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BigBite Wire Chamber Test

Wire chamber. Shower system. Optics Slot-slit. BigBite Wire Chamber Test. Xin Qian Duke University Feb 20th For TRANSVERSITY Collaboration. Scintillator. Gas Cerenkov. Magnetic field shielding. Trigger for cosmic test. Front scintillator. Back scintillator. Computers,CODA.

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BigBite Wire Chamber Test

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  1. Wire chamber Shower system Optics Slot-slit BigBite Wire Chamber Test Xin Qian Duke University Feb 20th For TRANSVERSITY Collaboration Scintillator Gas Cerenkov Magnetic field shielding

  2. Trigger for cosmic test Front scintillator Back scintillator Computers,CODA Forming Logic AND cable OR VME

  3. Wire Chamber Low Voltage HV for wire chamber Threshold

  4. Signal Output of Wire Chamber Signal from cards Level shifter cards Long flat cable VME FASTBUS

  5. Number_of_hits vs wire number Reference channel • Flat structure suggests no local problems except two broken cables. • The structure of the hits pattern is due to the trigger setup. Two bad cables

  6. Drift time for the first time t1 t2 • See a clear drift time • Most of T2 is out of T1 main peak. • T1 is the time for first hit on this channel (wire) • T2 is the time for the second hit on this channel.

  7. Second hit • 10% T2 • Normal

  8. Problems • Everything looks normal, except the number of hits. (First noticed by Xiaodong) • For run 249, we have about 10k trigger, number of hits on first plane is about 50k. • Several possible reasons: • Threshold is too low • High voltage is too high • Ground problems? • Other reason? Big tail RUN 249 X axis: Number of hits per event

  9. Threshold Change Lower threshold • Did not see clear change in slope. Higher threshold

  10. Threshold Change Low Threshld • No clear change in drift time plot High Threshld

  11. Threshold Change Lower threshold • Fewer second hit with higher threshold. Higher threshold

  12. Threshold Change Lower threshold • No clear change in correlation. Higher threshold

  13. Event Display • See Xin’s webpage • http://www.jlab.org/~xqian/TRANSVERSITY/testlab/index.html • “HV is too high” is ruled out.

  14. Conclusion • Data was taken for first wire chamber using front and back scintillator coincident trigger. • Data was recored using VME TDC. • Drift time & hitting pattern suggest no local problems. • Do see a problem with more hits than expected. (Not a VME problem, see the same thing on FASTBUS) • Rule out threshold, HV or any local problems. • Reason is not clear at this stage • Ground issue? • Flat cable? • Need expert’s suggestions.

  15. Acknowledgment • Kalyan and Xiaodong (co-worker) • Doug and Brad (useful suggestions, especially for OSP and telephone) • Xiaohui (Making the initial analysis code)

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