The CERN revamping project of the obsolete cryogenic control systems: Strategy and results

The cryogenic infrastructure at CERN was originated in the 1960s with the era of bubble chambers and the associated superconducting solenoids. Since then and especially with the construction of the LHC accelerator and its detectors, large and complex cryogenics plants have been installed to provide cooling power from 800 W to 18 kW at different temperatures down to 1.9 K, demanding high and distributed technical capabilities from the control systems. The size and the complexity of the dedicated cryogenics has required the adoption of the CERN standard control framework UNICOS in order to enhance ease of operation and maintenance, and to provide long-term availability. After the completion of the LHC construction, exploiting the gained experience, CERN has started the upgrade of several obsolete cryogenic control systems. This paper describes (i) the overall project challenges, (ii) the technical procedure used in order to meet the technological operational requirements in terms of installation constraints...