10,000 feet from X. Severe damage to gas holders occured out to 6,500 feet in both cities. All Japanese homes were seriously damaged up to 6,500 feet in Hiroshima, and to 8,000 feet in Nagasaki. Most Japanese homes were damaged up to 8,000 feet in Hiroshima and 10,500 feet in Nagasaki. The hillsides in Nagasaki were scorched by the flash radiation of heat as far as 8,000 feet from X; this scorching gave the hillsides the appearance of premature autumn. In Nagasaki, very heavy plaster damage was observed in many buildings up to 9,000 feet; moderate damage was sustained as far as 12,000 feet, and light damage up to 15,000 feet. The flash charring of wooden telegraph poles was observed up to 9,500 feet from X in Hiroshima, and to 11,000 feet in Nagasaki; some reports indicate flash burns as far as 13,000 feet from X in both places. Severe displacement of roof tiles was observed up to 8,000 feet in Hiroshima, and to 10,000 feet in Nagasaki. In Nagasaki, very heavy damage to window frames and doors was observed up to 8,000 feet, and light damage up to 12,000 feet. Roofs and wall coverings on steel frame buildings were destroyed out to 11,000 feet. Although the sources of many fires were difficult to trace accurately, it is believed that fires were started by primary heat radiation as far as 15,000 feet from X. Roof damage extended as far as 16,000 feet from X in Hiroshima and in Nagasaki. The actual collapse of buildings was observed at the extreme range of 23,000 feet from X in Nagasaki. Although complete window damage was observed only up to 12,000 feet from X, some window damage occurred in Nagasaki up to 40,000 feet, and actual breakage of glass occured up to 60,000 feet. Heavy fire damage was sustained in a circular area in Hiroshima with a mean radius of about 6,000 feet and a maximum radius of about 11,000 feet; similar heavy damage occured in Nagasaki south of X up to 10,000 feet, where it was stopped on a river course. In Hiroshima over 60,000 of 90,000 buildings were destroyed or severely damaged by the atomic bomb; this figure represents over 67% of the city's structures. In Nagasaki 14,000 or 27% of 52,000 residences were completely destroyed and 5,400, or 10% were half destroyed. Only 12% remained undamaged. This destruction was limited by the layout of the city. The following is a summary of the damage to buildings in Nagasaki as determined from a ground survey made by the Japanese: Destruction of Buildings and Houses Number Percentage (Compiled by Nagasaki Municipality) Total in Nagasaki (before atomic explosion) 50,000 100.0 Blasted (not burned) 2,652 5.3 Blasted and burned 11,494 23.0 Blasted and/or burned 14,146 28.3 Partially burned or blasted 5,441 10.9 Total buildings and houses destroyed 19,587 39.2 Undamaged 30,413 60.8 In Hiroshima, all utilities and transportation services were disrupted for varying lengths of time. In general however services were restored about as rapidly as they could be used by the depleted population. Through railroad service was in order in Hiroshima on 8 August, and electric power was available in most of the surviving parts on 7 August, the day after the bombing. The reservoir of the city was not damaged, being nearly 2 miles from X. However, 70,000 breaks in water pipes in buildings and dwellings were caused by the blast and fire effects. Rolling transportation suffered extensive damage. The damage to railroad tracks, and roads was comparatively small, however. The electric power transmission and distribution systems were badly wrecked. The telephone system was approximately 80% damaged, and no service was restored until 15 August. Despite the customary Japanese lack of attention to sanitation measures, no major epidemic broke out in the bombed cities. Although the conditions following the bombings makes this fact seem surprising, the experience of other bombed cities in both Germany and Japan show Hiroshima and Nagasaki not to be isolated cases. The atomic explosion over Nagasaki affected an over-all area of approximately 42.9 square miles of which about 8.5 square miles were water and only about 9.8 square miles were built up, the remainder being partially settled. Approximately 36% of the built up areas were seriously damaged. The area most severely damaged had an average radius of about 1 mile, and covered about 2.9 square miles of which 2.4 were built up. In Nagasaki, buildings with structural steel frames, principally the Mitsubishi Plant as far as 6,000 feet from X were severely damaged; these buildings were typical of wartime mill construction in America and Great Britain, except that some of the frames were somewhat less substantial. The damage consisted of windows broken out (100%), steel sashes ripped out or bent, corrugated metal or corrugated asbestos roofs and sidings ripped off, roofs bent or destroyed, roof trusses collapsed, columns bent and cracked and concrete foundations for columns rotated. Damage to buildings with structural steel frames was more severe where the buildings received the effect of the blast on their sides than where the blast hit the ends of buildings, because the buildings had more stiffness (resistance to negative moment at the top of columns) in a longitudinal direction. Many of the lightly constructed steel frame buildings collapsed completely while some of the heavily constructed (to carry the weight of heavy cranes and loads) were stripped of roof and siding, but the frames were only partially injured. The next most seriously damaged area in Nagasaki lies outside the 2.9 square miles just described, and embraces approximately 4.2 square miles of which 29% was built up. The damage from blast and fire was moderate here, but in some sections (portions of main business districts) many secondary fires started and spread rapidly, resulting in about as much over-all destruction as in areas much closer to X. An area of partial damage by blast and fire lies just outside the one just described and comprises approximately 35.8 square miles. Of this area, roughly 1/6th was built up and 1/4th was water. The extent of damage varied from serious (severe damage to roofs and windows in the main business section of Nagasaki, 2.5 miles from X), to minor (broken or occasionally broken windows at a distance of 7 miles southeast of X). As intended, the bomb was exploded at an almost ideal location over Nagasaki to do the maximum damage to industry, including the Mitsubishi Steel and Arms Works, the Mitsubishi-Urakami Ordnance Works (Torpedo Works), and numerous factories, factory training schools, and other industrial establishments, with a minimum destruction of dwellings and consequently, a minimum amount of casualties. Had the bomb been dropped farther south, the Mitsubishi-Urakami Ordnance Works would not have been so severely damaged, but the main business and residential districts of Nagasaki would have sustained much greater damage casualties. Calculations show that the structural steel and reinforced concrete frames which survived the blast fairly close to X could not have withstood the estimated peak pressures developed against the total areas presented by the sides and roof of the buildings. The survival of these frames is explained by the fact that they were not actually required to withstand the peak pressure because the windows were quickly knocked out and roof and siding stripped off thereby reducing total area and relieving the pressure. While this saved the building frame, it permitted severe damage to building interior and contents, and injuries to the building occupants. Buildings without large panel openings through which the pressure could dissipate were completely crushed, even when their frames were as strong as those which survived. The damage sustained by reinforced concrete buildings depended both on the proximity to X and the type and strength of the reinforced concrete construction. Some of the buildings with reinforced concrete frames also had reinforced concrete walls, ceilings, and partitions, while others had brick or concrete tile walls covered either with plaster or ornamental stone, with partitions of metal, glass, and plaster. With the exception of the Nagasaki Medical School and Hospital group, which was designed to withstand earthquakes and was therefore of heavier construction than most American structures, most of the reinforced concrete structures could be classified only as fair, with concrete of low strength and density, with many of the columns, beams, and slabs underdesigned and improperly reinforced. These facts account for some of the structural failures which occured. In general, the atomic bomb explosion damaged all windows and ripped out, bent, or twisted most of the steel window or door sashes, ripped doors from hinges, damaged all suspended wood, metal, and plaster ceilings. The blast concussion also caused great damage to equipment by tumbling and battering. Fires generally of secondary origin consumed practically all combustible material, caused plaster to crack off, burned all wooden trim, stair covering, wooden frames of wooden suspended ceilings, beds, mattresses, and mats, and fused glass, ruined all equipment not already destroyed by the blast, ruined all electrical wiring, plumbing, and caused spalling of concrete columns and beams in many of the rooms. Almost without exception masonry buildings of either brick or stone within the effective limits of the blast were severely damaged so that most of them were flattened or reduced to rubble. The wreckage of a church, approximately 1,800 feet east of X in Nagasaki, was one of the few masonry buildings still recognizable and only portions of the walls of this structure were left standing. These walls were extremely thick (about 2 feet). The two domes of the church had reinforced concrete frames and although they were toppled, they held together as units. Practically every wooden building or building with timber frame within 2.0 miles of X was either completely destroyed or very seriously damaged, and significant damage in Nagasaki resulted as far as 3 miles from X. Nearly all such buildings collapsed and a very large number were consumed by fire. A reference to the various photographs depicting damage shows that although most of the buildings within the effective limits of the blast were totally destroyed or severely damaged, a large number of chimneys even close to X were left standing, apparently uninjured by the concussion. One explanation is that concrete chimneys are approximately cylindrical in shape and consequently offer much less wind resistance than flat surfaces such as buildings. Another explanation is that since the cities were subject to typhoons the more modern chimneys were probably designed to withstand winds of high velocity. It is also probable that most of the recently constructed chimneys as well as the more modern buildings were constructed to withstand the acceleration of rather severe earthquakes. Since the bombs were exploded high in the air, chimneys relatively close to X were subjected to more of a downward than a lateral pressure, and consequently the overturning moment was much less than might have been anticipated. Although the blast damaged many bridges to some extent, bridge damage was on the whole slight in comparison to that suffered by buildings. The damage varied from only damaged railings to complete destruction of the superstructure. Some of the bridges were wrecked and the spans were shoved off their piers and into the river bed below by the force of the blast. Others, particularly steel plate girder bridges, were badly buckled by the blast pressure. None of the failures observed could be attributed to inadequate design or structural weaknesses. The roads, and railroad and street railway trackage sustained practically no primary damage as a result of the explosion. Most of the damage to railroads occurred from secondary causes, such as fires and damage to bridges or other structures. Rolling stock, as well as automobiles, trolleys, and buses were destroyed and burned up to a considerable distance from X. Streets were impassable for awhile because of the debris, but they were not damaged. The height of the bomb explosion probably explains the absence of direct damage to railroads and roads. A large part of the electric supply was interrupted by the bomb blast chiefly through damage to electric substations and overhead transmission systems. Both gas works in Nagasaki were severely damaged by the bomb. These works would have required 6-7 months to get into operation. In addition to the damage sustained by the electrical and gas systems, severe damage to the water supply system was reported by the Japanese government; the chief damage was a number of breaks in the large water mains and in almost all of the distributing pipes in the areas which were affected by the blast. Nagasaki was still suffering from a water shortage inside the city six weeks after the atomic attack. The Nagasaki Prefectural report describes vividly the effects of the bomb on the city and its inhabitants: "Within a radius of 1 kilometer from X, men and animals died almost instantaneously and outside a radius of 1 kilometer and within a radius of 2 kilometers from X, some men and animals died instantly from the great blast and heat but the great majority were seriously or superficially injured. Houses and other structures were completely destroyed while fires broke out everywhere. Trees were uprooted and withered by the heat. "Outside a radius of 2 kilometers and within a radius of 4 kilometers from X, men and animals suffered various degrees of injury from window glass and other fragments scattered about by the blast and many were burned by the intense heat. Dwellings and other structures were half damaged by blast. "Outside a radius of 4 kilometers and within a radius of 8 kilometers living creatures were injured by materials blown about by the blast; the majority were only superficially wounded. Houses were only half or partially damaged." The British Mission to Japan interpreted their observations of the destruction of buildings to apply to similar construction of their own as follows: A similar bomb exploding in a similar fashion would produce the following effects on normal British houses: Up to 1,000 yards from X it would cause complete collapse. Up to 1 mile from X it would damage the houses beyond repair. Up to 1.5 miles from X it would render them uninhabitable without extensive repair, particularly to roof timbers. Up to 2.5 miles from X it would render them uninhabitable until first-aid repairs had been carried out. The fire damage in both cities was tremendous, but was more complete in Hiroshima than in Nagasaki. The effect of the fires was to change profoundly the appearance of the city and to leave the central part bare, except for some reinforced concrete and steel frames and objects such as safes, chimney stacks, and pieces of twisted sheet metal. The fire damage resulted more from the properties of the cities themselves than from those of the bombs. The conflagration in Hiroshima caused high winds to spring up as air was drawn in toward the center of the burning area, creating a "fire storm". The wind velocity in the city had been less than 5 miles per hour before the bombing, but the fire-wind attained a velocity of 30-40 miles per hour. These great winds restricted the perimeter of the fire but greatly added to the damage of the conflagration within the perimeter and caused the deaths of many persons who might otherwise have escaped. In Nagasaki, very severe damage was caused by fires, but no extensive "fire storm" engulfed the city. In both cities, some of the fires close to X were no doubt started by the ignition of highly combustible material such as paper, straw, and dry cloth, upon the instantaneous radiation of heat from the nuclear explosion. The presence of large amounts of unburnt combustible materials near X, however, indicated that even though the heat of the blast was very intense, its duration was insufficient to raise the temperature of many materials to the kindling point except in cases where conditions were ideal. The majority of the fires were of secondary origin starting from the usual electrical short-circuits, broken gas lines, overturned stoves, open fires, charcoal braziers, lamps, etc., following collapse or serious damage from the direct blast. Fire fighting and rescue units were stripped of men and equipment. Almost 30 hours elapsed before any rescue parties were observable. In Hiroshima only a handful of fire engines were available for fighting the ensuing fires, and none of these were of first class type. In any case, however, it is not likely that any fire fighting equipment or personnel or organization could have effected any significant reduction in the amount of damage caused by the tremendous conflagration. A study of numerous aerial photographs made prior to the atomic bombings indicates that between 10 June and 9 August 1945 the Japanese constructed fire breaks in certain areas of the cities in order to control large scale fires. In general these fire breaks were not effective because fires were started at so many locations simultaneously. They appear, however, to have helped prevent fires from spreading farther east into the main business and residential section of Nagasaki. TOTAL CASUALTIES There has been great difficulty in estimating the total casualties in the Japanese cities as a result of the atomic bombing. The extensive destruction of civil installations (hospitals, fire and police department, and government agencies) the state of utter confusion immediately following the explosion, as well as the uncertainty regarding the actual population before the bombing, contribute to the difficulty of making estimates of casualties. The Japanese periodic censuses are not complete. Finally, the great fires that raged in each city totally consumed many bodies. The number of total casualties has been estimated at various times since the bombings with wide discrepancies. The Manhattan Engineer District's best available figures are: TABLE A Estimates of Casualties Hiroshima Nagasaki Pre-raid population 255,000 195,000 Dead 66,000 39,000 Injured 69,000 25,000 Total Casualties 135,000 64,000 The relation of total casualties to distance from X, the center of damage and point directly under the air-burst explosion of the bomb, is of great importance in evaluating the casualty-producing effect of the bombs. This relationship for the total population of Nagasaki is shown in the table below, based on the first-obtained casualty figures of the District: TABLE B Relation of Total Casualties to Distance from X Distance Total Killed per from X, feet Killed Injured Missing Casualties square mile 0 - 1,640 7,505 960 1,127 9,592 24,700 1,640 - 3,300 3,688 1,478 1,799 6,965 4,040 3,300 - 4,900 8,678 17,137 3,597 29,412 5,710 4,900 - 6,550 221 11,958 28 12,207 125 6,550 - 9,850 112 9,460 17 9,589 20 No figure for total pre-raid population at these different distances were available. Such figures would be necessary in order to compute per cent mortality. A calculation made by the British Mission to Japan and based on a preliminary analysis of the study of the Joint Medical-Atomic Bomb Investigating Commission gives the following calculated values for per cent mortality at increasing distances from X: TABLE C Per-Cent Mortality at Various Distances Distance from X, Per-cent Mortality in feet 0 - 1000 93.0% 1000 - 2000 92.0 2000 - 3000 86.0 3000 - 4000 69.0 4000 - 5000 49.0 5000 - 6000 31.5 6000 - 7000 12.5 7000 - 8000 1.3 8000 - 9000 0.5 9000 - 10,000 0.0 It seems almost certain from the various reports that the greatest total number of deaths were those occurring immediately after the bombing. The causes of many of the deaths can only be surmised, and of course many persons near the center of explosion suffered fatal injuries from more than one of the bomb effects. The proper order of importance for possible causes of death is: burns, mechanical injury, and gamma radiation. Early estimates by the Japanese are shown in D below: TABLE D Cause of Immediate Deaths City Cause of Death Per-cent of Total Hiroshima Burns 60% Falling debris 30 Other 10 Nagasaki Burns 95% Falling debris 9 Flying glass 7 Other 7 THE NATURE OF AN ATOMIC EXPLOSION The most striking difference between the explosion of an atomic bomb and that of an ordinary T.N.T. bomb is of course in magnitude; as the President announced after the Hiroshima attack, the explosive energy of each of the atomic bombs was equivalent to about 20,000 tons of T.N.T. But in addition to its vastly greater power, an atomic explosion has several other very special characteristics. Ordinary explosion is a chemical reaction in which energy is released by the rearrangement of the atoms of the explosive material. In an atomic explosion the identity of the atoms, not simply their arrangement, is changed. A considerable fraction of the mass of the explosive charge, which may be uranium 235 or plutonium, is transformed into energy. Einstein's equation, E = mc^2, shows that matter