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. 68           January 8, 1997

Table of Contents


    1. OPERATIONS UPDATE
    2. PROGRESS IN ELIMINATING SLOW ORBIT DISTORTIONS
    3. USERS--ARE YOUR ABSTRACTS IN YET? TWO WEEKS TO GO...
    4. ALS USER OPERATIONS BEFORE AND AFTER THE STRATEGIC FACILITIES INITIATIVE
    5. 74 INDEPENDENT INVESTIGATOR PROPOSALS RECEIVED

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

Beam reliability for December 9-23 was 94.9% overall and 95.5% for user shifts. The time between fills at 1.5 GeV was increased from 4 hours to 5 hours at user request.

Operations Summary for January 8 - January 27

Jan 08, 00:00-08:00           User scrubbing & special operations
                              (1.5-GeV/400-mA/304-bunch user operations)
Jan 08, 08:00- Jan 13, 07:15  1.9-GeV/300-mA/304-bunch user operations
Jan 13, 07:30-24:00           Maintenance & startup
Jan 14, 00:00-24:00           Accelerator physics
Jan 15, 00:00-08:00           User scrubbing & special operations
                              (1.5-GeV/400-mA/304-bunch user operations)
Jan 15, 08:00- Jan 20, 08:00  1.9-GeV/40-mA/2-bunch user operations
Jan 20, 08:00- Jan 21, 07:15  No operations - M.L. King, Jr. holiday
Jan 21, 07:30-24:00           Maintenance & startup
Jan 22, 00:00-24:00           Accelerator physics
Jan 23, 00:00-08:00           User scrubbing & special operations
Jan 23, 08:00- Jan 27, 07:15  1.9-GeV/40-mA/2-bunch user operations

2. PROGRESS IN ELIMINATING SLOW ORBIT DISTORTIONS
(contact: r_keller@lbl.gov)

Since the ALS began regular operation with feedback systems on, the decreased beam size has made some remaining beam-position instabilities more critical. Therefore, since September 1996, a special task force has been working to further stabilize the ALS electron beam and thereby to increase photon-beam stability for users. So far the task force has mainly tackled slow orbit distortions, with typical time ranges between five minutes and several hours and horizontal amplitudes up to 300 microns. Partial or complete solutions have been found for air-temperature-related distortions, and also for a crane-related distortion effect discovered by ALS users. All of these distortions are global in nature, affecting essentially all beamlines when they occur.

** TEMPERATURE-RELATED SLOW DISTORTIONS **
Temperature inside the storage ring tunnel is controlled by nine air-handling units and monitored by nine temperature sensors. At the end of November, all nine air-handling units were placed under the control of a single set value derived from the average of the nine temperature readings around the tunnel. The air outlet nozzles have been reoriented, forcing the air in the tunnel to flow in a counterclockwise helical motion that provides more uniform temperature around the ring as well as enhanced cooling of magnet supports and girders. The temperature sensors have been moved from their former positions near the cooled-air outlets to new locations on the outer perimeter of the girders, and new sensor heads with higher dynamic resolution have been installed. These changes have completely eliminated horizontal orbit distortions of ~70 microns (peak-to-peak amplitude) and 60-minute period, and have suppressed long-term drifts with ~3-hour duration from ~300 to 100 microns. A third class of distortions, with half-sine-wave shapes, ~5-hour time spans, and up to 100-micron horizontal amplitude, has recently been linked to faulty actuators in some of the air-handling units, leading to strong air-temperature oscillations in a few sectors in spite of only gradually changing controller settings. One unit was replaced just before the holiday break, and all other were thoroughly tested last week.

