CERN Accelerating science

CMS Note
Report number	CMS-CR-2017-266
Title	CMS GEM detector material study for the HL-LHC
Author(s)	Muhammad, Saleh (Quaid-i-Azam U.)
Collaboration	CMS Collaboration
Publication	2017
Imprint	16 Sep 2017
Number of pages	5
In:	PoS EPS-HEP2017 (2017) 799
In:	2017 European Physical Society Conference on High Energy Physics, Venice, Italy, 05 - 12 Jul 2017, pp.799
DOI	10.22323/1.314.0799
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; CMS
Abstract	A study on the Gaseous Electron Multiplier (GEM) foil material is performed to determine the moisture diffusion rate and saturation level and the moisture effects on its mechanical properties. The study is focused on the foil contact with ambient air and moisture to determine the value of the diffusion coefficient of water in the detector polyimide. The presence of water inside the detector foil can determine the changes in its mechanical and electrical properties. A simulated model is developed by taking into account the real GEM foil (hole dimensions, shapes and material), which describes the adsorption on a sample. This work describes the model, its experimental verification, the water diffusion within the entire sheet geometry of the GEM foil, thus gaining concentration profiles and the time required to saturate the system and the effects on the mechanical properties.
Copyright/License	Preprint: (License: CC-BY-4.0) publication: (License: CC-BY-NC-ND-4.0)

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