Identification of antiprotons in space using a compact RICH counter

A compact RICH (ring imaging Cherenkov) counter has been developed that has a very good separation power (10/sup -4/) between antiprotons and pions/muons up to 6 GeV/c momentum at perpendicular incidence and up to 2.3 GeV/c momentum at 25 degrees incidence angle of the particle. It uses a solid radiator of NaF and a photosensitive MWPC (multiwire proportional chamber) with pad readout to detect the faint Cherenkov light. Twenty photoelectrons are detected per event for beta =0.94 particles and 12 for beta =1 particles at perpendicular incidence. Such a detector will be used in a balloon-borne spectrometer to measure the energy spectrum of antiprotons and positrons in cosmic rays up to 6 GeV kinetic energy.<
>