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. 55           June 26, 1996

Table of Contents


    1. OPERATIONS UPDATE
    2. OVER 30 INDEPENDENT INVESTIGATOR PROPOSALS RECEIVED
    3. REVISED BEAMLINE DESIGN REQUIREMENTS PUBLICATION NOW AVAILABLE
    4. NEW USER ADVISORY ISSUED ON INTERLOCK REQUIREMENTS FOR TURBO PUMP SYSTEMS
    5. MORE FUN AND FASCINATING FACTS

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

Beam availability for the last two weeks was 93% overall and 92.3% for user shifts. All problems were of short duration. The longitudinal and transverse feedback system returned to operation on June 19. Beam was re-tuned near the coupling resonance to give 5-hour beam lifetimes at 400 mA.

Operations Summary for June 25 - July 15

June 25, 00:00-24:00           Accelerator Physics
June 26, 00:00-08:00           1.9-GeV/ user scrubbing and tests
                               (Beamline 9.3.2 specifies current)
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
July 2,  00:00-24:00           Accelerator Physics
July 3,  00:00-08:00           User Scrubbing & Special Operations
                               (1.9 GeV requested)
July 3,  08:00-July 4, 07:15   1.9-GeV/260-mA/320-bunch user operations
July 4,  08:00-July 5, 08:00   Holiday
July 5,  08:00-10:00           Startup
July 5,  10:00-July 8, 07:15   1.9-GeV/260-mA/320-bunch user operations
July 8,  07:30-24:00           Maintenance & Startup
July 9,  00:00-24:00           Accelerator Physics
July 10, 00:00-08:00           User Scrubbing & Special Operations
July 10, 08:00-July 15,07:15   1.9 Gev/260-mA/320-bunch user operations
July 15, 07:30-24:00           Maintenance & Startup

2. OVER 30 INDEPENDENT INVESTIGATOR PROPOSALS RECEIVED
(contact: nvsmith@lbl.gov)

The ALS received over 30 independent investigator proposals in the last submission period which ended in June. This represents an increase over the previous submission cycle and indicates the growing demand for access to the ALS research facility. The proposals will now undergo peer review by the Program Study Panel which will meet on July 17 to rate the proposals and make recommendations on the requisite beamtime. Highly rated proposals will be allocated beamtime between October and March by the ALS Scientific Program Head, Neville Smith, in consultation with PRT spokespersons. The deadline for submission for the next cycle is December 1, 1996.

3. REVISED BEAMLINE DESIGN REQUIREMENTS PUBLICATION NOW AVAILABLE
(contact: alsuser@lbl.gov)

A substantially revised and improved version of the ALS Beamline Design Requirements publication is coming off the press this week. This manual is a guide for researchers in designing beamlines and endstations acceptable for use at the ALS. It describes the beamline review process including required documentation, and gives guidelines and policies related to equipment and vacuum protection and personnel safety. New additions to the manual include a checklist and timeline for building a beamline, and an extensive list of contacts for additional information and technical questions. The new revision was initiated by Beamline Review Committee Chair Tony Warwick and coordinated by Elizabeth Moxon. Greg Vierra did the layout and graphic design. Copies of the publication are available from the ALS User Office [Tel: (510) 486-7745, Fax: (510) 486-4773, Email: alsuser@lbl.gov].

4. NEW USER ADVISORY ISSUED ON INTERLOCK REQUIREMENTS FOR TURBO PUMP SYSTEMS
ON ENDSTATIONS (contact: alsuser@lbl.gov)

The ALS has recently issued a new User Advisory "Interlock Requirements for Turbo Pump Systems on ALS Endstations (ALS Advisory 14)." The new advisory details ALS policy on the use of oil-lubricated vacuum pumps on endstations and specifies acceptable interlock configurations. To avoid contamination of beamlines or of the ALS storage ring, the use of oil-free pumping systems is strongly encouraged. If oil-lubricated pumps are used, an effective interlock system must be in operation before the endstation can be opened to the beamline. This user advisory outlines the three acceptable interlock configurations and provides detailed information about each one. The new user advisory replaces "ALS Policy for Exhausting of Mechanical Vacuum Pumps (ALS Advisory 10)."

The new advisory is available from the ALS User Office [Tel: (510) 486-7745; Fax: (510) 486-4773, Email: alsuser@lbl.gov], and is posted on the World Wide Web [http://www-als.lbl.gov/als/als_info.html].

5. MORE FUN AND FASCINATING FACTS

** HOW BIG OR HOW SMALL? **

How big is...
the linac?                 about 5 meters long
the booster synchrotron?   about 70 meters around and 20 meters across
the storage ring?          about 200 meters around and 60 meters across
an undulator?              typically 4.5 meters long
the average beamline?      typically about 30 meters long 

How small is...
the electron beam?         0.2 mm wide and 0.02 mm high
the photon beam?           when it hits a target, it is typically 
                           1000 microns (1 mm) across, but it can be
                           focused down to 0.1 micron

The electron beam in the machine can be stopped very quickly. This is done by turning off the accelerating chambers (rf cavities), which normally replenish the electrons' energy every time they go around the storage ring. Without this energy boost, but still under the influence of the bend magnets, the electrons will begin to spiral inward and collide with other electrons and the inner wall of the vacuum chamber. Each collision causes the electrons to lose energy until ultimately the beam is completely eliminated. The whole process of stopping the beam takes 10 milliseconds!

** HOW MANY TIMES DO THE ELECTRONS GO AROUND IN THE STORAGE RING? **

They go around it 1.5 million times a second; so in 4 hours the average electron goes around the ring 21.6 billion times.