Developmental solar blind photomultipliers suitable for use in the 1450-2800-a region

An account is given of the properties of a number of experimental EMI photomultipliers possessing solar blind photocathodes, which were specially developed for a program of stellar photometry above the earth's atmosphere (the measurements were made between 1963 and 1968). Quantum efficiency, dark current, cathode uniformity, and spectral response are examined in detail, and results are compared with data from similar detectors. Several discrepancies are evident between measurements made when the photomultipliers are tested immediately after manufacture and when they are tested several months later. A brief account is also given of the suitability of the photomultipliers for use in rocket environments. Additional information is also included for a number of photocells also produced by EMI. Typical spectral responses are given together with a number of plots of cathode uniformity at 2537 A.