Interactions of Antiprotons in Lead Glass

An analysis is presented of the pulse distribution produced by antiprotons of 1.2 Bev/c momentum entering a lead-glass {C} {C}{}erenkov counter. The calibration of the counter is described. Estimates of the efficiency of containment of the relativistic secondary particles and electronic showers from annihilation events are discussed and shown to be compatible with the observed pulse-height spectrum. Attenuation effects in a copper absorber preceding the counter, and in the first of two sections of the glass counter, demonstrate interaction and absorption cross sections that are nearly twice geometric and which probably increase as the antiproton kinetic energy decreases below 400 Mev.