Last night, the beams were dumped for the final time from the PEP-II rings and the BaBar experiment took its last data. It was the end of nine years of operation in which the design specifications were more than tripled. SLAC and BaBar staff and collaborators commemorated the last day of running with a set of short speeches on the SLAC green, followed by ice cream for everybody.
Read some comments on the final operations of PEP-II by Jonathan Dorfan, director of SLAC during most of PEP-II/BaBar running. Here is an extract:
Unseen by us except through the myriad of electronic signals shipped from the accelerator control system and displayed on a series of monitors at Babar, the PEP-II operators diagnose the fault, thrust the HER injection system into high gear and begin refilling the 1,760 electron bunches. Notwithstanding the violent loss of the electron beam, the 2.6 amperes of positrons have remained orbiting stably in the low energy ring. A scant 10 minutes after the beam loss, data-taking has recommenced at maximum luminosity and low backgrounds. The two Babar Run Coordinators, Georg Marks from Germany and Jacques Chauveau from France, smile-their admiration for what the PEP-II operations staff has just done, and do day-in-day-out, is clearly reflected on their faces. Data taking has been restored-PEP-II and Babar are ticking away in perfect unison, each executing an enormously complex set of technical feats, pushed up hard against the edge of feasibility. Clearly I am observing "factory" performance.
Below are some photos taken by Brad Plummer of the main control center in the last days of operation.