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

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1200 1300 1400 1500 1600 1700 1800 1900

Field Wire Voltage

Eff

icie

ncy

N. Morgan, Virginia Tech Qweak meeting,Oct ‘05

Singles RatePrototype I

0

50

100

150

200

250

300

350

400

450

500

500 700 900 1100 1300 1500 1700 1900

Field Wire Voltage

Sin

gle

s R

ate

(H

z)

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