Visual investigation of possible degradation in GEM foil under test

TL;DR

This paper presents a visual analysis of GEM foil imperfections, cleaning techniques to remove shorts, and evaluates the effectiveness through leakage current measurements, contributing to improved GEM foil quality control.

Contribution

It introduces a manual optical inspection method for GEM foil imperfections and discusses cleaning techniques to mitigate shorts and improve performance.

Findings

Identification of imperfections in GEM foil

Effective cleaning methods to reduce shorts

Leakage current decreases after cleaning

Abstract

Visual investigation of a Single Mask (SM) Gas Electron Multiplier (GEM) foil, showing small resistance~($\sim$ 40 k$\Omega$), is performed manually using an optical microscope. The GEM foil is scanned and the different imperfections in the foil are identified. Different techniques are used to clean the GEM foil to remove the short paths created between the GEM electrodes. The details of the method used for cleaning the GEM foil and the result of leakage current measurement after the cleaning of the foil are discussed in this article.