Response of a PbWO4-scintillator array to electrons in the energy regime below 1 GeV

PbWO4 has been selected as the most appropriate scintillator for future calorimeter projects at LHC to detect high energy photons in the multiple GeV range. In spite of the low yield of scintillation light, the applicability in photon and particle detection at energies well below 1 Gev has been studied using electrons between 180 and 855 MeV. The crystals (20x20x150mm(3)) are characterized by the optical quality and the response to low energy gamma-sources using hybrid photo diode tubes. The energy resolution of the electromagnetic shower deposited by electrons in a 3x3 crystal matrix amounts to sigma/E = 2.39%/root E + 0.20% (E given in GeV). The obtained time resolution of sigma less than or equal to 130 ps allows photon/particle discrimination via time-of-flight measurement.