Advances in Gaseous Photomultipliers

TL;DR

This paper reviews recent advances in gaseous photomultipliers, highlighting new electron multiplier techniques, improved ion-blocking, and applications in large-area detectors, cryogenics, and medical imaging.

Contribution

It introduces novel cascaded hole-multiplier designs with high ion-blocking and demonstrates DC-operated visible-sensitive GPMs with single-photon sensitivity.

Findings

Development of cascaded GEMs with CsI photocathodes for single-photon detection

Introduction of Thick-GEMs and resistive Thick-GEMs for large-area applications

Successful operation of GPMs at cryogenic temperatures for noble-liquid detectors

Abstract

We review latest progress in gaseous photomultipliers (GPM) combining solid photocathodes and various types of novel electron multipliers. Cascaded gaseous electron multipliers (GEM) coated with CsI photocathodes can efficiently replace UVsensitive wire chambers for single-photon recording in Cherenkov and other detectors. Other hole-multipliers with patterned electrodes (Micro-Hole and Strip Plates) and improved ion-blocking properties are discussed; these permit reducing considerably photon- and ion-induced secondary effects. Photon detectors with other electron-multiplier techniques are briefly described, among them GPMs based on Micromegas, capillary-plates, Thick-GEMs and resistive Thick GEMs. The two latter techniques, robust and economically produced, are particularly suited for large-area GPM applications, e.g. in RICH. Cascaded hole-multipliers with very high ion-blocking performance permitted the development and the first demonstration of DC-operated visible-sensitive gaseous photomultipliers with bialkali photocathodes and single-photon sensitivity. Recent progress is described in GPMs operated at cryogenic temperatures for rare-event noble-liquid detectors and medical imaging.