1 . MIRROR POSITIONING FEEDBACK MINIMIZES IR BEAM MOTION
(Contact: WRMcKinney@lbl.gov)

Initial tests of a new system for mirror positioning on the infrared beamline, Beamline 1.4, have shown that it reduces photon beam intensity fluctuations by an order of magnitude. The system uses visible light from the ALS and a position-sensitive detector as feedback to control the angle of the beamline's fifth mirror. The mirror is mounted on a two-axis piezoelectric stage that moves to maintain a consistent beam position relative to the detector. A subsequent mirror reflects the infrared light but allows the unwanted visible light to pass through. Preliminary tests showed a ten-fold decrease in intensity fluctuation at frequencies up to 100 Hz and some correction up to about 800 Hz. The system was developed by Wayne McKinney, Mike Chin, Greg Portmann, and Mike Martin (all of the ALS) with input from Ed Melczer (Lawrence Livermore National Laboratory) regarding similar systems in use at the Livermore lab.

2. SCIENTIFIC ADVISORY COMMITTEE MEETS ON LINE(S)

On June 3, the ALS Scientific Advisory Committee (SAC) held a conference-call meeting that featured more than the typical audio connection. While local members gathered to see presentations on site, more distant members tuned in by telephone and over the World Wide Web. As the presenters displayed viewgraphs in the ALS mezzanine conference room, members listening to the conference call clicked through the same viewgraphs on the Internet. They were also able to view the contents of handouts distributed at the meeting through the Web interface. The new approach was well received, and the ALS plans to use the same system for future conference calls.

The SAC members heard and approved several proposals. One of these was a proposal from a nationwide consortium of universities to build a pair of protein crystallography beamlines for molecular structural biology. A proposal to build a diffraction beamline for materials chemistry was also approved, as was a proposal to switch a future bend-magnet-based protein crystallography beamline to a superbend beamline. In addition, the SAC's ad-hoc microscopy review committee gave a preliminary report based on its February review.

3. NEW LONG-TERM SCHEDULE ON THE WEB
(Contact: GFKrebs@lbl.gov)

A new long-term operating schedule, extending to December 1999, has been approved by the Users' Executive Committee. The schedule can be seen on the Web at http://www-als.lbl.gov/als/schedules/current_ltsch.html. You can also reach it by following the "Operating Schedules" link from the ALS home page (http://www-als.lbl.gov/). For convenient printing, the schedule appears as a graphic, in Portable Document Format, as an Excel file, and as a Word document.

4. USER STOCK ROOM AND EQUIPMENT POOL MOVING
(Contact: DJHamamoto@lbl.gov)

Because of the construction of an elevator where the ALS equipment pool is currently located, the users' stock room and equipment pool will be relocated to Building 7. The new stock room will be accessible through the center door of building 7 facing the lower parking lot. Once in the hallway of Building 7, users will be able to open the stock room door with their key card. The move is expected to take place this week. In the process, the ALS will enlarge the stock room and expand on the inventory. Users who would like new items in the stock room should send their requests to Donna Hamamoto (510-486-5527, DJHamamoto@lbl.gov).

5. ELECTRICAL ENGINEERS AND MECHANICAL TECHNICIANS GET NEW LEADERS

Beginning July 1, the ALS will have a new Electrical Engineering Group Leader in the person of Walter Barry. Walter comes to us from the Berkeley Lab Accelerator and Fusion Research Division (AFRD), where he worked as a member of the Beam Electrodynamics Group. Walter is no stranger to the ALS. As part of his seven-year stint with AFRD, he worked on the design, development, and implementation of the transverse feedback systems for the ALS and for the B-Factory at the Stanford Linear Accelerator Center. The current Electrical Engineering Group Leader, Jim Hinkson, will return to the group's Instrumentation Section.

The Mechanical Technicians will also have several changes in leadership as of July 5. Dan Colomb will continue his role as Section Leader, working with the unit leaders assigned to the main ALS experiment floor and handling administrative duties for the section. Wayne "Wayno" Oglesby, head of the Mechanical Installation Unit, will take over Dan's other role as Building 80 Fabrication Facility Lead. Wayno will be responsible for completing formal ALS job orders and user fabrication requests. With Wayno's departure, Dennis Hull will take over leadership of the Mechanical Installation Unit. The installation team, in turn, will gain a new mechanical technician, Greg Hay. Greg's previous assignment was in AFRD's Superconductor and Cable Development Group, working at the cable winding facility in Building 52. The current leaders will assist the new ones during a three- to four-week overlap period.

6. USERS' MEETING T-SHIRT DESIGNS DUE FRIDAY, JULY 23
(Contact: EJMoxon@lbl.gov)

As we announced in the last issue of ALSNews, ALS users, staff, family, and friends are invited to submit designs for an ALS T-shirt. The winner will have his or her signed artwork featured on T-shirts for participants at this year's ALS Users' Meeting (October 18-20). Designs should be no larger than 8.5 in. by 11 in. (22 cm by 28 cm). The words "Advanced Light Source" or "ALS" must appear somewhere in the design.

Send designs by July 23 to Elizabeth Moxon, Advanced Light Source, Berkeley Lab, MS 4-230, Berkeley, CA 94720, or fax to 510-495-2111.

