Director’s Corner
By Jonathan Dorfan
The Laboratory is abuzz with activity. Like the blossoming of spring
these past few weeks, SLAC’s science program is in a period of
tremendous evolution and productivity. The range of activities is broad,
including: construction projects like the Gamma Ray Large Area Telescope
(GLAST) and the Linac Coherent Light Source (LCLS), the development of
exciting new theoretical ideas in particle physics, major R&D programs
like the Next Linear Collider (NLC) and the Enriched Xenon Observatory (EXO),
the development of new directions and instruments for particle
astrophysics, and new approaches to meet the enormous challenges we face
in computing, to name but a few. In addition to these exciting
developments for our future, we are of course vigorously operating our
accelerator facilities for the roughly 3,000 users world-wide who do
their research at SLAC. In this month’s column I would like to update
you on the operating facilities.
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(Photo by Diana
Rogers) |
SPEAR3 is doing science! The first
synchrotron light was brought into beam line 9 on March 8, and users are
now back at work, signaling a new era of synchrotron radiation
experimentation at SLAC. SPEAR3 will operate at 100 mA during this first
year, while beam-line components are upgraded in preparation for full
500-mA operation next year. This has been an exemplary project that has
set standards of competence that will be hard to match. SPEAR3 was built
on time, commissioned on time, has performed beautifully from the start
and of course, was on budget. We promised that SPEAR3 would be ready for
users in March and here they are! Everyone who contributed to this
Laboratory-wide project should feel justifiably proud of their
achievement.
The B Factory, too, is bursting with new developments and achievements.
A new mode of operation started on March 11, called the ‘dual trickle
injection’ mode, which injects new bunches of particles continuously
into both the electron and positron rings. Previously, BABAR
datataking had to be suspended about once every 40 minutes while the
storage ring currents were topped up to their maximum operating point.
Trickle feed means that BABAR
can take data virtually uninterrupted with both beams at full operating
current, leading to a significantly larger number of events logged per
day. New performance standards were set at the B Factory in March with
record PEP-II peak luminosity, record data collected, both in one shift
and in one day. PEP-II is the only accelerator in the world using this
new technique of ‘dual trickle injection’, maintaining SLAC’s tradition
of accelerator innovations. Don’t miss the article on the front page of
this TIP that explains this development in more detail. Congratulations
to the fabulous PEP-II team that made this breakthrough happen, and also
to the BABAR
folks who adjusted their detector data-acquisition to conform to this
very challenging mode of operation.
The primary electron beam, besides being used for injection into PEP-II,
is also currently the backbone of the Final Focus Test Facility (FFTB),
whose running hours are shared between the high energy physics program
and the synchrotron light program. FFTB is capable of delivering the
shortest pulses in the world, either a) in the form of the electrons
directly or b) after conversion in an undulator magnet, in the form of
x-rays. In recent months the running time has been shared between the
x-ray experiment SPPS and the E-164 collaboration which is doing
advanced accelerator R&D.
The E-157, E-162 and E-164 collaborations (SLAC, UCLA and USC) have been
studying the use of plasmas for future high-energy accelerators. Plasmas
have the potential to provide acceleration rates much greater than those
obtained using conventional technology. Data from E-162 experiments have
already shown peak acceleration on the order of 200 MeV per meter, which
is very exciting when compared to our linac’s average of 17 MeV per
meter. The E-164 and E-164X experiments finished their latest FFTB run
during which they were working toward attaining ultrahigh peak
acceleration of up to 10 GeV per meter. At a recent meeting in
Washington, DC, they showed preliminary results of accelerations in
excess of 1 GeV per meter.
SPPS, a nine institution, three-nation collaboration, is breaking new
ground in the use of ultra-fast pulses to study a wide range of
otherwise inaccessible material properties. Given that this ultra-short
pulse of synchrotron radiation is novel, much of what they are doing
involves the development of new detection strategies. SPPS has already
detected the arrival time and width of the electron beam in the FFTB
with subpicosecond (a millionth of a millionth of a second) resolution
and will work on developing similar techniques for the x-ray beam. They
have also focused the x-ray beam to a spot more than 100 times smaller
than a human hair. The combination of these developments will be
exploited in the coming year to study how materials behave when exposed
to peak x-ray power, approaching what is expected from the LCLS.
It is the Laboratory staff’s professionalism, dedication and their
strong identification for the success of our mission that has enabled
the current growth and change in so many sectors of the laboratory.
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