THE ELECTRONIC ALADDIN
NEWSLETTER NO. 30
November 2001 / March
7TH OPEN HOUSE WAS VERY SUCCESSFUL
Our yearly Open House event continues to be very popular
with the public. Visitors enjoyed themselves learning about our
research and participating in demonstrations and activities. Over
100 of the 249 people attending the Open House were children. During
the 12:00 to 4:00 PM event we led 22 tours of our facility. About
50% of the participants filled out our feedback form in which many
indicated how impressed they were with what they saw and also thanked
Staff and Users for their effort to reach out to the public.
This year our tour consisted of two introductory talks,
three stops around the ring, and a final stop at an "experts
table." The two talks introduced the public to synchrotron
light, how we make it, and how we use it (Mary Severson and Ken
Jacobs). The three stops included presentations on: 1) materials
science and how it has affected the development of magnetic storage
devices (Cliff Olson), 2) studying metal halide lamps to understand
how they work (Geoff Bonvallet and Dave Smith), and 3) using spectromicroscopy
techniques to study 4.4 billion year old zircon rocks to determine
Earth's early environment (Brad Frazer). At the "experts"
table, visitors were given a chance to ask more questions and give
feedback on the event (Roger Hansen).
2. BREAKING OF TIME REVERSAL SYMMETRY IN
Time reversal is one of the fundamental symmetry operations
in nature. Adam Kaminski at the University of Illinois Chicago and
a large team of collaborators undertook a difficult experiment at
the SRC to test whether this symmetry is broken in high temperature
superconductors. They used circularly polarized light combined with
angle-resolved photoemission to search for the subtle effects of
symmetry breaking. It took several months of preparation and data
acquisition to eliminate the many possible sources of systematic
errors. The results in cond-mat/0203133 (Nature, April 11) demonstrate
that time reversal symmetry is indeed broken, but only in the pseudo-gap
state of under-doped samples. Such a specific finding places strong
constraints on theories of superconductivity.
3. LOW EMITTANCE OPERATIONAL
As the next step in making lowered emittance fully
operational, a tuning of the Aladdin storage ring with a horizontal
emittance one third of the standard configuration is now being offered
regularly on Wednesday morning shifts. The horizontal beam size
measured in the optical diagnostic stations is about one third that
of the standard configuration. The average vertical beam size and
the beam-current lifetime product are about 10 % smaller than nominal.
Beam position variations from the normal mode appear to be small
enough to be operationally transparent to the beamlines and experiments.
Studies by the Accelerator Development and Operations Groups are
continuing during Development Periods to further improve the electron
beam optics, lifetime, and overall performance of low emittance
tunings. Some of this work is being carried out by physics graduate
student Ryan Miller as part of his degree program.
These Wednesday morning shifts are intended to provide Users and
staff a setting to explore together the opportunities offered by
lower emittance operation of Aladdin. In a recent run, Pupa De Stasio
and Brad Frazer acquired images of zircons with the SPHINX spectromicroscope
on the 6 m TGM 062 with the low emittance LF15 tuning and immediately
after re-injection, with the regular 800 MeV beam. All acquisition
parameters were identical; therefore, the only variation was due
to the beam emittance. They detected a 65% increase in the flux
density with LF15, compared to regular beam, after normalization
to the beam current.
4. SCIENTA 200 REFURBISHED
After a two quantum refurbishing period in December
and January, the Scienta 200 analyzer is back in operation!
In response to User feedback concerning the performance of the workhorse
SES 200 analyzer, an extended maintenance was undertaken to address
the issues of vacuum and sample lifetime, electronics and calibration,
and operational policies and procedures.
Here is a brief summary of the successful refurbishment process:
1) Additional pumping in the form of a cryopump near the measurement
area and an ion pump near the hemisphere has resulted in a factor
of three decrease in the base pressure to 3 x 10-11 torr and a commensurate
increase in sample lifetime,
2) The Scienta power supplies were all recalibrated resulting in
an energy repeatability of <1meV,
3) A User manual containing new policies and procedures for use
of the instrument has been generated which should aid in maintaining
the SES 200 in its pristine condition.
