Duke Aging Test 7

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• Duke Aging Test 7
• Chiho Wang
• Duke University

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Test Setup

• Test 7 (module 2)
• 15 wires in Xe-CO2 volume
• 2 plain wire (reference)
• 5(old)1(new) glass (G)
• 5(old)2(new) mylar encapsulated glass (GE)
• 19 wire in Xe-CF4-CO2 volume
• 2 plain wire (reference)
• 1 plain in high gain
• 4 thinner Au wires
• 4 PI wires
• 4 GE wires
• 4 peek
• (of the 4 wires, 2 in high gain 2 in low gain)

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Accumulated Dosage

• Averaged dosage (90cm) each wire (C/cm)
• Radiation is enhanced at the central region.
  Local dosage (20 cm around wire joint) should
  have 2-3 times of the average.

4
Wire Tension Loss

• In Xe-CF4-CO2 there seems to have more tension
  losses. This may be due to the fact that they are
  all new wires and are just settling down(?)
• In Xe-CO2 volume, the circled ones are new wires,
  the rest are old wires.

5
Gas Gain Monitor

• A Fe55 source was mounted on a stepping motor to
  scan the module 4 times a day.
• Each scan takes 12 min.. During that time Sr90s
  were shut off and HV restored to nominal voltage.
• ADC data were taken at 26 positions along the
  straw with an 1.5 interval.
• Step 1-14 are upstream of wire (wire joint is
  offset from center to face 2nd 50mCi Sr90 source)
• Step 15-26 are down stream of wire
• legend of subsequent plots

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Bare Glass, Gain vs Time in Xe-CO2
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GE, Gain vs Time in Xe-CO2
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GE, Gain vs Time in Xe-CF4-CO2
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Peek, Gain vs Time in Xe-CF4-CO2
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PI, Gain vs Time in Xe-CF4-CO2
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Thin Au, Gain vs Time in Xe-CF4-CO2

• Cleaned

• Not Cleaned

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Regular Plain Wire
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Summary

• 4 types of the wire joints (glass, GE, Peek PI)
  have been irradiated 2-3 C/cm near wire joint.
• No obvious degradation in wire tension slippage.
• Not much of wire darkening compared to previous
  run.
• Gain losses were seen in Xe-CF4-CO2 volume,
  consistent to local irradiation rates.
• No gain decreases were seen in Xe-CO2 volume.
• Wire joint type does not affect gain
• Wire cleaning does not affect gain
• Thinner Au wires suffer more gain loss than
  regular wires