R&D; strategies for optimizing greenhouse gases usage in the LHC particle detection systems

A wide range of gas mixtures is used for the operation of different gaseous detectors for particle physics research. Among them are greenhouse gases like C$_2$H$_2$F$_4$ (R134a), CF$_4$ (R14), C$_4$F$_{10}$ (R610) and SF$_6$ , which are used because they allow to achieve specific detector performance that are necessary for data taking at the LHC experiments (i.e. stability, long term performance, time resolution, rate capability, etc.). Such gases are currently subject to a phase down policy that started to affect the market with price increase and, in the long term, may cause a decrease in their availability. Four different strategies have been identified to optimize the gas usage. As immediate actions, during the LHC Long Shutdown 2 the gas systems will be upgraded to cope with new detector requirements and, in parallel, extensive campaigns for fixing leaks at detector level will be performed. The development of gas recuperation plants is going to be the next step. They aim in extracting greenhouse gases from the exhaust of gas recirculation systems allowing further re-use. Several plants of this type are already in use. Recent developments are concerning a system for R134a recuperation. Encouraging results have been obtained with a prototype and, giving the fact that R134a dominates the greenhouse gas consumption, this plant might have an important positive effect on the overall optimization process. For future long-term detector operation, R&D; studies are ongoing for finding green alternatives to the currently used gases (especially for R134a). Unfortunately, the new alternative gases developed by industry as refrigerant fluids are not behaving as the R134a in particle detectors which makes difficult the replacement for the present experiments. The last strategy consists in the possibility of using industrially developed plants for the disposal of greenhouse gases by decomposition in harmless compounds. This solution avoids the emission in the atmosphere, but it is not optimizing the gas usage and problems like gas availability and price for detector operation might become the challenge in the coming years due to the greenhouse phase down policy.