Strategies for reducing the use of greenhouse gases from particle detectors operation at the CERN LHC experiments

Abstract

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 at the CERN LHC experiments. Recent developments are concerning systems for CF 4 and R134a recuperation. Recently two systems for CF 4 were developed allowing to reduce the consumption by about 50%. The R134a recuperation plant is still in a R&D phase; however, encouraging results have been obtained. For future long-term detector operation, R&D studies are ongoing for finding alternatives to the currently used gases. The last strategy consists in 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. Moreover, problems like gas availability and price are not addressed and they might become the challenge in the years to come due to the greenhouse phase down policy.