Contents of this Issue:
1. Science Highlight — Speed Limit of
Magnetic Recording
(contact: Jo Stöhr,
stohr@ssrl.slac.stanford.edu)
Two important goals of technology are: smaller and faster. In line with this goal the 50 billion dollar per year magnetic recording industry has long wondered where it would run into obstacles set by fundamental physical principles. The basic questions concern the lateral sizes at which the magnetic domains that define the "1" and "0" bits become unstable and whether there is a speed limit for the writing process of the bits. While the size limit of the bits is well understood because it can readily be tested, exploration of a potential speed limit has been impeded by the unavailability of magnetic field pulses that are both ultrashort and sufficiently strong. In today's computers the switching time is about 1 nanosecond and in R&D laboratories switching times of about 100 picoseconds (ps) have been achieved. At this speed things still work fine.
As recently reported in Nature (428, 831-833 [22 April 2004]), an experiment performed at the Stanford Linear Accelerator Center has now shown the existence of a fundamental speed limit. The experiment made use of the unique capabilities of SLAC's 2-mile-long linear accelerator (linac) to produce ultrafast and strong magnetic field pulses, the fields that surround the electron beam in the linac. The beam consists of individual electron bunches that produce field pulses that are the world's shortest, down to about 100 femtoseconds and strongest, up to about 10 Tesla.
By recording the magnetic pattern written by the beam into a magnetic sample, the experiment showed that the switching becomes non-deterministic when the switching time is shortened to about 5 ps. A new mechanism is operative that leads to a fracture of the magnetization at very fast time scales and requires a new theory. This sets the speed limit to only a factor of 20 shorter than that available in today's most advanced R&D laboratories.
More information can be found be found on the following websites:
http://www-ssrl.slac.stanford.edu/research/highlights_archive/speedlimit.html
http://www.slac.stanford.edu/slac/media-info/20040423
http://www.stanford.edu/~itudosa/research/research.html
http://www-ssrl.slac.stanford.edu/stohr/
2. DOE Office of Science Reviews SLAC
(contact: Keith Hodgson,
hodgson@ssrl.slac.stanford.edu)
The DOE Office of Science conducted an on-site review on May 18. Dr. Raymond Orbach, head of the DOE Office of Science attended along with Dr. James Decker, Deputy Director of DOE-SC and representatives of other Office of Science Divisions including BES and BER (Drs. Patricia Dehmer and Ari Patrinos, respectively). Detailed presentations on the SLAC high energy physics and synchrotron science programs followed the overview talk given by SLAC Director Jonathan Dorfan. The synchrotron science discussion was led by Keith Hodgson and John Galayda, and it focused on the long-term future opportunities in the development of SPEAR3 and LCLS. There was an afternoon session on laboratory operations led by Jonathan Dorfan which covered ES&H, infrastructure and power costs and other issues. In the closeout session, Dr. Orbach and the Associate Directors shared their perspectives of the vision that was put forth by SLAC. Arthur Bienenstock, Vice Provost and Dean of Research and Graduate Policy at Stanford University attended the dinner and discussed his perspectives on the important SLAC-Stanford partnership. Overall, the meeting went very well and the discussions were engaging and constructive.
3. SMB Summer School Coming Up in August
(contact: Serena DeBeer George,
serena@slac.stanford.edu)
SSRL will hold a Structural Molecular Biology Summer School during the period of August 16-20, 2004. The course will highlight the use and applications of three synchrotron x-ray techniques in the study of biological systems: Small Angle X-ray Scattering (SAXS), X-ray Absorption Spectroscopy (XAS) and Macromolecular Crystallography (MC). Presentations from experts in the fields will be aimed at the graduate student level, but will also be appropriate for more experienced researchers entering the field. Lectures will be followed by practical sessions giving participants the opportunity to learn data collection and analysis techniques first hand. Participants may register for the lecture portion only (Track 1) or both the lectures and practical sessions (Track 2). The summer school will be held at facilities on the SLAC site and a block of rooms has been reserved at the SLAC Guest House for participants. Enrollment will be limited so prospective participants should apply before the June 30 deadline. More details will be posted to the website this week. http://smb.slac.stanford.edu/SR-School/SMB2004/
4. User Operations Update
(contact: Cathy Knotts,
knotts@slac.stanford.edu)
More beam lines opened during May including 2-1, 4-2, and 8. Beam Line 1 is expected to be opened in June. In early May, scheduled top offs (which are taking about 3 minutes) were changed from 4 times to 3 times a day, at 6 am, 2 pm, and 10 pm. Announcements are made before each fill, and users are asked to plan their experiments around these brief interruptions (users are discouraged from requesting any delays on the fill time). Without any major interruptions to the operating schedule, the average delivery rate for beam time scheduled for users increased to 95.7% by the last week in May. Users continue to report excellent data that are deriving significant benefit from the increased brightness and stability of SPEAR3. SPEAR3 updates are available on the website: http://www-ssrl.slac.stanford.edu/talk_display.html
5. SLAC Scientific Policy Committee Spring
Meeting
(contact: Keith Hodgson,
hodgson@ssrl.slac.stanford.edu)
The SLAC Scientific Policy Committee (SPC) met on May 7-8. The SPC is SLAC's highest level external advisory committee, reporting to Stanford University President John Hennessy. The SSRL-related presentations featured science vignettes on magnetic switching by Jo Stöhr and the structure of liquid water by Anders Nilsson. Keith Hodgson gave a talk on the SSRL research and operations program followed by John Galayda with an update on the LCLS project. Ashley Deacon gave a presentation on the structural genomics initiative (JCSG), reporting on the remarkable success over the past year of JCSG operations. The respective chairs of the high energy physics and synchrotron science Users' Organizations, Gabriella Sciolla and Benjamin Bostick, were invited to give talks as well. At its closeout session, the SPC found that the SSRL program was entering an exciting phase with the success of SPEAR3 installation and commissioning, the funding already in place for two new insertion device undulator beam lines, and SPPS and LCLS progressing very well.