that is transformed into energy may yield a total energy equivalent to the mass multiplied by the square of the velocity of light. The significance of the equation is easily seen when one recalls that the velocity of light is 186,000 miles per second. The energy released when a pound of T.N.T. explodes would, if converted entirely into heat, raise the temperature of 36 lbs. of water from freezing temperature (32 deg F) to boiling temperature (212 deg F). The nuclear fission of a pound of uranium would produce an equal temperature rise in over 200 million pounds of water. The explosive effect of an ordinary material such as T.N.T. is derived from the rapid conversion of solid T.N.T. to gas, which occupies initially the same volume as the solid; it exerts intense pressures on the surrounding air and expands rapidly to a volume many times larger than the initial volume. A wave of high pressure thus rapidly moves outward from the center of the explosion and is the major cause of damage from ordinary high explosives. An atomic bomb also generates a wave of high pressure which is in fact of, much higher pressure than that from ordinary explosions; and this wave is again the major cause of damage to buildings and other structures. It differs from the pressure wave of a block buster in the size of the area over which high pressures are generated. It also differs in the duration of the pressure pulse at any given point: the pressure from a blockbuster lasts for a few milliseconds (a millisecond is one thousandth of a second) only, that from the atomic bomb for nearly a second, and was felt by observers both in Japan and in New Mexico as a very strong wind going by. The next greatest difference between the atomic bomb and the T.N.T. explosion is the fact that the atomic bomb gives off greater amounts of radiation. Most of this radiation is "light" of some wave-length ranging from the so-called heat radiations of very long wave length to the so-called gamma rays which have wave-lengths even shorter than the X-rays used in medicine. All of these radiations travel at the same speed; this, the speed of light, is 186,000 miles per second. The radiations are intense enough to kill people within an appreciable distance from the explosion, and are in fact the major cause of deaths and injuries apart from mechanical injuries. The greatest number of radiation injuries was probably due to the ultra-violet rays which have a wave length slightly shorter than visible light and which caused flash burn comparable to severe sunburn. After these, the gamma rays of ultra short wave length are most important; these cause injuries similar to those from over-doses of X-rays. The origin of the gamma rays is different from that of the bulk of the radiation: the latter is caused by the extremely high temperatures in the bomb, in the same way as light is emitted from the hot surface of the sun or from the wires in an incandescent lamp. The gamma rays on the other hand are emitted by the atomic nuclei themselves when they are transformed in the fission process. The gamma rays are therefore specific to the atomic bomb and are completely absent in T.N.T. explosions. The light of longer wave length (visible and ultra-violet) is also emitted by a T.N.T. explosion, but with much smaller intensity than by an atomic bomb, which makes it insignificant as far as damage is concerned. A large fraction of the gamma rays is emitted in the first few microseconds (millionths of a second) of the atomic explosion, together with neutrons which are also produced in the nuclear fission. The neutrons have much less damage effect than the gamma rays because they have a smaller intensity and also because they are strongly absorbed in air and therefore can penetrate only to relatively small distances from the explosion: at a thousand yards the neutron intensity is negligible. After the nuclear emission, strong gamma radiation continues to come from the exploded bomb. This generates from the fission products and continues for about one minute until all of the explosion products have risen to such a height that the intensity received on the ground is negligible. A large number of beta rays are also emitted during this time, but they are unimportant because their range is not very great, only a few feet. The range of alpha particles from the unused active material and fissionable material of the bomb is even smaller. Apart from the gamma radiation ordinary light is emitted, some of which is visible and some of which is the ultra violet rays mainly responsible for flash burns. The emission of light starts a few milliseconds after the nuclear explosion when the energy from the explosion reaches the air surrounding the bomb. The observer sees then a ball of fire which rapidly grows in size. During most of the early time, the ball of fire extends as far as the wave of high pressure. As the ball of fire grows its temperature and brightness decrease. Several milliseconds after the initiation of the explosion, the brightness of the ball of fire goes through a minimum, then it gets somewhat brighter and remains at the order of a few times the brightness of the sun for a period of 10 to 15 seconds for an observer at six miles distance. Most of the radiation is given off after this point of maximum brightness. Also after this maximum, the pressure waves run ahead of the ball of fire. The ball of fire rapidly expands from the size of the bomb to a radius of several hundred feet at one second after the explosion. After this the most striking feature is the rise of the ball of fire at the rate of about 30 yards per second. Meanwhile it also continues to expand by mixing with the cooler air surrounding it. At the end of the first minute the ball has expanded to a radius of several hundred yards and risen to a height of about one mile. The shock wave has by now reached a radius of 15 miles and its pressure dropped to less than 1/10 of a pound per square inch. The ball now loses its brilliance and appears as a great cloud of smoke: the pulverized material of the bomb. This cloud continues to rise vertically and finally mushrooms out at an altitude of about 25,000 feet depending upon meteorological conditions. The cloud reaches a maximum height of between 50,000 and 70,000 feet in a time of over 30 minutes. It is of interest to note that Dr. Hans Bethe, then a member of the Manhattan Engineer District on loan from Cornell University, predicted the existence and characteristics of this ball of fire months before the first test was carried out. To summarize, radiation comes in two bursts--an extremely intense one lasting only about 3 milliseconds and a less intense one of much longer duration lasting several seconds. The second burst contains by far the larger fraction of the total light energy, more than 90%. But the first flash is especially large in ultra-violet radiation which is biologically more effective. Moreover, because the heat in this flash comes in such a short time, there is no time for any cooling to take place, and the temperature of a person's skin can be raised 50 degrees centigrade by the flash of visible and ultra-violet rays in the first millisecond at a distance of 4,000 yards. People may be injured by flash burns at even larger distances. Gamma radiation danger does not extend nearly so far and neutron radiation danger is still more limited. The high skin temperatures result from the first flash of high intensity radiation and are probably as significant for injuries as the total dosages which come mainly from the second more sustained burst of radiation. The combination of skin temperature increase plus large ultra-violet flux inside 4,000 yards is injurious in all cases to exposed personnel. Beyond this point there may be cases of injury, depending upon the individual sensitivity. The infra-red dosage is probably less important because of its smaller intensity. CHARACTERISTICS OF THE DAMAGE CAUSED BY THE ATOMIC BOMBS The damage to man-made structures caused by the bombs was due to two distinct causes: first the blast, or pressure wave, emanating from the center of the explosion, and, second, the fires which were caused either by the heat of the explosion itself or by the collapse of buildings containing stoves, electrical fixtures, or any other equipment which might produce what is known as a secondary fire, and subsequent spread of these fires. The blast produced by the atomic bomb has already been stated to be approximately equivalent to that of 20,000 tons of T.N.T. Given this figure, one may calculate the expected peak pressures in the air, at various distances from the center of the explosion, which occurred following detonation of the bomb. The peak pressures which were calculated before the bombs were dropped agreed very closely with those which were actually experienced in the cities during the attack as computed by Allied experts in a number of ingenious ways after the occupation of Japan. The blast of pressure from the atomic bombs differed from that of ordinary high explosive bombs in three main ways: A. Downward thrust. Because the explosions were well up in the air, much of the damage resulted from a downward pressure. This pressure of course most largely effected flat roofs. Some telegraph and other poles immediately below the explosion remained upright while those at greater distances from the center of damage, being more largely exposed to a horizontal thrust from the blast pressure waves, were overturned or tilted. Trees underneath the explosion remained upright but had their branches broken downward. B. Mass distortion of buildings. An ordinary bomb can damage only a part of a large building, which may then collapse further under the action of gravity. But the blast wave from an atomic bomb is so large that it can engulf whole buildings, no matter how great their size, pushing them over as though a giant hand had given them a shove. C. Long duration of the positive pressure pulse and consequent small effect of the negative pressure, or suction, phase. In any explosion, the positive pressure exerted by the blast lasts for a definite period of time (usually a small fraction of a second) and is then followed by a somewhat longer period of negative pressure, or suction. The negative pressure is always much weaker than the positive, but in ordinary explosions the short duration of the positive pulse results in many structures not having time to fail in that phase, while they are able to fail under the more extended, though weaker, negative pressure. But the duration of the positive pulse is approximately proportional to the 1/3 power of the size of the explosive charge. Thus, if the relation held true throughout the range in question, a 10-ton T.N.T. explosion would have a positive pulse only about 1/14th as long as that of a 20,000-ton explosion. Consequently, the atomic explosions had positive pulses so much longer then those of ordinary explosives that nearly all failures probably occurred during this phase, and very little damage could be attributed to the suction which followed. One other interesting feature was the combination of flash ignition and comparative slow pressure wave. Some objects, such as thin, dry wooden slats, were ignited by the radiated flash heat, and then their fires were blown out some time later (depending on their distance from X) by the pressure blast which followed the flash radiation. CALCULATIONS OF THE PEAK PRESSURE OF THE BLAST WAVE Several ingenious methods were used by the various investigators to determine, upon visiting the wrecked cities, what had actually been the peak pressures exerted by the atomic blasts. These pressures were computed for various distances from X, and curves were then plotted which were checked against the theoretical predictions of what the pressures would be. A further check was afforded from the readings obtained by the measuring instruments which were dropped by parachute at each atomic attack. The peak pressure figures gave a direct clue to the equivalent T.N.T. tonnage of the atomic bombs, since the pressures developed by any given amount of T.N.T. can be calculated easily. One of the simplest methods of estimating the peak pressure is from crushing of oil drums, gasoline cans, or any other empty thin metal vessel with a small opening. The assumption made is that the blast wave pressure comes on instantaneously, the resulting pressure on the can is more than the case can withstand, and the walls collapse inward. The air inside is compressed adiabatically to such a point that the pressure inside is less by a certain amount than the pressure outside, this amount being the pressure difference outside and in that the walls can stand in their crumpled condition. The uncertainties involved are, first, that some air rushes in through any opening that the can may have, and thus helps to build up the pressure inside; and, second, that as the pressure outside falls, the air inside cannot escape sufficiently fast to avoid the walls of the can being blown out again to some extent. These uncertainties are such that estimates of pressure based on this method are on the low side, i.e., they are underestimated. Another method of calculating the peak-pressure is through the bending of steel flagpoles, or lightning conductors, away from the explosion. It is possible to calculate the drag on a pole or rod in an airstream of a certain density and velocity; by connecting this drag with the strength of the pole in question, a determination of the pressure wave may be obtained. Still another method of estimating the peak pressure is through the overturning of memorial stones, of which there are a great quantity in Japan. The dimensions of the stones can be used along with known data on the pressure exerted by wind against flat surfaces, to calculate the desired figure. LONG RANGE BLAST DAMAGE There was no consistency in the long range blast damage. Observers often thought that they had found the limit, and then 2,000 feet farther away would find further evidence of damage. The most impressive long range damage was the collapse of some of the barracks sheds at Kamigo, 23,000 feet south of X in Nagasaki. It was remarkable to see some of the buildings intact to the last details, including the roof and even the windows, and yet next to them a similar building collapsed to ground level. The limiting radius for severe displacement of roof tiles in Nagasaki was about 10,000 feet although isolated cases were found up to 16,000 feet. In Hiroshima the general limiting radius was about 8,000 feet; however, even at a distance of 26,000 feet from X in Hiroshima, some tiles were displaced. At Mogi, 7 miles from X in Nagasaki, over steep hills over 600 feet high, about 10% of the glass came out. In nearer, sequestered localities only 4 miles from X, no damage of any kind was caused. An interesting effect was noted at Mogi; eyewitnesses said that they thought a raid was being made on the place; one big flash was seen, then a loud roar, followed at several second intervals by half a dozen other loud reports, from all directions. These successive reports were obviously reflections from the hills surrounding Mogi. GROUND SHOCK The ground shock in most cities was very light. Water pipes still carried water and where leaks were visible they were mainly above ground. Virtually all of the damage to underground utilities was caused by the collapse of buildings rather than by any direct exertion of the blast pressure. This fact of course resulted from the bombs' having been exploded high in the air. SHIELDING, OR SCREENING FROM BLAST In any explosion, a certain amount of protection from blast may be gained by having any large and substantial object between the protected object and the center of the explosion. This shielding effect was noticeable in the atomic explosions, just as in ordinary cases, although the magnitude of the explosions and the fact that they occurred at a considerable height in the air caused marked differences from the shielding which would have characterized ordinary bomb explosions. The outstanding example of shielding was that afforded by the hills in the city of Nagasaki; it was the shielding of these hills which resulted in the smaller area of devastation in Nagasaki despite the fact that the bomb used there was not less powerful. The hills gave effective shielding only at such distances from the center of explosion that the blast pressure was becoming critical--that is, was only barely sufficient to cause collapse--for the structure. Houses built in ravines in Nagasaki pointing well away from the center of the explosion survived without damage, but others at similar distances in ravines pointing toward the center of explosion were greatly damaged. In the north of Nagasaki there was a small hamlet about 8,000 feet from the center of explosion; one could see a distinctive variation in the intensity of damage across the hamlet, corresponding with the shadows thrown by a sharp hill. The best example of shielding by a hill was southeast of the center of explosion in Nagasaki. The damage at 8,000 feet from X consisted of light plaster damage and destruction of about half the windows. These buildings were of European type and were on the reverse side of a steep hill. At the same distance to the south-southeast the damage was considerably greater, i.e., all windows and frames, doors, were damaged and heavy plaster damage and cracks in the brick work also appeared. The contrast may be illustrated also by the fact that at the Nagasaki Prefectural office at 10,800 feet the damage was bad enough for the building to be evacuated, while at the Nagasaki Normal School to which the Prefectural office had been moved, at the same distance, the damage was comparatively light. Because of the height of the bursts no evidence was expected of the shielding of one building by another, at least up to a considerable radius. It was in fact difficult to find any evidence at any distance of such shielding. There appeared to have been a little shielding of the building behind the Administration Building of the Torpedo Works in Nagasaki, but the benefits were very slight. There was also some evidence that the group of buildings comprising the Medical School in Nagasaki did afford each other mutual protection. On the whole, however, shielding of one building by another was not noticeable. There was one other peculiar type of shielding, best exhibited by the workers' houses to the north of the torpedo plant in Nagasaki. These were 6,000 to 7,000 feet north of X. The damage to these houses was not nearly as bad as those over a thousand feet farther away from the center of explosion. It seemed as though the great destruction caused in the torpedo plant had weakened the blast a little, and the full power was not restored for another 1,000 feet or more. FLASH BURN As already stated, a characteristic feature of the atomic bomb, which is quite foreign to ordinary explosives, is that a very appreciable fraction of the energy liberated goes into radiant heat and light. For a sufficiently large explosion, the flash burn produced by this radiated energy will become the dominant cause of damage, since the area of burn damage will increase in proportion to the energy released, whereas the area of blast damage increases only with the two-thirds power of the energy. Although such a reversal of the mechanism of damage was not achieved in the Hiroshima and Nagasaki bombs, the effects of the flash were, however, very evident, and many casualties resulted from flash burns. A discussion of the casualties caused by flash burns will be given later; in this section will be described the other flash effects which were observed in the two cities. The duration of the heat radiation from the bomb is so short, just a few thousandths of a second, that there is no time for the energy falling on a surface to be dissipated by thermal defusion; the flash burn is typically a surface effect. In other words the surface of either a person or an object exposed to the flash is raised to a very high temperature while immediately beneath the surface very little rise in temperature occurs. The flash burning of the surface of objects, particularly wooden objects, occurred in Hiroshima up to a radius of 9,500 feet from X; at Nagasaki burns were visible up to 11,000 feet from X. The charring and blackening of all telephone poles, trees and wooden posts in the areas not destroyed by the general fire occurred only on the side facing the center of explosion and did not go around the corners of buildings or hills. The exact position of the explosion was in fact accurately determined by taking a number of sights from various objects which had been flash burned on one side only. To illustrate the effects of the flash burn, the following describes a number of examples found by an observer moving northward from the center of explosion in Nagasaki. First occurred a row of fence posts at the north edge of the prison hill, at 0.3 miles from X. The top and upper part of these posts were heavily charred. The