Channel electron multipliers: detection efficiencies with opaque MgF_2 photocathodes at XUV wavelengths

Abstract

The detection efficiencies of channel electron multipliers with opaque MgF(2) photocathodes have been measured at wavelengths between 44 A and 900 A. Efficiencies a factor of 2 greater than those of uncoated channel electron multipliers were obtained over the wavelength range from 50 A to 350 A. The absolute detection efficiencies were greater than 10% in the range from 67 A to 990 A for photocathodes illuminated at an angle of incidence of 45 degrees , with additional increases in sensitivity being obtained at short wavelengths using higher angles of incidence. Following an initial aging period, the photocathodes showed no degradation of response during storage under vacuum or in air.