LEAD FLUORIDE - AN ULTRA-COMPACT CHERENKOV RADIATOR FOR EM CALORIMETRY

We have tested the material PbF2 and found that it is a Cherenkov radiator suitable for electromagnetic calorimetry. It has a density of 7.77 g/cm3, a radiation length of 0.93 cm, a refractive index of 1.8, and an optical cutoff at about 280 nm. An electromagnetic shower is 15% shorter longitudinally, and its apparent lateral extent has a 1 3 smaller radius in PbF2 than in BGO. We have measured 1300 photoelectrons per GeV of deposited energy and have set an upper limit on the energy resolution of 5.1%/√E. The first measurements show PbF2 to be much more radiation resistant than lead glass; also, when damaged, it almost fully recovers after a short exposure to UV light. © 1990.