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. 73           March 19, 1997

Table of Contents


    1. OPERATIONS UPDATE
    2. NEW MICROSCOPE GETS ITS FIRST LOOK AT THE WORLD
    3. HAPPY ANNIVERSARY TO THE ALS
    4. ALS DIRECTOR'S REPORT

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

Beam reliability for the last two weeks was 91.5% overall and 91.2% for user shifts. All outages were of short duration.

Operations Summary for March 19 - April 7

Mar 19, 00:00-24:00           Accelerator physics
Mar 20, 00:00-08:00           User scrubbing & special operations
                                (Beamline 5.0 W16 operating at small
                                gaps will affect orbit for other users)
Mar 20, 08:00- Mar 24, 07:15  1.9-GeV/340-mA/288-bunch user operations
                                with "camshaft" available on request
Mar 24, 07:30-24:00           Maintenance & startup
Mar 25, 00:00-24:00           Accelerator physics
Mar 26, 00:00-08:00           User scrubbing & special operations
                                (Beamline 5.0 W16 operating at small
                                gaps will affect orbit for other users)
Mar 26, 08:00- Mar 31, 07:15  1.9-GeV/340-mA/288-bunch user operations
                                with "camshaft" available on request
Mar 31, 07:30-24:00           Maintenance & startup
Apr 01, 00:00-24:00           Accelerator physics
Apr 02, 00:00-08:00           User scrubbing & special operations
Apr 02, 08:00- Apr 07, 07:15  1.9-GeV/340-mA/288-bunch user operations

2. NEW MICROSCOPE GETS ITS FIRST LOOK AT THE WORLD

Researchers at the Beamline 7.0 Spectromicroscopy Facility reached a major milestone on March 12, when they took the first high-resolution images and spectra with a new scanning photoemission microscope (SPEM).

The new SPEM has a unique design, in which images are formed by moving the focused x-ray beam over the stationary sample surface. It is the first zone-plate photoemission microscope to operate in this way; the new design was chosen to open a wider range of problems to examination by photoemission spectroscopy. Researchers using the SPEM will be able to study samples that are cryogenically cooled or heated, or to examine small regions of large (25 mm) samples without having to cut the sample apart. The photon energy used in the SPEM can vary from about 200 eV to over 800 eV, offering researchers the flexibility of studying microscopic changes in valence band structure, as well as performing more traditional core-level spectroscopy studies.

In its first day of operation, the SPEM reached spatial resolutions better than 0.5 micron and high count rates of over 10 kHz in core-level emission from a Au/Cu test specimen. Spatial resolution of 0.2 microns is expected from the zone plates in use now, with improvements of a factor of 2 or more as finer zone plates become available.

The new SPEM is the result of a collaboration between the Beamline 7.0 Spectromicroscopy Facility participating research team and the ALS Experimental Systems Group, with Brian Tonner (University of Wisconsin-Milwaukee) and Tony Warwick (ALS) in the lead. People who have made major contributions to the project include Harald Ade (North Carolina State University), Stefeno Cerasari (University of Trieste and ALS), Jonathan Denlinger (University of Michigan), Keith Franck, Adrian Garcia (North Carolina State University and ALS), Steve Klingler, Greg Morrison, John Meng, Sudipta Seal, Rick Steele, and James Tobin (Lawrence Livermore National Laboratory).

For further information, contact Tony Warwick (warwick@lbl.gov) or Brian Tonner (tonner@csd.uwm.edu).

3. HAPPY ANNIVERSARY TO THE ALS

What were you doing four years ago? Many folks at the ALS should remember as on March 19, 1993 the ALS current reached 42 mA and fulfilled one of the final commissioning goals for the machine by exceeding 7.6 mA in a single bunch. For those with a yen for nostalgia, those with poor memories, or you newcomers, here's how the commissioning efforts were reported in the ALS Report newsletter.

