Visual investigation of possible degradation in GEM foil under test

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.