A gas leak rate measurement system for the ATLAS MUON BIS-monitored drift tubes

A low-cost and reliable system is presented which was developed for the gas leak rate measurement of the BIS-Monitored Drift Tubes (MDT) to be used for the Muon Spectrometer of the ATLAS experiment at LHC. In order to meet the ATLAS schedule, 100 MDTs are tested simultaneously each time by the developed setup. The method used is based on the measurement of the gas pressure drop in each MDT with respect to the pressure of a gas tight reference tube within a time interval of 48 h and is accomplished with a differential manometer. A high degree of temperature stability and homogeneity is achieved inside two thermally insulated boxes and leads to a satisfactory accuracy for the measurement of the gas leak rates. The developed system is appropriate within the ATLAS specifications for mass production. More than 18500 MDTs have been tested up to now and the obtained results are presented.