A Monte Carlo study of photoelectron extraction efficiency from CsI photocathodes into Xe–CH₄ and Ne–CH₄ mixtures

Abstract

Abstract. The extraction efficiency f for the photoelectrons emitted from a CsI photocathode into gaseous Xe-CH 4 and Ne-CH 4 mixtures is investigated by Monte Carlo simulation. The results are compared with earlier calculations in Ar-CH 4 mixtures and in the pure gases Xe, Ar, Ne and CH 4 . The calculations examine the dependence of f on the density-reduced electric field E/N in the 0.1-40 Td range, on the incident photon energy E ph in the 6.8-9.8 eV (183-127 nm) VUV range and on the mixture composition. Results calculated for irradiation of the photocathode with a Hg(Ar) lamp are compared with experimental measurements for this lamp. To test the electron scattering cross-sections used in the simulations, electron drift parameters in Xe, Ne and their mixtures with CH 4 are also presented and compared with available experimental data.

Status and perspectives of gaseous photon detectors

“…Recently, given the specific interest for THGEM applications, Ne-based mixtures have been characterized and photoelectron extraction efficiencies around 80% have been obtained in Ne/CH 4 80/20 and in Ne/CF 4 80/10 at atmospheric pressure and at a field of 2 kV/cm on the PC surface [53,60,61]; similar values have been obtained in Ar/CH 4 66/34 [62]. Detailed Monte Carlo studies on Ar-, Ne-and Xe-based mixtures with CH 4 , supporting those experimental results, can be found in [63].…”

On the possibility of positive-ion detection in gaseous TPCs and its potential use for neutrinoless double beta decay searches in 136Xe

“…The extraction efficiency increases monotonically with 𝐸 𝑝 ⁄ but tends to saturate at a value which may be considerably lower than 1. For some gases (e.g., Ar, Kr, Xe) it decreases with the kinetic energy of the emitted electron because the elastic scattering cross section increases with energy (for kinetic energies above the Ramsaeur-Townsend minimum of the elastic crosssection) [46]. In this case a lower work function will not necessarily lead to a higher effective IISEE yield because the kinetic energies of the emitted electrons will be higher, resulting in lower extraction efficiency.…”

Snowmass 2021 Instrumentation Frontier (IF5 - MPGDs) -- White Paper 2: Micro Pattern Gaseous Detectors for Nuclear Physics

“…• Photoelectron extraction -In gas atmosphere, the extracted photoelectrons can be elastically back scattered by the gas molecules and be reabsorbed in the photoconverter. Effective photoelectron extraction requires specific gas atmospheres and high electric field in front of the photoconverters [59,60,61,62,63]. MultiWire Proportional Chambers (MWPC) equipped with CsI photocathodes [64] have been successfully operated, for instance in HADES, COMPASS and ALICE RICHes, even if at low gain in order to limit the ion bombardment and the photon feedback.…”