m0 cooling in h4
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WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-1-
M0 COOLING IN H4• Cooling is a key issue :
– APD gain : ~ -2.4 % / C– XTAL response (scintillation) : ~ -1.9 % / C(“nominal values” from “old” measurements)
• Strict requirement :– contribution to (E)/E : < 0.5 %
– avoid to apply correction constant temperature of XTAL & APD : 0.05 C
• Goals in H4 this year :– provide stable conditions for the data taking
– validate some cooling principles for the future (cooling units, VFE cooling)
– better understanding of the system
• heat transfer (electronics ADPs & XTALs)
• dynamic of the system (characteristic time constant of ADPs & XTALs)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-2-
OUTLINE• M0 cooling :
– mechanic
– cooling units & circuits
– next year strategy
• Thermal stability during the data taking :– water circuits
– environment
– APDs (capsules)
– failures
• Thermal studies (covered in next talks)– heat transfer, temperature rise when electronics is turned on (P. Baillon)
– temperature steps (Roberto Salerno, J. Cogan)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-3-
COOLING MECHANIC (1)• Bare module = fully equipped module with 400 crystals
– final grid (cooled through 9 holes drilled along z)
– thermal shield ( attached to the APD connector mechanical assembly 10 lines)
– special thermal screen (2 layers of pipes around the 5 faces of the crystal basket)
– module isolated from its support by 4 cooled blocks of aluminum
– module isolated from the environment by 4 cm of rock wool
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-4-
COOLING MECHANIC (2)• Electronics = 20 VFE cards 10 blocks 100 channels
– FPPA + ADC + GLINK (+DRIVER) ( ~2.5W/Ch)
– copper housing manufactured to compensate for the different height of the components (minimal thickness = 0.7 mm)
– 0.5 mm thick gap pad between the copper housing and the components + contact at the bottom of the cards (1 mm thick 4 mm wide gap pad)
– 10 lines of cooling pipes ( 3/4 mm) brazed on the copper housing
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-5-
COOLING UNITS & CIRCUITS (1)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-6-
COOLING UNITS & CIRCUITS (2)• Regulating circuit : flows through the grid and then on the thermal shield
– q = 0.22 l/s (80 % of nominal flow) T(OUT-IN) typically few 1/100 C– water regulation and circulation done by a LAUDA
• Ambient circuit : flows in the thermal screen and on the insulating al. blocks
– q 0.1 l/s T(OUT-IN) typically few 1/10 C– water regulation and circulation done by a LAUDA
• Power circuit : cools the VFE boards
– q 0.14 l/s (M0) (+ ~0.14 l/s by pass) T(OUT-IN) typically few 1/10 C ; P 1.5 bar
– water under pressure (P~2.5 bar)
– water regulation and circulation :
• heat removal : chilled water + heat exchanger
• water regulation : heater (max = 2kW) controlled by a regulator (PID)
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-7-
NEXT YEAR STRATEGY• Cooling circuit : only one circuit
– cooling unit similar to this year power circuit
– work is in progress (dimensioning of the circuit, buying of the elements, control loop)
• Cooling of the electronics (is being decided)– from cooling point of view : same principle as this year (?)
– mechanically : cooling bars instead of brazed tubes (?)
– introduction of a mother board and additional kapton cables between the VFE and the APD connector
PID
Simplified schematic of the foreseen cooling unit
Mixed water
14.5 C
17.8 C
18.8 C
17.8 C
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-8-
SHORT-TERM STABILITY : WATER (1)Regulation circuit Power circuit
INLET
INLET
OUTLET OUTLET
0.05 C
1 week
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-9-
LONG-TERM STABILITY : WATER
0.05 C
Regulation circuit Power circuit
INLET INLET
OUTLET OUTLET
3 months (aug/sept/oct)
2 o’clock jumps
Lauda remote control off Power cut
?
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-10-
STABILITY : ENVIRONMENTRoom
(measured on a copper plate near the module)MEM
(output water temperature)
2 C3 months (aug/sept/oct)
1 C
Ambient circuit (inlet & outlet)
2 C
0.5 C
Primary circuit (inlet)
out of water
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-11-
STABILITY : CAPSULES
3 months (aug/sept/oct)
0.1 CLV block A
LV block B0.1 C
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-12-
STABILITY : FAILURES• Laudas remote control :
– setting of the Lauda controlled by a computer (to be able to change the temperature form the control room)
– induce instabilities and mysterious jumps ( ~0.02C) at 2 AM (related to computer activity ?)
– remote control disabled after 2nd temperature step (16/08/02) : small change in the setting (~0.02C )
• Chilled water failures :– Pb with chilled water in the area happened twice (last for less than 1 day) :
• 12/08/02
• 23/09/02
– induced a rise of temperature of the power circuit (~1C )
– induced a small rise of temperature on the APD
WACH4 26/11/2002 Julien Cogan CERN/EP/CMA-13-
CONCLUSION
• STABILITY : – Generally good thermal stability during all the data taking :
• constant temperature of the cooling water well within 0.05C
• constant temperature of the capsule well within 0.1C Probably no need to correct for temperature effect
– Very few failures
• M0’ cooling system :– validation of some principles for :
• cooling units
• VFE cooling
– give confidence for the future
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