Progress on large area GEMs

TL;DR

This paper reports advancements in large area GEM detectors, including innovative manufacturing techniques, simulation studies for optimization, and assessments of production scalability for potential applications.

Contribution

Introduces a single-mask fabrication technique for large GEMs, improving shape control and production scalability compared to traditional methods.

Findings

Single-mask technique enables larger GEMs with better shape control.

Simulation studies inform optimization of hole shape for performance.

Large-scale production of GEMs is feasible with new methods.

Abstract

In 2008, a triple GEM detector prototype with an area of ~2000 cm2 has been constructed, based on foils of 66*66 cm. GEMs of such dimensions had not been made before, and innovations to the existing technology were introduced to build this detector. This paper discusses these innovations and presents further work on large area GEM development. A single-mask technique overcomes the cumbersome practice of alignment of two masks, which limits the achievable lateral size. The holes obtained with this technique are conical, and have a so-called rim, a small insulating clearance around the hole in the substrate. Further refinements of this technique allow greater control over the shape of holes and the size of rims. Also, an improvement in homogeneity over large areas is expected. Simulation studies have been done to examine the effect of hole shape on the behavior of GEMs. Such studies can help understanding how to use new enhancements of the technique to optimize performance. Many potential applications for large area GEMs foresee large production volumes. Production issues have been studied, and single-mask GEMs turn out to be much more suitable for large scale production than standard GEMs.