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.12           February 7, 1995

Table of Contents


    1. OPERATIONS OVERVIEW
    2. TIMELY TOPICS

1. OPERATIONS OVERVIEW

The weekly scheduling meetings for ALS operations will resume on February 13, 1995, at 11 a.m. in the Building 6 conference room.

** NEW WEEKLY SCHEDULE IN EFFECT AFTER SHUTDOWN **
(contact: rmmiller@lbl.gov)

The ALS, responding to the expressed needs of its users, will begin a three-month trial of a new weekly operations schedule after the current shutdown. From February 22 through the end of May, the ALS will run on a seven-days-per-week schedule, with the "owl" shift eliminated (i.e., operations will now be from 0800 to 2315 each day rather than around-the-clock). There will still be 9 user shifts per week: swing shift (1600-2315) on Wednesdays, and day and swing shifts (0800-2315) on Thursday through Sunday.

Whether this schedule is adopted permanently (pending sufficient funds for 24-hour, 7-day operation) will depend on the pros/cons reported by the users during the trial period.

** LONG-TERM SCHEDULE ANNOUNCED FOR FEBRUARY-AUGUST **
(contact: fred_schlachter@lbl.gov)

ALS management, beamline spokespersons, and the Users' Executive Committee have agreed on a schedule for the next six months of ALS Operations. Time has been scheduled for various modes of operations, including 1.0, 1.5, and 1.9 GeV operations, and two-bunch operations. The maximum beam current at 1.9 GeV may be limited in 1995 due to limitations on radio-frequency power; we expect at least 200 mA current at 1.9 GeV.

The new long-term schedule will be available soon on the World Wide Web. Long-term and weekly schedules are accessible by choosing "Operations" from the ALS home page (http://www-als.lbl.gov/als/als_homepage.html). The long-term schedule is also available from ALS Administration, Attn: Request for long-term schedule, Fax: (510) 486-4960. Please include your mailing address with your request and we will send you a copy of the schedule.

2. TIMELY TOPICS

** MAGNET SYMPOSIUM ATTRACTS INTERNATIONAL AUDIENCE **
(contact: carr@slac.stanford.edu)

Colleagues and students of Klaus Halbach from around the world gathered at Lawrence Berkeley Laboratory (LBL) on February 3 for the Halbach Symposium on Magnet Technology. The synchrotron radiation community has benefited substantially from Klaus' work on accelerator magnets, computer models, and beam position monitors, and especially from his work on permanent magnet insertion devices which made third-generation rings such as the ALS feasible. He has consulted at most of the storage ring projects all around the world, many of which have installed Halbach design undulators and wigglers.

The Symposium, organized by Brian Kincaid and Ross Schlueter of the ALS and Roger Carr of Stanford Synchrotron Radiation Laboratory (SSRL), drew over 100 participants and featured technical presentations, personal recollections by colleagues and long-time associates, and the publication of two volumes assembled specifically for the meeting. The publications are entitled "The Art and Science of Magnet Design" and include a festschrift of technical papers written especially for the symposium and a selection of Klaus' scientific notes.

Max Cornacchia of SSRL described the way he and Klaus designed modified sextupole magnets that achieve chromaticity correction near the axis, but whose fields away from the axis are changed to allow higher dynamic aperture. These ideas can be used even more profitably with octupole magnets. Richard Post of Lawrence Livermore National Laboratory described how he uses Halbach motor/generator magnets in very high energy density flywheel storage systems for motor vehicles. These systems have greater energy output per pound than batteries or internal combustion engines; the Halbach magnet array is used to relax otherwise tight mechanical tolerances.

Kwang-Je Kim then described his new theory of transition radiation generation from insertion devices. When an electron beam enters such a device, its net drift velocity is reduced. Analogous to transition radiation, the electron beam will emit infrared radiation of high brightness; for a typical storage ring insertion device, this infrared photon beam will be squeezed into a few milliradians, as opposed to perhaps 100 mrad for a bending magnet.

After lunch, Shigemi Sasaki of Japan Atomic Energy Research Institute described how one can design an undulator that does not produce harmonics of the fundamental spectral peak, and so do not contaminate monochromatized radiation. This idea is a clever analogy to x-ray diffraction from quasicrystals. Rodolfo Bonifacio then described how one may generate harmonic radiation from a series of free electron lasers, where each uses the bunched beam from the preceding ones. In the last talk, Simon Yu of LBL described the use of low field permanent magnet quadrupole magnets in a two beam linear accelerator design. In this scheme, the radio-frequency energy that drives a high energy beam is derived from a parallel low energy electron beam that acts as a klystron, feeding energy to the high energy beam every two meters.

** A MESSAGE FROM THE CHAIR OF THE USERS' EXECUTIVE COMMITTEE **
(contact: tcallcot@utkvx.utk.edu)

As the chair of the ALS Users' Executive Committee (UEC), I have been invited to address the user community through ALSNews, explaining the role and current concerns of the UEC, and I am happy to do so.

The explicit purpose of the UEC is to represent the interests of ALS users to ALS management. As part of its responsibility, it helps plan and run the annual users' meeting. But, to my mind, one of its most important roles is to be a conduit for ideas for further improvements to the user interface, particularly for those "independent investigators" who come to work at the ALS without benefit of a collaborator experienced in how to access ALS and LBL resources.

Some of the issues currently being discussed between the UEC and the ALS which directly affect users are: - further upgrade of user facilities, particularly creation of a good stockroom and a receiving room for mail and equipment; - policies and procedures for reviewing and implementing independent investigator proposals; - scheduling of user shifts and special operating conditions; - availability of office space for users.

Thus, in large part, the principal responsibility of the UEC members is to lobby hard for continued improvements. If you have ideas about what those improvements should be, please feel free to contact me or one of the other UEC members (see ALSNews Vol. 10, 1/24/95). The next UEC meeting will be on February 24 to discuss general user issues, with another scheduled for late spring to plan the 1995 ALS Annual Users' Meeting to be held on October 23-24.

On behalf of the UEC, I would like to wish every user a successful run at the ALS, and please remember to let us know if we can help make your next run an even better one.

Tom Callcott, University of Tennessee