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. 116        November 25, 1998

Table of Contents


    1. INDEPENDENT INVESTIGATOR PROPOSALS: CRITICAL NOTICE
    2. NEW BEAMLINES AVAILABLE TO INDEPENDENT INVESTIGATORS IN 1999
    3. ALS TO GET NEW ADMINISTRATOR IN DECEMBER
    4. WHO'S IN TOWN: A SAMPLING OF ALS USERS
    5. OPERATIONS UPDATE

1. INDEPENDENT INVESTIGATOR PROPOSALS: CRITICAL NOTICE

Important notice to all users about physical science independent investigator proposals:

The deadline for submitting a proposal to be considered for beamtime from April to September 1999 is December 1, 1998. All proposals submitted by that date will remain active for a second scheduling cycle (i.e., October 1999 to March 2000) if and only if the ALS User Administrator (contact information below) is notified by June 1, 1999. Proposals that were submitted for the June 1, 1998, deadline will also be considered for beamtime in the April 1999 to September 1999 cycle if and only if the ALS User Administrator is notified by December 1, 1998. Otherwise, these proposals will become inactive. All other previously submitted proposals are no longer active.

The proposal form for independent investigators is available in Portable Document Format (PDF) on the Web (http://www-als.lbl.gov/als/quickguide/independinvest.html). Information on the proposal process and a summary of the proposal deadlines for both physical sciences and protein crystallography are available at the same location. Data sheets on beamlines at the ALS (available in Portable Document Format on the Web at http://www-als.lbl.gov/als/als_users_bl/datasheets.html) provide information that may be useful to prospective ALS users.

To request a proposal form by mail, contact:

Ruth Pepe, ALS User Administrator
Tel: (510) 486-5268
Fax: (510) 486-4773
Email: alsuser@lbl.gov

Gary Krebs, ALS User Services Group Leader
Tel: (510) 486-7727
Fax: (510) 486-4773
Email: g_krebs@lbl.gov

2. NEW BEAMLINES AVAILABLE TO INDEPENDENT INVESTIGATORS IN 1999
(Contacts: Beamline 7.3.1.1, sanders@lbl.gov; Beamline 10.0.1, jdbozek@lbl.gov)

Two new beamlines will be open for use by independent investigators beginning in February 1999. Beamline 7.3.1.1 provides light to the photoemission electron microscope (PEEM2), and Beamline 10.0.1 illuminates endstations for high-energy-resolution spectrometry (HERS) and high-resolution atomic and molecular electron spectrometry (HiRAMES).

Beamline 7.3.1.1

The PEEM2 system is designed for imaging samples via secondary electron emission as a function of the incident x-ray wavelength. Operating at voltages up to 30 kV, it uses a four-lens electrostatic system with one stigmator/deflector assembly and one deflector for image correction. It has four different apertures (2 mm, 50 microns, 20 microns, and 12 microns) that can be easily exchanged in situ. Images are acquired by a slow-scan CCD camera with a maximum rate of 4 images per second. Typical exposure times are a few seconds. Local near-edge x-ray absorption fine structure (NEXAFS) and x-ray magnetic circular dichroism (XMCD) spectra can be obtained in small areas of interest on the sample with a spatial resolution of 50 nm.

The microscope is equipped with a fast load lock and a three-sample parking stage. The sample transfer system can handle samples of arbitrary size with an accessible area of 1 cm x 1 cm. Samples must be solid, conductive to some degree, reasonably flat, and UHV compatible. The sample preparation chamber provides a sputtering gun for sample cleaning, several evaporators, a sample manipulation system to grow thin films and wedge-shaped multilayer structures, a sample heater (up to 1000 degrees C), and a low-energy electron diffraction (LEED) system for sample analysis.

The beamline's photon energy range is 250-1200 eV, and its resolving power is 1800. The beamline can deliver left and right circularly polarized and linearly polarized radiation by means of a movable mask upstream of the monochromator grating. The x rays are focused into a 30-micron spot with a photon flux of 3 x 10^12 photons per second. Downstream from PEEM2 is a chamber equipped with magnetic field coils for non-spatially resolved XMCD and NEXAFS spectroscopy for reference and overview spectra. The maximum field strength is 750 Oe.

