1. Limits of the current VTCS Ann Van Lysebetten Bart Verlaat Martin van Beuzekom VELO upgrade meeting 14/11/2008 pix module construction kick-off 09/11/2009

2. Limits & “bottlenecks” prim. System H2O 20  C Sec. System (freon) Tert. System (CO2) Detector waste heat (max 800W) 2 Tert. System (CO2) Detector waste heat (max 800W) Heat Transfer to the module! Limited by current compressor, freon injection, heat exchanger to CO2 Max massflow of pumps 18g/s Min CO2 temp -30  C heat exchanger to freon? prim. System air 20 stations * 10 Velopix -> 4 Watts/velopix = ~ 2W/cm2  T > 15 ‘C

3. Minimal upgrade allows ~ 6W/cm2 prim. System H2O 20  C Sec. System (freon) Tert. System (CO2) Detector waste heat (max 2.5kW) 3 Tert. System (CO2) Detector waste heat (max 2.5kW) new compressor, new freon injection, new heat exchanger to CO2 with CO2 massflow of 18g/s min at -35  C If necessary new heat exchanger to freon prim. System air But! to keep silicon at < -5  C  lower temp needed if interface not changed!

4. Cooling interface Current cooling interface (cookie) is one of limiting factors Try to integrate cooling pipe into module –But, no high pressure connectors in vacuum -> Orbital welding of module to cooling pipe Cut here

5. 5Summary  Current system can cool up to 800W  With some modifications it can reach 2.5 kW  -> CO2 cooling plant can do the job!  Large  T due to large thermal resistance and long path this means either lower CO2 temp needed OUTSIDE range of current system new freon/CO2 chiller, this has limits! module on/off temp difference large  Integrate cooling pipe into module/station shorter path, smaller  T over module small temp differences on/off connect modules to cooling system via orbital welding

7. The VTCS cooling principle Condenser Pump Heat exchanger Flooded evaporator Restriction 2-Phase Accumulator Heat in Heat out 1 25 9 1013 prim. System H2O 20  C Sec. System (freon) Tert. System (CO2) Detector waste heat (max 800W) Tertiary System: two phase accumulator controlled system 7 Tert. System (CO2) Detector waste heat (max 800W) Freon system prim. System air SP -25  C