A Fast Rich Detector For Jetset

A fast RICH is being prepared for installation in the forward region of the JETSET experiment at LEAR. In the absence of a magnetic field for momentum analysis, the RICH is intended to measure charged particle velocities in the range 0.68 < beta < 1, where dE/dx is decreasingly effective. A segment of the RICH detector, consisting of a modular wire chamber operating at room temperature and pressure with a He/C2H6 /TMAE gas mixture, has been tested with a planar quartz radiator in a p/pi beam of 1.0-3.5 GeV/c momentum. The analyis of the events and the resulting velocity resolution is presented. The measured photoelectron multiplicity is compared with Monte Carlo calculations. The measurements show a good efficiency and a low background for UV photon detection.