charring on the front of the posts was sharply limited by the shadow of a wall. This wall had however been completely demolished by the blast, which of course arrived some time after the flash. At the north edge of the Torpedo works, 1.05 miles from X, telephone poles were charred to a depth of about 0.5 millimeters. A light piece of wood similar to the flat side of an orange crate, was found leaning against one of the telephone poles. Its front surface was charred the same way as the pole, but it was evident that it had actually been ignited. The wood was blackened through a couple of cracks and nail holes, and around the edges onto the back surface. It seemed likely that this piece of wood had flamed up under the flash for a few seconds before the flame was blown out by the wind of the blast. Farther out, between 1.05 and 1.5 miles from the explosion, were many trees and poles showing a blackening. Some of the poles had platforms near the top. The shadows cast by the platforms were clearly visible and showed that the bomb had detonated at a considerable height. The row of poles turned north and crossed the mountain ridge; the flash burn was plainly visible all the way to the top of the ridge, the farthest burn observed being at 2.0 miles from X. Another striking effect of the flash burn was the autumnal appearance of the bowl formed by the hills on three sides of the explosion point. The ridges are about 1.5 miles from X. Throughout this bowl the foliage turned yellow, although on the far side of the ridges the countryside was quite green. This autumnal appearance of the trees extended to about 8,000 feet from X. However, shrubs and small plants quite near the center of explosion in Hiroshima, although stripped of leaves, had obviously not been killed. Many were throwing out new buds when observers visited the city. There are two other remarkable effects of the heat radiated from the bomb explosion. The first of these is the manner in which heat roughened the surface of polished granite, which retained its polish only where it was shielded from the radiated heat travelling in straight lines from the explosion. This roughening by radiated heat caused by the unequal expansion of the constituent crystals of the stone; for granite crystals the melting temperature is about 600 deg centigrade. Therefore the depth of roughening and ultimate flaking of the granite surface indicated the depth to which this temperature occurred and helped to determine the average ground temperatures in the instant following the explosion. This effect was noted for distances about 1 1/2 times as great in Nagasaki as in Hiroshima. The second remarkable effect was the bubbling of roof tile. The size of the bubbles and their extent was proportional to their nearness to the center of explosion and also depended on how squarely the tile itself was faced toward the explosion. The distance ratio of this effect between Nagasaki and Hiroshima was about the same as for the flaking of polished granite. Various other effects of the radiated heat were noted, including the lightening of asphalt road surfaces in spots which had not been protected from the radiated heat by any object such as that of a person walking along the road. Various other surfaces were discolored in different ways by the radiated heat. As has already been mentioned the fact that radiant heat traveled only in straight lines from the center of explosion enabled observers to determine the direction toward the center of explosion from a number of different points, by observing the "shadows" which were cast by intervening objects where they shielded the otherwise exposed surface of some object. Thus the center of explosion was located with considerable accuracy. In a number of cases these "shadows" also gave an indication of the height of burst of the bomb and occasionally a distinct penumbra was found which enabled observers to calculate the diameter of the ball of fire at the instant it was exerting the maximum charring or burning effect. One more interesting feature connected with heat radiation was the charring of fabric to different degrees depending upon the color of the fabric. A number of instances were recorded in which persons wearing clothing of various colors received burns greatly varying in degree, the degree of burn depending upon the color of the fabric over the skin in question. For example a shirt of alternate light and dark gray stripes, each about 1/8 of an inch wide, had the dark stripes completely burned out but the light stripes were undamaged; and a piece of Japanese paper exposed nearly 1 1/2 miles from X had the characters which were written in black ink neatly burned out. CHARACTERISTICS OF THE INJURIES TO PERSONS Injuries to persons resulting from the atomic explosions were of the following types: A. Burns, from 1. Flash radiation of heat 2. Fires started by the explosions. B. Mechanical injuries from collapse of buildings, flying debris, etc. C. Direct effects of the high blast pressure, i.e., straight compression. D. Radiation injuries, from the instantaneous emission of gamma rays and neutrons. It is impossible to assign exact percentages of casualties to each of the types of injury, because so many victims were injured by more than one effect of the explosions. However, it is certain that the greater part of the casualties resulted from burns and mechanical injures. Col. Warren, one of America's foremost radioligists, stated it is probable that 7 per cent or less of the deaths resulted primarily from radiation disease. The greatest single factor influencing the occurrence of casualties was the distance of the person concerned from the center of explosion. Estimates based on the study of a selected group of 900 patients indicated that total casualties occurred as far out as 14,000 feet at Nagasaki and 12,000 feet at Hiroshima. Burns were suffered at a considerable greater distance from X than any other type of injury, and mechanical injuries farther out than radiation effects. Medical findings show that no person was injured by radioactivity who was not exposed to the actual explosion of the bombs. No injuries resulted from persistent radioactivity of any sort. BURNS Two types of burns were observed. These are generally differentiated as flame or fire burn and so-called flash burn. The early appearance of the flame burn as reported by the Japanese, and the later appearance as observed, was not unusual. The flash burn presented several distinctive features. Marked redness of the affected skin areas appeared almost immediately, according to the Japanese, with progressive changes in the skin taking place over a period of a few hours. When seen after 50 days, the most distinctive feature of these burns was their sharp limitation to exposed skin areas facing the center of the explosion. For instance, a patient who had been walking in a direction at right angles to a line drawn between him and the explosion, and whose arms were swinging, might have burns only on the outside of the arm nearest the center and on the inside of the other arm. Generally, any type of shielding protected the skin against flash burns, although burns through one, and very occasionally more, layers of clothing did occur in patients near the center. In such cases, it was not unusual to find burns through black but not through white clothing, on the same patient. Flash burns also tended to involve areas where the clothes were tightly drawn over the skin, such as at the elbows and shoulders. The Japanese report the incidence of burns in patients surviving more than a few hours after the explosion, and seeking medical attention, as high as 95%. The total mortalities due to burns alone cannot be estimated with any degree of accuracy. As mentioned already, it is believed that the majority of all the deaths occurred immediately. Of these, the Japanese estimate that 75%, and most of the reports estimate that over 50%, of the deaths were due to burns. In general, the incidence of burns was in direct proportion to the distance from X. However, certain irregularities in this relationship result in the medical studies because of variations in the amount of shielding from flash burn, and because of the lack of complete data on persons killed outright close to X. The maximum distance from X at which flash burns were observed is of paramount interest. It has been estimated that patients with burns at Hiroshima were all less than 7,500 feet from the center of the explosion at the time of the bombing. At Nagasaki, patients with burns were observed out to the remarkable distance of 13,800 feet. MECHANICAL INJURIES The mechanical injuries included fractures, lacerations, contusions, abrasions, and other effects to be expected from falling roofs, crumbling walls, flying debris and glass, and other indirect blast effects. The appearance of these various types of mechanical injuries was not remarkable to the medical authorities who studied them. It was estimated that patients with lacerations at Hiroshima were less than 10,600 feet from X, whereas at Nagasaki they extended as far as 12,200 feet. The tremendous drag of wind, even as far as 1 mile from X, must have resulted in many injuries and deaths. Some large pieces of a prison wall, for example, were flung 80 feet, and many have gone 30 feet high before falling. The same fate must have befallen many persons, and the chances of a human being surviving such treatment are probably small. BLAST INJURIES No estimate of the number of deaths or early symptoms due to blast pressure can be made. The pressures developed on the ground under the explosions were not sufficient to kill more than those people very near the center of damage (within a few hundred feet at most). Very few cases of ruptured ear drums were noted, and it is the general feeling of the medical authorities that the direct blast effects were not great. Many of the Japanese reports, which are believed to be false, describe immediate effects such as ruptured abdomens with protruding intestines and protruding eyes, but no such results were actually traced to the effect of air pressure alone. RADIATION INJURIES As pointed out in another section of this report the radiations from the nuclear explosions which caused injuries to persons were primarily those experienced within the first second after the explosion; a few may have occurred later, but all occurred in the first minute. The other two general types of radiation, viz., radiation from scattered fission products and induced radioactivity from objects near the center of explosion, were definitely proved not to have caused any casualties. The proper designation of radiation injuries is somewhat difficult. Probably the two most direct designations are radiation injury and gamma ray injury. The former term is not entirely suitable in that it does not define the type of radiation as ionizing and allows possible confusion with other types of radiation (e.g., infra-red). The objection to the latter term is that it limits the ionizing radiation to gamma rays, which were undoubtedly the most important; but the possible contribution of neutron and even beta rays to the biological effects cannot be entirely ignored. Radiation injury has the advantage of custom, since it is generally understood in medicine to refer to X-ray effect as distinguished from the effects of actinic radiation. Accordingly, radiation injury is used in this report to mean injury due only to ionizing radiation. According to Japanese observations, the early symptons in patients suffering from radiation injury closely resembled the symptons observed in patients receiving intensive roentgen therapy, as well as those observed in experimental animals receiving large doses of X-rays. The important symptoms reported by the Japanese and observed by American authorities were epilation (lose of hair), petechiae (bleeding into the skin), and other hemorrhagic manifestations, oropharyngeal lesions (inflammation of the mouth and throat), vomiting, diarrhea, and fever. Epilation was one of the most spectacular and obvious findings. The appearance of the epilated patient was typical. The crown was involved more than the sides, and in many instances the resemblance to a monk's tonsure was striking. In extreme cases the hair was totally lost. In some cases, re-growth of hair had begun by the time patients were seen 50 days after the bombing. Curiously, epilation of hair other than that of the scalp was extremely unusual. Petechiae and other hemorrhagic manifestations were striking findings. Bleeding began usually from the gums and in the more seriously affected was soon evident from every possible source. Petechiae appeared on the limbs and on pressure points. Large ecchymoses (hemorrhages under the skin) developed about needle punctures, and wounds partially healed broke down and bled freely. Retinal hemorrhages occurred in many of the patients. The bleeding time and the coagulation time were prolonged. The platelets (coagulation of the blood) were characteristically reduced in numbers. Nausea and vomiting appearing within a few hours after the explosion was reported frequently by the Japanese. This usually had subsided by the following morning, although occasionally it continued for two or three days. Vomiting was not infrequently reported and observed during the course of the later symptoms, although at these times it generally appeared to be related to other manifestation of systemic reactions associated with infection. Diarrhea of varying degrees of severity was reported and observed. In the more severe cases, it was frequently bloody. For reasons which are not yet clear, the diarrhea in some cases was very persistent. Lesions of the gums, and the oral mucous membrane, and the throat were observed. The affected areas became deep red, then violacious in color; and in many instances ulcerations and necrosis (breakdown of tissue) followed. Blood counts done and recorded by the Japanese, as well as counts done by the Manhattan Engineer District Group, on such patients regularly showed leucopenia (low-white blood cell count). In extreme cases the white blood cell count was below 1,000 (normal count is around 7,000). In association with the leucopenia and the oropharyngeal lesions, a variety of other infective processes were seen. Wounds and burns which were healing adequately suppurated and serious necrosis occurred. At the same time, similar ulcerations were observed in the larynx, bowels, and in females, the gentalia. Fever usually accompanied these lesions. Eye injuries produced by the atomic bombings in both cities were the subject of special investigations. The usual types of mechanical injuries were seen. In addition, lesions consisting of retinal hemorrhage and exudation were observed and 75% of the patients showing them had other signs of radiation injury. The progress of radiation disease of various degrees of severity is shown in the following table: Summary of Radiation Injury Clinical Symptoms and Findings Day after Explo- sion Most Severe Moderately Severe Mild 1. 1. Nausea and vomiting 1. Nausea and vomiting 2. after 1-2 hours. after 1-2 hours. 3. NO DEFINITE SYMPTOMS 4. 5. 2. Diarrhea 6. 3. Vomiting NO DEFINITE SYMPTOMS 7. 4. Inflammation of the mouth and throat 8. 5. Fever 9. 6. Rapid emaciation 10. Death NO DEFINITE SYMPTOMS 11. (Mortality probably 2. Beginning epilation. 12. 100%) 13. 14. 15. 16. 17. 18. 3. Loss of appetite 19. and general malaise. 1. Epilation 20. 4. Fever. 2. Loss of appetite 21. 5. Severe inflammation and malaise. 22. of the mouth and throat 3. Sore throat. 23. 4. Pallor. 24. 5. Petechiae 25. 6. Diarrhea 26. 7. Moderate emacia- 27. 6. Pallor. tion. 28. 7. Petechiae, diarrhea 29. and nose bleeds (Recovery unless com- 30. plicated by previous 31. 8. Rapid emaciation poor health or Death super-imposed in- (Mortality probably 50%) juries or infec- tion). It was concluded that persons exposed to the bombs at the time of detonation did show effects from ionizing radiation and that some of these patients, otherwise uninjured, died. Deaths from radiation began about a week after exposure and reached a peak in 3 to 4 weeks. They practically ceased to occur after 7 to 8 weeks. Treatment of the burns and other physical injuries was carried out by the Japanese by orthodox methods. Treatment of radiation effects by them included general supportative measures such as rest and high vitamin and caloric diets. Liver and calcium preparations were administered by injection and blood transfusions were used to combat hemorrhage. Special vitamin preparations and other special drugs used in the treatment of similar medical conditions were used by American Army Medical Corps officers after their arrival. Although the general measures instituted were of some benefit no definite effect of any of the specific measures on the course of the disease could be demonstrated. The use of sulfonamide drugs by the Japanese and particularly of penicillin by the American physicians after their arrival undoubtedly helped control the infections and they appear to be the single important type of treatment which may have effectively altered the earlier course of these patients. One of the most important tasks assigned to the mission which investigated the effects of the bombing was that of determining if the radiation effects were all due to the instantaneous discharges at the time of the explosion, or if people were being harmed in addition from persistent radioactivity. This question was investigated from two points of view. Direct measurements of persistent radioactivity were made at the time of the investigation. From these measurements, calculations were made of the graded radiation dosages, i.e., the total amount of radiation which could have been absorbed by any person. These calculations showed that the highest dosage which would have been received from persistent radioactivity at Hiroshima was between 6 and 25 roentgens of gamma radiation; the highest in the Nagasaki Area was between 30 and 110 roentgens of gamma radiation. The latter figure does not refer to the city itself, but to a localized area in the Nishiyama District. In interpreting these findings it must be understood that to get these dosages, one would have had to remain at the point of highest radioactivity for 6 weeks continuously, from the first hour after the bombing. It is apparent therefore that insofar as could be determined at Hiroshima and Nagasaki, the residual radiation alone could not have been detrimental to the health of persons entering and living in the bombed areas after the explosion. The second approach to this question was to determine if any persons not in the city at the time of the explosion, but coming in immediately afterwards exhibited any symptoms or findings which might have been due to persistence induced radioactivity. By the time of the arrival of the Manhattan Engineer District group, several Japanese studies had been done on such persons. None of the persons examined in any of these studies showed any symptoms which could be attributed to radiation, and their actual blood cell counts were consistently within the normal range. Throughout the period of the Manhattan Engineer District investigation, Japanese doctors and patients were repeatedly requested to bring to them any patients who they thought might be examples of persons harmed from persistent radioactivity. No such subjects were found. It was concluded therefore as a result of these findings and lack of findings, that although a measurable quantity of induced radioactivity was found, it had not been sufficient to cause any harm to persons living in the two cities after the bombings. SHIELDING FROM RADIATION Exact figures on the thicknesses of various substances to provide complete or partial protection from the effects of radiation in relation to the distance from the center of explosion, cannot be released at this time. Studies of collected data are still under way. It can be stated, however, that at a reasonable distance, say about 1/2 mile from the center of explosion, protection to persons from radiation injury can be afforded by a layer of concrete or other material whose thickness does not preclude reasonable construction. Radiation ultimately caused the death of the few persons not killed by other effects and who were fully exposed to the bombs up to a distance of about 1/2 mile from X. The British Mission has estimated that people in the open had a 50% chance of surviving the effects of radiation at 3/4 of a mile from X. EFFECTS OF THE ATOMIC BOMBINGS ON THE INHABITANTS OF THE BOMBED CITIES In both Hiroshima and Nagasaki the tremendous scale of the disaster largely destroyed the cities as entities. Even the worst of all other previous bombing attacks on Germany and Japan, such as the incendiary raids on Hamburg in 1943 and on Tokyo in 1945, were not comparable to the paralyzing effect of the atomic bombs. In addition to the huge number of persons who were killed or injuried so that their services in rehabilitation were not available, a panic