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.

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ALSNews           Vol. 3           November 15, 1994

Table of Contents


    1. ADMINISTRIVIA  
    2. OPERATIONS OVERVIEW  
    3. BEAMLINE BREAKTHROUGHS
    4. TIMELY TOPICS

1. ADMINISTRIVIA
(contact: alsnews@lbl.gov)

Apologies to those of you who sent in your ALSNews subscription form and have not been receiving ALSNews until this issue. Our subscriber list is now up-to-date and, starting with the December 6 issue, only those persons who have asked to be placed on the permanent newsletter distribution list will continue to receive ALSNews. If you haven't responded yet, please email alsnews@lbl.gov and include your complete internet address in the body of the message. We will also be making current and past issues of ALSNews available on the ALS World Wide Web Homepage in mid-December.

2. OPERATIONS OVERVIEW
(contact: rmmiller@lbl.gov)

Operations for Wednesday, Nov. 16, thru Wednesday, Nov. 30:
Standard 320 bunch 400 mA operation for users:
Nov. 16.......from 00:00-24:00 
Nov. 17-18..from 08:00-24:00
Nov. 22.......from 00:00-24:00
Nov. 30.......from 08:00-24:00
Two-bunch operation:
Nov. 17-18..from 00:00-08:00
Nov. 23...... from 00:00-24:00
Nov. 30...... from 00:00-08:00
Maintenance and startup:  Mondays
Accelerator physics: Tuesdays except for Nov. 22 which will be user shifts.
Holiday: Weekends and November 24, 25 for Thanksgiving.

**ALS PERFORMANCE**
The availability of accelerator operations for experimenters (actual beamtime/scheduled beamtime) was 95% Oct. 1 thru Nov. 12! Availability for last week was 87%. Operations interruptions last week were caused by air trapped in the cooling water system, a wiring problem on SR07U limit micro switches and several storage ring RF trips. A buss bar connection problem on a booster quad was repaired during storage ring operations with no down time for the experimenters.

** 1.9 GeV OPERATION -- PLANS AND MOTIVATIONS **
(contact: howard_padmore@macmail.lbl.gov)

Recent accelerator physics efforts have included successfully storing and characterizing the ALS electron beam at 1.9 GeV (nominal storage ring energy is 1.5 GeV). The next step is to compare photon flux for particular experiments at 1.5 and 1.9 GeV using 50 mA storage ring current (full 400-mA tests are tentatively planned for March 1995, pending the outcome of the first tests).

The ALS is designed to operate at storage ring energies from 1.0 to 1.9 GeV. Low-energy operation is desirable for certain chemical dynamics and chemical analysis experiments which take advantage of the lowest available photon energies, and in this vein, a successful 1.3 GeV test took place earlier this year. On the other end of the ALS spectrum are the users who need maximum photon flux at high energies (above ~500 eV) for x-ray fluorescence spectroscopy, x-ray lithography, hard x-ray microscopy, protein crystallography, and other experiments. These users will see the most benefit from 1.9 GeV operation. Undulator users can expect the energy of each undulator harmonic to rise by a factor of 1.6 going from 1.5 to 1.9 GeV, thus creating more usable flux of high-energy photons. Bend-magnet experiments using hard (~10 keV) x rays can expect about 20 times more flux at 1.9 than at 1.5 GeV, while those using soft (lower energy) x rays will not see much change in their available flux.

3. BEAMLINE BREAKTHROUGHS

** 6.3.2: NEW MONOCHROMATOR DESIGN PERFORMING WELL **
(contact: jhunderwood@lbl.gov)

The team at Beamline 6.3.2 spent part of October testing a varied line spacing plane grating monochromator (VLS-PGM), the first of its kind at the ALS. While the SGM designs used on the other ALS beamlines use a spherical grating and a movable exit slit, the VLS-PGM design uses a combination of a spherical mirror and plane grating, together with a fixed exit slit. The VLS-PGM also has no entrance slit and demagnifies the ALS source by a factor of 10. These features make it remarkably compact: the entire monochromator sits on a single table about 2 meters long. This first VLS-PGM, having produced excellent nitrogen test spectra on October 20, is now being dismantled and shipped to the BESSY synchrotron facility in Berlin, Germany, for evaluation and joint experiments. A version specifically designed and optimized for the ALS as part of a beamline funded by the Advanced Research Projects Agency (ARPA) is scheduled for operation by the end of November. It will work over the energy range 50-1000 eV with a projected spectral resolving power of 10,000. A team from the Center for X-Ray Optics at LBL led by James Underwood developed the beamline.

Beamline 6.3.2 is designed for the calibration of x-ray and EUV optical components such as mirrors, gratings, multilayers and detectors, and the provision of standards of intensity and wavelength at x-ray wavelengths. The initial research will focus on measuring the optical quality (reflectivity, uniformity, degradation, etc.) of multilayer optics for projection lithography in the extreme ultraviolet, at a wavelength of 130 angstroms. However, the beamline has been designed with sufficient flux, and spatial and spectral resolution to be valuable for a wide variety of surface physics and chemistry studies.

4. TIMELY TOPICS

** CALL FOR INDEPENDENT INVESTIGATOR PROPOSALS **

The ALS is now soliciting proposals from scientists who wish to conduct research at the facility as independent investigators during 1995. The ALS has two scheduling cycles per year: April-September and October-March. The submission deadline for April-September 1995 is December 1, 1994.

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

For beamline and PRT information, contact:
Fred Schlachter, ALS User Liaison
Tel: (510) 486-4892
Fax: (510) 486-7696
email: fred_schlachter@lbl.gov

** LONG-TERM SCHEDULING MEETING DECEMBER 5 ** (contact: fred_schlachter@lbl.gov)

On Monday, December 5, there will be a long-term operations scheduling meeting covering the period between the end of the coming shutdown (scheduled to start December 22 with user operations resuming February 22, 1995) and the beginning of the next shutdown (provisionally scheduled to begin in September 1995). The meeting will be held in the Building 6 conference room from 11:00 a.m. to noon, following the weekly scheduling meeting.

A spokesperson from each beamline should submit a detailed request from that beamline's research groups for nominal operation (320 bunch, 400 mA, 1.5 GeV) and for any unusual operation conditions desired. The request should include the number of shifts needed and information on the desired configuration of shifts (should 6 shifts of 1.9-GeV operation be scheduled on two consecutive days, on successive owl shifts, or in some other way?). The request should also state if exact dates are needed, or if special operations can take place at any time within the period being scheduled. Spokespersons from different beamlines are encouraged to coordinate with each other on requests for the same unusual conditions (e.g., two-bunch operation).

After this information is gathered on December 5, a draft plan will be reviewed by beamline spokespersons. The ALS Users' Executive Committee will then review a final draft before the schedule is finalized and distributed.

Writers: jccross@lbl.gov, deborah_dixon@macmail.lbl.gov