"The final phase of the construction project, commissioning the storage ring, thrilled participants and observers alike. Its most remarkable aspect was the speed with which it progressed. Every few days of the year's first quarter seemed to bring another breakthrough. March 16 was especially significant. It was the day we turned on the rf power system for the first time and immediately stored an electron beam. From then on the electron-beam current increased almost daily toward the 50-mA goal required for project completion. We surpassed this a week ahead of schedule on March 24, when 65 mA of current were stored in the ring. But the real culmination of commissioning came about two weeks later when the ALS stored 407 mA, exceeding the 400-mA design goal." Congratulations and Happy Anniversary to all who were involved!

4. ALS DIRECTOR'S REPORT

(A summary of ALS Director Brian Kincaid's Report to ALS staff and users, delivered March 6, 1997.)

"Full Speed Ahead" summarizes the past year's activities of the ALS. Large numbers of people, working on the leading edge of the synchrotron radiation field, have contributed to our successful operation and R&D efforts. We've continued to build our concentration of skill, talent, and dedication, with engineers, scientists, and staff at the ALS working to provide a technically excellent machine and a strong base of user support. We're extremely pleased to see our high-powered user community is taking these resources and running with them, generating scientific results at an accelerating pace.

This acceleration is due in part to the Scientific Facilities Initiative initially funded by Congress in October 1995, which boosted FY96 funding for the ALS and other DOE national user facilities by several million dollars. With this boost in funding, we increased the number of operating hours for users by 73% and built several new beamlines, with more due to become available soon. It is an encouraging sign that the top FY98 priorities for the DOE Energy Research Program (which provides the bulk of ALS funding) include maintaining utilization of scientific facilities like the ALS. Funding for FY98 has yet to be appropriated, of course, but the President's budget request calls for approximately the same funding (in constant dollars) as in FY97, with both slightly below the FY96 bump generated by the Scientific Facilities Initiative. We will make our best use of ALS funding to continue serving our users effectively while pushing the boundaries of synchrotron research and development.

The success and growth of the ALS scientific program depends directly on the quality of operations the facility provides, and to users this means a reliable, high-quality beam. To this end, we brought new coupled-bunch longitudinal and transverse feedback systems on line in March 1996. However, with feedback systems on, the decreased beam size has made some remaining beam-position instabilities more critical. In September 1996, therefore, we established a special task force of ALS accelerator physicists, engineers, scientists, operators, and users led by Rod Keller. The task force has been working with remarkable success to further stabilize the ALS electron beam and thereby to increase photon-beam stability for users.

We have also expanded our range of operating modes in the past year. We now operate at 1.9 GeV more than half the time to deliver higher photon flux to users in commonly used photon-energy ranges, and we have increased the maximum current available in this mode from 150 mA to 340 mA. Narrow-gap vacuum chambers in sectors 8 (to be installed May 1997) and 7, as well as longer-period undulators, are meeting most experimenters' needs for low-energy photons at 1.5 GeV, so that we no longer need to operate at 1.0 GeV (though we still offer up to a few weeks each year of 1.3-GeV operations). A new "camshaft" fill pattern provides for a range of timing experiments without interfering with more conventional uses of the beam.

Our beamline and instrumentation development is truly leading the field. Some examples include:

• Micro-XPS at Beamline 7.3.1. (See ALSNews Vol. 70, February 5, 1997, and Vol. 71, February 19, 1997 for more information.)
• Macromolecular Crystallography and Structural Biology Support Facilities. (First light to Beamline 5.0 was reported in ALSNews Vol. 69, January 22, 1997.)
• Elliptical Polarization Undulators (EPUs). A working scale model for these new insertion devices, which shift rows of magnets to produce light in any polarization from linear (any orientation) to circular (either helicity), was recently completed. The EPUs will serve Beamline 4.0 which will be dedicated to magnetic spectroscopy and microscopy. The beamline is scheduled to be commissioned in 1998.
• Adaptive Optics. The ALS is taking the lead in designing new types of bending mirrors that meet or exceed tough specifications for slope error and spot size, and is also addressing the challenges of designing mirrors with small radii of curvature.