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Thermal Testing of TOB/TEC Hybrids at UCSB

Thermal Testing of TOB/TEC Hybrids at UCSB. Why Thermal Test?. The CMS detector will run at –20 C in order to lessen radiation damage to the silicon. Why Thermal Test Hybrids?. Some Hybrids fail at –20 C APVs do not output Hybrid fails to initialize

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Thermal Testing of TOB/TEC Hybrids at UCSB

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  1. Thermal Testing of TOB/TEC Hybrids at UCSB Lance Simms

  2. Why Thermal Test? The CMS detector will run at –20 C in order to lessen radiation damage to the silicon Lance Simms

  3. Why Thermal Test Hybrids? Some Hybrids fail at –20 C • APVs do not output • Hybrid fails to initialize • Noise increases in cold (peltier current?) APV: Analog Pipeline Voltage Mode Chip Lance Simms

  4. The 4 Hybrid Cold Box How to thermally test hybrids? 4 at a time. Cold box design and photo courtesy of: Bruno Wittmer and Giacomo Squazzoni @ CERN Lance Simms

  5. The Set-up at CERN Picture courtesy of CERN Lance Simms

  6. The Set-up at CERN Lance Simms

  7. A question at Tracker week Lance Simms

  8. Building our own Construction & Repair Lance Simms

  9. Slow Control First order of business: hooking things up • 5 temperature sensors • 1 humidity sensor 1 Water Flow Sensor 1 Air Flow Sensor Lance Simms

  10. Interfacing to a PC: ACDC Lance Simms

  11. Cooling Down Cooling Mechanism: Peltier Unit Supercool Peltier: • Voltage = 28 V • Current = 13 A • Power = 350 W Lance Simms

  12. Cooling Down How long should/does it take to get to –20? Air Water Flow (14 L/min) Cold chamber Chiller Peltier + Plate Air Flow (0.05 L/min) Lance Simms

  13. Simplifying things S= surface area of enclosure (m ) k=thermal conductivity of walls (W/m C) h=convection factor (W/m C) x=thickness of walls (m) Lance Simms

  14. Simplifying things Assumptions: • Most of the heat transferred to the system goes into cooling the aluminum peltier plate (specific heat of aluminum is much greater than that of air) m= 2.0 kg c= 910 J/kg C Lance Simms

  15. Simplifying things Assumptions 2) The convection factor can be calculated by waiting until the system comes to equilibrium Temp at equilibrium Lance Simms

  16. Simplifying things Waiting… (I was too impatient to wait for t ) h= 7.55 (W/m C) Lance Simms

  17. Calculating time to -20 First order linear differential equation: Solution: (T(t=0)=295K) Lance Simms

  18. Not quite… Calculation says that plate should reach –20 in ~14 minutes. Actual time: ~21 minutes Possible problems: • Unaccounted heat influx through leaks or grounding strips connecting plate to outside • assumptions made are flawed • Missing term in differential equation Lance Simms

  19. -20 Reached: On to Testing Set-up in Clean Room Electronics Cold Box Gas/Water Flow Control PC for Monitoring + Controlling Chiller Lance Simms

  20. Testing Software: ARCSAPV Readout Control Software Communicates With ACDC via TCP/UDP Lance Simms

  21. What are we testing for? Shorted channels: On each clock, charge injected into every 8th channel. Shorted channels share, ADC amplitude is diminished. 128 Channels per APV -6 APV hybrids: 768 -4 APV hybrids: 512 Lance Simms

  22. What are we testing for? Open Channels: Inject charge through Capacitive coupling of pitch adapter to antenna carrying TTL Pulse Antenna Pitch Adapter Lance Simms

  23. Easier said than done Lance Simms Slide courtesy of G.Squazzoni

  24. We thought it was the pulser LVDS ARC Board NIM TTL NIM Logic Lance Simms

  25. LVDS Signal? • ARC Boards with functioning External Bus • Ser 29 • Ser 31 • ARC Boards with non-functioning External Bus • Ser 56 • Ser 57 • Ser 59 LVDS Signal Noise Lance Simms

  26. ARC Controller Problem • Bad Batch of ARC BOARDS: LVDS Driver and LVDS Receiver U32 and U33 were switched during board assembly. Problem was never discovered. • External Buss connector and associated IC’s on lower left of photo. U32 Lance Simms

  27. With Pulser Operational… • Opens detectable in “Scope Mode” Intentionally Plucked Bonds Show up in Pedestal Profile Lance Simms

  28. With Pulser Operational…. • Opens are also detectable in Pedestal & Noise Test Plucked Bonds Lance Simms

  29. Grounding Issues Huge spikes in noise at APV edges Same Problem CERN was having…. Lance Simms

  30. Grounding • Ferrite Ring around Coax • G10/copper strips connect peltier plate to front end ground Lance Simms

  31. Much Better Old Grounding New Grounding Lance Simms

  32. Thermal Cycle Test “One Button” test Three Sets of Tests: • Pedestal & Noise • Pulser • Short Detection Lance Simms

  33. Automated Test Results Final Report After Thermal Cycle Test: Lists -Shorts -Opens -Noisy Channels Lance Simms

  34. The testing goes on… So far, about 100 hybrids have been thermal cycled. At maximum capacity: ~28 per day And the cycling will continue… Lance Simms

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