Use of Fibre Bragg Grating sensors for Gas Electron Multiplier HEP detectors

The GE1/1 CMS muon system upgrade consists of 144 GEM chambers based on the triple-GEM technology (three GEM foils flat parallel closely spaced). The GE1/1 assembly procedure employs a mechanical stretching procedure to apply tension to the GEM foils by means of a series of lateral stretchers. This novel technology allows mechanical assembly of the GEM chamber without the use of internal spacers or glue. This procedure reduces the assembly time and allows the user to replace one or more GEM foils after the chamber has been assembled. However this mechanical stretching technique needs to be validated to prove that the mechanical stretching technique applies a uniform tensile load on the triple-GEM stack able to fulfil the design specifications which require that foils are planar and uniformly spaced.