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Region 2 Drift Chambers

Region 2 Drift Chambers. Status Report Qweak Collaboration Meeting October 2005. Prototype I. 40cm X 40cm 32 20 m m Gold-plated Tungsten Sense Wires 33 100 m m Gold-plated Beryllium-copper Wires. Prototype I. Test Setup. Hurdles Jumped. TDC readout using MIDAS DAQ

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Region 2 Drift Chambers

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  1. Region 2 Drift Chambers Status Report Qweak Collaboration Meeting October 2005

  2. Prototype I 40cm X 40cm 32 20mm Gold-plated Tungsten Sense Wires 33 100mm Gold-plated Beryllium-copper Wires

  3. Prototype I Test Setup

  4. Hurdles Jumped • TDC readout using MIDAS DAQ • “Feedback” from TDC ribbon cables to the chamber wires caused oscillations at ~22MHz. - Tried shielding the ribbon cables (no luck) - installed filter capacitors on the amplifier input (allowed us to take data but reduced amplifier sensitivity) - Wrapped the chamber with Aluminized mylar (Now operating without filter capacitors. Aluminum shield reduces feedback to below 30mV Threshold level) • Noise when DAQ running - Raised threshold to 50mV level

  5. Prototype I Tests • 10% CO2 90% argon gas • Nanometrics N-277 Amplifier/Discriminator cards • Threshold set at 1.5mamp (50mV) • Scintillators above and below chamber • Efficiency = (# events with at least one hit)/(# 3-fold scint. triggers)

  6. Cathode at –2000V

  7. Singles Rate

  8. Garfield Equipotential Lines (1800V)

  9. Garfield electron arrival times (1800V)

  10. # of hits/event Prototype I Events

  11. hits

  12. hits

  13. Continuing Tests • Voltage studies (Cathode/Field) to obtain optimum drift velocity and efficiency • Garfield simulations • Different gases (Argon/CO2/CF4)(Argon/Ethane)? • Mapping of active area to check uniformity

  14. Proposed New chamber

  15. New chamber

  16. Design Parameters • Four chambers with six planes each • Wire pitch 4.6 mm • 20mm gold-plated Tungsten sense wires • 75mm gold-plated Be-Cu field wires • 1664 electronics channels Nanometrics preamp/descriminators 100 x 16 channels/board = ~$35k

  17. Plans for 2006 • Build and test a chamber with the final dimensions xuv sense planes four cathode planes 208 electronics channels

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