Development of cryogenic installations for large liquid argon neutrino detectors

A proposal for a very large liquid argon (68,000 kg) based neutrino detectoris being studied. To validate the design principles and the detector technology, and to gain experience in the development of the cryostatsand the cryogenicsystems needed for such large experiments, several smaller scale installationswill be developed and implemented, at Fermilaband CERN.The cryogenicsystems for these installationswill be developed, constructed, installedand commissioned by an international engineering team. These installations shallbring the required cooling power under specific conditions to the experiments for the initial cool-downand the long term operation, and shallalso guarantee the correct distribution of the cooling power within the cryostatsto ensure a homogeneous temperature distribution within the cryostatitself. The cryogenicsystems shallalso include gaseous and liquid phase argon purification devices to be used to reach and maintain the very stringent purity requirements needed for these installations(parts per trillion of oxygen equivalentcontamination).This paper gives an overview of the installationsinvolved in these cryogenicprojects, describes the functional demands made to these cryogenicsystems and presents the initial studies on which these future cryogenicsystems will be based.