Previous Editions____________________________________________________________________________SSRL Headlines Vol. 11, No. 1 July, 2010____________________________________________________________________________
Contents of this Issue:
A team of scientists led by Catherine Drennan of MIT used SSRL Beam Line 11-1
and a beam line at ALS to decipher the mechanism of CODH's reaction. They
solved crystal structures which depict the C-cluster bound to a substrate and
an inhibitor. Analyzing the structures, they were able to deduce the roles of
the bound metals and the mechanism of the reaction.
This clearer understanding of how this microbial enzyme performs this difficult
chemistry may lead to methods to control pollutants and greenhouse gases in our
atmosphere. This work was published in Biochemistry.
To learn more about this research see the full scientific highlight
A team led by Karen Trentelman of the Getty Conservation Institute in Los
Angeles used SSRL Beam Line 2-3 to analyze the chemical composition of layers
of glaze and aging on a funeral lekythoi, a Greek vessel for storing oil, from
5th century BCE Attica. They were particularly interested in a purplish
discoloration on the surface layer of the lekythoi, and on many others like it.
Using a variety of techniques, including electron probe microanalysis (EPMA),
scanning electron microscopy (SEM), Micro x-ray absorption near edge structure
(XANES), and extended x-ray absorption fine structure (EXAFS), the researchers
found chemical evidence that the lekythoi was broken then burned with the body
of the deceased as part of the funeral ceremony.
The analysis of this vessel deepens our understanding of Athenian customs.
Using this technique, other museum artifacts might also share more of their
ancient secrets. This work was published in the May 2010 issue of the Journal
of Archeological Science.
To learn more about this research see the full scientific highlight
In a report published in the July 1 issue of Nature, a team led by
Argonne National Laboratory physicist Linda Young describes how they were able
to tune LCLS pulses to selectively strip electrons, one by one, from atoms of
neon gas. By varying the photon energies of the pulses, they could do it from
the outside in or—a more difficult task—from the inside out,
creating so-called "hollow atoms."
In another report, published June 22 in Physical Review Letters, a team
led by physicist Nora Berrah of Western Michigan University—the third
group to conduct experiments at the LCLS—describes the first experiments
on molecules. Her group also created hollow atoms, in this case within
molecules of nitrogen gas, and found surprising differences in the way short
and long laser pulses of exactly the same energies stripped and damaged the
nitrogen molecules.
SLAC's Joachim Stöhr, director of the LCLS, said, "When we thought of the
first experiments with LCLS ten years ago, we envisioned that the LCLS beam may
actually be powerful enough to create hollow atoms, but at that time it was
only a dream. The dream has now become reality." Read the full
press
release.
At the risk of repeating my column from last year, 2010 has been a great year
for SSRL operations. We ran for the first time in true top-off mode, in which
the current was kept constant in SPEAR3 by frequent (every 10 minute)
injections. This mode of operation was approved for routine use only in June.
The users have been extremely pleased with this operating mode-no more
interruption of scans to wait for the injection to take place, and a 20 percent
higher intensity since the beam is no longer allowed to decay for eight hours
before filling. This mode of operation puts severe constraints on the
reliability of all the SPEAR3 systems since the injector system must run
continuously-any errors show up as a missed fill, which is evident on the beam
current display. The occasional missed fill does not adversely affect the
users. The goal of zero missed fills comes from a sense of pride from the
operations staff and probably a few side-bets. Read more at:
http://today.slac.stanford.edu/feature/2010/dir-20100730.asp
SSRL passed several more milestones on the road to realizing the full potential
of the SPEAR3 upgrade in the past several weeks.
On June 28, just as SSRL staff were celebrating the start of frequent fill
operations for users, the DOE approved the SSRL beam line safety envelope for
500 mA operations. Shortly thereafter, on July 13, all SSRL insertion device
beam lines were operated successfully at 350 mA for radiological surveys and
performance characterization. The results from this test were sufficiently
encouraging that SSRL will start up in the fall with beam lines tuned and
operating for users at 350 mA rather than the present 200 mA default current.
After gaining further experience in the fall with 350 mA operation of beam line
optics, detectors, etc. subsequent current increases towards the 500 mA SPEAR3
design current are envisioned for the 2011 run.
Higher current operations result in faster beam decay, so another welcome
development was the July 9 approval of increased SPEAR3 injection power to 5 W.
