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Production of GEM-like structures for cryogenic applications, using laser-cutting techniques

D. Rodas-Rodríguez, A. F. V. Cortez, M. Kuźniak, D. González-Díaz, P. A. O. C. Silva, A. Gnat, G. Nieradka, T. Sworobowicz, E. Alario, C. D. R. Azevedo, K. T. Floethner, P. Gasik, J. Llerena, C. M. B. Monteiro, R. Oliveira, A. Pallas, D. Tenreiro, V. Peskov, J. M. F. dos Santos

TL;DR

The paper addresses scalability and light-detection challenges in EL-based dual-phase TPCs for rare-event searches by developing Field Assisted Transparent Gaseous Electroluminescence Multipliers (FAT-GEMs) built from 5 mm PMMA and enhanced with TPB WLS coatings inside holes. The approach leverages laser-cut, conical-hole geometries and optimized electrode configurations (ITO and Al) to maximize light collection while enabling cryogenic operation. In argon at near-LAr density, the first production batch achieves an energy resolution of $23.5 ± 1.0%$ at 5.9 keV and demonstrates about a 21% improvement in light yield over earlier FAT-GEMs, with stable performance up to $4.0 kV cm^-1 bar^-1$ and no charging-up observed; a second batch at CERN indicates scalable manufacturing. These results suggest a low-cost, high-volume, radiation-tolerant optical readout solution that could enhance next-generation large-area dual-phase TPCs for rare-event searches.

Abstract

A novel concept for electroluminescence (EL) structures was recently proposed. In it, a wavelength-shifting material is deposited inside the holes of GEM-like structures which, after suitable optical treatment of its electrodes, improves the light collection and detection efficiency in noble gas TPCs. This new development directly addresses problems related with the scalability of future dual-phase TPCs for rare-event searches, matching (and potentially exceeding) the performance of conventional EL techniques. We report the newest developments on the production of such structures using laser-based techniques, namely the manufacture of a first batch of the so-called FAT-GEMs. This process allows low-cost and reproducible manufacturing of a high volume of such structures. In addition to the detailed description of the production, we present a performance assessment in pure argon, at a gas density close to the one expected in LAr conditions. An energy resolution of 23.5$\pm$1~\% (FWHM) at 5.9~keV was obtained, indicating a consistent improvement over previous batch. The optical treatment of the electrode surfaces has been greatly simplified and modestly improved, while charging-up effects arising from the use of laminates eliminated.

Production of GEM-like structures for cryogenic applications, using laser-cutting techniques

TL;DR

The paper addresses scalability and light-detection challenges in EL-based dual-phase TPCs for rare-event searches by developing Field Assisted Transparent Gaseous Electroluminescence Multipliers (FAT-GEMs) built from 5 mm PMMA and enhanced with TPB WLS coatings inside holes. The approach leverages laser-cut, conical-hole geometries and optimized electrode configurations (ITO and Al) to maximize light collection while enabling cryogenic operation. In argon at near-LAr density, the first production batch achieves an energy resolution of at 5.9 keV and demonstrates about a 21% improvement in light yield over earlier FAT-GEMs, with stable performance up to and no charging-up observed; a second batch at CERN indicates scalable manufacturing. These results suggest a low-cost, high-volume, radiation-tolerant optical readout solution that could enhance next-generation large-area dual-phase TPCs for rare-event searches.

Abstract

A novel concept for electroluminescence (EL) structures was recently proposed. In it, a wavelength-shifting material is deposited inside the holes of GEM-like structures which, after suitable optical treatment of its electrodes, improves the light collection and detection efficiency in noble gas TPCs. This new development directly addresses problems related with the scalability of future dual-phase TPCs for rare-event searches, matching (and potentially exceeding) the performance of conventional EL techniques. We report the newest developments on the production of such structures using laser-based techniques, namely the manufacture of a first batch of the so-called FAT-GEMs. This process allows low-cost and reproducible manufacturing of a high volume of such structures. In addition to the detailed description of the production, we present a performance assessment in pure argon, at a gas density close to the one expected in LAr conditions. An energy resolution of 23.51~\% (FWHM) at 5.9~keV was obtained, indicating a consistent improvement over previous batch. The optical treatment of the electrode surfaces has been greatly simplified and modestly improved, while charging-up effects arising from the use of laminates eliminated.
Paper Structure (5 sections, 3 figures, 1 table)

This paper contains 5 sections, 3 figures, 1 table.

Table of Contents

  1. Introduction
  2. Field Assisted Transparent Gaseous Electroluminescence Multiplier (FAT-GEM)
  3. Fabrication process
  4. Performance Assessment
  5. Conclusions

Figures (3)

  • Figure 1: Schematic representation of a typical FAT-GEM configuration with a combination of reflective and transparent electrodes, with a transparent substrate and WLS material deposited in the conical-shaped holes achieved through laser drilling. The scheme also represents how the light wavelength is shifted from the VUV emmission (yellow) to the visible range (blue).
  • Figure 2: Left: Scheme of the production steps for the upgraded and scalable FAT-GEM manufacturing.. Right: Finalized samples showing different configurations: S2-enhanced (left) and S1-enhanced (right), in this case with a VUV-transparent mesh-like cathode.
  • Figure 3: Left: Energy resolution (%). Right: Scintillation yield. Results are shown for structures C and E in comparison with previous production leardini2024fat.