Colliding Beams under Way At CEA, Planned for SLAC

The Cambridge Electron Accelerator, a 6‐GeV alternating‐gradient electron synchrotron, is being modified to produce and store counter‐rotating beams of 3–3.5‐GeV electrons and positrons in the synchrotron itself. Both beams should be circulating in about two years. At Stanford University, where the first experiments with colliding electron beams of 330 MeV were reported one year ago, an experiment at 550 MeV is under way. Stanford is hoping to build a 3–4‐GeV electron‐positron colliding‐beam facility to be fed by the 20‐GeV linac. Although the Weisskopf high‐energy advisory committee recently recommended that the ring be built, it has not yet been authorized.