A Novel Manufacturing Process for Glass THGEMs and First Characterisation in an Optical Gaseous Argon TPC

TL;DR

This paper introduces a new abrasive machining process for manufacturing glass THGEMs with customizable properties, and demonstrates their initial characterization in an optical gaseous argon TPC, highlighting advantages over traditional methods.

Contribution

The paper presents a novel abrasive machining technique for glass THGEMs, enabling versatile, customizable, and high-quality electrodes for gaseous TPC applications.

Findings

Abrasive machining produces THGEMs with tailored substrate and hole geometries.

Glass THGEMs show promising performance in optical GArTPC tests.

Compared to traditional FR4 THGEMs, glass variants exhibit distinct charging and scintillation behaviors.

Abstract

This paper details a novel, patent pending, abrasive machining manufacturing process for the formation of sub-millimetre holes in THGEMs, with the intended application in gaseous and dual-phase TPCs. Abrasive machining favours a non-ductile substrate such as glasses or ceramics. This innovative manufacturing process allows for unprecedented versatility in THGEM substrates, electrodes, and hole geometry and pattern. Consequently, THGEMs produced via abrasive machining can be tailored for specific properties, for example: high stiffness, low total thickness variation, radiopurity, moisture absorption/outgassing and/or carbonisation resistance. This paper specifically focuses on three glass substrate THGEMs (G-THGEMs) made from Schott Borofloat 33 and Fused Silica. Circular and hexagonal hole shapes are also investigated. The G-THGEM electrodes are made from Indium Tin Oxide (ITO), with a resistivity of 150 $\Omega$/Sq. All G-THGEMs were characterised in an optical (EMCCD) readout GArTPC, and compared to a traditionally manufactured FR4 THGEM, with their charging and secondary scintillation (S2) light production behaviour analysed.