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Last Updated: | 26 MAR 2001 |
| Content Owner: | L. Dunn | |
| Page Editor: | L. Dunn |
**** **** **** * * * * * * **** **** **** * * * * * * **** **** * * **** HEADLINES - a digital monthly publication
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1. The VISA SASE Experiment Achieves High Gain
(contacts: Max Cornacchia - cornacchia@ssrl.slac.stanford.edu
Claudio Pellegrini - pellegrini@physics.ucla.edu)
The VISA (VIsible Sase Amplification) experiment was designed, built, installed and carried out by a BNL-LLNL-SLAC-UCLA collaboration within the broader framework of the LCLS R&D program funded by DOE-BES. The experiment, located in the Accelerator Test Facility (ATF) at the National Synchrotron Light Source at BNL, was designed to test the physics of Free-Electron Lasers (FELs) based on the Self-Amplified- Spontaneous-Emission (SASE) collective instability regime, and to demonstrate the possibility of producing an electron beam having characteristics close to those needed for the LCLS, the future Linac Coherent Light Source (LCLS) whose remarkable performance would also be based on SASE (at much shorter wavelengths around 1 A).
Earlier in March, VISA demonstrated a gain of 2x106, and an exponential growth rate of 18.5 cm. There is also clear evidence of saturation of the FEL intensity at about 3.6 m from the undulator entrance. These results are particularly exciting because they have been achieved under electron beam and alignment tolerance conditions that are close to those of the LCLS, and thus demonstrate the feasibilty of LCLS itself. Additional measurements will be done during the next few months to obtain more data and more information on the spectral and angular characteristics of the FEL radiation.
2. 1st Annual Meeting of Joint Center for Structural Genomics
(JCSG)
(Linda Brinen - brinen@slac.stanford.edu)
The first annual meeting of the JCSG was held at The Scripps Research Institute in La Jolla, CA on March 12-13. SSRL is the lead institution for the structure determination core of the JCSG. Participating scientists and collaborators from all three cores (BioInformatics, Crystallomics and Structure Determination) as well as representatives of the NIH National Institute for General Medical Sciences (NIGMS - the funding agency for the U.S. program in structural genomics) were present for a very informative and exciting forum. Highlights of the meeting included overview presentations by the principal investigators from each core, live and virtual tours of the robotic systems in development and in use for protein production and crystallization and crystallographic data collection. The meeting was a success and clearly showed the strengths of the cores as an integrated development team.
3. SPEAR Continues Rapid Recovery from BL10
Wiggler Failure
(contact: Max Cornacchia - cornacchia@ssrl.slac.stanford.edu)
As reported in the February edition of HEADLINES, SPEAR suffered a major vacuum loss with the failure of the BL10 wiggler. A marathon effort by SSRL engineering and technical staff resulted in remarkably rapid recovery for such a severe problem. Due to the extensive damage both to the BL10 wiggler magnet and its vacuum chamber, both had to be taken out of the ring. This was accomplished within one day and a replacement spool piece installed and the system put under vacuum the following day. Beam was re-established February 25 and delivered to Users exactly one week later, on March 1. Initially there were three fills per day, but this was reduced to two by March 7, given the very rapid recovery of vacuum quality. To help make up the lost time two days of scheduled Accelerator Physics were cancelled and given to user groups who lost time. We are already nearing the point where we can return to one fill per 24 hours.
The wiggler and vacuum chamber are currently being repaired off-line. Measurements to determine the extent of the damage to the insertion device vacuum chamber have commenced. The damaged section in the chamber was temporarily patched and leak tested to confirm that no other damage to the chamber had occurred. Measurements of the position of the magnets in relation to their poles have also commenced and a solution engineered so that this failure mode will not occur in the future has been devised. These will be used to help determine the new gap and field strengths. It is hoped that the BL10 wiggler and chamber can be reinstalled during this coming summer shutdown.
4. 2nd Workshop on FEL Methods and Instrumentation
(contact: John Arthur - arthur@ssrl.slac.stanford.edu)
On March 1-2, SSRL hosted a workshop on experimental methods and instrumentation to be used with x-ray free-electron laser sources including the Linac Coherent Light Source (LCLS). This workshop, the second in a series sponsored jointly by SLAC and the German research lab DESY, considered methods and instrumentation for exploiting the sub-picosecond pulse and extreme peak power aspects of FEL x-ray sources.
About 40 scientists attended from the US, Europe and Japan. It was clear from the presentations and discussion that there is widespread scientific interest in the special characteristics of x-ray FEL radiation, and that progress is being made toward developing practical techniques for exploiting these characteristics. In particular, much progress has been made in the ability to measure the time correlation between x-ray and laser pulses with sup-ps resolution. Also, progress is being made in theoretical modeling of the effects of FEL x-ray pulses on materials.
The final conclusion of the workshop was that progress in developing FEL methods and instrumentation is limited by funding, rather than by a lack of exciting ideas and interested scientists.
5. Berkeley-Stanford Summer School in Synchrotron Radiation
(contact: Anders Nilsson - nilsson@ssrl.slac.stanford.edu)
The first ever joint Berkeley-Stanford Summer School devoted to synchrotron radiation and its applications will be held on July 8-14, 2001. Anders Nilsson and David Atwood (attwood@eecs.berkeley.edu) are organizing and co-chairing the school, which is directed towards first and second-year graduate students working in the field of physical sciences. The curriculum will include a series of lectures on the synchrotron radiation process, associated technologies and scientific applications. Lectures will be presented by professors and scientists from the sponsoring organizations (UC-Berkeley, Stanford University, LBNL, SSRL and the Division of Continuing Education in Engineering, UC Berkeley Extension) and affiliated user communities. The school, while primarily held at the Clark Kerr campus of the University of California, Berkeley, will also include visits to the ALS and SSRL giving the students opportunities to interact with staff scientists and graduate students at both facilities.
For a more detailed announcement, including application information,
see:
http://www-ssrl.slac.stanford.edu/PhysSci-School.html
6. User Research Administration Announcements
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7. SSRL Job Opportunities
(Stephanie Carlson - steph@slac.stanford.edu)
SSRL currently has positions available for mechanical, electronic and
beam line engineers, technicians and administrative staff. More
information is available at the following web site:
http://www-ssrl.slac.stanford.edu/jobs.html
SSRL Headlines is published electronically monthly to inform SSRL users, sponsors and other interested people about happenings at SSRL. SSRL is a national synchrotron user facility operated by Stanford University for the U.S. Department of Energy Office of Basic Energy Sciences. Additional support for the structural biology program is provided by the DOE Office of Biological and Environmental Research, the NIH National Center for Research Resources and the NIH Institute for General Medical Sciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site: http://www-ssrl.slac.stanford.edu/
You can subscribe or remove your name from the distribution list by sending a brief email with your request to Lisa Dunn, editor, at lisa@ssrl.slac.stanford.edu.