A common analysis station for the gas systems of the Compact Muon experiment at the CERN Large Hadron Collider

The Compact Muon Solenoid (CMS) experiment at the CERN Large Hadron Collider (LHC) is equipped with four gas systems, one per each of the muon detectors (i.e. Cathode Strip Chambers, Drift Tube and Resistive Plate Chambers) and one for the inner detectors neutral gas flushing (pixel, tracker, Electromagnetic and Hadron calorimeters). Each gas detector is suitable operated with a well defined gas mixture and also the levels of contaminants (commonly O₂, N₂, H₂O, etc.) that can affect the detector performances are well defined. Therefore, the necessity of a tool able to verify the gas mixture composition was always considered as a fundamental requirement. Moreover, after three years of operation few critical points have been identified and this allowed to define the requirement of a new analysis station already installed that will soon monitor the mixture composition for all the detectors. The analysis station is based on a gas chromatograph with a system of three multi-ways valves that will allow to analyze almost automatically up to 48 gas stream coming from different detectors and also from several region of the experiment subjected to different level of radiation.