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M0  COOLING IN H4

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

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M0  COOLING IN H4

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  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) 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) 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 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 Julien Cogan CERN/EP/CMA

  5. COOLING UNITS & CIRCUITS (1) 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) 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 18.8 C 14.5 C Mixed water PID 17.8 C 17.8 C Simplified schematic of the foreseen cooling unit Julien Cogan CERN/EP/CMA

  8. SHORT-TERM STABILITY : WATER (1) Regulation circuit Power circuit INLET 0.05 C INLET 1 week OUTLET OUTLET Julien Cogan CERN/EP/CMA

  9. LONG-TERM STABILITY : WATER 2 o’clock jumps Power circuit Regulation circuit Power cut Lauda remote control off 0.05 C ? INLET INLET 3 months (aug/sept/oct) OUTLET OUTLET Julien Cogan CERN/EP/CMA

  10. STABILITY : ENVIRONMENT MEM (output water temperature) Room (measured on a copper plate near the module) out of water 1 C 2 C 3 months (aug/sept/oct) Ambient circuit (inlet & outlet) Primary circuit (inlet) 0.5 C 2 C Julien Cogan CERN/EP/CMA

  11. STABILITY : CAPSULES LV block A 0.1 C 3 months (aug/sept/oct) LV block B 0.1 C 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 ( ~0.02C) at 2 AM (related to computer activity ?) • remote control disabled after 2nd temperature step (16/08/02) : small change in the setting (~0.02C ) • 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 (~1C ) • induced a small rise of temperature on the APD 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 0.05C • constant temperature of the capsule well within 0.1C •  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 Julien Cogan CERN/EP/CMA

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