Region 2 Drift Chambers
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Transcript of Region 2 Drift Chambers
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Region 2 Drift Chambers
Status Report
Qweak Collaboration Meeting
October 2005
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Prototype I
40cm X 40cm
32 20mm Gold-plated Tungsten Sense Wires
33 100mm Gold-plated Beryllium-copper Wires
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Prototype I
Test Setup
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
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
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
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)
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Cathode at –2000V
Prototype I
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Field Wire Voltage
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N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Singles RatePrototype I
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Field Wire Voltage
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N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Garfield Equipotential Lines (1800V)
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Garfield electron arrival times (1800V)
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
# of hits/event
Events
Prototype I
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
hits
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
hits
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
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
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Proposed New chamber
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
New chamber
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
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
N. Morgan, Virginia Tech Qweak meeting,Oct ‘05
Plans for 2006
• Build and test a chamber with the final dimensions
xuv sense planes
four cathode planes
208 electronics channels