Previous Editions__________________________________________________________________________SSRL Headlines Vol. 9, No. 12 June, 2009__________________________________________________________________________
Contents of this Issue:
On June 25, after having received the required approvals, SSRL for the first
time performed top-off injection of the SPEAR3 storage ring (that is injection
with the beam line injection stoppers open). This represented a major
milestone and came as a result of an approximately three-year effort led by the
SSRL Accelerator Systems Division. Top-off injection approval required an
extensive SPEAR3 Accelerator Physics study and injector optimization in
collaboration with the SLAC Radiation Protection Department to prove that no
injected electrons could escape the SPEAR3 accelerator and travel down beam
lines into an x-ray hutch. A new electron beam containment system was designed
based on the study results and was recently installed and commissioned.
Initially BLs 4, 5, 10 and 11 will remain open during injection and all other
BLs will close. It is expected that BLs 6, 7 and 9 will be approved for top-off
injection soon. BLs 12 and 13 may be approved for top-off before the end of the
current run cycle, while bending magnet BLs 1, 2, 8 and 14 will not be approved
until after the 2009 summer shutdown since they require new equipment
installation. Thus it is anticipated that all BLs will be approved for top-off
injection during the FY2010 run.
Implementing top-off injection is a significant milestone and an important step
towards operations at higher current. SSRL is working to obtain approval to
increase the stored current in SPEAR3 up to 200 mA this run, which ends August
10.
See also June 25, 2009
SLAC Today Article by Brad Plummer
A research group led by Nicholas E. Pingitore Jr. of the University of Texas at
El Paso analyzed soil and air samples from El Paso using SSRL Beam Lines 7-3
and 11-2. To identify the major chemical forms of lead in the air, they
subjected 20 samples collected at three sites in 1999 and 2005 to x-ray
absorption fine structure experiments. The advantage of using XAFS rather than
other techniques is its sensitivity to very small amounts of an element and its
ability to identify or characterize different forms or compounds of an element,
in this case, lead. They found that the major component of lead in air was in
the form of lead humate. Since lead humate forms exclusively in soil, the
researchers conclude that the most of the lead in air came from the soil.
The U.S. has seen great reductions in lead contamination - both in the
environment and its people's bodies - since it began efforts to reduce lead,
but further lowering the levels of lead may be difficult. Greater reduction of
the amount of lead in the air cannot be accomplished by solely reducing the
current release of lead into the environment by industrial activities, since so
much lead already exists in soil and is leaking into the air. But soil
remediation is difficult and costly. The researchers suggest that investigation
of the bioavailability lead humate, which relates to its health risk potential,
will help inform public policy decisions. This work was published by the
Public Library of Science ONE.
Soluble iron can reach oceans by water currents carrying dusts or by air
currents carrying aerosols. For example, glaciers in Alaska can produce
iron-rich dust and aerosols as they grind rocks. Carried by air and water, the
nutrients find their way to the North Pacific Ocean, supporting its ecosystems.
Iron-rich aerosols do not only come from natural sources but are also made by
burning fossil fuels. Not all aerosols are created equally; some contain iron
that is thousands of times more soluble, and thus more life-supporting, than
others. The solubility depends on the chemical form of the iron they carry.
A research team led by Benjamin C. Bostick from Dartmouth College and Andrew
Schroth of the United States Geological Survey used SSRL Beam Lines 2-3 and
11-2 to measure the solubility of iron from various aerosol sources, both
natural and man-made. Through x-ray absorption spectroscopy, they determined
the iron's chemical forms in the samples. The sample with the highest iron
solubility came from fossil fuel combustion, and that with the lowest iron
solubility came from aerosols originating in the Saharan desert. The aerosols
created when glaciers grind rocks beneath them had intermediate solubility.
This research suggests a complex relationship between iron cycles and climate
change. While the burning of fossil fuels adds to carbon in the atmosphere, it
also adds iron to the oceans that, through aquatic organisms, takes carbon out
of the atmosphere. Additionally, receding glaciers caused by climate change
will increase the amount and type of rock dust making its way to the oceans,
which can also increase biological activity and carbon capture. This work was
published in the April 26 issue of the journal Nature Geoscience.
A team of researchers from the University of Washington and the University of
British Columbia used SSRL Beam Lines 9-2 and 7-1, as well as the Canadian
Light Source, to determine the macromolecular crystal structure of the pennate
diatom's ferritin. They found that the ferritin forms a hollow ball made from
24 monomer subunits. Minimizing the potential for cell damage from storing such
a reactive metal, the ferritin first oxidizes the iron atoms into a less
reactive form then stores thousands of them in the hollow center of the
complex. The ferritin storage subunits are localized to the chloroplasts, which
require iron for capturing solar energy through photosynthesis.
