ALSNews is a biweekly electronic newsletter to keep users and other interested parties informed about developments at the Advanced Light Source, a national user facility located at Lawrence Berkeley National Laboratory, University of California. To be placed on the mailing list, send your name and complete internet address to ALSNews@lbl.gov. We welcome suggestions for topics and content.

Previous Issues are available.


ALSNews           Vol. 50           April 17, 1996

Table of Contents


    1. OPERATIONS UPDATE
    2. USERS WORK WITH OPERATORS TO TRACK DOWN ACCELERATOR PROBLEM
    3. ALS IN THE NEWS
    4. NOTES FROM TOWN MEETING
    5. WANTED: IDEAS FOR ALS ANNUAL USERS' MEETING WORKSHOPS
    6. CALL FOR INDEPENDENT INVESTIGATOR PROPOSALS

1. OPERATIONS UPDATE
(contact: rmmiller@lbl.gov)

Beam availability for the last two weeks was 89.9% overall and 88.1% for user shifts. All problems were repaired and of short duration. Last week's average was lowered by frequent fills when running at 1.5 GeV with feedback on.

The ALS is in a scheduled shutdown for major installations and maintenance (a list of major shutdown activities appears in ALSNews Vol. 48, March 20, 1996). User operations are scheduled to resume on May 22.

2. USERS WORK WITH OPERATORS TO TRACK DOWN ACCELERATOR PROBLEM

Early on the morning of March 30, an alert group of users detected and, with the help of two operators, diagnosed an accelerator problem. The observation led to the discovery and prompt correction of damage to components in the temperature control circuit for storage ring rf cavity 2.

Gunter Kaindl and Konrad Schultz of Freie Universitaet Berlin and Fred Schlachter and John Bozek from the ALS were collaborating on an atomic physics experiment on beamline 9.0.1, measuring doubly excited autoionizing states of helium atoms by photoabsorption. This work uses very small (1-5 micron) slits on the monochromator to achieve exceptionally high spectral resolution. The experimenters observed that an intensity fluctuation with a period of approximately 2 minutes was perturbing their measurements.

After ruling out all possible beamline and experimental origins for the fluctuation, the experimenters visited the ALS control room. Operators Sue Daly and James McDonald searched storage ring parameters for a fluctuation with a two-minute period. They found that a 0.5-degree-C fluctuation in the temperature of rf cavity 2 had that period. The operators plotted the temperature change over 15 minutes, convincingly showing the periodicity. Meanwhile, the experimenters obtained data from users on beamline 9.3.2 that showed the same periodic fluctuation in intensity on that beamline. Subsequent analysis by electrical engineering staff led to discovery of damaged components in the temperature control circuit for cavity 2, which has now been repaired.

3. ALS IN THE NEWS

IBM research scientist George Castro and his custom-designed x-ray microscope at the ALS were featured in the first episode of a special Public Broadcasting System television program, "BreakThrough: The Changing Face of Science In America." The episode, entitled "The Path of Most Resistance," profiled four scientists who faced resistance on their respective paths toward professional recognition. Castro talked about the challenge and reward of trying something completely new in science, the test being when you try it for the first time and see if it works. In the program, which was filmed in 1994, Castro and researchers from the University of Wisconsin are shown commissioning the Paraxial-Ray-Imaging Spectromicroscope (PRISM) endstation, then newly constructed, on ALS Beamline 7.0. Castro retired from IBM last year and is now associate dean of the College of Science at San Jose State University.

The six-part BreakThrough series profiles 20 contemporary African American, Latino, and Native American scientists and engineers who are making advances in biology, astronomy, physics, mathematics, and many other scientific disciplines. Castro, a Latino and former senior research scientist at IBM, doubted whether he should even become a scientist. But, he says, "You realize that breaks come every day to someone. It's what you make of them." The first four programs appeared April 8 and 15 and will continue on Monday, April 22 on PBS (check local listings). The program's Web site includes information on the series, profiles of the scientists, and educational materials for use in the classroom (http://www.blackside.com/).

3. NOTES FROM TOWN MEETING
(contact: fred_schlachter@lbl.gov)

A town meeting of users, the ALS Users' Executive Committee, and ALS management was held on Friday, April 12. One of the main topics addressed was beam stability and how to improve it as users' needs become ever more exacting. Another focus of discussion was the tradeoff between shorter beam lifetime and improved beam brightness with the use of feedback. One way to improve beam lifetime with a minimal effect upon observed beam brightness, except at higher photon energies, would be to use skew quadrupole magnets installed in the storage ring to enlarge the vertical beam size. Accelerator physics studies of the use of skew quadrupoles will be required before this mode of operations can be implemented. At the suggestion of users, the ALS will plan a series of meetings to inform users of ongoing work in the ALS accelerator physics and experimental systems groups so that users can make more informed decisions about experiment planning and execution.

4. WANTED: IDEAS FOR ALS ANNUAL USERS' MEETING WORKSHOPS
(contact: jbokor@eecs.berkeley.edu)

The ALS Users' Executive Committee (UEC) is soliciting ideas for informal workshops to be held on the afternoon of Wednesday, October 23, immediately following this year's Annual Meeting of the ALS Users' Association on October 21 and 22, 1996. Ideas for topics should be submitted to UEC Chair Jeff Bokor by May 1. Workshops already proposed include Atomic and Molecular Physics (organizer - Nora Berrah), Spectromicroscopy (organizer - Harald Ade), and Soft X-Ray Fluorescence (organizer - Tom Callcott). The morning of October 23 will feature a tutorial-style workshop on synchrotron-based research.

5. CALL FOR INDEPENDENT INVESTIGATOR PROPOSALS

The ALS has two cycles per year for soliciting proposals from scientists who wish to conduct research at the facility as independent investigators: April-September and October-March. The next submission deadline is June 1, 1996, for beamtime from October 1996 to March 1997.

To request a proposal form, contact:
Elizabeth Saucier, ALS User Administrator
Tel: (510) 486-6166
Fax: (510) 486-4960
E-mail: alsuser@lbl.gov

For beamline and PRT information, contact:
Fred Schlachter, ALS Scientific Outreach
Tel: (510) 486-4892
Fax: (510) 486-6499
E-mail: fred_schlachter@lbl.gov