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Power & Cooling: Design Status of BPIX

This document provides an overview of the current status and upgrade goals for the power and cooling design of the BPIX detector. The focus is on improving tracking precision and adapting for higher luminosity. The implications of adding a 4th detection layer and the need for more power and readout channels are discussed. The potential use of a DC-DC converter and the challenges with CO2 cooling are also addressed.

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Power & Cooling: Design Status of BPIX

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  1. Power & Cooling:Design Status of BPIX W. Bertl PSI

  2. BPIX Upgrade Goals: Schedule: • Improve tracking precision >2014 • More hits / track → add a 4th detection layer (Phase I) • Innermost layer closer to IP (smaller beam pipe!) • Less material to obstruct tracks • Full digitization at the detector (→ ROC modification) • Adapt for higher luminosity (>2*1034 cm-2s-1) >2017 • → requires new ROC design to keep efficiency high (Phase II) • power and cooling concept likely to be reworked W. Bertl PSI

  3. Implications of a 4th layer # of modules increase (from 768 to 1216) → need for more power → need for more readout channels → new design to keep material budget low → cooling reconsidered W. Bertl PSI

  4. More Power for BPIX Modified ROC (full digitization, higher read-out bandwidth, buffer size, but no changes in analog and column part, some simplifications of present design) : Assumption: Power consumption equal: Modified ROC ↔ Present ROC Ianalog = 25.4 mA / ROC Idigital = 27.35 + 0.17 * #Hits[MHz/cm2] mA/ROC BPIX Detector power (L=1034): 1612 W (2008) → 2576 W (2014) (+60%) Power Cables: replacement/upgrade virtually impossible ! →→ BPIX Cable losses (L=1034): 1540 W (2008) → 3887 W (2014) (+152%) BPIX Supply power ( “ ): 3150 W (2008) → 6444 W (2014) (+105%) Very inconvenient ratio used/wasted power) ! Cable losses could result in thermal overload in cable trays Present power supplies unable to fulfill request Doubled luminosity: cable losses increase by >200% ►use DC-DC-Converter W. Bertl PSI

  5. DC-DC-Converter Mounted on outer end of service tube (close to PP0) What conversion ratio ? * Converter efficiency: 80% ↑ limit:120 ↑ limit:14↑ limit:10.5V Phase I : Ratio 2 chosen → present PS o.k. Phase II : replace converter with ratio>2, replace PS Aachen: converter development based on Cern-ASIC. Test with modules soon! W. Bertl PSI

  6. Summary: BPIX power If IpresentROC ~ InewROC and εconverter ~ 80% Then (*) present CAEN power supplies can be used up to L=2x1034 (minor mod.) 2:1 Converter developed in Aachen/Cern fit on service tube converter output 4.9A ev. to high, can be solved by changing assignment converter test with 4 real modules connected to CAEN PS in preparation ► stability/noise test under realistic load conditions Else modify power supplies to deliver higher voltage Converter with higher ratio to be developed (*) should be known in one year from now W. Bertl PSI

  7. More read-out channel Read-out: increase bandwidth from 40 to 320 MHz (full digitization on module!) One fiber/module is sufficient for L<2x1034 (presently layer 1&2: 2 fibers/module) ►increase of fibers from 1184 to 1216 Contrary to the number of power cables there exist (4) multiribbon spares New lasers with new fibers required for service tube Few additional FEDs required, all FEDs upgraded to 320 MHz ► new piggy board developed in Vienna W. Bertl PSI

  8. Material budget Total mass within η = 2.17: 16894g (3.3 * more) Total mass within η = 2.17:5231g 2014 BPIX w C6F10 cooling: ~6800g (w/o ST) (53% of weight devoted to cooling !) Scaling detector to 4 layers: ~13000g (w/o ST) (with ST: ~ 4.4 * BPIX 2014 !!!) W. Bertl PSI

  9. W. Bertl PSI

  10. CO2 Two-phase Cooling Substitution of CO2 for C6F10 gains ~3.2kg on detector weight and even more if service tube is also considered. How is this possible? High latent heat → low mass flow Micro sized pipes (di =1.4mm) can be used density = 1.03 g/cm3 long loops can be used → no manifolds needed Further advantages: radiation hard low liquid/vapor density ratio low viscosity high heat transfer coefficient cheap Problems: high pressure on supply pipes at room temperature (60bar) two-phase flow in micro tubes difficult to calculate W. Bertl PSI

  11. Difficulties with CO2 Cooling High pressure: Supply tubes through CMS reach elastic limit at 150bar → o.k. for 60bar Lancashire fittings between PP1 and PP0 must be replaced Flow calculation: Evaporating liquid changes flow pattern with increasing heat transfer Pressure drop is driven by frictional loss which depends on flow pattern no adequate theoretical model seems to exist for our setup But our composition of parallel cooling loops require reliable pressure drop calculations for variable operating conditions: different loop length; beam on/off; operating temperature; luminosity etc. W. Bertl PSI

  12. Cern meas. vs Friedel correlation W. Bertl PSI

  13. W. Bertl PSI

  14. Summary Cooling CO2 cooling could save more than 3 kg of material budget Test setups have been studied at Cern, Lyon, Aachen demonstrating that e.g. 220W on a 5.5m long pipe (d=1.5mm) can be handled But it turned out difficult to explain the measurements by calculations. This is needed to prove that all conceivable operation modes can be handled without a local cooling deficit. Further studies/tests needed: optimize carbon fiber material concerning heat transfer large pressure drop results in a drop of saturation temperature (up to ~12°C) → thermal stress on modules! flow parameters for supply pipes to be determined stability of prototype cooling plant with realistic pipe layout / load W. Bertl PSI

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