Bandpass photon detector with high efficiency for inverse photoemission spectroscopy

Abstract

We report on a significant improvement of a simple, but effective bandpass photon detector specially suited for inverse photoemission studies. It consists of a commercial open CuBe multiplier with a CaF₂ entrance window. The latter acts as a low pass, the high pass and the quantum efficiency in the new version are determined by the photoyield of KBr evaporated onto the first dynode, resulting in a bandpass with maximum efficiency at ℏω=9.8 eV and ΔE=0.6 eV (FWHM). This detector is easy to operate and up to one order of magnitude more efficient than other systems currently used. Further improvement concerning combined efficiency and resolution seems possible by suitable variation of the cathode material and entrance window.