The CO2 cooling system is built to serve for new ATLAS IBL detector. It is designed to cool 14 individual staves with evaporating CO2 at a given pressure. It has to remove all heat produced inside the IBL detector by sensors, chips and service resistance and maintain the silicon sensors at the appropriate temperature for different operating states. Cooling system will allow for continuous operation at adjustable evaporation temperature inside the stave in range of -400C to +200C.

The control system of the ATLAS IBL CO2 cooling station with one accumulator will contain four main elements: two fully redundant cooling plants A and B placed in USA15, transfer line connecting USA15 and UX15 caverns and distribution system inside ATLAS toroid.

Main system elements:

• The chillers system is required as the low temperature heat sink to condensate returning two phase CO2 from the detector into the condenser and to regulate pressure into the accumulator. Both chillers, for system A and B, will be equipped with water and air cooled condenser.

• 2-phase accumulator is the pressure vessel filled with liquefied and gaseous CO2. By regulating the pressure into the accumulator, system sets the evaporation pressure equal to evaporation temperature into the cooling channel. Accumulator is equipped with cooling spiral with control valve on the supply and heater element in bottom part to control operating pressure.

• Liquid LEWA membrane pump with three heads is used to ensure CO2 circulation without pulsations.

• Transfer line is used as internal heat exchanger to heat up liquid CO2 before delivering it into the IBL detector.

LINKS

SHAREPOINT “CO2 for IBL”: https://espace.cern.ch/CO2-IBL/default.aspx

EDMS ATLAS IBL cooling: https://edms.cern.ch/cedar/plsql/navigation.select_tree?cookie=13132505…

EDMS DT cooling: https://edms.cern.ch/nav/P:CERN-0000006814:V0/P:CERN-0000096251:V0/TAB3