Perfluorocarbons and their use in cooling systems for semiconductor particle detectors

We report on the development of evaporative fluorocarbon cooling for the semiconductor pixel and micro-strip sensors of inner tracking detector of the ATLAS experiment at the future CERN large hadron collider (LHC). We proceeded with studies using perfluoro-n-propane (3M-“PFG 5030”; C3F8), perfluoro-n-butane (3M-“PFG 5040”; C4F10), trifluoro-iodo-methane (CF3I) and custom C3F8/C4F10 mixtures. Certain thermo-physical properties had to be verified for these fluids. Sound velocity was calculated for the pure fluids and custom mixtures. A sonar instrument was developed for the measurement of sound velocity in the above fluids at a variety of temperatures and pressures. Irradiation studies were made on the fluids using neutrons and gamma rays to determine their suitability for use in the high radiation environment at LHC.