First studies on cascaded dual-phase liquid hole-multipliers in xenon

TL;DR

This study investigates a bubble-free liquid hole-multiplier design in xenon to improve photon detection efficiency, achieving over five times better performance than previous bubble-assisted methods, with potential for further enhancements.

Contribution

It introduces a novel bubble-free LHM configuration with a CsI-coated Thick GEM, demonstrating significant performance improvements over prior bubble-assisted designs.

Findings

>5-fold improvement in S1'/S2 ratio

PDE achieved is around 4%

Proposed design shows potential for further optimization

Abstract

Challenges in scaling up noble-liquid time projection chambers prompted the exploration of new detection concepts. The liquid hole-multiplier (LHM) was introduced as a potential component, enabling the detection of ionization electrons and VUV photons. Prior studies focused on perforated electrodes coated with CsI immersed in the liquid and electroluminescence amplification produced on a bubble trapped underneath. However, the performance was hindered by electron transfer across the liquid-gas interface. Here, we explored a bubble-free variant, placing a CsI-coated Thick Gas Electron Multiplier electrode below the liquid-gas interface to improve the transfer efficiency across it. Results show >5-fold improvement in the S1'/S2 ratio (a proxy for the photon detection efficiency (PDE)) compared to the bubble-assisted LHM. Although the achieved PDE is still below expectation ($\sim$4%), we propose potential improvements to enhance the performance of this detector.