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

3. Schematic + temperature sensor locations

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

5. 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

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

7. Roland’s Talk, 14/05/09

8. 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

9. 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

10. Distribution of temperatures, Run no. 2

11. 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

12. 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