Precision measurements of the electromagnetic form factors of the proton in the time-like region and detailed vector meson spectroscopy

This chapter investigates vector meson spectroscopy in the mass range 1-1.7 GeV. Two electron final states are expected to be detected and measured using the Low-Energy Antiproton Ring (LEAR). Topics covered include the shower detector, drift tubes, the Cerenkov counters, and the central detector. The branching ratios vary from 3 X 10-7 at rest to 10-8 at 2 GeV/c, so that a fast and efficient electron identification is needed in order to have a reasonable signal to noise ratio already at trigger level (200-600 ns). The experimental apparatus consists of (starting from the magnet center) a hydrogen target, a central detector (CD), Cerenkov counters (C), an H1 hodoscope (H1), drift tubes (DT), a shower detector (SD, 2 rad. lengths), an H2 hodoscope (H2), and a shower detector (SD, 5.5 r.l.). An electron is identified by C, SD, H2 and is timed by C X H1 X H2