7. TWO POSTDOC POSITIONS IN SOFT X-RAY SPECTROSCOPY
(Contact: TCallcott@utk.edu)

The soft x-ray (SX) spectroscopy Participating Research Team (PRT) for Beamline 8.0 at the ALS is soliciting applications for two postdoctoral positions, to be available in September 1999. Position #1 is for an endstation manager to maintain and schedule the SX fluorescence endstation currently installed on Beamline 8.0. Position #2 is for a scientist to oversee construction and commissioning of a new endstation enabling angle-resolved measurements of both SX photons and photoelectrons. Both scientists are expected to also conduct a personal research program using the PRT's facilities. For further information, see the University of Tennessee Department of Physics and Astronomy job listings at http://www.phys.utk.edu/jobs.htm or contact T.A. Callcott, University of Tennessee (TCallcott@utk.edu, 423-974-6765).

8. RECENT PUBLICATIONS

Bhatia, C.S., W. Fong, C. Chen, J. Wei, D. Bogy, S. Anders, T. Stammler, and J. Stohr, "Tribo-chemistry at the head/disk interface," IEEE Trans. Magn. 35, 910-915 (1999).

Hansen, D.L., K.T. Leung, P. Neill, R.C.C. Perera, M. Simon, Y. Uehara, S.B. Whitfield, D.W. Lindle, G.R. Fisher, R. Martin, et al., "Multi-ion coincidence measurements of methyl chloride following photofragmentation near the chlorine K-edge," J. Phys. B 32(3), 1 (1999).

Heske, C., R. Treusch, F.J. Himpsel, S. Kakar, L.J. Terminello, and H.J. Weyer, "Band widening in graphite," Phys. Rev. B 59, 4680-4684 (1999).

Hillier, B.J., K.S. Christopherson, K.E. Prehoda, D.S. Bredt, and W.A. Lim, "Unexpected modes of PDZ domain scaffolding revealed by structure of nNOS-syntrophin complex," Science 284(5415), 812-815 (1999).

Magnuson, M., J. Guo, C. Sathe, J. Rubensson, J.E. Nordgren, P.N. Glans, Li Yang, P. Salek, and H. Agren, "Competition between decay and dissociation of core-excited carbonyl sulfide studied by x-ray scattering," Phys. Rev. A: At., Mol., Opt. Phys. 59, 4281-4288 (1999).

Ohrwall, G., P. Baltzer, and J.D. Bozek, "Synchrotron radiation excited photoelectron spectrum of H2+ with rotational resolution," J. Phys. B 32(3), 51-56 (1999).

Prehoda, K., D. Lee, and W.A. Lim, "Structure of the enabled/VASP homology 1 domain-peptide complex: A key component in the spatial control of actin assembly," Cell 97(4), 471-480 (1999).

9. 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 1.4.2: Chris Weber (Berkeley Lab), Joe Orenstein (Univ. of California, Berkeley, and Berkeley Lab), and Michael Martin (Berkeley Lab) will be testing a new cryostat system with the goal of measuring far-IR spectra of many novel, highly correlated electron materials.

Beamline 1.4.3: Ted Raab (Univ. of Colorado, Boulder) will be studying rhizosphere plant/soil interactions. Marni Goldman (Berkeley Lab) will study bioactive glass layers on metal implants. Miqin Zhang (Univ. of California, Berkeley) will study cell/metal interactions. Kathy Gough (Univ. of Manitoba, Canada) and collaborators will use IR spectromicroscopy for biodiagnostics--the analysis of spectral changes in human tissues and fluids--looking for changes at the onset of disease. Hoi-Ying Holman (Berkeley Lab) and collaborators will study spectral changes in individual cells when exposed to environmental toxins.

Beamline 6.3.2: Jeffrey Kortright (Berkeley Lab) will conduct resonant scattering studies of chemical and magnetic heterogeneity in magnetic recording media, and K.T. Leung (Univ.of Waterloo, Ontario) will conduct element-specific photo-breakdown studies of "environmentally safe" freon substitutes.

Beamline 7.3.1.1: Zi Qiang Qiu (Univ. of California, Berkeley) will use PEEM2 to study interlayer coupling of magnetic multilayers.

Beamline 7.3.3: Christian Bressler and Melanie Saes (Univ. of Lausanne, Switzerland) and Rafael Abela (Swiss Light Source) will be performing time-resolved x-ray absorption studies of iodine ions in water, excited by a short laser pulse.

Beamline 8.0.1: Richard Saykally (Univ. of California, Berkeley) will study the structure of water in the deeply supercooled region, and Dennis Lindle (Univ. of Nevada Las Vegas) will probe the limits of fundamental approximations in x-ray photoelectron spectroscopy.

Beamline 9.3.2: Harald Braeuning (Gesellschaft fuer Schwerionenforschung, Darmstadt) will measure fully differential cross-sections for double photoionization of neon.

Beamline 10.3.1: The research group of Harvey Doner (Univ. of California, Berkeley) will study trace element distributions in soil samples.

10. OPERATIONS UPDATE
(Contact: RMMiller@lbl.gov)

The ALS has just completed a planned shutdown for installations and maintenance. User operations resumed at 8:00 a.m. on June 21, as scheduled.

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.