flight of the population took place from both cities immediately following the atomic explosions. No significant reconstruction or repair work was accomplished because of the slow return of the population; at the end of November 1945 each of the cities had only about 140,000 people. Although the ending of the war almost immediately after the atomic bombings removed much of the incentive of the Japanese people toward immediate reconstruction of their losses, their paralysis was still remarkable. Even the clearance of wreckage and the burning of the many bodies trapped in it were not well organized some weeks after the bombings. As the British Mission has stated, "the impression which both cities make is of having sunk, in an instant and without a struggle, to the most primitive level." Aside from physical injury and damage, the most significant effect of the atomic bombs was the sheer terror which it struck into the peoples of the bombed cities. This terror, resulting in immediate hysterical activity and flight from the cities, had one especially pronounced effect: persons who had become accustomed to mass air raids had grown to pay little heed to single planes or small groups of planes, but after the atomic bombings the appearance of a single plane caused more terror and disruption of normal life than the appearance of many hundreds of planes had ever been able to cause before. The effect of this terrible fear of the potential danger from even a single enemy plane on the lives of the peoples of the world in the event of any future war can easily be conjectured. The atomic bomb did not alone win the war against Japan, but it most certainly ended it, saving the thousands of Allied lives that would have been lost in any combat invasion of Japan. EYEWITNESS ACCOUNT Hiroshima--August 6th, 1945 by Father John A. Siemes, professor of modern philosphy at Tokyo's Catholic University Up to August 6th, occasional bombs, which did no great damage, had fallen on Hiroshima. Many cities roundabout, one after the other, were destroyed, but Hiroshima itself remained protected. There were almost daily observation planes over the city but none of them dropped a bomb. The citizens wondered why they alone had remained undisturbed for so long a time. There were fantastic rumors that the enemy had something special in mind for this city, but no one dreamed that the end would come in such a fashion as on the morning of August 6th. August 6th began in a bright, clear, summer morning. About seven o'clock, there was an air raid alarm which we had heard almost every day and a few planes appeared over the city. No one paid any attention and at about eight o'clock, the all-clear was sounded. I am sitting in my room at the Novitiate of the Society of Jesus in Nagatsuke; during the past half year, the philosophical and theological section of our Mission had been evacuated to this place from Tokyo. The Novitiate is situated approximately two kilometers from Hiroshima, half-way up the sides of a broad valley which stretches from the town at sea level into this mountainous hinterland, and through which courses a river. From my window, I have a wonderful view down the valley to the edge of the city. Suddenly--the time is approximately 8:14--the whole valley is filled by a garish light which resembles the magnesium light used in photography, and I am conscious of a wave of heat. I jump to the window to find out the cause of this remarkable phenomenon, but I see nothing more than that brilliant yellow light. As I make for the door, it doesn't occur to me that the light might have something to do with enemy planes. On the way from the window, I hear a moderately loud explosion which seems to come from a distance and, at the same time, the windows are broken in with a loud crash. There has been an interval of perhaps ten seconds since the flash of light. I am sprayed by fragments of glass. The entire window frame has been forced into the room. I realize now that a bomb has burst and I am under the impression that it exploded directly over our house or in the immediate vicinity. I am bleeding from cuts about the hands and head. I attempt to get out of the door. It has been forced outwards by the air pressure and has become jammed. I force an opening in the door by means of repeated blows with my hands and feet and come to a broad hallway from which open the various rooms. Everything is in a state of confusion. All windows are broken and all the doors are forced inwards. The bookshelves in the hallway have tumbled down. I do not note a second explosion and the fliers seem to have gone on. Most of my colleagues have been injured by fragments of glass. A few are bleeding but none has been seriously injured. All of us have been fortunate since it is now apparent that the wall of my room opposite the window has been lacerated by long fragments of glass. We proceed to the front of the house to see where the bomb has landed. There is no evidence, however, of a bomb crater; but the southeast section of the house is very severely damaged. Not a door nor a window remains. The blast of air had penetrated the entire house from the southeast, but the house still stands. It is constructed in a Japanese style with a wooden framework, but has been greatly strengthened by the labor of our Brother Gropper as is frequently done in Japanese homes. Only along the front of the chapel which adjoins the house, three supports have given way (it has been made in the manner of Japanese temple, entirely out of wood.) Down in the valley, perhaps one kilometer toward the city from us, several peasant homes are on fire and the woods on the opposite side of the valley are aflame. A few of us go over to help control the flames. While we are attempting to put things in order, a storm comes up and it begins to rain. Over the city, clouds of smoke are rising and I hear a few slight explosions. I come to the conclusion that an incendiary bomb with an especially strong explosive action has gone off down in the valley. A few of us saw three planes at great altitude over the city at the time of the explosion. I, myself, saw no aircraft whatsoever. Perhaps a half-hour after the explosion, a procession of people begins to stream up the valley from the city. The crowd thickens continuously. A few come up the road to our house. We give them first aid and bring them into the chapel, which we have in the meantime cleaned and cleared of wreckage, and put them to rest on the straw mats which constitute the floor of Japanese houses. A few display horrible wounds of the extremities and back. The small quantity of fat which we possessed during this time of war was soon used up in the care of the burns. Father Rektor who, before taking holy orders, had studied medicine, ministers to the injured, but our bandages and drugs are soon gone. We must be content with cleansing the wounds. More and more of the injured come to us. The least injured drag the more seriously wounded. There are wounded soldiers, and mothers carrying burned children in their arms. From the houses of the farmers in the valley comes word: "Our houses are full of wounded and dying. Can you help, at least by taking the worst cases?" The wounded come from the sections at the edge of the city. They saw the bright light, their houses collapsed and buried the inmates in their rooms. Those that were in the open suffered instantaneous burns, particularly on the lightly clothed or unclothed parts of the body. Numerous fires sprang up which soon consumed the entire district. We now conclude that the epicenter of the explosion was at the edge of the city near the Jokogawa Station, three kilometers away from us. We are concerned about Father Kopp who that same morning, went to hold Mass at the Sisters of the Poor, who have a home for children at the edge of the city. He had not returned as yet. Toward noon, our large chapel and library are filled with the seriously injured. The procession of refugees from the city continues. Finally, about one o'clock, Father Kopp returns, together with the Sisters. Their house and the entire district where they live has burned to the ground. Father Kopp is bleeding about the head and neck, and he has a large burn on the right palm. He was standing in front of the nunnery ready to go home. All of a sudden, he became aware of the light, felt the wave of heat and a large blister formed on his hand. The windows were torn out by the blast. He thought that the bomb had fallen in his immediate vicinity. The nunnery, also a wooden structure made by our Brother Gropper, still remained but soon it is noted that the house is as good as lost because the fire, which had begun at many points in the neighborhood, sweeps closer and closer, and water is not available. There is still time to rescue certain things from the house and to bury them in an open spot. Then the house is swept by flame, and they fight their way back to us along the shore of the river and through the burning streets. Soon comes news that the entire city has been destroyed by the explosion and that it is on fire. What became of Father Superior and the three other Fathers who were at the center of the city at the Central Mission and Parish House? We had up to this time not given them a thought because we did not believe that the effects of the bomb encompassed the entire city. Also, we did not want to go into town except under pressure of dire necessity, because we thought that the population was greatly perturbed and that it might take revenge on any foreigners which they might consider spiteful onlookers of their misfortune, or even spies. Father Stolte and Father Erlinghagen go down to the road which is still full of refugees and bring in the seriously injured who have sunken by the wayside, to the temporary aid station at the village school. There iodine is applied to the wounds but they are left uncleansed. Neither ointments nor other therapeutic agents are available. Those that have been brought in are laid on the floor and no one can give them any further care. What could one do when all means are lacking? Under those circumstances, it is almost useless to bring them in. Among the passersby, there are many who are uninjured. In a purposeless, insensate manner, distraught by the magnitude of the disaster most of them rush by and none conceives the thought of organizing help on his own initiative. They are concerned only with the welfare of their own families. It became clear to us during these days that the Japanese displayed little initiative, preparedness, and organizational skill in preparation for catastrophes. They failed to carry out any rescue work when something could have been saved by a cooperative effort, and fatalistically let the catastrophe take its course. When we urged them to take part in the rescue work, they did everything willingly, but on their own initiative they did very little. At about four o'clock in the afternoon, a theology student and two kindergarten children, who lived at the Parish House and adjoining buildings which had burned down, came in and said that Father Superior LaSalle and Father Schiffer had been seriously injured and that they had taken refuge in Asano Park on the river bank. It is obvious that we must bring them in since they are too weak to come here on foot. Hurriedly, we get together two stretchers and seven of us rush toward the city. Father Rektor comes along with food and medicine. The closer we get to the city, the greater is the evidence of destruction and the more difficult it is to make our way. The houses at the edge of the city are all severely damaged. Many have collapsed or burned down. Further in, almost all of the dwellings have been damaged by fire. Where the city stood, there is a gigantic burned-out scar. We make our way along the street on the river bank among the burning and smoking ruins. Twice we are forced into the river itself by the heat and smoke at the level of the street. Frightfully burned people beckon to us. Along the way, there are many dead and dying. On the Misasi Bridge, which leads into the inner city we are met by a long procession of soldiers who have suffered burns. They drag themselves along with the help of staves or are carried by their less severely injured comrades...an endless procession of the unfortunate. Abandoned on the bridge, there stand with sunken heads a number of horses with large burns on their flanks. On the far side, the cement structure of the local hospital is the only building that remains standing. Its interior, however, has been burned out. It acts as a landmark to guide us on our way. Finally we reach the entrance of the park. A large proportion of the populace has taken refuge there, but even the trees of the park are on fire in several places. Paths and bridges are blocked by the trunks of fallen trees and are almost impassable. We are told that a high wind, which may well have resulted from the heat of the burning city, has uprooted the large trees. It is now quite dark. Only the fires, which are still raging in some places at a distance, give out a little light. At the far corner of the park, on the river bank itself, we at last come upon our colleagues. Father Schiffer is on the ground pale as a ghost. He has a deep incised wound behind the ear and has lost so much blood that we are concerned about his chances for survival. The Father Superior has suffered a deep wound of the lower leg. Father Cieslik and Father Kleinsorge have minor injuries but are completely exhausted. While they are eating the food that we have brought along, they tell us of their experiences. They were in their rooms at the Parish House--it was a quarter after eight, exactly the time when we had heard the explosion in Nagatsuke--when came the intense light and immediately thereafter the sound of breaking windows, walls and furniture. They were showered with glass splinters and fragments of wreckage. Father Schiffer was buried beneath a portion of a wall and suffered a severe head injury. The Father Superior received most of the splinters in his back and lower extremity from which he bled copiously. Everything was thrown about in the rooms themselves, but the wooden framework of the house remained intact. The solidity of the structure which was the work of Brother Gropper again shone forth. They had the same impression that we had in Nagatsuke: that the bomb had burst in their immediate vicinity. The Church, school, and all buildings in the immediate vicinity collapsed at once. Beneath the ruins of the school, the children cried for help. They were freed with great effort. Several others were also rescued from the ruins of nearby dwellings. Even the Father Superior and Father Schiffer despite their wounds, rendered aid to others and lost a great deal of blood in the process. In the meantime, fires which had begun some distance away are raging even closer, so that it becomes obvious that everything would soon burn down. Several objects are rescued from the Parish House and were buried in a clearing in front of the Church, but certain valuables and necessities which had been kept ready in case of fire could not be found on account of the confusion which had been wrought. It is high time to flee, since the oncoming flames leave almost no way open. Fukai, the secretary of the Mission, is completely out of his mind. He does not want to leave the house and explains that he does not want to survive the destruction of his fatherland. He is completely uninjured. Father Kleinsorge drags him out of the house on his back and he is forcefully carried away. Beneath the wreckage of the houses along the way, many have been trapped and they scream to be rescued from the oncoming flames. They must be left to their fate. The way to the place in the city to which one desires to flee is no longer open and one must make for Asano Park. Fukai does not want to go further and remains behind. He has not been heard from since. In the park, we take refuge on the bank of the river. A very violent whirlwind now begins to uproot large trees, and lifts them high into the air. As it reaches the water, a waterspout forms which is approximately 100 meters high. The violence of the storm luckily passes us by. Some distance away, however, where numerous refugees have taken shelter, many are blown into the river. Almost all who are in the vicinity have been injured and have lost relatives who have been pinned under the wreckage or who have been lost sight of during the flight. There is no help for the wounded and some die. No one pays any attention to a dead man lying nearby. The transportation of our own wounded is difficult. It is not possible to dress their wounds properly in the darkness, and they bleed again upon slight motion. As we carry them on the shaky litters in the dark over fallen trees of the park, they suffer unbearable pain as the result of the movement, and lose dangerously large quantities of blood. Our rescuing angel in this difficult situation is a Japanese Protestant pastor. He has brought up a boat and offers to take our wounded up stream to a place where progress is easier. First, we lower the litter containing Father Schiffer into the boat and two of us accompany him. We plan to bring the boat back for the Father Superior. The boat returns about one-half hour later and the pastor requests that several of us help in the rescue of two children whom he had seen in the river. We rescue them. They have severe burns. Soon they suffer chills and die in the park. The Father Superior is conveyed in the boat in the same manner as Father Schiffer. The theology student and myself accompany him. Father Cieslik considers himself strong enough to make his way on foot to Nagatsuke with the rest of us, but Father Kleinsorge cannot walk so far and we leave him behind and promise to come for him and the housekeeper tomorrow. From the other side of the stream comes the whinny of horses who are threatened by the fire. We land on a sand spit which juts out from the shore. It is full of wounded who have taken refuge there. They scream for aid for they are afraid of drowning as the river may rise with the sea, and cover the sand spit. They themselves are too weak to move. However, we must press on and finally we reach the spot where the group containing Father Schiffer is waiting. Here a rescue party had brought a large case of fresh rice cakes but there is no one to distribute them to the numerous wounded that lie all about. We distribute them to those that are nearby and also help ourselves. The wounded call for water and we come to the aid of a few. Cries for help are heard from a distance, but we cannot approach the ruins from which they come. A group of soldiers comes along the road and their officer notices that we speak a strange language. He at once draws his sword, screamingly demands who we are and threatens to cut us down. Father Laures, Jr., seizes his arm and explains that we are German. We finally quiet him down. He thought that we might well be Americans who had parachuted down. Rumors of parachutists were being bandied about the city. The Father Superior who was clothed only in a shirt and trousers, complains of feeling freezing cold, despite the warm summer night and the heat of the burning city. The one man among us who possesses a coat gives it to him and, in addition, I give him my own shirt. To me, it seems more comfortable to be without a shirt in the heat. In the meantime, it has become midnight. Since there are not enough of us to man both litters with four strong bearers, we determine to remove Father Schiffer first to the outskirts of the city. From there, another group of bearers is to take over to Nagatsuke; the others are to turn back in order to rescue the Father Superior. I am one of the bearers. The theology student goes in front to warn us of the numerous wires, beams and fragments of ruins which block the way and which are impossible to see in the dark. Despite all precautions, our progress is stumbling and our feet get tangled in the wire. Father Kruer falls and carries the litter with him. Father Schiffer becomes half unconscious from the fall and vomits. We pass an injured man who sits all alone among the hot ruins and whom I had seen previously on the way down. On the Misasa Bridge, we meet Father Tappe and Father Luhmer, who have come to meet us from Nagatsuke. They had dug a family out of the ruins of their collapsed house some fifty meters off the road. The father of the family was already dead. They had dragged out two girls and placed them by the side of the road. Their mother was still trapped under some beams. They had planned to complete the rescue and then to press on to meet us. At the outskirts of the city, we put down the litter and leave two men to wait until those who are to come from Nagatsuke appear. The rest of us turn back to fetch the Father Superior. Most of the ruins have now burned down. The darkness kindly hides the many forms that lie on the ground. Only occasionally in our quick progress do we hear calls for help. One of us remarks that the remarkable