The ICARUS T600 Liquid Argon Detector Operation in the Underground Gran Sasso Laboratory

The ICARUS T600 Module is the largest liquid argon detector (760 t LAr mass) ever realized to study neutrino oscill ations and matter stability in the deep underground Gran Sasso Laboratory. One of t he key elements for the detector performance is the liquid argon purity: residual electronegative compounds in argon have to be kept as low as 0.1 part s per billion all over the detector run. The T600 Module design was finalized by the ICARUS Collaboration after years of R&D studies that brought to the viable and scalable industrial solutions necessary for sized experiments with severe safety prescriptions for the underground operation . We present the T600 Module successful commissioning and the 3-years efficient, stable and continuous operation with extraordinary LAr purity, high performance and zero dead time data taking . This result demonstrates for the first time the feasibility of activation and long-term run in safe conditions of sized cryogenic detectors even in a confined underground location and represents a milestone for future neutrino projects at higher mass scale (MODULAr, ICARUS - NESSIE, LBNE, LBNO ,... )