First results of a large-area cryogenic gaseous photomultiplier coupled to a dual-phase liquid xenon TPC

TL;DR

This paper demonstrates the first successful recording of both primary and secondary scintillation signals using a cryogenic gaseous photomultiplier coupled to a liquid xenon TPC, showing promise for dark matter detection.

Contribution

It presents the first implementation of a large-area cryogenic GPM capable of detecting both S1 and S2 signals in a dual-phase LXe TPC, with high gain and timing resolution.

Findings

GPM operated stably at 180 K with gains above 10^5.

S1 signals recorded with 1.2 ns time resolution.

S2 energy resolution of ~9% for 5.5 MeV alpha particles.

Abstract

We discuss recent advances in the development of cryogenic gaseous photomultipliers (GPM), for possible use in dark matter and other rare-event searches using noble-liquid targets. We present results from a 10 cm diameter GPM coupled to a dual-phase liquid xenon (LXe) TPC, demonstrating - for the first time - the feasibility of recording both primary ("S1") and secondary ("S2") scintillation signals. The detector comprised a triple Thick Gas Electron Multiplier (THGEM) structure with cesium iodide photocathode on the first element; it was shown to operate stably at 180 K with gains above 10^5, providing high single-photon detection efficiency even in the presence of large alpha particle-induced S2 signals comprising thousands of photoelectrons. S1 scintillation signals were recorded with a time resolution of 1.2 ns (RMS). The energy resolution ({\sigma}/E) for S2 electroluminescence of 5.5 MeV alpha particles was ~9%, which is comparable to that obtained in the XENON100 TPC with PMTs. The results are discussed within the context of potential GPM deployment in future multi-ton noble-liquid detectors.