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.

Previous Issues are available.


ALSNews           Vol. 54           June 12, 1996

Table of Contents


    1. OPERATIONS UPDATE
    2. HIGH-SPEED X-RAY AREA DETECTOR UNDER DEVELOPMENT
    3. UPDATE ON CRYSTALLOGRAPHY BEAMLINE
    4. ALS USERS' MEETING T-SHIRT CONTEST
    5. ALS BEAMLINE SPECIFICATIONS FOR 1996-97

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

Beam availability for the last two weeks was 84.5% overall and 86.3% for user shifts. A bend magnet power supply for the booster-to-storage-ring line (BTS B2) required repairs, which were completed in two shifts. All other problems were repaired and were of short duration.

Operations Summary for June 11 - July 1

June 11, 00:00-24:00           Maintenance & Startup
June 12, 00:00-08:00           User Scrubbing & Special Operations
                               (1.1 GeV requested)
June 12, 08:00-June 17, 07:15  1.5-GeV/400-mA/320-bunch user operations
June 17, 07:30-24:00           Maintenance & Startup
June 18, 00:00-24:00           Accelerator Physics
June 19, 00:00-08:00           User Scrubbing & Special Operations
June 19, 08:00-June 24, 07:15  1.5-GeV/400-mA/320-bunch user operations
June 24, 07:30-24:00           Maintenance & Startup
June 25, 00:00-24:00           Accelerator Physics
June 26, 00:00-08:00           User Scrubbing & Special Operations
June 26, 08:00-July 1, 07:15  1.9-GeV/260-mA/320-bunch user operations
July 1,  07:30-24:00           Maintenance & Startup

2. HIGH-SPEED X-RAY AREA DETECTOR UNDER DEVELOPMENT
(contact: jemillaud@lbl.gov or tnearnest@lbl.gov)

Scientists from Berkeley Lab's Engineering and Structural Biology Divisions, the ALS, and the University of California, San Diego, are into the second year of a multiyear project that will culminate in a high-speed, two-dimensional (area) detector for the x-ray crystallography beamline now under construction at the ALS (see item #3). A major advancement of the detector (called a pixel detector) is that it will be able to read out diffraction data as soon as it is detected to a data-storage computer, i.e., there are no unproductive intervals in which the detector cannot register data as is the case with current state-of-the-art electronic systems such as that initially planned for the crystallography beamline. Hence, the pixel detector will ensure even more efficient use of the beamline, which is expected to be heavily subscribed.

Synchrotron radiation offers several advantages for the study of the structure of biological molecules and other materials by x-ray diffraction, including high flux, high brightness, and tunability over a broad range of wavelengths. These features result in more rapid rates of data collection and more accurate data, plus the ability to look at tiny microcrystals, to use methods that require more than one wavelength, and to make time-resolved measurements of dynamic processes. However, to take full advantage of these features, researchers need x-ray detectors that can detect and read out the diffraction information as rapidly as it is generated such as the pixel detector now under development.

The idea behind the pixel detector is conceptually simple. To provide position sensitivity over an area, the designers split the detector into rows and columns of identical elements (pixels), each of which possesses its own autonomous processing electronics. The basic unit is an array of x-ray sensitive semiconductor (PIN) diodes bonded to custom-designed integrated circuit chips (ASICs for application-specific integrated circuits). Each array comprises 50 by 50 pixels. Four such units are then assembled into a module with additional circuitry for read-out based on columns of pixels (the designers use the term column architecture). Finally, a full detector of the desired size consists of the requisite number of modules arranged in a matrix. The collaborators are aiming for an operational detector with an area of 15 cm by 15 cm containing one million pixels. Recent work on the project includes the fabrication of a complete digital instrumentation chain for an array of 16 by 16 pixels, which is now being characterized. Next year, the research group plan to advance to a prototype "quarter-scale" detector before building the full-scale detector in the last year of the project.

3. UPDATE ON CRYSTALLOGRAPHY BEAMLINE
(contact: rsdigennaro@lbl.gov)

Construction work on the crystallography beamline and hutch is proceeding well. The monochromator for the protein crystallography beamline arrived at the ALS in early April. Manufactured by Oxford Instruments, UK, it is modeled after a double crystal monochromator installed at the European Synchrotron Radiation Facility. One of the key features of the instrument is that it has the capability to use a directly cooled crystal. In the design, the "cooled" first crystal absorbs most of the heat and the second crystal (which is not cooled) has significantly less heat load and provides the wavelength resolution. For the cooled crystal, a Si(111) crystal with 0.5 mm minichannels is being fabricated by Rockwell's Rocketdyne division in collaboration with Berkeley Lab. This is a cost effective alternative to the "pin-post" crystal cooling scheme which is in use at other synchrotron crystallography beamlines while maintaining high performance.