The researchers found that diatoms containing iron-storing ferritin performed
more cell divisions when grown in iron-free seawater than their counterparts
that lack ferritin, suggesting that ferritin gives the cells an advantage in
iron-limited ocean environments that receive intermittent iron fertilization.
This work was published in the January 22 issue of the journal Nature.
Recently-predicted and much-sought, the material allows electrons on its
surface to travel with no loss of energy at room temperatures and can be
fabricated using existing semiconductor technologies. Such material could
provide a leap in microchip speeds, and even become the bedrock of an entirely
new kind of computing industry based on spintronics, the next evolution of
electronics.
Physicists Yulin Chen, Zhi-Xun Shen and their colleagues tested the behavior of
electrons in the compound bismuth telluride. The results, published online June
11 in Science Express, show a clear signature of what is called a topological
insulator, a material that enables the free flow of electrons across its
surface with no loss of energy.
The discovery was the result of teamwork between theoretical and experimental
physicists at the Stanford Institute for Materials & Energy Science (SIMES), a
joint SLAC-Stanford institute. In recent months, SIMES theorist Shoucheng Zhang
and colleagues predicted that several bismuth and antimony compounds would act
as topological insulators at room-temperature. The new paper confirms that
prediction in bismuth telluride. "The working style of SIMES is perfect," Chen
said. "Theorists, experimentalists, and sample growers can collaborate in a
broad sense."
The experimenters examined bismuth telluride samples using x-rays from BL5-4 at
SSRL and BL10.0.1 at the ALS. When Chen and his colleagues investigated the
electrons' behavior, they saw the clear signature of a topological insulator.
Not only that, the group discovered that the reality of bismuth telluride was
even better than theory. Read the full SLAC news release.
A team of Stanford University researchers working in the lab of Nobel laureate
Roger Kornberg recently used the high energy x-rays at the Stanford Synchrotron
Radiation Lightsource to examine one such mechanism, the proofreading function
of a vital protein called RNA polymerase. According to Dong Wang, a
post-doctoral fellow with Kornberg's lab and the principal investigator in the
study, the findings will not only provide scientists with a better idea of how
protein production works, but could also give fresh insight into the design of
cancer-fighting drugs. The results were published in the May 28 issue of
Science.
Protein synthesis occurs in two main stages-first, DNA inside the nucleus is
transcribed to RNA. During this step, called transcription, RNA polymerase
skims along the DNA template, producing a complementary strand of RNA as it
goes. In the second step, called translation, the cell's machinery reads the
RNA and constructs the corresponding proteins. Read the full
story.
Clearly the eyes of the x-ray world are presently on LCLS due to its
spectacular early success of producing a lasing x-ray beam and the upcoming
first x-ray experiments in September. I expect LCLS to remain in the spotlight
for well over a decade, with additional expansions of its early capabilities,
facilities and revolutionary discoveries. But extending the horizon, say to ten
to fifteen years, I see major opportunities for growth at SSRL. There are
several reasons for this likely development.
In a December 2008 briefing paper of the incoming Obama administration, the
four Department of Energy-funded x-ray facilities in the US-the Advanced Light
Source, Advanced Photon Source, National Synchrotron Light Source and
SSRL-produced a joint vision paper entitled "Science and Technology of Future
Light Sources." This paper discusses the broader scientific challenges before
us, including those in the major areas of energy, environment, health and
technology, and focuses on the role x-rays can play in addressing them. It
specifically looks at the types of future x-ray sources needed and comes to the
conclusion that the nation's scientific needs will not be entirely met by the
current ALS, APS, NSLS and SSRL facilities or even the LCLS and NSLS-II
facilities under construction. It also emphasizes the need for two generic
types of complementary x-ray sources based on linear accelerators and rings,
respectively. The report therefore opens the door for a new x-ray facility at
SLAC, which will be built after LCLS and its envisioned upgrades. This
complementary ring-based light source, PEP-X, takes advantage of the existing
PEP tunnel, accelerator components and infrastructure and will replace SPEAR3.
It will provide the SSRL user program with one of the world's leading
ring-based x-ray sources.
Operated either as a very low emittance storage ring or in conjunction with an
energy recovery linac, PEP-X has already been incorporated as a key component
into SLAC's long-term strategic plan. The combination of LCLS and PEP-X, in
conjunction with SLAC/Stanford science programs that utilize these facilities,
promises to make SLAC the world's leading photon science laboratory. Since both
facilities are based on large accelerators, they are not only enabled by SLAC's
strength in accelerator science and technology but more broadly help maintain
accelerator science as a key core competency and capability of the lab, in good
accord with the continued use of the word "accelerator" in the lab's new name.
Toward the PEP-X goal, the SSRL Scientific Advisory Committee has recently
recommended that future instrumentation and science programs be established in
preparation for the greatly enhanced PEP-X brightness, and that new beam lines,
if possible, be planned to be transferable to PEP-X. While the 10-15 year
period toward the new source may appear daunting, experience with the planning
and construction of new light sources has shown this to be quite a normal
timeframe. After all, LCLS was first proposed seventeen years ago. Great things
take time.