6. SSRL Users Organization Update
(contact: Benjamin Bostick,
benjamin.c.bostick@dartmouth.edu)
The SSRL Users Organization Executive Committee (SSRLUOEC) met on Monday, May 10. This was a lively meeting resulting in several recommendations: 1) discourage users from requesting delays on the fills (the SSRLUOEC feels that users can best and most efficiently plan their experiments if fills go on as scheduled); 2) have the Duty Operator announce the fills at 60 minutes prior, 30 minutes, 15 minutes, and as the fill occurs so users are reminded to plan accordingly; 3) encourage users to complete an End-of-Run Summary after each visit to SSRL for data collection by posting notices around the beam lines and having user support staff, duty operators, and program managers remind users to complete these surveys before they leave SSRL; and 4) explore the capability of continuous scans at SSRL.
Except for closed sessions which will be announced, SSRLUOEC meetings are open to all interested SSRL users. We encourage users to participate in these meetings and/or to contact any of the EC members if they have issues that they want to raise. The SSRLUOEC meets 3-4 times each year, with the next meetings tentatively scheduled for August 2, 2004 and October 22, 2004. More details (time, location, agenda) will be posted to the web in advance of each meeting: http://www-ssrl.slac.stanford.edu/users/ssrluo/ssrluoec-mtgs.html
In mid May, the Users' Organization forwarded a notice from the American Chemical Society (ACS) encouraging users to link to the ACS Legislative Action Center to stay informed and support current issues; http://capwiz.com/chemical. If you have not already done so, please take a minute to check out this link to locate and contact your local policy makers in support of funding for basic sciences.
SSRLUOEC minutes are posted to the web at:
http://www-ssrl.slac.stanford.edu/users/ssrluo/ssrluo-minutes.html
7. SLAC Guest House Implements Slight Rate
Increase
(contact: Cathy Knotts,
knotts@slac.stanford.edu)
As anyone who has stayed there knows, the Guest House is a fabulous addition to SLAC providing very affordable, elegant accomodations and allowing users and visitors to maximize their most precious resource -- time. Unfortunately, the average monthly occupancy rates have not grown as fast as had been projected, and SLAC finds itself falling short of the income needed to break even on operating costs. Regrettably, we are forced to raise the nightly rates by $9 per night for all reservations made after June 1, 2004: a Standard room rate with a full-sized bed will be $59, larger rooms with a queen-sized bed will be $74, and larger room with two full-sized beds be $89. These rates are still significantly below the going "market" price. We encourage you to continue to support the SLAC Guest House. Reservations can be made online (select "SSRL" under "Reservations for Groups"). http://www.stanford.edu/dept/hds/SLAC/reservations.html
8. User Administration Update
(contact: Cathy Knotts,
knotts@slac.stanford.edu; Lisa Dunn, lisa@slac.stanford.edu)
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SSRL Headlines is published electronically monthly to inform SSRL users, sponsors and other interested people about happenings at SSRL. SSRL is a national synchrotron user facility operated by Stanford University for the U.S. Department of Energy Office of Basic Energy Sciences. Additional support for the structural biology program is provided by the DOE Office of Biological and Environmental Research, the NIH National Center for Research Resources and the NIH Institute for General Medical Sciences. Additional information about SSRL and its operation and schedules is available from the SSRL WWW site.
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