Summer student Ryan Lewis working with Dick DiGennaro of the ALS Mechanical Engineering Group is modifying the crystal support subassembly so that it may be adjusted remotely during commissioning of the monochromator without requiring disassembly of the vacuum vessel. This should dramatically reduce the time required to commission the instrument (planned for early fall).

4. ALS USERS' MEETING T-SHIRT CONTEST
(contact: jccross@lbl.gov)

Feeling blue? Stuck in a box? Release your creative energy by entering the 2nd annual ALS T-Shirt Design Contest sponsored by the ALS Users' Executive Committee. The winner will have his or her signed artwork featured on T-shirts for participants at this year's ALS Users' Association Meeting (October 21-22) and will serve on the committee to judge designs in next year's contest. Last year's winner, ALS user Eli Rotenberg from the University of Oregon, will assist in judging this year's artful entries.

T-shirt designs should be no larger than 22 cm high by 28 cm wide (8.5 by 11 inches) and should use four or fewer colors. Rough drawings or concepts are acceptable as well as more polished artwork. The words "Advanced Light Source" or "ALS" must appear somewhere in the design.

Send your designs by July 20 to

Jane Cross
Advanced Light Source
Lawrence Berkeley National Laboratory, MS 2-400
1 Cyclotron Road
Berkeley, CA 94720

5. ALS BEAMLINE SPECIFICATIONS FOR 1996-97
Several subscribers to ALSNews requested information on the current and future beamlines and areas of research planned for the ALS. The following table summarizes this information for beamlines in operation or planned for 1996-97.

Beamline  Source*  Areas of Research            Energy Range  Available

1.4       Bend     Infrared spectromicroscopy          0.05-1 eV   1996
3.1       Bend     Diagnostic beamline                200-280 eV    Now
4.0.1     EPU5     Magnetic spectroscopy              20-1800 eV   1997
4.0.2     EPU5     Magnetic microscopy               100-1600 eV   1997
5.0       W16      Protein crystallography              4-14 keV   1996
6.1       Bend     High-resolution zone-plate         250-600 eV    Now
                     microscopy
6.3.1     Bend     Calibration and standards,        500-4000 eV   1996
                     EUV optics testing
6.3.2     Bend     Calibration and standards,         50-1000 eV    Now
                     EUV optics testing, atomic,
                     molecular & materials science
7.0.1     U5       Surface and materials science,     60-1000 eV    Now
                     spectromicroscopy
7.0.2     U5       Coherent optics experiments         70-650 eV   1996
7.3.1.1   Bend     Magnetic microscopy,              260-1200 eV   1996
                     spectromicroscopy
7.3.1.2   Bend     Surface and materials science,    260-1200 eV   1996
                     spectromicroscopy  
7.3.3     Bend     Deep-etch x-ray lithography          3-12 keV   1996
                     (LIGA)**
8.0       U5       Surface and materials science      70-1200 eV    Now
9.0.1     U10      Atomic and molecular science        20-310 eV    Now
9.0.2.1   U10      Chemical reaction dynamics,           5-30 eV    Now
                     photochemistry
9.0.2.2   U10      Photoionization dynamics              5-30 eV    Now
9.3.1     Bend     Atomic and molecular science,     700-6000 eV    Now
                     materials science
9.3.2     Bend     Chemical and materials science     30-1500 eV    Now
10.3.1    Bend     Fluorescence x-ray microprobe        3-12 keV    Now
10.3.2    Bend     Deep-etch x-ray lithography          3-12 keV    Now
                     (LIGA)**, materials science 
12.0      U8       EUV lithography, surface and        60-320 eV    Now
                     materials science, optics  
                     development

* Sources: Bend    bend magnet
           EPUx    x-cm-period elliptically polarizing undulator 
           Wx      x-cm-period wiggler
           Ux      x-cm-period undulator

** LIGA will move to 7.3.3 in the late summer of 1996.