GEM-based photon detector for RICH applications

Abstract

We describe the performance of a photon detector based on the Gas Electron Multiplier (GEM). With a CsI photocathode deposited on the first GEM in a cascade, the device permits to efficiently detect and localize single photoelectrons produced by UV photons between the CsI threshold (~6.2 eV) and the quartz window cutoff (~7.5 eV). The single-photon position accuracy achieved, ~55 µm rms, and the excellent multi-photon resolution makes it well suited for Cherenkov Ring Imaging applications

The gas electron multiplier (GEM): Operating principles and applications

“…56 [115]. The reduction of the effective surface of the photocathode due to its optical transparency is compensated by the larger photoionization efficiency of thick reflective layers, also easier to manufacture as they do not require a strict thickness tolerance.…”

Ion-induced effects in GEM and GEM/MHSP gaseous photomultipliers for the UV and the visible spectral range

“…The UV-sensitive ''reflective'' multi-GEM GPM is a mature technique; large-area detectors are under construction for a Hadron-Blind Cherenkov detector (HBD) of the PHENIX (RHIC-BNL) relativistic heavy-ion experiment [15]; others are developed for RICH [19]. Similar photon detectors, operated at cryogenic temperatures, are conceived for the XENON dark-matter experiment [20], for dark-matter and neutrino physics [21], for a liquid-Xe PET project [22] etc.…”

2-D imaging with cascaded GEM/MHSP multipliers

“…This is not for example the case with other readout schemes, e.g. with crossed x-y strips connected to individual amplifiers [36] were spatial resolutions ~125 µm (FWHM) for single-photons had been reported or to delay-line elements [6]; the resolutions recorded in the latter (100 × 100 mm 2 3-GEM detector) were 170 µm (FWHM) for soft X-rays.…”