Nanodiamond photocathodes for MPGD-based single photon detectors at future EIC

TL;DR

This paper explores the development of nanodiamond-based photocathodes for gaseous photon detectors at the future Electron Ion Collider, aiming to find more robust alternatives to traditional CsI photocathodes.

Contribution

It introduces nanodiamond layers as a novel, less delicate photocathode material and reports initial characterization results for their use in GEM-based detectors.

Findings

Nanodiamond photocathodes show promising photoconversion properties.

Initial tests indicate robustness against ion bombardment.

Potential for more durable photocathodes in gaseous detectors.

Abstract

We are developing gaseous photon detectors for Cherenkov imaging applications in the experiments at the future Electron Ion Collider. CsI, converting photons in the far ultraviolet range, is, so far, the only photoconverter compatible with the operation of gaseous detectors. It is very delicate to handle due to its hygroscopic nature: the absorbed water vapour decomposes the CsI molecule. In addition, its quantum efficiency degrades under ion bombardment. These are the key reasons to quest for novel, less delicate materials for photocathodes adequate for gaseous photon detectors. Layers of hydrogenated nanodiamond particles have recently been proposed as an alternative material and have shown promising characteristics. The performance of nanodiamond photocathodes coupled to thick GEM-based detectors is the object of our ongoing R\&D. The first phase of these studies includes the characterization of thick GEM coated with nanodiamond layers and the robustness of its photoconverting properties with respect to the bombardment by ions from the multiplication process in the gaseous detector. The approach is described in detail as well as all the results obtained so far within these exploratory studies.