Evaluation of New Photomultipliers for Scintillation Counting

This paper presents a comprehensive evaluation of a new bi-alkaliphotocathode photomultiplier developed specifically for scintillation counting. This recently developed photomultiplier is compared to existing photomultiplier types, and data are presented showing photocathode quantum efficiency as a function of wavelength, pulse-height resolution for Cs137 and Fe55, dark-noise spectra at 25 C and -100 C, anode rise time and pulse shape, and pulse-height stability with respect to time and count rate. A method is described for measuring the spatial uniformity of photomultipliers, utilizing a dot-pattern-scanned cathode-ray-tube light source, a pulse-height analyzer, and a live cathode-ray-tube display.