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In this issue:
symmetry: Talk and Chalk
People Today: Michael Levashov: Wired for Science
Cranking out the Undulators
Energy Tip of the Week

SLAC Today

Wednesday - August 15, 2007

symmetry: Talk and Chalk

Theoretical physicists Mu-Chun Chen and Jack Laiho are on opposite sides of the Great Board Divide.

Theorists can't help it: When asked to explain something, they reach for a piece of chalk. The language of math and physics seems to require a writing implement and a large vertical surface.

For two centuries, scientists have turned to blackboards to grapple their thoughts into coherent equations and to intellectually commune with like-minded people. You can't describe supersymmetry by waving your hands. You can't quickly draw a magnet layout for a student using a graphics program.

While the world at large is converting to whiteboards, the iconic blackboard still holds a fond and prominent spot wherever theoretical physicists gather—in hallways, auditoriums, and meeting rooms of old buildings and new.

"A lot of what theorists do is very creative. We need to talk and interact with each other. Drawing diagrams is a very efficient way to communicate," says SLAC Theorist JoAnne Hewett.  Read more...

(Weekly Column - Profile)

Michael Levashov:
Wired for Science

Summer student Michael Levashov with the test stand he constructed for calibrating LCLS magnets.

Often in science families, the electron doesn't fall far from the accelerator—SLAC's Yurii and Michael Levashov are no different. Father Yurii has worked in SLAC's Magnetic Measurement group for three years, and for the last two summers, son Michael has joined the team to work with Linac Coherent Light Source (LCLS) measurement equipment.

A senior at the University of Maryland, Michael says working as a summer student at SLAC has given him hands-on training unlike anything possible at college. He has spent the last three summers at SLAC, with his first summer spent working with what is now the International Linear Collider group. His experiences so far have put his double major in aerospace engineering and physics to good use.

"SLAC's a great place," he says. "It's a physics lab, but much of the day to day work is engineering."

Michael's latest project thoroughly combines his two disciplines of interest: assembling a test stand from components designed at SLAC to help calibrate quadrupole electromagnets. Called a vibrating wire system, Michael has assembled the platform, and will spend the final weeks of his summer commissioning the equipment.  Read more...

Cranking out the Undulators

Scott Jansson makes rough-tuning adjustments manually for one of 40 LCLS undulator magnets.

Since last fall, SLAC's Magnetic Measurement Group has been a mill of activity preparing undulators for the Linac Coherent Light Source (LCLS). In all, 40 undulator magnet arrays have arrived from Argonne National Laboratory, which was responsible for the design of these and other LCLS magnets.

So far, SLAC engineers have meticulously tuned 11 of the undulators. Each array comprises rows of ceramic permanent magnets with an adjustable gap through which the LCLS beam pipe will pass. Scott Jansson (pictured above) uses wedged metal shims to adjust the pole assemblies based on measurements of the field strength between the gaps.

Jansson adjusts the shims manually, however even "rough tuning" using this approach allows adjustment to a precision of just a few micrometers. After rough tuning, the undulator is taken to a second test stand for even finer adjustments.

Energy Tip of the Week

A significant amount of energy is required to cool (or heat) outside air to comfortable indoor temperatures, so please keep your building's exterior and freight doors closed as often as possible.

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