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

PbWO₄ has been selected as the most appropriate scintillator material for future calorimeter projects at LHC to detect high energy photons in the GeV range. In spite of the low yield of scintillation light, the applicability of the scintillator to detect photons and particles at energies well below 1 GeV has been studied using monoenergetic electrons between 180 and 855 MeV. The individual crystals (20×20×150 mm³) are characterized by the optical quality and the response to low energy γ-sources using hybrid photo diode tubes. The energy resolution of the EM-shower deposited by electrons in a 3×3 crystal matrix amounts to σ/E=2.39%/√E+0.20% (E given in GeV). The obtained time resolution of σ⩽130 ps allows photon/particle discrimination via time-of-flight measurement