Big Bite Wire Chamber Test Shower system Wire
Big. Bite Wire Chamber Test Shower system Wire chamber Optics Slot-slit Xin Qian Duke University Feb 20 th For TRANSVERSITY Collaboration Scintillator Gas Cerenkov Magnetic field shielding
Trigger for cosmic test Front scintillator Back scintillator Computers, CODA Forming Logic AND cable OR VME
Wire Chamber HV for wire chamber Low Voltage Threshold
Signal Output of Wire Chamber Signal from cards Long flat cable Level shifter cards VME FASTBUS
Number_of_hits vs wire number Reference channel v Flat structure suggests no local problems except two broken cables. Two bad cables of the hits pattern is due to the v The structure trigger setup.
Drift time for the first time v See at 1 clear drift time t 2 is out of T 1 main peak. v Most of T 2 v T 1 is the time for first hit on this channel (wire) v T 2 is the time for the second hit on this channel.
Second hit v 10% T 2 v Normal
Problems v Everything looks normal, except the number of hits. (First noticed by Xiaodong) For run 249, we have about 10 k trigger, number of hits. Bigon tail first plane is about 50 k. Several possible reasons: v Threshold is too low RUN 249 v High voltage is too high X axis: v Ground problems? Number of hits per event v Other reason?
Threshold Change v Did not see clear change in slope. Lower threshold Higher threshold
Threshold Change v No Low Threshld clear change in drift time plot High Threshld
Threshold Change Lower threshold v Fewer second hit with higher threshold. Higher threshold
Threshold Change Lower threshold v No clear change in correlation. Higher threshold
Event Display v See Xin’s webpage v http: //www. jlab. org/~xqian/TRANSVERSITY /testlab/index. html v “HV is too high” is ruled out.
Conclusion Data was taken for first wire chamber using front and back scintillator coincident trigger. v Data was recored using VME TDC. v Drift time & hitting pattern suggest no local problems. v Do see a problem with more hits than expected. (Not a VME problem, see the same thing on FASTBUS) v Rule out threshold, HV or any local problems. v Reason is not clear at this stage v Ground issue? Flat cable? Need expert’s suggestions.
Acknowledgment v Kalyan and Xiaodong (co-worker) v Doug and Brad (useful suggestions, especially for OSP and telephone) v Xiaohui (Making the initial analysis code)
- Slides: 15