Fast and compact lead tungstate-based electromagnetic calorimeter for the PANDA detector at GSI

Experiments with a cooled antiproton beam at the future accelerator facility at the Gesellschaft fur Schwer Ionenforschung, Darmstadt, Germany, will be performed with the 4π detector proton antiproton at Darmstadt comprising a high-resolution, compact, and fast homogeneous electromagnetic calorimeter to detect photons between 10 MeV and 10 GeV energy inside a superconducting solenoid (2 T). PbWO₄ (PWO) crystals, readout with large size avalanche photodiodes, represent an envisaged detector concept. The first results of a new generation of significantly improved PWO crystals, operated at different temperatures, are presented and discussed in detail. The requirements for the photo sensor are outlined based on first test measurements. A new fast hybrid photomultiplier (PLANACON 85001-501, BURLE) with channel plate amplification was investigated for comparison.