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In this issue:
Low-Alpha Mode Increases Possibilities at SSRL
Science Today: The Next Generation of RF Power Sources
Pief My Ride

SLAC Today

Thursday - September 20, 2007

Low-Alpha Mode Increases Possibilities at SSRL

Andrei Terebilo, James Safranek, and Xiaobiao Huang.
(Click on image for larger version.)

Since the Stanford Synchrotron Radiation Laboratory (SSRL) began experiments in 1973, it has proven to be a bottomless well of scientific discovery. Now, a team of SLAC accelerator physicists is working to add new functionality to the SPEAR synchrotron accelerator. The team, comprising James Safranek, Xiaobiao Huang and Andrei Terebilo has tested a new "low-alpha mode" for SPEAR that results in shorter x-ray pulses that could be advantageous for some users.

The path a particle travels around the 234-meter SPEAR ring can vary slightly because of minute differences in the energy of each electron in the beam. This causes accelerator magnets to create slightly different paths around the ring for each particle. Because the beam is actually 280 separate packets of particles—the length of which determines the length of pulses of x-rays created—the small variations in how far each particle travels—alpha—affects how short the pulses of x-rays can be made.

Shorter x-ray pulses allow scientists to study tiny processes in extremely short time frames, such as the movement of molecules of liquid water. In fact, short x-ray pulses are one of the defining characteristics of the Linac Coherent Light Source (LCLS) project currently under construction at SLAC. Although SPEAR's x-rays are longer than those that will be created by the LCLS, they are less powerful and won't damage fragile samples.  Read more...

(Daily Column - Science Today)

The Next Generation
of RF Power Sources


The LSBK Conceptual Design.
(Click on image for larger version.)

Continuing the tradition of extending the state-of-the-art of klystron design, the Klystron and Microwave Department is currently working on the next generation of accelerator radio frequency (RF) power sources to power the International Linear Collider (ILC): the Sheet Beam Klystron (SBK).

An SBK is a klystron that uses a broad sheet-like electron beam rather than the intense round beams used in traditional klystrons. This type of beam allows the device to operate at lower voltage and higher current than conventional klystrons while having the low beam current densities required for high operating efficiencies. Furthermore, the wide beam geometry allows for greater internal surface area of the klystron reducing beam interception and circuit heating problems that have plagued earlier conventional klystrons. Another means to this same end is the multi-beam klystron (MBK) being produced by industry and used in the current ILC baseline design. The SBK is potentially a lower cost and higher reliability alternative to the MBK.

Read more...

Pief My Ride


Pief Panofsky with his customized  "Piefmobile."
Photo courtesy of Diana Rogers.
(Click on image for larger version.)

Former SLAC Director Pief Panofsky has obtained a lot of hardware over the years including the Matteucci Medal, the National Medal of Science, the Franklin Medal and the Ernest O. Lawrence Medal. And now he has been given the ultimate gift...a tricked-out ride.

Pief's cart, now affectionately called the "Piefmobile," recently received a few custom upgrades courtesy of Ellie Lwin. Lwin secretly arranged to have SLAC paint shop pro Joe Stafford—with the help of George Sandoval—apply custom-ordered flame decals and a license plate that reads "e-XLR8TR 2" to Pief's cart on his lunch break. She then surprised Pief with the newly decorated cart.

"I went on the premise that it's easier to seek forgiveness than ask permission," said Lwin. "In the end, Pief loved it."

But Lwin isn't done yet. She plans to put a matching license plate on the back, add flared tail pipes to the sides and take the NEV number off of the front. Meanwhile, Panofsky can be seen cruising around the lab in his new favorite method of transportation.




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