INCIDENCE ANGLE DEPENDENCE OF THE OUTPUT RESPONSE UNIFORMITY OF PHOTOMULTIPLIERS

A simple system is described that allows the study of the photoelectro n collection and quantum efficiency uniformity, i. e. the output respo nse of a photomultiplier as a function of the angle of incidence of th e light for a variety of wavelengths. Results are presented for the EM I 9956QQB and discussed for both this model and the 9956QB photomultip liers, tubes frequently used in gas proportional scintillation counter s. It is shown that the response uniformity is better for the shorter wavelengths and for incidence angles not too large.