The analyzer completed two successful quanta on the 081 NIM, causing
one user to comment: "This is the best condition the Scienta
has been in since I have used it." It is currently installed
on the PGM where it will remain until the end of the first half
of 2002 schedule.
5. SCIENTA 2002 UPDATE
SRC's second Scienta system for Users, the SES 2002,
is getting close for a first test run. Currently, the shop is working
on parts for the sample cryostat which should be ready for assembly
within the next two weeks. The system will then be moved to the
4m undulator NIM beam line for first test measurements. If the system
performance is up to specifications and the vacuum conditions meet
User requirements, the analyzer will be scheduled as a User instrument
and should be available during the second half of the 2002 beam
6. CONGRATULATIONS TO SRC RESEARCHERS
James W. Allen, a long-time SRC user from the University
of Michigan, received the 2002 Frank Isakson Prize of the American
Physical Society (APS). The prize recognizes Jim "for his outstanding
contributions to the field of spectroscopy in strongly correlated
electron systems leading to elucidation of many-body physics."
Details of his work can be found at: http://www.aps.org/praw/isakson/02allen.html
Victor Aristov at the Commisariat a l'Energie Atomique
(CEA) in Saclay, France, has been awarded the 2001 Russian National
Prize in Science and Technology ("Poutine Prize"), together
with Alferov (2000 Nobel prize winner) and Lifshitz (the one of
Landau and Lifshitz). He received the honor for his work on "Electronic
and Atomic Processes at Solid Surfaces", in particular for
semiconductor surfaces investigated by STM and synchrotron radiation.
He worked at the SRC for 5 months in 1994 with Patrick Soukiassian
(then at Northern Illinois University) and published seminal papers
on the formation of semiconductor interfaces.
Art Ellis, SRC user and professor of chemistry at
the UW-Madison, was honored by the NSF Distinguished Teaching Scholar
Award, based on his contributions to research and to undergraduate
education. His research at the SRC has been on photoemission studies
of chemical surface passivation of GaN, with plans to add infrared
spectroscopy as additional diagnostic tool. He is engaged in a variety
of educational and outreach activities at the Madison MRSEC on Nanostructured
Materials and has helped the SRC getting started with such activities.
Esther Olson is one of the two recipients of the 2002
Wisconsin Alumni Association Award for Excellence in Leadership.
Her contributions as Assistant Director of the SRC and the Physical
Sciences Laboratory (PSL) were acknowledged. "She has the ability
to marshal the people, capital, and intellectual resources of the
university ... and does that "with civility,
passion, and energy" said Henry Cuthbert, Senior University
James W. Taylor, former director of the SRC and professor
emeritus at the UW-Madison, has been selected as the winner of the
J. Calvin Giddings Award for Excellence in Education by the American
Chemical Society. He was chosen because of his remarkable success
in training PhD students, his development of graduate and undergraduate
instrumental analysis, his role in creating the University of Wisconsin's
teaching Academy, and many other educational activities.
The following current and former Users of the SRC
were recently elected fellows of the American Physical Society (APS):
Paul Canfield (Ames Laboratory) for crystal growth
and characterization of novel materials such as heavy fermion compounds,
magnetic superconductors and quasicrystals, leading to important
advanced in condensed matter and materials physics.
Juan-Carlos Campuzano (University Illinois Chicago)
for fundamental contributions to the physics of high temperature
cuprate superconductors by use of angle resolved photoemission spectroscopy.
Franco Cerrina (Center for Nanotechnology and Dept.
of Electrical and Computer Engineering, UW-Madison), for innovative
physics applications in the domains of lithography, x-ray optics
Alfonso Franciosi (Instituto Nazionale di Fisica della
Materia) for his contribution to the understanding of the properties
of interfaces, including semiconductor heterojunctions and metal/semiconductor
contacts, and his efforts to bridge the gap between basic interface
science and applications.
Boyd Veal (Argonne National Laboratory) for significant
contributions to photoemission studies of transition and actinide
metal compounds and for seminal studies and innovations within the
YBCO family of cuprate high-temperature superconductors.
Congratulations to all!