1. CO 2 Cooling for High-Energy Physics Experiments EU-FP7 Project CRISPCooling Method CO 2 Cooling Prototype Systems Dr. Johann M. Heuser* * GSI Helmholtz Center for Heavy Ion Research GmbH, Darmstadt, Germany CRISP - Cluster of Research Infrastructures for Synergies in Physics www.crisp-fp7.eu CRISP is a partnership that builds collaborations and creates long- term synergies between research infrastructures on the ESFRI (European Strategy Forum on Research Infrastructure) Roadmap in the field of physics, astronomy and analytical facilities to facilitate their implementation and enhance their efficiency and attractiveness. Activities from 16 european physics research centers are covered spanning the topics “industry synergies”, “accelerators”, “detectors & data acquisition”, “instruments & experiments”, and “IT & data management”. Objective: An efficient and lightweight cooling system is a component of paramount importance for advanced particle detectors, notably detector systems for charged-particle track reconstruction requiring low-temperature operation. CO 2 has excellent thermo-dynamical properties and is likely to be the technological choice for most future particle tracking detectors, as well as for the refrigeration industry in general, while fluorocarbon fluids will be progressively banned by increasingly stringent environmental regulations. CO 2 two-phase cooling has been chosen as baseline for the upgrade of the silicon tracking systems of the LHC detectors at CERN where extended expertise on its application has been acquired. It is also suitable for silicon imaging and tracking detectors in experiments under design at the international accelerator facility FAIR (GSI), at EuroFEL (DESY), and at XFEL. A spread of knowledge and the deployment of a generic prototype cooling system shall be achieved through the CRISP project. Two-phase accumulator controlled loop A-B-C-D – A pump transports sub-cooled CO 2 to the evaporator in the detector. E-F – On its way to the detector the CO 2 is heated up to the right evaporation temperature by a thermal contact with the returning CO 2 vapour. C-D – At the detector the CO 2 is distributed to the parallel evaporators by capillaries. D-E – In the evaporators the heat is absorbed from the detector. F-A – The returned CO 2 liquid/vapour mixture is liquified and sub-cooled by a heat exchanger with a primary cooling machine that is running at a temperature below the operating temperature of the CO 2 two-phase accumulator controlled loop. G – The “accumulator” is the key element for the control of the evaporation temperature. It is a pressure regulated vessel filled with two-phase CO 2 that is in direct contact with the inlet of the condenser. The CO 2 pressure in the accumulator therefore directly determines the evaporation pressure, and hence the CO 2 temperature in the detector. https://espace.cern.ch/ CO2cool4PHYS CO 2 cooling for CMS CO 2 cooling working space CORA (CO 2 testing unit) http://www.ohio.edu/mechanical/thermo/property_tables/CO2/ph_CO2.html Operation regimes: Participating institutes in CRISP work package 13 “CO 2 cooling“: CERN (activity leader), DESY, FAIR, XFEL Standardized compact unit MARCO for CO 2 cooling from 0.1-1 kW in the temp. range -40 ÷ + 20 °C. Prototype in the CERN Cryo Lab. TRACI (100 W CO 2 cooling unit) MARCO (1 kW CO 2 cooling unit) → objective for CRISP Developments at CERN: