PEP

Brief descriptions on the parameters of the machine PEP, the construction effort now going on, and the experiments planned for the turning-on of the machine or soon thereafter, are presented. Both electrons and positrons can be injected directly from the linear accelerator with energy from 4 to 18 GeV in the Stanford Linear Accelerator Center, Stanford, California, U.S.A. The six interaction regions are spaced symmetrically around a magnet ring of 2200 m circumference. Major excavation and construction works for PEP began a little more than one yer ago. The first beam is now scheduled on October 1, 1979, and the experimenters hope to start physics experiments relatively soon thereafter. A rather varied program of first generation experiments for PEP has been approved. They are, in the order of their proposal numbers, PEP 2, Monopole search; PEP 4, TPC (Time projection chamber which enables charged particle tracking and identification over almost the entire momentum range available at PEP); PEP 5, Mark 2 (A central cylindrical drift chamber within a 5 kG conventional solenoidal magnet); PEP 6, Magnetic calorimeter; PEP 9, Two-gamma experiment for two photon physics; PEP 12, HRS (High resolution spectrometer for charged particles); PEP 14, Quard search; PEP 20, DELCO (Its principal unique feature is very good electron identification by Cerenkov counters over a substantial part of the solid angle). As seen above, PEP has a full program of physics already planned. (Wakatsuki, Y.)