Performance of CsI photocathodes in liquid Xe, Kr, and Ar

Abstract The successful detection of the UV scintillation light in liquid Xe, Kr and Ar by a reflective CsI photocathode with liquid-phase electron extraction is reported. High quantum efficiencies of 31% in liquid Xe, 17% in liquid Kr, and 10% in liquid Ar have been achieved. Excellent intrinsic energy resolutions of 2.8% FWHM for liquid Xe, 5.2% FWHM for liquid Kr, and 8.4% FWHM for liquid Ar have been measured for 5.5 MMeV alpha particles. The enhancement of the quantum efficiency due to the applied electric field and the favorable effect of the negative electron affinity of liquid rare gases on electron extraction from the photocathode are discussed.