burned smell reminds him of incinerated corpses. The upright, squatting form which we had passed by previously is still there. Transportation on the litter, which has been constructed out of boards, must be very painful to the Father Superior, whose entire back is full of fragments of glass. In a narrow passage at the edge of town, a car forces us to the edge of the road. The litter bearers on the left side fall into a two meter deep ditch which they could not see in the darkness. Father Superior hides his pain with a dry joke, but the litter which is now no longer in one piece cannot be carried further. We decide to wait until Kinjo can bring a hand cart from Nagatsuke. He soon comes back with one that he has requisitioned from a collapsed house. We place Father Superior on the cart and wheel him the rest of the way, avoiding as much as possible the deeper pits in the road. About half past four in the morning, we finally arrive at the Novitiate. Our rescue expedition had taken almost twelve hours. Normally, one could go back and forth to the city in two hours. Our two wounded were now, for the first time, properly dressed. I get two hours sleep on the floor; some one else has taken my own bed. Then I read a Mass in gratiarum actionem, it is the 7th of August, the anniversary of the foundation of our society. Then we bestir ourselves to bring Father Kleinsorge and other acquaintances out of the city. We take off again with the hand cart. The bright day now reveals the frightful picture which last night's darkness had partly concealed. Where the city stood everything, as far as the eye could reach, is a waste of ashes and ruin. Only several skeletons of buildings completely burned out in the interior remain. The banks of the river are covered with dead and wounded, and the rising waters have here and there covered some of the corpses. On the broad street in the Hakushima district, naked burned cadavers are particularly numerous. Among them are the wounded who are still alive. A few have crawled under the burnt-out autos and trams. Frightfully injured forms beckon to us and then collapse. An old woman and a girl whom she is pulling along with her fall down at our feet. We place them on our cart and wheel them to the hospital at whose entrance a dressing station has been set up. Here the wounded lie on the hard floor, row on row. Only the largest wounds are dressed. We convey another soldier and an old woman to the place but we cannot move everybody who lies exposed in the sun. It would be endless and it is questionable whether those whom we can drag to the dressing station can come out alive, because even here nothing really effective can be done. Later, we ascertain that the wounded lay for days in the burnt-out hallways of the hospital and there they died. We must proceed to our goal in the park and are forced to leave the wounded to their fate. We make our way to the place where our church stood to dig up those few belongings that we had buried yesterday. We find them intact. Everything else has been completely burned. In the ruins, we find a few molten remnants of holy vessels. At the park, we load the housekeeper and a mother with her two children on the cart. Father Kleinsorge feels strong enough, with the aid of Brother Nobuhara, to make his way home on foot. The way back takes us once again past the dead and wounded in Hakushima. Again no rescue parties are in evidence. At the Misasa Bridge, there still lies the family which the Fathers Tappe and Luhmer had yesterday rescued from the ruins. A piece of tin had been placed over them to shield them from the sun. We cannot take them along for our cart is full. We give them and those nearby water to drink and decide to rescue them later. At three o'clock in the afternoon, we are back in Nagatsuka. After we have had a few swallows and a little food, Fathers Stolte, Luhmer, Erlinghagen and myself, take off once again to bring in the family. Father Kleinsorge requests that we also rescue two children who had lost their mother and who had lain near him in the park. On the way, we were greeted by strangers who had noted that we were on a mission of mercy and who praised our efforts. We now met groups of individuals who were carrying the wounded about on litters. As we arrived at the Misasa Bridge, the family that had been there was gone. They might well have been borne away in the meantime. There was a group of soldiers at work taking away those that had been sacrificed yesterday. More than thirty hours had gone by until the first official rescue party had appeared on the scene. We find both children and take them out of the park: a six-year old boy who was uninjured, and a twelve-year old girl who had been burned about the head, hands and legs, and who had lain for thirty hours without care in the park. The left side of her face and the left eye were completely covered with blood and pus, so that we thought that she had lost the eye. When the wound was later washed, we noted that the eye was intact and that the lids had just become stuck together. On the way home, we took another group of three refugees with us. They first wanted to know, however, of what nationality we were. They, too, feared that we might be Americans who had parachuted in. When we arrived in Nagatsuka, it had just become dark. We took under our care fifty refugees who had lost everything. The majority of them were wounded and not a few had dangerous burns. Father Rektor treated the wounds as well as he could with the few medicaments that we could, with effort, gather up. He had to confine himself in general to cleansing the wounds of purulent material. Even those with the smaller burns are very weak and all suffered from diarrhea. In the farm houses in the vicinity, almost everywhere, there are also wounded. Father Rektor made daily rounds and acted in the capacity of a painstaking physician and was a great Samaritan. Our work was, in the eyes of the people, a greater boost for Christianity than all our work during the preceding long years. Three of the severely burned in our house died within the next few days. Suddenly the pulse and respirations ceased. It is certainly a sign of our good care that so few died. In the official aid stations and hospitals, a good third or half of those that had been brought in died. They lay about there almost without care, and a very high percentage succumbed. Everything was lacking: doctors, assistants, dressings, drugs, etc. In an aid station at a school at a nearby village, a group of soldiers for several days did nothing except to bring in and cremate the dead behind the school. During the next few days, funeral processions passed our house from morning to night, bringing the deceased to a small valley nearby. There, in six places, the dead were burned. People brought their own wood and themselves did the cremation. Father Luhmer and Father Laures found a dead man in a nearby house who had already become bloated and who emitted a frightful odor. They brought him to this valley and incinerated him themselves. Even late at night, the little valley was lit up by the funeral pyres. We made systematic efforts to trace our acquaintances and the families of the refugees whom we had sheltered. Frequently, after the passage of several weeks, some one was found in a distant village or hospital but of many there was no news, and these were apparently dead. We were lucky to discover the mother of the two children whom we had found in the park and who had been given up for dead. After three weeks, she saw her children once again. In the great joy of the reunion were mingled the tears for those whom we shall not see again. The magnitude of the disaster that befell Hiroshima on August 6th was only slowly pieced together in my mind. I lived through the catastrophe and saw it only in flashes, which only gradually were merged to give me a total picture. What actually happened simultaneously in the city as a whole is as follows: As a result of the explosion of the bomb at 8:15, almost the entire city was destroyed at a single blow. Only small outlying districts in the southern and eastern parts of the town escaped complete destruction. The bomb exploded over the center of the city. As a result of the blast, the small Japanese houses in a diameter of five kilometers, which compressed 99% of the city, collapsed or were blown up. Those who were in the houses were buried in the ruins. Those who were in the open sustained burns resulting from contact with the substance or rays emitted by the bomb. Where the substance struck in quantity, fires sprang up. These spread rapidly. The heat which rose from the center created a whirlwind which was effective in spreading fire throughout the whole city. Those who had been caught beneath the ruins and who could not be freed rapidly, and those who had been caught by the flames, became casualties. As much as six kilometers from the center of the explosion, all houses were damaged and many collapsed and caught fire. Even fifteen kilometers away, windows were broken. It was rumored that the enemy fliers had spread an explosive and incendiary material over the city and then had created the explosion and ignition. A few maintained that they saw the planes drop a parachute which had carried something that exploded at a height of 1,000 meters. The newspapers called the bomb an "atomic bomb" and noted that the force of the blast had resulted from the explosion of uranium atoms, and that gamma rays had been sent out as a result of this, but no one knew anything for certain concerning the nature of the bomb. How many people were a sacrifice to this bomb? Those who had lived through the catastrophe placed the number of dead at at least 100,000. Hiroshima had a population of 400,000. Official statistics place the number who had died at 70,000 up to September 1st, not counting the missing ... and 130,000 wounded, among them 43,500 severely wounded. Estimates made by ourselves on the basis of groups known to us show that the number of 100,000 dead is not too high. Near us there are two barracks, in each of which forty Korean workers lived. On the day of the explosion, they were laboring on the streets of Hiroshima. Four returned alive to one barracks and sixteen to the other. 600 students of the Protestant girls' school worked in a factory, from which only thirty to forty returned. Most of the peasant families in the neighborhood lost one or more of their members who had worked at factories in the city. Our next door neighbor, Tamura, lost two children and himself suffered a large wound since, as it happened, he had been in the city on that day. The family of our reader suffered two dead, father and son; thus a family of five members suffered at least two losses, counting only the dead and severely wounded. There died the Mayor, the President of the central Japan district, the Commander of the city, a Korean prince who had been stationed in Hiroshima in the capacity of an officer, and many other high ranking officers. Of the professors of the University, thirty-two were killed or severely injured. Especially hard hit were the soldiers. The Pioneer Regiment was almost entirely wiped out. The barracks were near the center of the explosion. Thousands of wounded who died later could doubtless have been rescued had they received proper treatment and care, but rescue work in a catastrophe of this magnitude had not been envisioned; since the whole city had been knocked out at a blow, everything which had been prepared for emergency work was lost, and no preparation had been made for rescue work in the outlying districts. Many of the wounded also died because they had been weakened by under-nourishment and consequently lacked in strength to recover. Those who had their normal strength and who received good care slowly healed the burns which had been occasioned by the bomb. There were also cases, however, whose prognosis seemed good who died suddenly. There were also some who had only small external wounds who died within a week or later, after an inflammation of the pharynx and oral cavity had taken place. We thought at first that this was the result of inhalation of the substance of the bomb. Later, a commission established the thesis that gamma rays had been given out at the time of the explosion, following which the internal organs had been injured in a manner resembling that consequent upon Roentgen irradiation. This produces a diminution in the numbers of the white corpuscles. Only several cases are known to me personally where individuals who did not have external burns later died. Father Kleinsorge and Father Cieslik, who were near the center of the explosion, but who did not suffer burns became quite weak some fourteen days after the explosion. Up to this time small incised wounds had healed normally, but thereafter the wounds which were still unhealed became worse and are to date (in September) still incompletely healed. The attending physician diagnosed it as leucopania. There thus seems to be some truth in the statement that the radiation had some effect on the blood. I am of the opinion, however, that their generally undernourished and weakened condition was partly responsible for these findings. It was noised about that the ruins of the city emitted deadly rays and that workers who went there to aid in the clearing died, and that the central district would be uninhabitable for some time to come. I have my doubts as to whether such talk is true and myself and others who worked in the ruined area for some hours shortly after the explosion suffered no such ill effects. None of us in those days heard a single outburst against the Americans on the part of the Japanese, nor was there any evidence of a vengeful spirit. The Japanese suffered this terrible blow as part of the fortunes of war ... something to be borne without complaint. During this, war, I have noted relatively little hatred toward the allies on the part of the people themselves, although the press has taken occasion to stir up such feelings. After the victories at the beginning of the war, the enemy was rather looked down upon, but when allied offensive gathered momentum and especially after the advent of the majestic B-29's, the technical skill of America became an object of wonder and admiration. The following anecdote indicates the spirit of the Japanese: A few days after the atomic bombing, the secretary of the University came to us asserting that the Japanese were ready to destroy San Francisco by means of an equally effective bomb. It is dubious that he himself believed what he told us. He merely wanted to impress upon us foreigners that the Japanese were capable of similar discoveries. In his nationalistic pride, he talked himself into believing this. The Japanese also intimated that the principle of the new bomb was a Japanese discovery. It was only lack of raw materials, they said, which prevented its construction. In the meantime, the Germans were said to have carried the discovery to a further stage and were about to initiate such bombing. The Americans were reputed to have learned the secret from the Germans, and they had then brought the bomb to a stage of industrial completion. We have discussed among ourselves the ethics of the use of the bomb. Some consider it in the same category as poison gas and were against its use on a civil population. Others were of the view that in total war, as carried on in Japan, there was no difference between civilians and soldiers, and that the bomb itself was an effective force tending to end the bloodshed, warning Japan to surrender and thus to avoid total destruction. It seems logical to me that he who supports total war in principle cannot complain of war against civilians. The crux of the matter is whether total war in its present form is justifiable, even when it serves a just purpose. Does it not have material and spiritual evil as its consequences which far exceed whatever good that might result? When will our moralists give us a clear answer to this question? 
548	----	PROJECT TRINITY 1945-1946 by Carl Maag and Steve Rohrer United States Atmospheric Nuclear Weapons Tests Nuclear Test Personnel Review Prepared by the Defense Nuclear Agency as Executive Agency for the Department of Defense Destroy this report when it is no longer needed. Do not return to sender. PLEASE NOITIFY THE DEFENSE NUCLEAR AGENCY, ATTN: STTI, WASINGTON D.C. 20305, IF YOUR ADDRESS IS INCORRECT, IF YOU WISH TO BE DELETED FROM THE DISTRIBUTION LIST, OR IF THE ADDRESSEE IS NO LONGER EMPLOYED BY YOUR ORGANIZATION. Since declassified CONTENTS: LIST OF FIGURES LIST OF ABBREVIATIONS AND ACRONYMS REPORT DOCUMENTATION PAGE FACT SHEET PREFACE CHAPTERS: 1 INTRODUCTION 1.1 Historical Background of Project TRINITY 1.2 The Project TRINITY Site 1.3 The Project TRINITY Organization 1.4 Military and Civilian Participants in Project TRINITY 2 THE ACTIVITIES AT PROJECT TRINITY 2.1 Preshot Activities 2.2 Detonation and Postshot Activities 2.3 Activities after 16 July 1945 3 RADIATION PROTECTION AT PROJECT TRINITY 3.1 Organization 3.2 Site Monitoring Group 3.3 Offsite Monitoring Group 4 DOSIMETRY ANALYSIS OF PARTICIPANTS IN PROJECT TRINITY 4.1 Film Badge Records 4.2 Gamma Radiation Exposure REFERENCE LIST LIST OF FIGURES 1-1 Location of Alamogordo Bombing Range 1-2 TRINITY Site and Major Installations 1-3 Tent Used as Guard Post at Project TRINITY 1-4 Truck Used as Guard Post at Project TRINITY 1-5 Organization of Project TRINITY 2-1 The TRINITY Shot-tower 2-2 The TRINITY Detonation, 0530 Hours, 16 July 1945 2-3 The South Shelter (Control Point) 2-4 Inside One of the Shelters 2-5 The Base Camp, Headquarters for Project TRINITY 2-5 The Base Camp, Headquarters for Project TRINITY 2-6 Project TRINITY Personnel Wearing Protective Clothing 2-7 "JUMBO" after the TRINITY Detonation LIST OF ABBREVIATIONS AND ACRONYMS The following abbreviations and acronyms are used in this volume: AEC Atomic Energy Commission DOD Department of Defense LASL Los Alamos Scientific Laboratory MAUD [Committee for the] Military Application of Uranium Detonation MED Manhattan Engineer District R/h roentgens per hour UTM Universal Transverse Mercator REPORT DOCUMENTATION PAGE SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered): UNCLASSIFIED 1. REPORT NUMBER: DNA 6028F 2. GOVT ACCESSION NO.: 3. RECIPIENT'S CATALOG NUMBER: 4. TITLE (and Subtitle): PROJECT TRINITY 1945-1946 5. TYPE OF REPORT & PERIOD COVERED: Final Report 6. PERFORMING ORG. REPORT NUMBER: JRB 2-816-03-423-00 7. AUTHOR(S): Carl Maag, Steve Rorer 8. CONTRACT OR GRANT NUMBER(S): DNA 001-79-C-0473 9. PERFORMING ORGANIZATION NAME AND ADDRESS: JRB Associates 8400 Westpark Drive McLean, Virginia 22102 10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS: Subtask U99QAXMK506-08 11. CONTROLLING OFFICE NAME AND ADDRESS: Director Defense Nuclear Agency Washington, D.C. 20305 12. REPORT DATE: 15 December 1982 13. NUMBER OF PAGES: 76 14. MONITORING AGENCY NAME & ADDRESS(if different from Controlling Office): 15. SECURITY CLASS. (of this report): UNCLASSIFIED 15a. DECLASSIFICATION/DOWNGRADING SCHEDULE: N/A Since UNCLASSIFIED 16. DISTRIBUTION STATEMENT (of this Report): Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of the abstract entered In Block 20, If different from Report): 18. SUPPLEMENTARY NOTES: This work was sponsored by the Defense Nuclear Agency under RDT&E RMSS Code B350079464 U99QAXMK50608 H2590D. For sale by National Technical Information Service, Springfield, VA 22161. The Defense Nuclear Agency Action Officer, Lt. Col. H. L. Reese, USAF, under whom this work was done, wishes to acknowledge the research and editing contribution of numerous reviewers in the military services and other organizations in addition to those writers listed in block 7. 