Gas Electron Multiplier foil holes: a study of mechanical and deformation effects

Abstract

Compact Muon Solenoid (CMS) experiment during Long Shutdown II of the LHC in 2018. The GEM foil is a basic part of the detector which consists of a composite material, i.e. polyimide coated with copper and perforated with a high density of micro holes. In this paper the results of the GEM foil material characterization are reported, and a campaign of tensile and holes deformation tests is performed. During the tests, the complex radiation environment at CMS is taken into account and samples are prepared accordingly to see the impacts of the radiation on the GEM foil, i.e. non-irradiated samples are used as the reference and compared with neutrons-and gamma-irradiated. These studies provide the information necessary to optimize the stress level without damaging the foil and holes during the detector assembly in which the GEM foils stack is stretched simultaneously to maintain the uniform gap among the foils in order to get the designed performance of the detector. Finally, an estimate of the Young's modulus of the GEM foil is provided by using the tensile test data. K: Gaseous detectors; Materials for gaseous detectors; Radiation damage to detector materials (gas detectors); Electron multipliers (gas)

A study of asymmetric tensile properties of large area GEM foil

“…This study is an extension of the previous work on tensile properties of GEM foils in harsh radiation and environmental conditions [12,13]. For asymmetry study, two types of tests are performed, namely (i) holes deformation and (ii) tensile tests.…”