SRN-ALSIRWorkshop2002 submitted.doc


[Title] 
 
Workshop on Applications of Coherent Infrared Synchrotron Radiation 
 
 
[Text] 
 
A workshop focused on scientific applications of and plans for a coherent far-infrared 
(FIR) synchrotron source at the ALS was convened on October 11, 2002 as part of the 
annual Advanced Light Source users’ meeting. It was organized by Michael C. Martin 
(ALS), Wayne McKinney (ALS), Dmitri Basov (University of California, San Diego), 
and Joseph Orenstein (University of California, Berkeley, and Berkeley Lab). Coherent 
synchrotron radiation (CSR) presents an opportunity to create a source with intensities 
about six orders of magnitude higher than conventional FIR sources. This workshop was 
held to further explore different types of science that could be enabled by such a novel 
source in this traditionally difficult spectral region. 
 
Following a welcome by Martin, the first speaker was Tatiana Globus (University of 
Virginia). She described her group’s recent measurements and theoretical modeling of the 
transmission spectroscopy of biological macromolecules at submillimeter wavelengths. 
High resolution and very good signal-to-noise ratios are required for these measurements, 
and a higher intensity source extending to wavelengths longer than a millimeter would be 
very useful for these studies. Next, Erik Helgren (University of California, Los Angeles) 
discussed his recent investigations of a Coulomb glass system with microwave and 
millimeter-wave spectroscopy. 
 
The workshop then turned towards recent CSR source developments starting with a talk 
by Martin, standing in for George Neil (Thomas Jefferson National Accelerator Facility), 
describing the very high-power THz CSR observed using a energy-recovery linac. These 
exciting results were recently published [Nature 420, 153, (2002)]and verify that a gain 
of 100,000 in intensity over conventional far-IR sources is truly achieved. John Byrd 
(ALS) then presented recent work showing that the onset of broadband self-amplified 
spontaneous coherent terahertz synchrotron radiation in a storage ring is now understood 
and can be avoided in the design of a dedicated CSR source. 
 
The workshop attendees then heard from Ulrich Shade (BESSY) about the recent 
achievement of powerful, steady-state coherent THz synchrotron radiation at BESSY II. 
This accomplishment, made possible by lowering the momentum compaction in the 
storage ring, provides the first demonstration of stable CSR from a storage ring. This talk 
was followed by a presentation by Jason Singley (ALS) who described the general need 
for a new far-IR source for the study of strongly correlated materials and a proposal for a 
specific experiment to try and measure the Josephson plasma resonance in the high-
temperature superconductor Bi2Sr2CaCu2O8 with the CSR source at BESSY II. 
 
The workshop concluded with a presentation by Martin on the current state of plans for a 
dedicated coherent FIR storage ring at the ALS. This source would be built on top of the 



ALS booster ring, and would be designed specifically for creating and using CSR in the 
THz region. Several unique features of the ring design were pointed out, and the planned 
next steps towards a full proposal for this source were presented. 
 
 
[Author and Institution] 
 
Michael C. Martin 
Advanced Light Source, Berkeley Lab 
 
 
[Figure Caption—IRring.tif] 
 
Drawing showing the main ALS storage ring and a proposed dedicated coherent far-
infrared (FIR) ring (in color) located on top of the shielding for the ALS booster ring. 
The red and purple show the shielding for the new IR ring, and the green tables 
schematically show where FIR beamlines can be located.