Tests on a dummy facet of PIX upgrade using CO2 cooling Nick Lumb Didier Contardo Peter Calabria David Ducimetière

Schematic + temperature sensor locations

Raw temperature outputs Outlet thermal bath Outlet bottle Oulet HEX warm side Oulet HEX cold side Flow rate Turn on CO2 Heater @ 144W Heater @ 54W Fridge cycles

Pixel upgrade ‘facet’ test structure Layer 1 prototype Add heat load (foils) at extremities Circulate cold CO2 Measure delta T (coolant, sensor) 3W per sensor Temp. range -15 → -30C Dummy facet

Cross section through test structure Silicon area: 60 x 18 mm Heating foils exactly cover this area Heat input to capillary @ max. power = 25 W/m per foil

Roland’s Talk, 14/05/09

Temp. Sensor positions Temp. Sensors: Analog Devices AD590 Calibrated using thermal bath to +/-0.2°C Attached to wafers and pipes using thermal epoxy, 0.76 W/m.K

CO2 flow rate: 1.0 g/s; freezer temp.: -20C Heaters ON 2 x 3W Decrease power 2 x 1.5W Run no. 1 (Preliminary run) Run no. 2 (Better insulation) Run no. 3 (Copper plates) Plate mounted on CF On wafer On pipes below wafer CO2 flow rate: 1.0 g/s; freezer temp.: -20C Increase CO2 flow 1.5 g/s Plate mounted on pipes

Distribution of temperatures, Run no. 2

Run no. 3 - copper plates Thickness 3mm Square channels filled with conductive paste No serious attempt at good thermal contact One plate mounted as shown Second plate mounted on CF frame with conductive paste, 0.77 W/m.K

Conclusions ΔT fluid – wafer ~20°C with current design Main problem is poor heat transfer between capillary and CF Heat transfer CF to wafer probably not too bad Results could be checked using CERN set-up