19. KEY WORDS (Continue on reverse side if necessary and Identify by block number): TRINITY Los Alamos Scientific Laboratory Alamogordo Bombing Range Manhattan Engineer District Manhattan Project Personnel Dosimetry Radiation Exposure Nuclear Weapons Testing 20. ABSTRACT: This report describes the activities of an estimated 1,000 personnel, both military and civilian, in Project TRINITY, which culminated in detonation of the first nuclear device, in New Mexico in 1945. Scientific and diagnostic experiments to evaluate the effects of the nuclear device were the primary activities engaging military personnel. FACT SHEET Defense Nuclear Agency Public Affairs Office Washington, D C. 20305 Subject: Project TRINITY Project TRINITY, conducted by the Manhattan Engineer District (MED), was designed to test and assess the effects of a nuclear weapon. The TRINITY nuclear device was detonated on a 100-foot tower on the Alamogordo Bombing Range in south-central New Mexico at 0530 hours on 16 July 1945. The nuclear yield of the detonation was equivalent to the energy released by detonating 19 kilotons of TNT. At shot-time, the temperature was 21.8 degrees Celsius, and surface air pressure was 850 millibars. The winds were nearly calm at the surface; at 10,300 feet above mean sea level, they were from the southwest at 10 knots. The winds blew the cloud resulting from the detonation to the northeast. From 16 July 1945 through 1946, about 1,000 military and civilian personnel took part in Project TRINITY or visited the test site. The location of the test site and its major installations are shown in the accompanying figures. Military and Scientific Activities All participants in Project TRINITY, both military and civilian, were under the authority of the MED. No military exercises were conducted. The Los Alamos Scientific Laboratory (LASL), which was staffed and administered by the University of California (under contract to the MED), conducted diagnostic experiments. Civilian and military scientists and technicians, with assistance from other military personnel, placed gauges, detectors, and other instruments around ground zero before the detonation. Four offsite monitoring posts were established in the towns of Nogal, Roswell, Socorro, and Fort Sumner, New Mexico. An evacuation detachment consisting of 144 to 160 enlisted men and officers was established in case protective measures or evacuation of civilians living offsite became necessary. At least 94 of these personnel were from the Provisional Detachment Number 1, Company "B," of the 9812th Technical Service Unit, Army Corps of Engineers. Military police cleared the test area and recorded the locations of all personnel before the detonation. A radiological monitor was assigned to each of the three shelters, which were located to the north, west, and south of ground zero. Soon after the detonation, the monitors surveyed the area immediately around the shelters and then proceeded out the access road to its intersection with the main road, Broadway. Personnel not essential to postshot activities were transferred from the west and south shelters to the Base Camp, about 16 kilometers southwest of ground zero. Personnel at the north shelter were evacuated when a sudden rise in radiation levels was detected; it was later learned that the instrument had not been accurately calibrated and levels had not increased as much as the instrument indicated. Specially designated groups conducted onsite and offsite radiological surveys. Safety Standards and Procedures The safety criteria established for Project TRINITY were based on calculations of the anticipated dangers from blast pressure, thermal radiation, and ionizing radiation. The TR-7 Group, also known as the Medical Group, was responsible for radiological safety. A limit of 5 roentgens of exposure during a two-month period was established. The Site and Offsite Monitoring Groups were both part of the Medical Group. The Site Monitoring Group was responsible for equipping personnel with protective clothing and instruments to measure radiation exposure, monitoring and recording personnel exposure according to film badge readings and time spent in the test area, and providing for personnel decontamination. The Offsite Monitoring Group surveyed areas surrounding the test site for radioactive fallout. In addition to these two monitoring groups, a small group of medical technicians provided radiation detection instruments and monitoring. Radiation Exposures at Project TRINITY Dosimetry information is available for about 815 individuals who either participated in Project TRINITY activities or visited the test site between 16 July 1945 and 1 January 1947. The listing does not indicate the precise military or unit affiliation of all personnel. Less than six percent of the Project TRINITY participants received exposures greater than 2 roentgens. Twenty-three of these individuals received exposures greater than 2 but less than 4 roentgens; another 22 individuals received between 4 and 15 roentgens. PREFACE From 1945 to 1962, the U.S. Government, through the Manhattan Engineer District (MED) and its successor agency, the Atomic Energy Commission (AEC), conducted 235 tests of nuclear devices at sites in the United States and in the Atlantic and Pacific Oceans. In all, an estimated 220,000 Department of Defense (DOD)* participants, both military and civilian, were present at the tests. Project TRINITY, the war-time effort to test-fire a nuclear explosive device, was the first atmospheric nuclear weapons test. * The MED, which was part of the Army Corps of Engineers, administered the U.S. nuclear testing program until the AEC came into existence in 1946. Before DOD was established in 1947, the Army Corps of Engineers was under the War Department. In 1977, 15 years after the last above-ground nuclear weapons test, the Centers for Disease Control** noted a possible leukemia cluster among a small group of soldiers present at Shot SMOKY, a test of Operation PLUMBBOB, the series of atmospheric nuclear weapons tests conducted in 1957. Since that initial report by the Centers for Disease Control, the Veterans Administration has received a number of claims for medical benefits from former military personnel who believe their health may have been affected by their participation in the weapons testing program. ** The Centers for Disease Control are part of the U.S. Department of Health and Human Services (formerly the U.S. Department of Health, Education, and Welfare). In late 1977, DOD began a study to provide data to both the Centers for Disease Control and the Veterans Administration on potential exposures to ionizing radiation among the military and civilian participants in atmospheric nuclear weapons testing. DOD organized an effort to: o Identify DOD personnel who had taken part in the atmospheric nuclear weapons tests o Determine the extent of the participants' exposure to ionizing radiation o Provide public disclosure of information concerning participation by military personnel in Project TRINITY. METHODS AND SOURCES USED TO PREPARE THIS VOLUME This report on Project TRINITY is based on historical and technical documents associated with the detonation of the first nuclear device on 16 July 1945. The Department of Defense compiled information for this volume from documents that record the scientific activities during Project TRINITY. These records, most of which were developed by participants in TRINITY, are kept in several document repositories throughout the United States. In compiling information for this report, historians, health physicists, radiation specialists, and information analysts canvassed document repositories known to contain materials on atmospheric nuclear weapons tests conducted in the southwestern United States. These repositories included armed services libraries, Government agency archives and libraries, Federal repositories, and libraries of scientific and technical laboratories. Researchers examined classified and unclassified documents containing information on the participation of personnel from the MED, which supervised Project TRINITY, and from the Los Alamos Scientific Laboratory (LASL), which developed the TRINITY device. After this initial effort, researchers recorded relevant information concerning the activities of MED and LASL personnel and catalogued the data sources. Many of the documents pertaining specifically to MED and LASL participation were found in the Defense Nuclear Agency Technical Library and the LASL Records Center. Information on the fallout pattern, meteorological conditions, and nuclear cloud dimensions is taken from Volume 1 of the General Electric Company-TEMPO's "Compilation of Local Fallout Data from Test Detonations 1945-1962, Extracted from DASA 1251," unless more specific information is available elsewhere. ORGANIZATION OF THIS VOLUME The following chapters detail MED and LASL participation in Project TRINITY. Chapter 1 provides background information, including a description of the TRINITY test site. Chapter 2 describes the activities of MED and LASL participants before, during, and after the detonation. Chapter 3 discusses the radiological safety criteria and procedures in effect for Project TRINITY, and chapter 4 presents the results of the radiation monitoring program, including information on film badge readings for participants in the project. The information in this report is supplemented by the Reference Manual: Background Materials for the CONUS Volumes." The manual summarizes information on radiation physics, radiation health concepts, exposure criteria, and measurement techniques. It also lists acronyms and includes a glossary of terms used in the DOD reports addressing test events in the continental United States. CHAPTER 1 INTRODUCTION Project TRINITY was the name given to the war-time effort to produce the first nuclear detonation. A plutonium-fueled implosion device was detonated on 16 July 1945 at the Alamogordo Bombing Range in south-central New Mexico. Three weeks later, on 6 August, the first uranium-fueled nuclear bomb, a gun-type weapon code-named LITTLE BOY, was detonated over the Japanese city of Hiroshima. On 9 August, the FAT MAN nuclear bomb, a plutonium-fueled implosion weapon identical to the TRINITY device, was detonated over another Japanese city, Nagasaki. Two days later, the Japanese Government informed the United States of its decision to end the war. On 2 September 1945, the Japanese Empire officially surrendered to the Allied Governments, bringing World War II to an end. In the years devoted to the development and construction of a nuclear weapon, scientists and technicians expanded their knowledge of nuclear fission and developed both the gun-type and the implosion mechanisms to release the energy of a nuclear chain reaction. Their knowledge, however, was only theoretical. They could be certain neither of the extent and effects of such a nuclear chain reaction, nor of the hazards of the resulting blast and radiation. Protective measures could be based only on estimates and calculations. Furthermore, scientists were reasonably confident that the gun-type uranium-fueled device could be successfully detonated, but they did not know if the more complex firing technology required in an implosion device would work. Successful detonation of the TRINITY device showed that implosion would work, that a nuclear chain reaction would result in a powerful detonation, and that effective means exist to guard against the blast and radiation produced. 1.1 HISTORICAL BACKGROUND OF PROJECT TRINITY The development of a nuclear weapon was a low priority for the United States before the outbreak of World War II. However, scientists exiled from Germany had expressed concern that the Germans were developing a nuclear weapon. Confirming these fears, in 1939 the Germans stopped all sales of uranium ore from the mines of occupied Czechoslovakia. In a letter sponsored by group of concerned scientists, Albert Einstein informed President Roosevelt that German experiments had shown that an induced nuclear chain reaction was possible and could be used to construct extremely powerful bombs (7; 12)*. * All sources cited in the text are listed alphabetically in the reference list at the end of this volume. The number given in the text corresponds to the number of the source document in the reference list. In response to the potential threat of a German nuclear weapon, the United States sought a source of uranium to use in determining the feasibility of a nuclear chain reaction. After Germany occupied Belgium in May 1940, the Belgians turned over uranium ore from their holdings in the Belgian Congo to the United States. Then, in March 1941, the element plutonium was isolated, and the plutonium-239 isotope was found to fission as readily as the scarce uranium isotope, uranium-235. The plutonium, produced in a uranium-fueled nuclear reactor, provided the United States with an additional source of material for nuclear weapons (7; 12). In the summer of 1941, the British Government published a report written by the Committee for Military Application of Uranium Detonation (MAUD). This report stated that a nuclear weapon was possible and concluded that its construction should begin immediately. The MAUD report, and to a lesser degree the discovery of plutonium, encouraged American leaders to think more seriously about developing a nuclear weapon. On 6 December 1941, President Roosevelt appointed the S-1 Committee to determine if the United States could construct a nuclear weapon. Six months later, the S-1 Committee gave the President its report, recommending a fast-paced program that would cost up to $100 million and that might produce the weapon by July 1944 (12). The President accepted the S-1 Committee's recommendations. The effort to construct the weapon was turned over to the War Department, which assigned the task to the Army Corps of Engineers. In September 1942, the Corps of Engineers established the Manhattan Engineer District to oversee the development of a nuclear weapon. This effort was code-named the "Manhattan Project" (12). Within the next two years, the MED built laboratories and production plants throughout the United States. The three principal centers of the Manhattan Project were the Hanford, Washington, Plutonium Production Plant; the Oak Ridge, Tennessee, U-235 Production Plant; and the Los Alamos Scientific Laboratory in northern New Mexico. At LASL, Manhattan Project scientists and technicians, directed by Dr. J. Robert Oppenheimer,* investigated the theoretical problems that had to be solved before a nuclear weapon could be developed (12). * This report identifies by name only those LASL and MED personnel who are well-known historical figures. During the first two years of the Manhattan Project, work proceeded at a slow but steady pace. Significant technical problems had to be solved, and difficulties in the production of plutonium, particularly the inability to process large amounts, often frustrated the scientists. Nonetheless, by 1944 sufficient progress had been made to persuade the scientists that their efforts might succeed. A test of the plutonium implosion device was necessary to determine if it would work and what its effects would be. In addition, the scientists were concerned about the possible effects if the conventional explosives in a nuclear device, particularly the more complex implosion-type device, failed to trigger the nuclear reaction when detonated over enemy territory. Not only would the psychological impact of the weapon be lost, but the enemy might recover large amounts of fissionable material. In March 1944, planning began to test-fire a plutonium-fueled implosion device. At LASL, an organization designated the X-2 Group was formed within the Explosives Division. Its duties were "to make preparations for a field test in which blast, earth shock, neutron and gamma radiation would be studied and complete photographic records made of the explosion and any atmospheric phenomena connected with the explosion" (13). Dr. Oppenheimer chose the name TRINITY for the project in September 1944 (12). 1.2 THE PROJECT TRINITY SITE The TRINITY site was chosen by Manhattan Project scientists after thorough study of eight different sites. The site selected was an area measuring 29 by 39 kilometers* in the northwest corner of the Alamogordo Bombing Range. The Alamogordo Bombing Range was located in a desert in south-central New Mexico called the Jornada del Muerto ("Journey of Death"). Figure 1-1 shows the location of the bombing range. The site was chosen for its remote location and good weather and because it was already owned by the Government. MED obtained permission to use the site from the Commanding General of the Second Air Force (Army Air Forces) on 7 September 1944 (12). Figure 1-2 shows the TRINITY site with its major installations. * Throughout this report, surface distances are given in metric units. The metric conversion factors include: 1 meter = 3.28 feet; 1 meter = 1.09 yards; and 1 kilometer = 0.62 miles. Vertical distances are given in feet; altitudes are measured from mean sea level, while heights are measured from surface level, unless otherwise noted. Ground zero for the TRINITY detonation was at UTM coordinates 630266.** Three shelters, located approximately 9,150 meters (10,000 yards) north, west, and south of ground zero, were built for the protection of test personnel and instruments. The shelters had walls of reinforced concrete and were buried under a few feet of earth. The south shelter was the Control Point for the test (12). The Base Camp, which was the headquarters for Project TRINITY, was located approximately 16 kilometers southwest of ground zero. The principal buildings of the abandoned McDonald Ranch, where the active parts of the TRINITY device were assembled, stood 3,660 meters southeast of ground zero. Seven guard posts, which were simply small tents or parked trucks like the ones shown in figures 1-3 and 1-4, dotted the test site (9). ** Universal Transverse Mercator (UTM) coordinates are used in this report. The first three digits refer to a point on an east- west axis, and the second three digits refer to a point on a north-south axis. The point so designated is the southwest corner of an area 100 meters square. 1.3 THE PROJECT TRINITY ORGANIZATION The organization that planned and conducted Project TRINITY grew out of the X-2 Group. LASL, though administered by the University of California, was part of the Manhattan Project, supervised by the Army Corps of Engineers Manhattan Engineer District. The chief of MED was Maj. Gen. Leslie Groves of the Army Corps of Engineers. Major General Groves reported to both the Chief of Engineers and the Army Chief of Staff. The Army Chief of Staff reported to the Secretary of War, a Cabinet officer directly responsible to the President. Figure 1-5 outlines the organization of Project TRINITY. The director of the Project TRINITY organization was Dr. Kenneth Bainbridge. Dr. Bainbridge reported to Dr. J. Robert Oppenheimer, the director of LASL. A team of nine research consultants advised Dr. Bainbridge on scientific and technical matters (3). The Project TRINITY organization was divided into the following groups (3): o The TRINITY Assembly Group, responsible for assembling and arming the nuclear device o The TR-1 (Services) Group, responsible for construction, utilities, procurement, transportation, and communications o The TR-2 Group, responsible for air-blast and earth-shock measurements o The TR-3 (Physics) Group, responsible for experiments concerning measurements of ionizing radiation o The TR-4 Group, responsible for meteorology o The TR-5 Group, responsible for spectrographic and photographic measurements o The TR-6 Group, responsible for the airblast-airborne condenser gauges o The TR-7 (Medical) Group, responsible for the radiological safety and general health of the Project TRINITY participants. Each of these groups was divided into several units. Individuals were also assigned special tasks outside their groups, such as communications and tracking the TRINITY cloud with a searchlight (3). 1.4 MILITARY AND CIVILIAN PARTICIPANTS IN PROJECT TRINITY From March 1944 until the beginning of 1946, several thousand people participated in Project TRINITY. These included not only the LASL scientists, but also scientists, technicians, and workmen employed at MED installations throughout the United States. According to entrance logs, film badge data, and other records, about 1,000 people either worked at or visited the TRINITY site from 16 July 1945 through 1946 (1; 3; 8; 15; 16). Although supervised by Major General Groves and the Army Corps of Engineers, many Manhattan Project personnel were civilians. Military personnel were assigned principally to support services, such as security and logistics, although soldiers with special skills worked with the civilians (7; 12). Most of the military personnel were part of the Army Corps of Engineers, although Navy and other Army personnel were also assigned to the project (4; 12). CHAPTER 2 THE ACTIVITIES AT PROJECT TRINITY The TRINITY nuclear device was detonated on a 100-foot tower (shown in figure 2-1) at UTM coordinates 630266 on the Alamogordo Bombing Range, New Mexico, at 0530 Mountain War Time, on 16 July 1945. The detonation had a yield of 19 kilotons and left an impression 2.9 meters deep and 335 meters wide. The cloud resulting from the detonation rose to an altitude of 35,000 feet (5). The TRINITY detonation is shown in figure 2-2. At shot-time, the temperature was 21.8 degrees Celsius, and the surface air pressure was 850 millibars. Winds at shot-time were nearly calm at the surface but attained a speed of 10 knots from the southwest at 10,300 feet. At 34,600 feet, the wind speed was 23 knots from the southwest. The winds blew the cloud to the northeast (5). 