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					    Irradiation Effects

                      Chiho Wang
                      Duke University




                  1
Chiho Wang                        ATLAS TRT
Duke University               CERN, Feb. 2002
                                   Test Setup

 Test 5 (module 2)
        15 wires in Xe-CO2 volume
              1 plain wire (reference)
              7 bare glass (G)
              7 mylar encapsulated glass (GE)
        17 wire in Xe-CF4-CO2 volume
              1 plain wire (reference)
              8 GE
              8 peek
        Peek wire joint is made of wire with gold thickness ~0.3-0.4m,
         while others are ~0.5-0.7 m.




                                     2
 Chiho Wang                                                       ATLAS TRT
 Duke University                                              CERN, Feb. 2002
                       Accumulated Dosage


 Averaged dosage (~90cm) each wire (C/cm)




                    Bare glass  GE  Peek
 Radiation is enhanced at the central region.
  Local dosage (~20 cm around wire joint)
  should have 2-3 times of the average.




                               3
 Chiho Wang                                       ATLAS TRT
 Duke University                              CERN, Feb. 2002
                  Wire Tension




                    4
Chiho Wang                           ATLAS TRT
Duke University                  CERN, Feb. 2002
                   Wire Joint Pull Test




 pulled out peek joint has “no melt” at pulled out end
  (manufacture defect)
                           5
 Chiho Wang                                     ATLAS TRT
 Duke University                            CERN, Feb. 2002
                   Wire Visual De-coloration


 Wires in Xe-CF4-CO2 volume show
  darkened area in central region



       • GE • Peek




 Darkened area is ~ proportional to radiation



                           6
 Chiho Wang                                    ATLAS TRT
 Duke University                           CERN, Feb. 2002
                     Gas Gain Monitor


 A 100 mCi Fe55 mounted on a stepping
  motor scans the module 4 times a day.
 Each scan takes ~12 min.. During that time
  Sr90s were closed and HV restored to
  normal.
 ADC data were taken at 26 positions along
  the straws 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:




                            7
 Chiho Wang                                     ATLAS TRT
 Duke University                            CERN, Feb. 2002
                  Gain Changes in Xe-CO2




                         8
Chiho Wang                              ATLAS TRT
Duke University                     CERN, Feb. 2002
                  Gain Changes in Xe-CF4-CO2




                           9
Chiho Wang                                ATLAS TRT
Duke University                       CERN, Feb. 2002
                           Summary


 3 types of the wire joints (glass, GE & Peek)
  have been irradiated for ~ 1 C/cm.
 No obvious mechanical degradation in:
        Wire tension slippage
        Wire joint strength against pulling
 Radiation has darkened/damaged section of
  wires proportional to the dosage.
 Gas gain losses were seen in Xe-CF4-CO2
  volume, consistent to local irradiation rates.
 No, or very slight gain decreases were seen
  in Xe-CO2 volume.




                           10
 Chiho Wang                                        ATLAS TRT
 Duke University                               CERN, Feb. 2002

				
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posted:5/9/2013
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