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. 113          October 14, 1998

Table of Contents


    1. ELLIPTICAL POLARIZATION UNDULATOR DELIVERS FIRST LIGHT
    2. PRESIDENT'S SCIENCE ADVISOR VISITS ALS
    3. QUANTUM INTERFERENCE RESEARCH HIGHLIGHTED ON THE WEB
    4. WHO'S IN TOWN: A SAMPLING OF ALS USERS
    5. OPERATIONS UPDATE

1. ELLIPTICAL POLARIZATION UNDULATOR DELIVERS FIRST LIGHT
By Lori Tamura (Contact: ATYoung@lbl.gov)

On the evening of September 29, as fiscal year 1998 was winding down, the gap of the first elliptical polarization undulator (EPU) at the ALS was closed, and the first photons from this beamline were detected on a diagnostic paddle located just downstream of the beamline's monochromator entrance slit. The 5.0-cm-period EPU, located at Beamline 4.0, will provide a powerful tool for experiments involving magnetic circular dichroism--the phenomenon in which atoms with a magnetic moment produce different spectra depending on whether they are exposed to left- or right-handed circularly polarized light. This EPU will provide a high flux of polarized x rays with a great deal of flexibility: the light can be linearly polarized in the vertical or horizontal direction, elliptically polarized right or left, and circularly polarized right or left.

The detection of the EPU light represents a significant milestone in a process that began in 1995, when design of the EPU and beamline was begun. The next step will be to continue with the installation of the rest of the beamline, which includes the monochromator vessel and endstation system. The monochromator is optimized for high-resolution spectroscopy, with an energy range of 55-2000 eV and a resolving power of up to 10,000. To maximize its availability to users, the endstation system has been designed with moving endstation carriages to rapidly switch between three experiment stations.

Tony Young is the project scientist/leader. The EPU was designed by the Insertion Device Engineering Group, consisting of Egon Hoyer, Steve Marks, Ross Schlueter, Dave Plate, Jan DeVries, Yoshi Minamihara, and Paul Pipersky; it was fabricated by the staff of the assembly shop, led by Bill Gath. Work on the EPU beamline is funded by the U.S. Department of Energy, Office of Basic Energy Sciences and Office of Biological and Environmental Research.

2. PRESIDENT'S SCIENCE ADVISOR VISITS ALS

On September 30, presidential science advisor Neal Lane toured the ALS with Director Daniel Chemla as part of a tour of Berkeley Lab. Lane visited several beamlines, discussing x-ray microscopy with researcher Carolyn Larabell, protein crystallography with Macromolecular Crystallography Facility Director Thomas Earnest, EUV lithography with CXRO Head David Attwood, and photoemission spectroscopy with researcher Charles Fadley. Formerly the director of the National Science Foundation, Lane was appointed earlier this year to serve as Director of the Office of Science and Technology Policy and as Assistant to the President for Science and Technology Policy.

3. QUANTUM INTERFERENCE RESEARCH HIGHLIGHTED ON THE WEB
(Contact: qiu@physics.berkeley.edu)

A new Science Highlight about the observation of quantum interference in thin films at Beamline 7.0.1 (reported in "Quantum Interference Observed in Thin Films," ALSNews Vol. 112) is now available on the Web. The highlight shows the variations in photoemission intensities for wedges of copper and cobalt stacked at right angles to each other on a nickel substrate, revealing interference between quantum well states in the copper and cobalt layers. To see it, point your browser to http://www-als.lbl.gov/als/science/sci_archive/QWS.html or follow the "Recent Science Highlight" link on the ALS home page.

4. WHO'S IN TOWN: A SAMPLING OF ALS USERS

To highlight the richness of our user community and help introduce recent arrivals, we offer this listing of some of the experimenters who will be collecting data during the next two weeks at the ALS.

Beamline 1.4.1: Joel Ager, Wei Shan, and Eugene Haller (Berkeley Lab) will continue their studies of the ultraviolet photoluminescence of wide-band-gap semiconductors.

Beamline 1.4.3: John Byrd and Michael Martin (Berkeley Lab) will study electron beam motion using Fourier transform infrared spectroscopy. Ted Raab (Univ. of Colorado, Boulder) will continue his work on amino acids in soils, focusing on surface reactivity near plant roots. Hoi-Ying Holman, Regina Goth-Goldstein, and Michael Martin will study the effect of toxins on human liver cells.

Beamline 7.3.1.1: Andy Smith (Daresbury Laboratory Synchrotron Radiation Department) will be working on photoemission electron microscope studies of geological samples.

Beamline 7.3.1.2: Patrick Taylor (Mitsubishi Silicon America) will be conducting studies on silicon wafers in collaboration with Scott McHugo (Berkeley Lab). Sergei Rouvimov (Berkeley Lab) will be looking at compositional variation in thin films.

Beamline 8.0.1: Elke Arenholz (Berkeley Lab), in collaboration with Chuck Fadley (Univ. of California, Davis; Berkeley Lab) will probe multi-atom resonant photoexcitation effects with x-ray fluorescence spectroscopy.

Beamline 9.3.2: Satish Myneni (Berkeley Lab) will be characterizing aqueous transition-metal organic and inorganic complexes from L-edge spectra, Chuck Fadley (Univ. of California, Davis; Berkeley Lab) will perform resonant photoemission studies, and Ed Moler (Berkeley Lab) will continue commissioning the FTSX spectrometer.

5. OPERATIONS UPDATE
(Contact: rmmiller@lbl.gov)

Beam reliability for the last two weeks was 94.9% overall and 98% for user shifts. There was no significant down time.

Long-term and weekly operations schedules are available on the Web (http://www-als.lbl.gov/als/accelinfo.html). Weekly operations scheduling meetings are held on Fridays at 3:30 p.m. in the Building 6 conference room. The Accelerator Status Hotline at (510) 486-6766 (ext. 6766 from Lab phones) features a recorded message giving up-to-date information on the operational status of the accelerator.