Tests on 1999 Vacuum Photodiodes for the CMS Ecal Endcaps

The permormance of fifty-five, one inch about 25 mm diameter Vacuum Phototriodes ( VPT) has been studied and twenty-five have been selected for CERN test beam runs. VPT paramaters measured over a range of bias voltages are: anode and photocurrent dark currents, photocathode response, DC current gain, and the ratio of the pulse gain in a 4.7T axial magnetic field to the corresponding pulse gain in zero field