The transmission of photoelectrons emitted from CsI photocathodes into Xe, Ar, Ne and their mixtures:: a Monte Carlo study of the dependence on E/N and incident VUV photon energy

Although ultraviolet photosensor devices offer many advantages when used in radiation detectors, there is often a significant reduction in pulse amplitude when the photosensor operates in a detector filled with a noble gas. This is due to the back scattering of electrons by the noble gas atoms. In this study, we investigate the problem of the backscattering of the photoelectrons emitted from a CsI photocathode into Xe, Ar. and Ne and the binary mixtures Xe-Ar, Ar Ne and Xe-Ne using a detailed Monte Carlo simulation. Results for the photoelectron transmission efficiencies are presented and discussed for the case of a CsI photocathode irradiated with photons with energies in the range E-ph = 6.8-9.8 eV (183-127 nm) and for applied reduced electric fields in the range E/N = 1-40 Td. The dependence on incident photon energy, nature of the oas and applied electric field are examined, and the results are explained in terms of electron scattering in the different noble gases.