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. 53           May 29, 1996

Table of Contents


    1. OPERATIONS UPDATE
    2. CALLING ALL POTENTIAL PICASSOS
    3. IMPROVEMENTS TO LOW-CONDUCTIVITY WATER SYSTEM

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

The shutdown for major installations and maintenance ended well on May 22 as the ALS resumed user operations as scheduled with a 260 mA, 1.9- GeV beam and the multibunch feedback system on and working well. The only piece of equipment not fully functional is the undulator for Beamline 7.0, whose gap controller occasionally gets "hung-up." This problem has not yet been solved, but it is probably caused by electrical interference from the drive system getting back into the controller, an old problem that seems to have reappeared. Beam availability since resuming user operations was 85% through Friday, May 24.

The primary task of the successful shutdown was the installation of the W16 wiggler into straight section 5 of the storage ring for the protein crystallography beamline. A few of the other scheduled tasks included installation of a new LEP detector, modification of injection straight flexband/birdcage assemblies, magnet power supply modifications and tests, and LCW (see item #3 below) and AC power system maintenance and modifications.

Nothing is ever as simple as it seems, however, and the startup week (the week preceding the start of user operations) did carry some frustrations for the accelerator physicists. The startup was delayed because of some last-minute vacuum problems on the front end for the new infrared beamline, and at startup it was found that the storage ring vacuum was a lot worse than after previous shutdowns, resulting in a poor-quality beam (large beam size from electron-ion interactions) and short beam lifetimes. The vacuum situation was improved considerably by beam scrubbing, fixing a leak on the front end of Beamline 3.1, and activating the titanium sublimation pumps in the vacuum chamber of the new wiggler. Despite these problems and a shortened startup period, the storage ring was re-tuned to its standard operating point (new quadrupole power supplies had been installed), the chromaticities were reset, the closed orbit was corrected, the 1.9-GeV ramp tables were re- established, and the undulator feed-forward tables were regenerated before the start of user operations. Also, corrector sensitivity matrices were taken and used to confirm that the new quadrupole power supplies are indeed closer to specification.

Operations Summary for May 28 - June 16

May 28,  07:30-24:00           Maintenance & Startup
May 29,  00:00-24:00           Accelerator Physics
May 30,  00:00-08:00           User Scrubbing & Special Operations
                               (1.5 GeV/low beam current requested)
May 30,  08:00- June 3, 07:15  1.9-GeV/260-mA/320-bunch user operations
June 3,  07:30-24:00           Maintenance & Startup
June 4,  00:00-24:00           Accelerator Physics
June 5,  00:00-08:00           User Scrubbing & Special Operations
                               (1.9 GeV requested)
June 5,  08:00- June 10, 07:15 1.5-GeV/400-mA/320-bunch user operations
June 10, 07:30-24:00           Maintenance & Startup
June 11, 00:00-24:00           Accelerator Physics
June 12, 00:00-08:00           User Scrubbing & Special Operations
June 12, 08:00- June 17, 07:15 1.5-GeV/400-mA/320-bunch user operations

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.

** REMINDER: SPECIAL OPERATIONS USER SHIFT **
Reminder to users: the Wednesday owl shift (00:00-08:00) is designated a special operations request shift for users to request special operating conditions such as scrubbing beam, lower-energy operation, different bunch modes, etc. If there are no requests for special operations or scrubbing, the shift for that week will default to the planned energy/fill pattern scheduled for the remainder of that week. Requests for scrubbing beam should be sent to Bob Miller [email: rmmiller@lbl.gov, phone: (510) 486-4738] no later than the scheduling meeting on the Friday before. Other requests for special operations should be sent to Bob at least one week in advance of the shift requested.

2. CALLING ALL POTENTIAL PICASSOS
(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

3. IMPROVEMENTS TO LOW-CONDUCTIVITY WATER SYSTEM
Improvements to the low-conductivity water (LCW) cooling system made during the shutdown are expected to make ALS beams more stable. In addition to meeting routine maintenance needs, the upgrades will give the ALS tighter control over the temperature of the LCW (within one tenth of a degree Fahrenheit). Fluctuations in LCW temperature have been linked to unwanted beam motion in the storage ring and in user beamlines. (See ALSNews Vol. 30 for details.)

One approach to controlling water temperature is a new stainless-steel pipeline that brings water directly to the ALS from the cooling tower. The stainless-steel system bypasses older aluminum supply lines, which were prone to corrosion. In a concurrent upgrade, fan and pump motors in the cooling tower were replaced with variable-speed models, and the fan blades were replaced. A bypass circuit for use when putting new pumps on line was also installed. This additional plumbing makes it possible to bring a new pump up to an efficient speed without affecting the rest of the system.

Berkeley Lab's Facilities Department staff took advantage of the shutdown to complete other time-intensive maintenance tasks. For example, the water filter that serves the entire ALS building was replaced in an annual, week-long operation. In addition, 26 of 28 steel valves whose insulating finish was wearing off were replaced with stainless-steel valves. The remaining two valves will be replaced during a regular Monday shutdown.