Installation and commissioning of the helium refrigeration system for the CMS magnet

A new helium refrigeration plant with a cooling capacity of 800 W at 4.45 K, 4500 W between 60 K and 80 K, and 4 g/s liquefaction simultaneously has been installed in its temporary position inside the Compact Muon Solenoid assembly hall at CERN. The commissioning of the compressor station has been achieved, the commissioning of the cold box and the cryostats is under way. First operation results are presented.