** FAST DISTORTIONS **
Another, totally unrelated orbit-distortion effect was first discovered by users who noticed that their beam intensity changed abruptly as one of the two large building cranes was moved. A dedicated study showed that it is the change in crane positions from their default parking spots, not their motion itself, that causes the perturbation. Position changes of both the inner and outer (annex) cranes are associated with sudden orbit changes. Measurements on inner crane movements show significant perturbations of the magnet field near the electron beam; such measurements have not yet been taken for the outer crane. It is not clear whether all the abrupt orbit changes of 5-15 minute duration in the last year can be explained by crane movements. Another phenomenon under investigation is "snapping" changes in the shape of one girder (the one in sector 10 is particularly under suspicion) due to temperature variation and heavy friction in some of its ball joints. Tests using a hot-air blower have generated girder snaps of up to 16 microns, which would lead to orbit distortions of ~150 microns. In any case, however, the crane effects are so severe that movement of both major cranes has been restricted to times when the storage ring is not running for users, such as during maintenance shifts or refilling.

** FUTURE ORBIT-STABILIZATION PLANS AND USER INPUT **
Near-future tasks for the Stability Task Force include resolving remaining problems with the air-handling units and establishing a system of temperature observations and preventive maintenance. We can then expect that the electron beam will exhibit very good stability, already achieved during many night shifts. In the not-so-near future, fast orbit distortions with frequencies up to 50 kHz will become the focus of attention. All user input, positive or negative, on orbit stability is appreciated. The best way to give your input is to send email to Rod Keller (via QuickMail or at r_keller@lbl.gov), stating your observation or concern and including your phone number.

3. USERS--ARE YOUR ABSTRACTS IN YET? TWO WEEKS TO GO...
(contact: alsuser@lbl.gov)

In early December, we sent out a call for abstracts to be included in a compendium of ALS user abstracts, targeted for publication in the spring of 1997. We were pleased to hear from a few users that they have so many abstracts they'd like to submit that they need more preparation time! Therefore, we are extending the deadline, formerly January 10, to January 24. If you have done experiments at the ALS and we haven't received abstracts from you by then, don't be surprised if you hear from us: we're making every effort to compile as comprehensive a volume as possible.

If you have ever conducted an experiment at the ALS and you did not receive the call for abstracts and author guidelines, please send email immediately to alsuser@lbl.gov with "send author guidelines" in the subject line and your name, complete mailing address, and fax number in the body of the message, so we can send you an author packet.

4. ALS USER OPERATIONS BEFORE AND AFTER THE STRATEGIC FACILITIES INITIATIVE
(contact: b_feinberg@lbl.gov)

The numbers are in -- and the Strategic Facilities Initiative (SFI), which increased funding for the ALS and other Department of Energy national user facilities during fiscal 1996, dramatically improved the service we were able to offer our users. The Strategic Facilities Initiative, approved by Congress in November 1995, provided funding for increased operating time and staff, for capital equipment such as new beamlines, and for new instrumentation.

Between the increased operating time and the construction of new beamlines, we were able to serve many more experiments beginning in FY96. The total hours of beam we delivered for users increased 73% from FY95 to FY96, and the total instrument hours (hours of beam multiplied by available beamlines) increased by 92%.

                                          FY 95           FY 96 

Total Hours of Operation for Users        2,580           4,461
Total Instrument Hours                   22,946          44,024
Users                                       213             296

                                          FY 95           FY 96 

Percentage LBNL                             46%             25%
Percentage other DOE Lab                     2%             13%
Percentage other Federal                    18%              3%
Percentage University & Non-Profit          20%             40%
Percentage Industry                          7%              6%
Percentage International                     7%             13%

5. 74 INDEPENDENT INVESTIGATOR PROPOSALS RECEIVED
(contact: nvsmith@lbl.gov)

The ALS received 74 independent investigator proposals in the last submission period which ended in December. This represents twice as many proposals as the previous submission cycle and indicates a growing demand for access to the ALS research facility. The Proposal Study Panel met on December 17 to rate the proposals and make recommendations. Highly rated proposals will be allocated beamtime between June and November 1997 by the ALS Scientific Program Head, Neville Smith, in consultation with PRT spokespersons.

In order to get back in synchronism with the fiscal year, the next scheduling cycle (now termed the winter semester) will be a short one, January-March, 1998. The deadline for proposals will be July 15, 1997.