Increased injected beam power translates to faster fills as witnessed by peak
injection rates in excess of 60 mA/minute with 5 W injection and routine top
off injections which now require 3 seconds rather than the 5-6 seconds prior to
the 5 W authorization. The increased authorized power is the culmination of
several years of effort to improve the SPEAR3 injection efficiency thus
resulting in lower injected beam loss and associated injected beam dose rates.
Planned further improvements in the booster and the injection beam transport
system promise enhanced injection reliability and reduced stored beam motion on
injection. In fact, SSRL staff who participated in the 350 mA beam line test
program were treated to a sneak peek into this future as the SPEAR3 fill
frequency was doubled during this test to maintain approximately 0.5% current
stability. During the 2011 run users will make their own acquaintance with such
improvements.
The Department of Energy has announced the creation of a new Energy
Innovation Hub aimed at finding a practical way of making fuels with an
artificial version of photosynthesis. Led by the California Institute of
Technology and Lawrence Berkeley National Laboratory, the new Joint Center for
Artificial Photosynthesis will include work at SLAC, Stanford, and University
of California campuses in Berkeley, Santa Barbara, Irvine and San Diego.
Scientists have been looking for years for a way to mimic the way plants
generate energy from the sun, a process that is the basis for nearly all life
on Earth.
"This is something you can't do today," said SLAC's Anders Nilsson. "You can
demonstrate it in principle, but it doesn't really work for practical use. The
idea is that the hub will conduct research to see if this can be developed. If
this could work, it would have a huge impact that will change our society."
Read more at: http://today.slac.stanford.edu/feature/2010/photosynthesis.asp
Plan to participate in the Annual SSRL/LCLS Users' Meeting and Workshops,
October 17-21, 2010 to learn about new developments and share exciting user
research at LCLS and SSRL.
Please take a few moments to consider nominating your colleagues or students
for one or more of the following awards which will be presented at the Joint
SSRL and LCLS Users' Meeting, October 17-21, 2010:
Our 2010 experimental run ended on July 26, and operations will resume in
November; see our 2011
operating schedule.
SSRL BEAM TIME REQUEST DEADLINES. Proposal spokespersons or
their authorized
lead contacts can submit new beam time requests for the first scheduling period
in our 2011 experimental run (late November 2010 - February 2011) by September
1. Requests for time on Macromolecular Crystallography (PX) time are due
September 15. Proposals submitted June 1 (X-ray/VUV) and July 1 (PX) are
currently under review and will be eligible for beam time during this first
period. Ratings for these proposals should be distributed within the next few
weeks. Request beam time via the user portal.
SUBMIT NEW SSRL PROPOSALS BY SEPTEMBER 1 OR DECEMBER 1. New proposals
can be submitted 3 times a year: June 1, September 1, and December 1 for
X-ray/VUV and April 1, July 1, and December 1 for Macromolecular
Crystallography (PX). X-ray/VUV proposals submitted by September 1 will be
peer reviewed, rated and eligible for beam time beginning in February 2011.
Both X-ray/VUV and PX proposals should be submitted via the user portal.
COMPLETE END OF RUN SURVEY. Comments about your experience at SSRL
are extremely important to us, and we need your feedback to meet our mission
requirements, including assessment and reporting. If you haven't already done
so, please submit an End of Run Summary Form through the
user portal.
INFORM US OF PUBLICATIONS. After data have been collected, analyzed
and prepared for publication, please inform us and acknowledge the user
facility and funding agencies in your publications using the formats posted on
the website: http://www-ssrl.slac.stanford.edu/pubs/. We
strongly encourage you to contact us when exciting results are about to be
published. We can work with users and the SLAC Office of Communication to
develop the story and to communicate user research findings to a broader
audience.
AT&T customers should notice an improvement in their cell phone signal at SLAC.
A temporary cell tower, which went up behind Building 50 now provides service
to the SLAC campus and immediate surrounding areas. A permanent tower will be
installed on the roof of Building 50 after a seismic retrofit of the building
is completed, within the next year. Read more at: http://today.slac.stanford.edu/feature/2010/att-tower.asp
The girls began their adventure at the Visitors' Center, where SLACers Zoe Van
Hoover and Kelen Tuttle introduced them to the lab's history and science.
Apurva Mehta and Deborah Bard then explained x-rays and astrophysics. The
afternoon offered opportunities for hands-on activities at SSRL.
"A major aim of our summer program is giving academically-motivated fifth-grade
girls from low-income backgrounds access to and knowledge about exciting
scientific exploration," said Mary Hurlbut, the girls' teacher. She said she
was thrilled by their enthusiasm.
__________________________________________________________________________
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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