Longitudinal Uniformity Scans of PbWO4 Crystals Using 120 GeV Electrons in H4 Testbeam

During April and May 1996 some data were taken in the H4 test beam with electrons incident on the side faces of lead tungstate crystals in order to extract detailed measurements of the longitudinal crystal uniformities. Results are presented for fifteen crystals ( three rows in the 5x5 matrix) with 120 GeV incident electrons. The data were corrected for geometrical effects using a GEANT simulation, whilst a ray-tracing program was used to study focusing and wrapping effects in the crystals. The effects of the measured uniformity curves on the ECAL resolution were also studied.