2.1 PRESHOT ACTIVITIES Construction of test site facilities on the Alamogordo Bombing Range began in December 1944. The first contingent of personnel, 12 military policemen, arrived just before Christmas. The number of personnel at the test site gradually increased until the peak level of about 325 was reached the week before the detonation (2; 12). On 7 May 1945 at 0437 hours, 200 LASL scientists and technicians exploded 100 tons of conventional high explosives at the test site. The explosives were stacked on top of a 20-foot tower and contained tubes of radioactive solution to simulate, at a low level of activity, the radioactive products expected from a nuclear explosion. The test produced a bright sphere which spread out in an oval form. A column of smoke and debris rose as high as 15,000 feet before drifting eastward. The explosion left a shallow crater 1.5 meters deep and 9 meters wide. Monitoring in the area revealed a level of radioactivity low enough to allow workers to spend several hours in the area (3; 12). The planned firing date for the TRINITY device was 4 July 1945. On 14 June 1945, Dr. Oppenheimer changed the test date to no earlier than 13 July and no later than 23 July. On 30 June, the earliest firing date was moved to 16 July, even though better weather was forecast for 18 and 19 July. Because the Allied conference in Potsdam, Germany, was about to begin and the President needed the results of the test as soon as possible, the TRINITY test organization adjusted its schedules accordingly and set shot-time at 0400 hours on 16 July (3; 12; 14). The final preparations for the detonation started at 2200 on 15 July. To prevent unnecessary danger, all personnel not essential to the firing activities were ordered to leave the test site. During the night of 15 July, these people left for viewing positions on Compania Hill,* 32 kilometers northwest of ground zero. They were joined by several spectators from LASL (3; 12). * "Compania" also appears as "Compana," "Campagne," or "Compagna" in various sources. Project personnel not required to check instruments within the ground zero area stationed themselves in the three shelters or at other assigned locations. The military police at Guard Posts 1, 2, and 4 blocked off all roads leading into the test site, and the men at Guard Post 8, the only access to the ground zero area from the Base Camp, ensured that no unauthorized individuals entered the area (9; 12). At 0100 hours on 16 July, military policemen from Guard Posts 3, 5, 6, and 7 met to compare their logs of personnel authorized to be in the ground zero area. The guards then traveled along the access roads to clear out all project personnel. As individuals left for their assigned shelters or stations, their departures from the test area were recorded in the military police logs. By 0200 the area sweep was completed, and the military police went to their shelters and stations. A final check of personnel was made in each shelter (3; 9; 12). At the time of detonation, 99 project personnel were in the three shelters: 29 in the north shelter, 37 in the west shelter, and 33 in the south shelter. Dr. Oppenheimer, Dr. Bainbridge, and other key personnel awaited the firing at the south shelter, which served as the Control Point. Figure 2-3 shows the exterior of the south shelter; figure 2-4 gives an interior view of one of the shelters, most likely the south. Although most of the shelter occupants were civilians, at least 23 military participants were spread among the three shelters (1; 12). The remainder of the test site personnel were positioned at the Base Camp 16 kilometers south-southwest of ground zero, or on Compania Hill, or at the guard posts. Important Government officials, such as General Groves and Dr. Vannevar Bush, Director of the U.S. Office of Scientific Research and Development, viewed the detonation from a trench at the Base Camp. The Base Camp is depicted in figure 2-5. The military police of Guard Posts 1 and 2 were instructed to be in foxholes approximately five kilometers west and north, respectively, from their posts. The military police of Guard Posts 3 and 4 were instructed to be in foxholes south of Mockingbird Gap. A radiological safety monitor was assigned to the group from Guard Post 4. Guard Post 5 personnel were to be in the south shelter, Guard Post 6 personnel in the west shelter, and Guard Post 7 personnel in the north shelter. The military police of Guard Post 8 remained at that post, 400 meters east of the Base Camp (9). An evacuation detachment of between 144 and 160 officers and enlisted men was stationed near Guard Post 2, about 14 kilometers northwest of ground zero. These men were on standby in case ranches and towns beyond the test site had to be evacuated. Five radiological safety monitors were assigned to this detachment. Ninety-four men of the evacuation detachment belonged to Provisional Detachment Number 1, Company "B," of the 9812th Technical Service Unit, Army Corps of Engineers, from LASL. The identity of the remaining evacuation personnel has not been documented (3; 4; 8; 10; 15). With the exception of the shelter occupants (99 personnel) and evacuation detachment (between 144 and 160 men), the number of personnel at the test site at the time of detonation has not been documented. Film badge records show that approximately 355 people were at the test site at some time during 16 July. The shelter occupants and 44 men of the evacuation detachment are on this list. It has not been possible to pinpoint the location of many of the remaining personnel. Some were at the Base Camp or on Compania Hill. Since many of these people returned to the test site after shot-time to work on experiments, their film badges registered exposures from residual radioactivity on 16 July. Based on the documented personnel totals, at least the following 263 individuals were at the test site when the device was detonated (1; 4; 8-10; 13; 15): o 99 shelter occupants at shelters 9,150 meters north, south, and west of ground zero o 144 to 160 officers and enlisted men of the evacuation detachment, located 14 kilometers northwest of ground zero near Guard Post 2 o Five radiological safety monitors assigned to the evacuation detachment to perform offsite monitoring of nearby towns and residences o One radiological safety monitor assigned to Guard Post 4 o Two military policemen at each of the seven guard posts (indicated by photographs such as figures 1-3 and 1-4). 2.2 DETONATION AND POSTSHOT ACTIVITIES Because of bad weather, the Project TRINITY director (Dr. Bainbridge) delayed the detonation, which had been scheduled for 0400 hours. By 0445, however, the forecast was better, and shot-time was set for 0530. This gave the scientists 45 minutes to arm the device and prepare the instruments in the shelters. The final countdown began at 0510, and the device was detonated at 0529:45 Mountain War Time from the Control Point in the south shelter (3; 12). No one was closer than 9,150 meters to ground zero at the time of the detonation. With the exception of a few men holding the ropes of barrage balloons or guiding cameras to follow the fireball as it ascended, all shelter personnel were in or behind the shelters. Some left the shelters after the initial flash to view the fireball. As a precautionary measure, they had been advised to lie on the ground before the blast wave arrived. Project personnel located beyond the shelters, such as at the Base Camp and on Compania Hill, were also instructed to lie on the ground or in a depression until the blast wave had passed (1). However, the blast wave at these locations was not as strong as had been expected. In order to prevent eye damage, Dr. Bainbridge ordered the distribution of welder's filter glass. Because it was not known exactly how the flash might affect eyesight, it was suggested that direct viewing of the fireball not be attempted even with this protection. The recommended procedure was to face away from ground zero and watch the hills or sky until the fireball illuminated the area. Then, after the initial flash had passed, one could turn around and view the fireball through the filter glass. Despite these well-publicized instructions, two participants did not take precautions. They were temporarily blinded by the intense flash but experienced no permanent vision impairment (1; 17). People as far away as Santa Fe and El Paso saw the brilliant light of the detonation. Windows rattled in the areas immediately surrounding the test site, waking sleeping ranchers and townspeople. To dispel any rumors that might compromise the security of Project TRINITY, the Government announced that an Army munitions dump had exploded. However, immediately after the destruction of Hiroshima, the Government revealed to the public what had actually occurred in the New Mexico desert (12; 13). Immediately after the shot, Medical Group personnel began the radiological monitoring activities described in section 3.1.2. At 0815, when most of the monitoring activities were completed, preparations began for entrance into the ground zero area. To regulate entry into the area, a "Going-in Board" was established, consisting of Dr. Bainbridge, the Chief of the Medical Group, and a special scientific consultant. Its purpose was to determine whether a party had a valid reason for entering the ground zero area. The board functioned for three days. Military police at Guard Post 4 and at three roadblocks set up along Broadway controlled entry into the area. Guard Posts 3, 5, 6, and 7 were within 3,000 meters of ground zero and thus remained unmanned. At the south shelter, the Medical Group set up a "going-in" station where personnel were required to stop to put on protective clothing (coveralls, booties, caps, and cotton gloves) and pick up monitoring equipment before entering the ground zero area. Since it was not known how much radioactive material might be suspended in the air, all personnel entering the ground zero area wore complete protective covering and respirators for the first three days after the detonation. Figure 2-6 shows two Project TRINITY personnel wearing protective clothing (1). On the day of the shot, five parties entered the ground zero area. One party consisted of eight members of the earth-sampling group. They obtained samples by driving to within 460 meters of ground zero in a tank specially fitted with rockets to which retrievable collectors were fastened in order to gather soil samples from a distance. This group made several sampling excursions on 16 and 17 July. The tank carried two personnel (a driver and a passenger) each trip. No member of this party received a radiation exposure of more than 1 roentgen (1). Five other men from the earth-sampling group entered the ground zero area in a second tank, lined with lead for radiation protection. The tank, carrying the driver and one passenger, made five trips into the ground zero area to retrieve soil samples on 16 and 17 July. On two trips, the tank passed over ground zero; on the others, it approached to within about 90 meters of ground zero. The men scooped up soil samples through a trap door in the bottom of the tank. One driver who made three trips into the ground zero area received the highest exposure, 15 roentgens (1). This lead-lined tank was also used by ten men to observe the radiation area. These men, traveling two at a time, made five trips into the area on shot-day but never approached closer than 1,370 meters to ground zero. The highest exposure among these ten men was 0.3 roentgens (1). The next party to approach ground zero consisted of a photographer and a radiological safety monitor. Wearing protective clothing and respirators, the two men were about 730 meters northwest of ground zero photographing "JUMBO" from 1100 to 1200 hours. "JUMBO," shown in figure 2-7, was a massive container built to contain the high-explosive detonation of the TRINITY device and to allow recovery of the fissionable material if the device failed to produce a nuclear detonation. The plan to use "JUMBO," however, was abandoned when the scientists concluded that a fairly large nuclear explosion was certain. The container remained on the ground near the shot-tower during the detonation. Both the photographer and the monitor received an estimated radiation exposure between 0.5 and 1 roentgen (1; 7). The last party to "go in" on shot-day consisted of six men retrieving neutron detectors. They entered the test area at 1430 hours. Three of the men went to a point 730 meters south of ground zero to pull out cables carrying neutron detectors located 550 meters south of ground zero. The group wore protective clothing and respirators and spent about 30 minutes in the area. The remaining three men drove as close as 320 meters southwest of ground zero to retrieve neutron detectors. They got out of their vehicle only once, at about 460 meters from ground zero, and spent a total of about ten minutes making this trip through the area. Each man's radiation exposure measured less than 1 roentgen (1). Most of the soldiers of the evacuation detachment remained in their bivouac area near Guard Post 2. According to a report written by the detachment commander, a reinforced platoon was sent to the town of Bingham, about 29 kilometers northeast of the test site, while offsite radiological safety monitors surveyed the area. The evacuation detachment was dismissed at 1300 hours on shot-day when it became evident from offsite monitoring that evacuations would not be undertaken. The detachment returned to LASL at 0400 on 17 July (15). Two B-29 aircraft from Kirtland Field, Albuquerque, New Mexico, participated in post-shot events. Their planned mission was to pass over the test area shortly before the explosion to simulate a bomb drop. After the TRINITY device had been detonated, the aircraft would circle near ground zero, while the men onboard would measure the atmospheric effects of the nuclear explosion. This would enable them to determine whether a delivery aircraft would be endangered. However, because of bad weather on shot-day, Dr. Oppenheimer canceled the aircraft's flight in the ground zero area. Instead, the two B-29s, each with 12 men onboard, flew along the perimeter of the bombing range and observed the shot from a distance of 19 to 29 kilometers. Among those observers was a Navy captain who was also the MED Chief of Ordnance (6; 12; 13). 2.3 ACTIVITIES AFTER 16 JULY 1945 On 17, 18, and 19 July, all personnel and visitors had to receive permission to approach ground zero from the "Going-in Board." On these three days, 21 groups were authorized to go beyond the Broadway roadblocks. Most of those who sought this authorization were scientists and military support personnel whose job required that they work near ground zero. Except for a group of two military men and three civilians who went to ground zero on 16 and 17 July and a group of two civilians who approached as close as 90 meters on 18 July, the reentry personnel came no closer than 180 meters to ground zero. Of these personnel, the individual who received the highest exposure during the three days was an Army sergeant who received 15 roentgens. During the same period, two civilians received 10 roentgens and 7.5 roentgens, respectively. All other personnel received exposures of 5 roentgens or less (1; 3). After the "Going-In Board" was disbanded on 19 July, permission to enter the ground zero area had to be obtained from Dr. Bainbridge or one of his deputies. Many scientists entered the ground zero area after 19 July to retrieve instruments or to perform experiments. The population of the TRINITY test site was diminishing, however, as the emphasis shifted to preparing the devices that were to be dropped on Japan (1). On 23 July, a week after the shot, chain barricades with prominent signs warning against trespassing were placed 910 meters north, south, and west of ground zero. These barricades were supplemented with two concentric circles of red flags 1,830 and 2,740 meters from ground zero. Except during bad weather, the entire ground zero area was visible from the roadblocks. No unauthorized person was ever detected entering the ground zero area (1). On 10 August, the Broadway roadblocks were removed, and mounted military policemen began patrolling around ground zero at a distance of 730 meters. Each guard was assigned to a daily six-hour shift for a period of two weeks; in the third week, the guard was assigned tasks away from the ground zero area. The mounted guards and their horses wore film badges. No exposure greater than 0.1 roentgen was registered. On 1 September, the mounted patrol moved to a distance of 460 meters from ground zero, just outside a fence installed a week earlier to seal off the area. The same rotating patrol schedule was used. The guards' film badge readings showed an average daily exposure of 0.02 roentgens. The mounted patrol at the fence continued until early 1947 (1). Between 20 July 1945 and 21 November 1945, 67 groups entered the ground zero area. Most of these parties entered in the month after shot-day. These were the scientists and technicians conducting experiments or retrieving data. By the beginning of September, most of those who entered the ground zero area were invited guests (1). Also during the period 20 July through 21 November, at least 71 soldiers were at the TRINITY test site. Twenty-five of these men were support personnel who never went within 460 meters of ground zero. The remaining 46 men were technical personnel, laborers who erected the 460-meter fence, or military policemen who served as guides. Eleven of these men, probably members of the fence detail, spent several days at about 460 meters from ground zero. Working three to five hours per day between 9 August and 25 August, they would have been the only group to stay longer than one hour in the ground zero area. Of the remaining personnel who approached within 460 meters from ground zero, 25 spent 15 minutes and ten spent between 30 minutes and one hour in the ground zero area. Only 11 people received exposures of 3 to 5 roentgens between 20 July and 21 November. Most received less than 1 roentgen. After 21 November 1945, no one approached closer than the fence which was 460 meters from ground zero, although about 200 civilian and military personnel worked at or visited the TRINITY site through 1946 (1; 16). According to dosimetry data, entrance logs, and other records, about 1,000 individuals were at the test site at some time between 16 July 1945 and the end of 1946. This number includes not only the scientists, technicians, and military personnel who were part of Project TRINITY but also many visitors. Some of the scientists took their wives and children on a tour of the area near ground zero, particularly to view the green glass called "trinitite," which covered the crater floor. Trinitite was the product of the detonation's extreme beat, which melted and mixed desert sand, tower steel, and other debris (1; 8; 9; 16). CHAPTER 3 RADIATION PROTECTION AT PROJECT TRINITY The TR-7 or Medical Group, shown in the figure 1-5 organizational chart, was responsible for radiological safety at Project TRINITY. Many of the physicians and scientists in the Medical Group had worked with radioactive materials before and were trained in radiological safety procedures. The Chief of the Medical Group supervised the radiological safety operations and reported to the TRINITY director. In addition to providing medical care to TRINITY personnel, this group established radiological safety programs to: o Minimize radiation exposure of personnel on the test site and in offsite areas o Provide monitors to conduct radiological surveys onsite and offsite o Provide and maintain radiation detection instruments o Provide protective clothing and equipment. An exposure limit of 5 roentgens during a two-month period was established. Personnel were provided with radiation detection instruments to determine their exposures (1). 3.1 ORGANIZATION The Medical Group consisted of physicians, scientists, and administrators, as well as radiological monitors. Many of these personnel were nonmilitary, but all worked on the Manhattan Project under the administration of the Army Corps of Engineers Manhattan Engineer District. The Medical Group was divided into two monitoring groups, the Site Monitoring Group, which was responsible for onsite monitoring, and the Offsite Monitoring Group. Each reported to the Chief of the Medical Group, and each communicated with the other during the monitoring activities. In addition to these two groups, a small group of medical technicians provided radiation detection instruments to Medical Group personnel (1; 10). 