SSRL will contribute to the Center for Inverse Design, or CID, a project headed
by the Department of Energy's National Renewable Energy Laboratory in Golden,
Colorado. CID is one of 46 DOE-funded Energy Frontier Research Centers. The
EFRCs, announced by the White House April 27, will investigate ways to wean the
U.S. energy economy off fossil fuels.
As its name suggests, CID will take an unconventional approach to materials
design. Traditionally, scientists looking for materials or structures with
certain properties, such as highly efficient solar cells, empirically test many
possibilities before finding something suitable. Instead of relying on such
trial-and-error methods, CID will use quantum theory and powerful computers to
identify and design materials with the desired properties and, in favorable
cases, synthesize them in the lab.
"The goal is to fundamentally change the way we make materials," said SSRL
staff scientist Michael Toney, one of CID's 12 principal investigators and
supervisor of its work at SSRL. Read the full story.
The LCLS had a dramatic start up at its shortest wavelength (1.5 Å)
reaching saturation in April with 1.1 mJ per pulse energy (see press
release) and P. Emma's
paper at PAC 2009. This is the baseline performance, but there is room for
more.
A workshop will be held at SLAC July 29-31, 2009, to discuss the scientific
opportunities that near-term options for enhanced performance (wavelength
reach, polarization, pulse duration, etc.) will enable as well as the science
drivers for the long-term development of LCLS. This will be an opportunity for
the broad scientific community to interact with the LCLS team and the FEL
physicists to investigate what is wanted and where the science of LCLS might
go. The format will allow for significant discussion amongst participants and
will be an opportunity for community input as we look out over the next several
years and beyond. User input into these discussions could expand our present
scientific reach and take the LCLS in new scientific directions. For additional
information, contact: Jerry Hastings (jbh@slac.stanford.edu), Sebastien Boutet
(sboutet@slac.stanford.edu), David Reis (dreis@slac.stanford.edu), or Aymeric
Robert (aymeric@slac.stanford.edu).
Register at: http://www-conf.slac.stanford.edu/hardxray/
The 2009 SMB Summer School will focus on the use and application of X-ray
Absorption Spectroscopy, Macromolecular Crystallography and Small Angle X-ray
Scattering. Invited lectures from experts in these fields will be at the
graduate student/post-doctoral level, but will also be appropriate for
experienced researchers with expertise in one technique and an interest in
learning other techniques to further the scope of their research. The four-day
summer school will feature two days of lectures covering theoretical and
experimental aspects, and two days of hands on training in data analysis. The
afternoon of the last day will be reserved for question-and-answer sessions
hosted by the co-chairs, which will be aimed at addressing specific queries
from the participants.
Co-chairs for the 2009 SMB Summer School are SSRL Staff Scientists Ritimukta
Sarangi (ritis@slac.stanford.edu), Clyde Smith (csmith@slac.stanford.edu) and
Thomas Weiss (weiss@slac.stanford.edu). Funding for the SMB Summer School
program is provided by NIH-NCRR and DOE-BER.
Apply at: http://www-conf.slac.stanford.edu/smb-ss/2009/
Plan to participate in the Annual LCLS/SSRL Users' Meeting and Workshops,
October 18-21, 2009 to learn about the latest plans, new developments and
exciting user research at LCLS and SSRL. It is also a great time to interact
with other scientists, potential colleagues, and vendors of light source
related products and services.
The event kicks off on October 18 with a special symposium celebrating 35 years
of outstanding science at the Stanford Synchrotron Radiation Lightsource. In
addition to reviewing technical accomplishments and research highlights, future
scientific and technical opportunities for SSRL will be discussed.
LCLS/SSRL 2009 officially begins on October 19 with a joint plenary session
featuring updates from SLAC and DOE, a preview of the workshops, a user science
poster session, and a keynote presentation. The Spicer Young Investigator
Award, Klein Professional Development Award, Lytle Award, and the Outstanding
Student Poster Session Awards will be presented on this day.
Separate sessions focusing on SSRL and LCLS facility development,
instrumentation, and user science will be held concurrently on October 20,
followed by meetings of the respective SSRL and LCLS Users' Organizations.
On October 21, several concurrent workshops will be held including
Microimaging; Nanoscale Imaging with the SSRL STXM; Macromolecular
Crystallography; Soft X-ray Beam Line Experiment Preparation; and X-ray Pump
Probe Experiment Preparation.
Conference Website: http://www-conf.slac.stanford.edu/ssrl-lcls/2009/default.asp
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 18-21, 2009:
William
E. Spicer Young Investigator Award
—due August 1
Melvin
P. Klein Professional Development Award —due August 1
Farrel
W. Lytle Award —due August 15
__________________________________________________________________________
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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