By Kate Metropolis
For the development of new techniques to control particle beams, Dmitry
Teytelman (ARDA) will receive the 2004 APS Outstanding Doctoral Thesis
Research in Beam Physics Award. Teytelman did his research at SLAC while a
graduate student in Stanford’s Electrical Engineering Department and is
now an engineer in ARDA.
Dmitry Teytelman is the sixth SLAC graduate student to
win the APS’s award since it was first bestowed in 1991.
by Diana Rogers)
Scientists who use electron storage rings have insatiable appetites for
higher beam current, which translates into more data and brighter
synchrotron light sources.
But you can’t just keep packing more particles into a ring. Put bunches
of particles close enough, and they become electromagnetically coupled.
Think of the bunches as rubber balls connected by springs—if one rubber
ball hits a bump, the springs transmit the shock to all the other balls.
In a high-current ring, the moving particles excite electromagnetic
fields, which in turn bump the beam and make it so unstable that it is
almost instantaneously lost.
Teytelman worked out new techniques that sample the motion of bunches
in the ring, compute the best way to damp the beam’s longitudinal
deviation from the desired path and generate signals to correct the beam.
The task requires parallel processing of billions of operations per
"These particles can be moving at very nearly the speed of light, in
bunches just nanoseconds apart," says John Fox, Teytelman’s advisor. "Dmitry
found some very, very clever ways to understand what beams are doing and
An International Solution
Because many labs would be facing the same challenge, Fox helped form a
collaboration to address it among SLAC, LBL, and LNF, the Italian lab that
is home to DAFNE. "Labs usually do very one-of-a-kind custom things," Fox
said. "We did a very general solution and all the labs can directly share
the operating experience. It’s been a great thing to do."
Teytelman first worked on these longitudinal multibunch feedback
systems in the Advanced Light Source (ALS) at LBL. From this initial
testbed, the SLAC/LBL/LNF group went on to construct instability control
systems for the PEP-II B factory at SLAC; DAFNE, the phi-meson
factory in Italy; the Pohang Light Source in Korea; and the BESSY II light
source in Germany. Teytelman commissioned all of these systems, each of
which uses his control techniques and software.
"Twelve or thirteen years ago, people recognized that beam instability
in a high-current ring would be a serious problem," said John Byrd, leader
of the Beam Electrodynamics Group at LBL. "Now, it’s a solved problem,
thanks to the approach championed by John Fox and in large part designed
and implemented by Dmitry when he was a graduate student."
"Solving the instability problem is critical for this kind of machine,"
said Greg Stover, ALS project electronics engineer. "Dmitry’s undaunted
efforts and creative intelligence were the sine qua non of the
commissioning process; it just wouldn’t have happened without him."
"Dmitry Teytelman is internationally recognized as one of the top
experts in the field," said Mario Serio, leader of DAFNE’s beam
diagnostics and controls group. "I consider his work a major step toward
the comprehension and control of high-current multibunch dynamics in
storage rings present and future. The whole accelerator community has
gained from his activities."
From Minsk to SLAC, with a Pause in Brooklyn
Teytelman’s career path had a few perturbations of its own. The son of
two mathematicians, he received an electronics kit for his tenth birthday
with which he constructed such devices as a radio signal generator and a
moisture detector. "I’d always been interested in math and physics; that
got me interested in electronics," he said.
After completing high school in his home town of Minsk, Teytelman
entered the prestigious Moscow Institute of Physics and Technology. A year
later, in 1990, he experienced a major longitudinal shift: he immigrated
with his family to Brooklyn.
Teytelman presented himself at the admissions office of Columbia
University, where he was informed that March was too late to apply for
admission the next fall, and that his transcript from Moscow did not carry
the same weight here as in the former Soviet Union. Demoralized, he went
to work as a technician in a TV/VCR repair shop.
Through his younger brother, Teytelman met a professor from the City
University of New York, Staten Island, who generated a well-calculated
correction signal: "Come down tomorrow to register. These are the courses
you’ll take your first semester." Three years later, Teytelman had
completed two B.S. degrees, in electrical engineering and in physics.
When Teytelman began graduate studies at Stanford, he was interested in
"the pure electronics" of very fast systems. But, as the path of an
electron in a particle beam is influenced by the electrons ahead of it,
his interest began to shi. as he worked at SLAC with accelerator
"At SLAC, I came into contact with top-notch people in accelerator
physics. Working alongside them was a great learning experience,"
"His thesis wasn’t pure theory, and it wasn’t pure technology," said
Fox. "It was a beautiful combination that required deep mastery of both
the beam dynamics and the technology of digital signal processing."
The annual award includes an honorarium of $2,500, a certificate and an
invitation to present the work at the Division of Physics of Beams annual
SLAC Students Dominate Awards
In addition to
Teytelman, five of the other thirteen recipients did
their graduate research at SLAC:
David Pritzkau, a student of Bob Siemann
Boris Podobedov, a student of Bob Siemann (2002);
a student of John Fox (2001);
Zhirong Huang, a student of Ron Ruth (1999);
Tor Raubenheimer, a student of Ewan Paterson (1994). Any doctoral
student in the world is eligible for the APS Beam Physics dissertation
award, established in 1990.
John Fox, advisor to two of the six SLAC students whose dissertations
have been recognized by the Division of Physics of Beams award, commented
on the significance of the awards. They reflect, he said, both "the high
quality of the graduate students we can attract from Stanford," and "the
caliber of the projects SLAC can offer those students."