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Archives, History & Records Office

Hours: By appointment Monday-Friday during regular work hours.


Archives E-mail: slacarc[@]
RM E-mail: recordsmgt[@]
Phone: (650)926-3091
Post: SLAC Archives and History Office, M/S 82, 2575 Sand Hill Road, Menlo Park, CA 94025.

Office Location: Bldg.50, Rm.122

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A story from Gary Feldman

The psi was discovered at SPEAR on the weekend of November 9-10, 1974. The discovery did not require any elaborate analysis -- it was obvious from just looking at the online event display. When the SPEAR energy was set precisely to the psi mass, the event display, which normally showed mostly cosmic rays going through the detector, came to life and displayed annihilation events as fast as the computer could process them. Pief came down to the SPEAR control room, watched the event display for a few minutes, and commented, "My God, what we have been telling people about e+ e- annihilation all this time is actually true!"

- Gary Feldman

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Last Updated: 03/29/2022