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In this issue:
Electrons in Hot Water
Pief Honored in Germany
symmetry: SLAC's Water Cycle

SLAC Today

Friday - July 14, 2006

The original engineering sketch of the high-power beam dump used to dissipate the energy of SLAC's linac. (Click on image for larger version.)



Electrons in Hot Water

SLAC's two-mile linear accelerator, with all its klystrons and vacuum chambers, is ultimately committed to one thing—producing beams of high-energy electrons and positrons. But once the scientific usefulness of those beams is exhausted, after the pulses of electrons have collided with positrons or zapped into a research instrument, what do you do with all the left-over energy? The best, time-tested solution, it turns out, is to make hot water.

Back in the early 1960s, before researchers could switch on SLAC's linear accelerator (linac) for the first time, physicists and engineers had to figure out what to do with the beam at the end of its two-mile ride. The old way of stopping a beam involved using a dense barrier like a lead brick or a copper plate to absorb the flow of electrons, but that was simply not enough to dissipate the millions of watts contained in the new beam.  Read more...

Pief Honored in Germany

(Photo - Pief and ) The President of the University of Hamburg Senate presents Pief Panofsky (with wife Adele) with the title of honorary senator of the University.  (Image courtesy of I. Hoffmann)

SLAC's Pief Panofsky took part in two ceremonies last week at the University of Hamburg, Germany—one of which was held in the lecture hall named after his father.

The university is starting a new Center for Science and Peace Research. Its opening ceremonies last Friday included a colloquium on arms control, at which Pief was invited to speak. His talk, titled "Between Physics and Politics—Observations and Experiences of an Involved Physicist," focused on the knowledge he has gained in working separately on nuclear and high energy physics research and on political negotiations.

At a second ceremony, Pief was made an honorary senator of the university. "I'm touched by them doing it," he says, describing the gesture as having great value to him. He was awarded the honor in Erwin Panofsky Lecture Hall, named for his father, a professor of art history who taught at the university from 1919 until 1934 when the Nazis forced the Panofsky family to leave Germany.

Before the family left in 1934, the Hamburg Philharmonic wind section performed a Mozart piece as a farewell gift for Erwin Panofsky. In honor of his father, Pief chose a number of Mozart compositions performed by flute, oboe and English horn as the musical accompaniment to his award ceremony.

symmetry:
SLAC's Water Cycle


In addition to being a main component of the linac's beam dump (see above story), water also rushes through the lab's cooling towers to cool vacuum systems, klystrons, magnets, and other parts that drive the accelerators. (Image courtesy of Diana Rogers.)

Along the Loop Road at Stanford Linear Accelerator Center, the roar of falling water and a refreshing mist filled the air after six solid weeks of California rain. But the water cascading down the inside of Campus Cooling Tower 101, and landing in a frothy pool, is hardly scenic. The corrugated metal building sprouts pipes of all sizes. The bottom section of the front facade is open except for mineral-encrusted slats, allowing Loop Road walkers to experience an industrial facsimile of the small falls that spring to life in the winter hills of California.

The perennial cooling tower is one of six at SLAC that cools vacuum systems, klystrons, magnets, and other parts that drive the accelerators. Cooling Tower 101 lowers the temperature of the chillers that cool computer components in the Computer Building.

Water flows through pipes next to hot equipment, soaking up the heat. The pipes run to nearby heat exchangers, transferring the heat to water in another set of pipes. The cooling water flows back to the cooling tower, like blood returns to the lungs for more oxygen.
Read more in symmetry...

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