Electromagnetic calorimetry with PbWO4 in the energy regime below 1 GeV

The study of the performance and application of PbWO4 in electromagnetic ca lorimetry at energies far below 1GeV has been continued. The significantly improved optical and scintillation properties of 15cm long Nb/La-doped crys tals, optimized for the ECAL/CMS calorimeter, are documented. The lineshape , energy and time response of a 5x5 matrix are tested with monoenergetic ph otons up to 790MeV energy and compared to previous measurements. First atte mpts have been made to enhance the scintillation yield by suitable dopants (Mo, Tb) for applications at very low photon energies. As a first large scale project at medium energies, the proposed concept for a compact photon spectrometer to be implemented into the ANKE magnetic spe ctrometer at COSY (KFA Julich) is illustrated.