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.4           November 22, 1994

Table of Contents


    1. ADMINISTRATIVIA  
    2. SINCE YOU ASKED
    3. OPERATIONS OVERVIEW  
    4. BEAMLINE BREAKTHROUGHS
    5. TIMELY TOPICS

1. ADMINISTRATIVIA
(contact: alsnews@lbl.gov)

The first few issues of ALSNews are being sent to a standard distribution list of people we thought might be interested in subscribing. In early December, only those persons who have asked to be placed on the permanent newsletter distribution list will continue to receive ALSNews. If you haven't responded yet, please email alsnews@lbl.gov and include your complete internet address in the body of the message. We would also appreciate receiving suggestions for the information or topics you would like to see covered in ALSNews.

2. SINCE YOU ASKED

Visitors to the ALS experiment floor often ask what we are cooking in those large cylindrical ovens (just the right size for a 20-lb turkey) covered with aluminum foil. To satisfy this curious crowd, we have been perfecting one of our favorite recipes so we could share it with you in the spirit of the American Thanksgiving Holiday on November 24.

Baked VV a` la ALS

Ingredients:
    1 steel or aluminum vacuum vessel (VV) (preferably one with undesired water
      and hydrocarbon impurities)
    Lots of aluminum foil
    Electric heating tapes and vacuum pumps as needed, depending on size and
      shape of VV

Directions:
1) "Dress" the VV:
    - Wrap in a tight layer of aluminum foil (optional)
    - Wrap with electric heating tapes
    - Cover with more foil**

2) Activate vacuum pumps to whisk away impurities as they are driven from the inner walls during baking. Be sure to attach a residual gas analyzer to identify and measure the impurities!

3) Bake for 5-10 days, allowing a day at the beginning to bring the VV up to its maximum temperature and a day at the end for slow cooling, during which you may need to re-torque the vacuum seals to prevent loss of vacuum and re-contamination. Note: When baking steel VVs, it is often desirable to start with a "hard bake" at 200 degrees Celsius to drive off hydrocarbons such as oils from fingerprints or residuals from the precleaning process. Then, after more delicate optics have been installed and aligned, a "soft bake" at about 125 degrees Celsius eliminates remaining moisture and gases (sorry, no basting).

4) When done, the VV's residual pressure should be on the order of 10**-10 torr. Use as desired!

Serves: Many users

** The first layer of foil, depending on which cook you consult, is to distribute the heat evenly (since aluminum is a much better thermal conductor than stainless steel) and/or to prevent oxidation of the steel surfaces due to direct contact with the heating tapes. The outer layer of foil serves mainly to insulate the equipment by reflecting infrared (heat) radiation back in toward the VV being baked.

3. OPERATIONS OVERVIEW
(contact: rmmiller@lbl.gov)

Operations for Wednesday, Nov. 23, thru Wednesday, Dec. 7:
Standard 320 bunch, 400 mA operation for users:
    Nov. 30,  08:00-24:00
    Dec. 1-2, 08:00-24:00
One/two-bunch operation:
    Nov. 23, 00:00-24:00
    Nov. 30, 00:00-08:00
    Dec. 1-2, 00:00-08:00
Maintenance and startup:  Mondays and Dec. 6
Accelerator physics: Nov. 29 and Dec. 7
Holidays:  November 24, 25 for Thanksgiving.

4. BEAMLINE BREAKTHROUGHS

** R&D MAGAZINE FEATURES BEAMLINE 8.0 EXPERIMENT **
(contact: anders.nilsson@fysik.uu.se)

Beamline 8.0 researcher Anders Nilsson of Uppsala University, Sweden, is using a new experimental endstation that recently attracted the attention of R&D Magazine (October 1994, pp. 105-106). The endstation's three detectors (x-ray spectrometer, electron spectrometer, and near-edge x-ray absorption fine structure detector) can rotate about the analysis chamber under UHV conditions and can collect data simultaneously on the same sample. R&D notes an advantage of this scheme: it "...eliminates reference and contamination problems associated with experiments on the same sample using individual instruments performed at different times, some of which can be months apart." The rotating chamber can also collect angle-resolved spectroscopy data. Nilsson and the Uppsala group have used this ability to separate spectral information arising from normal photoemission and ordinary auger decay, two effects which often interfere with each other and thus decrease the information available from photoemission spectra.

5. TIMELY TOPICS

** CALL FOR INDEPENDENT INVESTIGATOR PROPOSALS **

The ALS is now soliciting proposals from scientists who wish to conduct research at the facility as independent investigators during 1995. The ALS has two scheduling cycles per year: April-September and October-March. The submission deadline for April-September 1995 is December 1, 1994.

To request a proposal form, contact:
Elizabeth Saucier, ALS User Administrator
Tel: (510) 486-6166
Fax: (510) 486-4960
email: alsuser@lbl.gov

For beamline and PRT information, contact:
Fred Schlachter, ALS User Liaison
Tel: (510) 486-4892
Fax: (510) 486-7696
email: fred_schlachter@lbl.gov

Writers: jccross@lbl.gov, deborah_dixon@macmail.lbl.gov