3.2 SITE MONITORING GROUP The Site Monitoring Group consisted of a chief monitor, three other monitors, and several medical doctors. This group had the following functions (1; 10): o Conduct ground surveys of the test area and mark areas of radioactivity o Conduct surveys of the Base Camp and roads leading into the test area o Provide protective clothing and equipment, including film badges and pocket dosimeters, to personnel o Monitor all personnel for radioactive contamination and provide for their decontamination o Maintain a record of radiation exposures received by personnel. The Site Monitoring Group monitored the radiation exposures of personnel in the test area. The time spent by personnel in radiation areas was limited, and radiation detection instruments were provided to permit continuous monitoring of exposure rates. In many cases, a monitor from the Site Monitoring Group accompanied project personnel into the test area to monitor exposure rates (1; 10). Two members of the Site Monitoring Group, a monitor and a physician with radiological safety training, were assigned to each shelter. The supervising monitor was stationed at the Base Camp and was in radio and telephone communication with all three shelters and the offsite ground and aerial survey teams. Before any personnel were allowed to leave the shelter areas, a radiological safety monitor and a military policeman from each shelter advanced along the roads to Broadway to check radiation levels. They wore respirators to prevent them from inhaling radioactive material (1; 10). Since it was expected that any dust from the cloud would fall on one of the shelter areas within 30 minutes of the shot, plans had been made to evacuate personnel as soon as the monitors completed their initial survey. Because the cloud moved to the northeast, the south shelter (the Control Point) was not completely evacuated, although nonessential personnel were sent to the Base Camp. The west shelter was emptied of all personnel except a searchlight crew spotlighting the cloud as it moved away (1; 10). Only at the north shelter did an emergency evacuation occur. About 12 minutes after the shot, a detection instrument indicated a rapid rise in the radiation levels within the shelter. At the same time, a remote ionization monitoring device detected a rapid increase in radiation. Because of these two readings, all north shelter personnel were immediately evacuated to the Base Camp, 25 kilometers to the south. Film badges worn by personnel stationed at the north shelter, however, showed no radiation exposure above the detectable level. It was later discovered that the meter of the detector in the north shelter had not retained its zero calibration setting, and radiation at the north shelter had not reached levels high enough to result in measurable exposures of the personnel who had been positioned there. However, fallout activity was later detected in the north shelter area, proof that part of the cloud did head in that direction. This also explains why the monitoring device detected rising radiation levels (1; 12). After ascertaining that radiation levels along the roads leading from the shelters to Broadway were within acceptable limits, the radiological safety monitors and military police established roadblocks at important intersections leading to ground zero. The north shelter monitor and military police set up a post where the North Shelter Road ran into Broadway. The west shelter monitor and a military policeman blocked Vatican Road where it intersected Broadway. The south shelter monitor and military police set up a roadblock where Broadway intersected Pennsylvania Avenue (1). The monitor assigned to Guard Post 4 surveyed the Mockingbird Gap area to ensure that it was safe for the guards to return to their post. This position controlled access to the McDonald Ranch Road, which led directly to ground zero (1). At 0540 hours, the chief monitor departed from the Base Camp with a military policeman to monitor the entire length of Broadway. They first checked the roadblock at Pennsylvania Avenue and Broadway. Next they drove to the roadblock at Vatican Road and Broadway. Upon the chief monitor's arrival, the west shelter monitor traveled about nine kilometers west on Vatican Road to monitor Guard Post 1 so that the military police could reoccupy the post. The monitoring excursion to Guard Post 1 continued until the chief monitor had returned from Guard Post 2, located 17 kilometers northwest of the Vatican Road roadblock on Broadway (1; 18). The chief monitor arrived at Guard Post 2 at about 0550 hours and found the post empty. He then continued five kilometers north along Broadway to the foxholes from which the military police had watched the detonation. There he found the guards, the five radiological safety monitors assigned to the evacuation detachment, and the Commanding Officer of the evacuation detachment (1; 18). The military policemen refused to return to Guard Post 2, insisting that they had received orders over their two-way radio from the Base Commander to evacuate their post and head for San Antonio, New Mexico, a town 28 kilometers northwest of the Guard Post. The Base Commander had noted that portions of the cloud were heading northwestward and, fearing that fallout from the cloud would contaminate Guard Post 2, had ordered the military police to evacuate. The chief monitor, however, had found no significant radiation levels anywhere along the northern part of Broadway nor around Guard Post 2. The Base Commander, after being contacted by the chief monitor, drove to the foxholes and ordered the guards to return to their post. This was the only unplanned incident during the onsite monitoring (1). After Guard Post 2 was reoccupied, the chief monitor returned to the roadblock at the intersection of Broadway and the North Shelter Road. The north shelter monitor informed the chief monitor of the sudden evacuation of the north shelter, whereupon the chief monitor surveyed the north shelter area and found intensities of only 0.01 and 0.02 roentgens per hour (R/h). The chief monitor then contacted the south shelter and informed Dr. Bainbridge that the north shelter region was safe for those who needed to return, that Broadway was safe from the Base Camp to Guard Post 2, and that Guard Post 2 was now manned so that personnel leaving for LASL could be checked out (1). The chief monitor then returned to the south shelter and assembled the monitors from the three roadblocks and Guard Post 4 to prepare for entrance into the ground zero area. The time was about 0815 hours. The military police at the roadblocks were given radiation meters to survey the adjoining area. Broadway from the south shelter to Guard Post 2 was remonitored occasionally to reassure the military police that there was no radiation problem. Monitors also surveyed the Base Camp for 24 hours after the detonation. No radiation above background levels was detected there (1). The following brief description of the radiological environment in the TRINITY test area is based primarily on the results of the remote gamma recorders situated in the test area and on results of the road surveys conducted after the detonation (1). Within about 1,400 meters of ground zero (except to the north), radiation intensities between 0.2 and 1.3 R/h were detected during the first few minutes after the detonation. These readings decreased to less than 0.1 R/h within a few hours. At greater distances to the east, south, and west, radiation levels above background were not detected (1). The cloud drifted to the northeast, and higher gamma readings due to fallout were encountered in this direction. About five minutes after the detonation, a reading of 3 R/h was recorded 1,400 meters north of ground zero. Several minutes later, the intensity there had increased to greater than 7 R/h, and it continued to increase for several more minutes. Gamma detectors 9,150 meters north of ground zero, however, recorded no radiation above background levels. This indicated that the cloud had passed over or near the 1,400-meter area and only partially over the 9,150-meter area where the north shelter was located. Subsequent ground surveys of this area found no gamma intensities higher than 0.02 R/h (1). Gamma radiation levels at and around ground zero were much higher than in other onsite areas because of induced activity in the soil. Twenty-four hours after the detonation, the gamma intensity at ground zero was estimated to be 600 to 700 R/h. This estimate was based on data provided by the tank crew that drove to ground zero to obtain soil samples. The intensity decreased to about 2 R/h at 725 meters from ground zero. Gamma intensities of 0.1 R/h or more were confined within a circular area extending about 1,100 meters from ground zero (except in areas of fallout). One week after the shot, the gamma intensity at ground zero was about 45 R/h. After 30 days, intensities at ground zero had decreased to 15 R/h, and intensities of 0.1 R/h or more were not encountered beyond about 365 meters from ground zero. Gamma intensities of 3 to 10 R/h were found at ground zero three months after the detonation (1; 19). 3.3 OFFSITE MONITORING GROUP Four two-man teams and one five-man team supervised by the chief offsite monitor constituted the Offsite Monitoring Group. Before the detonation, the four two-man teams established monitoring posts in towns outside the test area. These towns were Nogal, Roswell, Fort Sumner, and Socorro, all in New Mexico. The five-man team remained at Guard Post 2 to assist in evacuation of nearby residences if the TRINITY cloud drifted in that direction. These residences, the Fite house and the homes in the town of Tokay, were 24 and 32 kilometers northwest of ground zero, respectively. Since the cloud drifted to the northeast, evacuation was not required. All offsite monitoring teams were in radio or telephone contact with personnel at the Base Camp (11). Offsite monitoring teams in areas northeast of ground zero encountered gamma readings ranging from 1.5 to 15 R/h two to four hours after the detonation. Three hours after the detonation, surveys taken in Bingham, New Mexico (located 30 kilometers northeast of ground zero) found gamma intensities of about 1.5 R/h. Radiation readings at the town of White, nine kilometers southeast of Bingham, were 6.5 R/h three hours after the detonation and 2.5 R/h two hours later. Another team monitoring in a canyon 11 kilometers east of Bingham found a gamma intensity of about 15 R/h. Five hours later, the intensity had decreased to 3.8 R/h. It was estimated that peak intensities of gamma radiation from fallout on shot-day were about 7 R/h at an occupied ranch house in this canyon area (1; 11; 19). Monitoring teams resurveyed these towns about one month after the TRINITY detonation. At Bingham, gamma readings of 0.003 R/h and 0.0001 R/h were found at ground level outdoors and at waist level inside a building, respectively. At the town of White, the highest outdoor gamma reading was 0.008 R/h. Inside a building, the highest reading was 0.0005 R/h (11). Surveys taken in the canyon area one month after the detonation indicated that gamma intensities at ground level had decreased to 0.032 R/h. The occupied ranch house was also surveyed, both inside and outside. The highest reading outdoors was 0.028 R/h, and the highest reading indoors was 0.004 R/h (11; 19). Monitoring was also conducted in offsite areas other than those to the north and northeast of ground zero. Monitors found no radiation readings above background levels (11). Significant fallout from the TRINITY cloud did not reach the ground within about 20 kilometers northeast of ground zero. From this point, the fallout pattern extended out 160 kilometers and was 48 kilometers wide. Gamma intensities up to 15 R/h were measured in this region several hours after the detonation. One month later, intensities had declined to 0.032 R/h or less (11). CHAPTER 4 DOSIMETRY ANALYSIS OF PARTICIPANTS IN PROJECT TRINITY This chapter summarizes the radiation doses received by participants in various activities during Project TRINITY. The sources of this dosimetry information are the safety and monitoring report for personnel at TRINITY, which includes a compilation of film badge readings for all participants up to 1 January 1946, and film badge data from the records of the Reynolds Electrical and Engineering Company, which contain readings through 1946 (1; 16). These sources list individual participants with their cumulative gamma radiation exposures. 4.1 FILM BADGE RECORDS During TRINITY, the film badge was the primary device used to measure the radiation dose received by individual participants. The site monitoring plan indicates that film badges were to be issued to participants. The film badge was normally worn at chest level on the outside of clothing and was designed to measure the wearer's exposure to gamma radiation from external sources. These film badges were insensitive to neutron radiation and did not measure the amount of radioactive material that might have been inhaled or ingested (1). Personnel from the Medical Group had responsibility for issuing, receiving, processing, and interpreting film badges for Project TRINITY. The Site Monitoring Group compiled the film badge records for both onsite and offsite personnel. Radiological safety personnel and military police recorded the names and identification numbers of individuals as they entered the test area. This information was recorded in an entry logbook and on a personal exposure data card. Upon leaving the test area, individuals returned their film badges to the check station. When the film badges were processed and interpreted, the reading was entered on the individuals exposure data card. In this manner, the number of times an individual entered the test area and his cumulative exposure history were recorded and maintained (1). 4.2 GAMMA RADIATION EXPOSURE The safety and monitoring report lists film badge readings for about 700 individuals who participated in Project TRINITY from 16 July 1945 to 1 January 1946 (1). This list includes both military and nonmilitary personnel who were involved with the TRINITY operation and postshot activities. However, records are available for only 44 of the 144 to 160 members of the evacuation detachment (1). In addition, some of these film badge listings may be for personnel who were only peripherally involved with TRINITY activities, such as family members and official guests who visited the site. According to the safety and monitoring report, by 1 January 1946, 23 individuals had received cumulative gamma exposures greater than 2 but less than 4 roentgens. An additional 22 individuals received gamma exposures between 4 and 15 roentgens. Personnel who received gamma exposures exceeding 2 roentgens represent less than six percent of the Project TRINITY participants with recorded exposures. As described below, these exposures generally resulted when personnel approached ground zero several times (1). Information is available regarding the activities of some of these personnel. One of the drivers of the earth-sampling group's lead-lined tank, an Army sergeant who traveled three times to ground zero, received an exposure of 15 roentgens. A second tank driver, also an Army sergeant, received an exposure of 3.3 roentgens. Three members of the earth-sampling group, all of whom traveled in the tank to ground zero, received exposures of 10, 7.5, and 5 roentgens. An Army photographer who entered the test area six times between 23 July and 20 October received 12.2 roentgens (1). Four individuals involved with excavating the buried supports of the TRINITY tower from 8 October to 10 October 1945 received gamma exposures ranging from 3.4 to 4.7 roentgens. Film badge readings for this three-day period indicate that the two individuals who operated mechanical shovels received 3.4 and 4.3 roentgens, while the two who supervised and monitored the excavation received exposures of 4.2 and 4.7 roentgens. The individual receiving 4.7 roentgens during the excavation operation had received 1.3 roentgens from a previous exposure, making his total exposure 6 roentgens (1). An Army captain who accompanied all test and observer parties into the ground zero area between 1 September and 11 October 1945 received a total gamma exposure of 2.6 roentgens (1). The activities and times of exposure are not known for other personnel with exposures over 2 roentgens. According to the dosimetry records for 1946, about 115 people visited the test site that year. No one ventured inside the fence surrounding ground zero, and no one received an exposure greater than 1 roentgen (1; 16). REFERENCE LIST The following list of references represents the documents consulted in preparation of the Project TRINITY volume. AVAILABILITY INFORMATION An availability statement has been included at the end of the reference citation for those readers who wish to read or obtain copies of source documents. Availability statements were correct at the time the bibliography was prepared. It is anticipated that many of the documents marked unavailable may become available during the declassification review process. The Coordination and Information Center (CIC) and the National Technical Information Service (NTIS) will be provided future DNA-WT documents bearing an EX after the report number. Source documents bearing an availability statement of CIC may be reviewed at the following address: Department of Energy Coordination and Information Center (Operated by Reynolds Electrical & Engineering Co., Inc.) ATTN: Mr. Richard V. Nutley 2753 S. Highland P.O. Box 14100 Las Vegas, Nevada 89114 Phone: (702) 734-3194 FTS: 598-3194 Source documents bearing an availability statement of NTIS may be purchased from the National Technical Information Service. When ordering by mail or phone, please include both the price code and the NTIS number. The price code appears in parentheses before the NTIS order number. National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 Phone: (703) 487-4650 (Sales Office) Additional ordering information or assistance may be obtained by writing to the NTIS, Attention: Customer Service, or by calling (703) 487-4660. PROJECT TRINITY REFERENCES *Available from NTIS; order number appears before the asterisk. **Available at CIC. ***Not available, see Availability Information page. ****Requests subject to Privacy Act restrictions. 1. Aebersold, Paul. July 16th Nuclear Explosion-Safety and Monitoring of Personnel (U). Los Alamos Scientific Laboratory, Atomic Energy Commission. Los Alamos, NM.: LASL. LA-616. January 9, 1947. 170 Pages.*** 2. Bainbridge, K. T. Memorandum to All Concerned, Subject: TR Circular No. 18--Total Personnel at TR. [Base Camp, Trinity Site: NM.] July 3, 1945. 1 Page.** 3. Bainbridge, K. T. TRINITY. Los Alamos Scientific Laboratory. Los Alamos, NM.: LASL, LA-6300-H and Washington, D. C.: GPO. May 1976. 82 Pages.** 4. Bramlet, Walt. Memorandum for Thomas J. Hirons, Subject: DOD Participants in Atmospheric Tests, wo/encl. Los Alamos Scientific Laboratory. Los Alamos, NM. ISD-5. February 20, 1979. 4 Pages.** 5. General Electric Company--TEMPO. Compilation of Local Fallout Data from Test Detonations 1945-1962. Vol. 1: "Continental US Tests." Washington, D. C.: Defense Nuclear Agency. DNA 1251-1(EX.). 1979. 619 Pages. (A99) AD/AO79 309.* 6. Groves, Leslie R., LTG, USA. Memorandum for Secretary of War, [Subject: TRINITY]. [Washington, D.C.] 18 July 1945. 13 Pages.** 7. Groves, Leslie R., LTG, USA (Ret.). Now It Can Be Told: The Story of the Manhattan Project. New York, NY.: Harper and Row. 1962. 444 Pages. 8. Headquarters, 9812th Technical Service Unit, Provisional Detachment No. I (Company "B"). [Extract from: Daily Diary, Provisional Detachment No. 1 (Company "B"), 9812th Technical Service Unit.] Army Corps of Engineers, Department of War. [Santa Fe, NM.] 14 July 1945. 2 Pages.** 9. Headquarters, Special Service Detachment. Supplemental Special Guard Orders, with Appendix. Los Alamos Scientific Laboratory, Manhattan Engineer District. [Alamogordo, NM.] 14 July 1945. 4 Pages.** 10. Hempelmann, L. H., M.D. [Extracts from: "Preparation and Operational Plan of Medical Group (TR-7) for Nuclear Explosion 16 July 1945."] Los Alamos Scientific Laboratory, Atomic Energy Commission. Los Alamos, NM.: LASL. LA-631(Deleted). June 13, 1947. 32 Pages.*** 11. Hoffman, J. G. [Extracts from "Health Physics Report on Radioactive Contamination throughout New Mexico Following the Nuclear Explosion, Part A--Physics."] Los Alamos Scientific Laboratory, Manhattan Engineer District. [Los Alamos, NM.] [1945.] 31 Pages.** 12. Lamont, Lansing. Day of TRINITY. New York, NY.: Atheneum. 1965. 331 Pages. 13. Los Alamos Scientific Laboratory, Public Relations Office. "Los Alamos: Beginning of an Era, 1943-1945." Atomic Energy Commission. Los Alamos, NM.: LASL. 1967. 65 Pages.** 14. Oppenheimer, J. R. Memorandum for Group Leaders, Subject: TRINITY Test. Los Alamos Scientific Laboratory. Los Alamos, NM. June 14, 1945. 2 Pages.** 15. Palmer, T. O., Maj., USA. Evacuation Detachment at TRINITY. [Manhattan Engineer District, Army Corps of Engineers.] [Los Alamos, NM.] [18 July 1945.] 2 Pages.** 16. Reynolds Electrical & Engineering Company, Inc. [Personnel Radiation Exposures, 1945, 1946] Las Vegas, NV. Microfilm.**** 17. Warren, S. L., COL., USA. Directions for Personnel at Base Camp at Time of Shot. Los Alamos Scientific Laboratory, Manhattan Engineer District. [Alamogordo, NM.] 15 July 1945. 1 Page.** 18. Warren, S. L., COL, USA; Hempelmann, L. H., M.D. Extracts from: Personal Notes, Subject: Events in Camp Immediately Following Shot--July 16, 1945. 1945. 2 Pages.** 19. Weisskopf, V.; Hoffman, J.; Aebersold, Paul; Hempelmann, L. H. Memorandum for George Kistiakowsky, Subject: Measurement of Blast, Radiation, Heat and Light and Radioactivity at Trinity. [Los Alamos, NM.] 5 September 1945. 2 Pages.**