Beamline 10.0.1

A new 4.5-m-long, 10-cm-period undulator delivers light to Beamline 10.0.1. The beamline itself was in large part constructed from the former Beamline 9.0.1, which shared another undulator with Beamline 9.0.2. The new beamline incorporates the old one's spherical-grating monochromator and other reusable elements. New vacuum components and optics have replaced the shared portions of the previous beamline. A new refocusing mirror directs the beam into either one of the two branchlines, 10.0.1.1 or 10.0.1.3.

Branchline 10.0.1.1's high-energy-resolution spectrometer (HERS) for angle-resolved photoemission experiments is dedicated to the study of highly correlated electron systems. The business end of the experimental station is a state-of-the-art, angle-resolved electron energy analyzer (Scienta SES-200) mounted on a chamber that rotates about the photon beam axis. The analyzer, with its angle-resolving mode and high-precision low-temperature sample goniometer, allows photoemission experiments with ultra-high energy and momentum resolution. A high-efficiency electron-spin detector currently under construction will allow determination of all three components of electron spin with high energy resolution (comparable to kT).

The high-resolution atomic and molecular electron spectrometer (HiRAMES) endstation on Branchline 10.0.1.3 is designed to study electronic processes in atoms and molecules in the greatest detail. The endstation includes a Scienta SES-200 electron energy analyzer mounted on a chamber that rotates about the photon beam axis. A rotatable seal maintains the vacuum integrity of the system when it is rotating, allowing quick changes in the angle of the spectrometer. Gaseous samples are introduced into a gas cell mounted on the end of the electron lens. The cell has differentially pumped openings for the photon beam and for a slit that allows electrons to leave the cell in the direction of the analyzer. Sample pressures as high as 10^-5 Torr are isolated from the ultra-high-vacuum requirements of the beamline by windowless differential pumping.

3. ALS TO GET NEW ADMINISTRATOR IN DECEMBER
(Contact: jtkrupnick@lbl.gov)

Current ALS Administrator Elizabeth Saucier has been offered an opportunity to assist in running the Administrative Services Department for Berkeley Lab and will begin this new role during the month of December. The ALS will miss Elizabeth, who was instrumental in setting up the ALS Administration and User Administration during its initial period of operations. Fortunately, Nancy Talcott has accepted the assignment to become the new ALS Administrator. Nancy has a great deal of familiarity with the ALS, having held this position during the ALS construction project. The actual moves are expected to take place around December 7, and Elizabeth will be involved in overlap training with Nancy through December.

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, Eugene Haller, and Wei Shan (Berkeley Lab) will continue photoluminescence studies of wide-band-gap semiconductors under pressure.

Beamline 1.4.3: Ted Raab (Univ. of Colorado at Boulder) will perform infrared spectromicroscopy on plants and soils from the areas around plant roots. Hoi-Ying Holman and Regine Goth-Goldstein (Berkeley Lab) will continue their studies of toxin uptake by cells.

Beamline 7.0.1: Phil Woodruff (Univ. of Warwick , UK) will study chemically-resolved photoelectron diffraction of molecules on surfaces. Jeff Kortright (Berkeley Lab) will be doing imaging studies of magnetic interactions in magnetic multilayers. Tim Grundl (Univ. of Wisconsin-Milwaukee) will perform spectromicroscopy studies of clay minerals.

Beamline 10.3.1: Henry Hieslmair (Berkeley Lab) will examine iron at structural defects in polycrystalline silicon.

Beamline 10.3.2: Mark Conrad and William Stringfellow (Berkeley Lab) will be continuing their experiment on the speciation of transition metals in lichen from Hawaain basalt rock. Leah Cox (Jet Propulsion Laboratory) will be looking at the reduction of iron oxides by the bacteria shewanella putrefaciens. Sharon Borglin (Berkeley Lab) will investigate the structure and mechanism of cesium adsorption on iron oxide barrier material.

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

Beam reliability for the last two weeks (November 9-22) was 92% overall and 94% for user shifts. The majority of beamtime lost was due to a longer-than-scheduled startup after the installation shutdown of November 16 and 17.

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.