Incident angle effect on the quantum efficiency of CsI photocathodes

Abstract A systematic investigation of the effect of incident angle of the incoming UV light on the quantum efficiency of CsI photocathodes in the spectral range 140–220 nm is presented. The measurements were made in vacuum. A decrease of the photocurrent with an increase of the photon angle of incidence is observed, reaching a relative loss of 30% for an incidence angle of 55° at a wavelength of 210 nm.