Photon-to-electron conversion efficiency and reflectance of photomultiplier tubes as a function of incidence angle of photon

The photon-to-photoelectron conversion efficiency and the reflectance of a photomultiplier have been measured as a function of the photon incident angle. Appreciably large conversion efficiency and reflectance were obtained for a incident angle near 45°. A calculation was made for an optical model of a photomultiplier. The results were consistent with the experimental results.