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Pass the Salad—and a Piece of History

(Photo - Salad Bowl)For years, whenever former SLAC director Burton Richter and his wife needed to serve a salad, they pulled out their large, stainless steel bowl. But when their recent move to a smaller residence prompted them to thin out their belongings, they decided it was time for the salad bowl to go—and Richter thought the perfect place for it was SLAC.

That's because the bowl isn't technically a salad bowl at all, but the last remnant of the first colliding-beam machine ever built, the Princeton-Stanford Electron-Electron Collider. The machine, designed by Richter and his colleagues, forever changed the way particle physicists do particle physics.

In the early years of accelerator-based research, fixed-target machines, which fire a single beam of accelerated particles at a stationary target, were standard technology.

But in the mid-1950s, Richter and a group of Stanford and Princeton collaborators led by Princeton's G. K. O'Neill became interested in developing a new machine that would use two particle beams instead of one. The beams would be made to collide into each other as they circled in opposite directions in separate, intersecting storage rings. In 1958, the group secured funds to build such a collider at Stanford's High Energy Physics Laboratory, and with that, says Richter, "we started off to revolutionize the world."

Revolutionize the world they did. Richter and his colleagues completed the collider in 1962 and soon thereafter it successfully stored its first beam. The beam's current, at 0.6 amperes, remained unsurpassed until the B-factories at SLAC and KEK came along nearly four decades later. The machine achieved a center-of-mass energy of 1,000 MeV—15 times higher in the electron-electron system than the most powerful fixed-target machine at the time—giving physicists a tool to produce massive particles and probe matter more deeply than ever before. The device was the precursor of all the colliders that followed, and today, these machines are the new standard for particle physics research.

The Princeton-Stanford Electron-Electron Collider was dismantled around 1970, and now only the "salad bowl" remains. The piece served as a spare part, a twin of a bowl that formed part of the vacuum chamber in the historic machine's collision region.

As useful as the colliderware has been in the kitchen all these years, for Richter, of course, the bowl is about much more than just leafy greens. "It represents the machine that started me in colliding beams and the machine that was the ancestor of SPEAR," he says. The SPEAR collider eventually produced two Nobel Prize-winning discoveries at SLAC: Richter discovered the J/psi particle in 1974, and Martin Perl discovered the tau particle in 1976.

"The bowl should be in the Smithsonian, but they don't have a place for it," Richter says. "Jonathan [Dorfan] could use it for fancy dinners if he'd like."

The bowl will be on display in the office of Communications Director Neil Calder (Building 40, Room G106) for the next three weeks.

—Jennifer Yauck
    SLAC Today, November 14, 2006

Above image: The only remaining piece of the Princeton-Stanford Electron-Electron Collider is a stainless steel bowl that served as a spare part. (Image courtesy of Melodi Masaniai. Click on image for larger version.)