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VME and TGC Update

VME and TGC Update. July 18 th TGC meeting. Update Summary. Delay problems TGC Signal threshold TGC efficiency Positive voltage problem. Delay issue. Problem: Trigger Gate (purple) from scintillators must include all of TGC signal (blue) Delay between them is about 65ns. Delay issue.

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VME and TGC Update

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  1. VME and TGC Update July 18th TGC meeting

  2. Update Summary • Delay problems • TGC Signal threshold • TGC efficiency • Positive voltage problem

  3. Delay issue • Problem: Trigger Gate (purple) from scintillators must include all of TGC signal (blue) • Delay between them is about 65ns

  4. Delay issue • Problem due to small TGC-to-buffer cable (2m here as opposed to 9m at Weizmann) • Also, PMT’s were slower than TGC output • Solutions – buy faster PMT’s, get longer TGC-to-buffer cord, delay all TGC channels • Decided to delay all TGC channels by about 80 ns

  5. Delay issue

  6. Delay issue

  7. Delay issue • Example of delayed TGC pulse (yellow) comfortably within trigger gate • Tested all channels, all working

  8. Threshold analysis • Because we are triggering off two large scintillators, many triggers will not include a TGC signal • However, due to VME hardware, there is a pedestal ADC value in the VME output • Thus, we must compute a threshold to reject events where scintillators detect a muon but the TGC does not

  9. Threshold analysis • Took large amounts of pedestal (TGC off) data • ~240 is mean of pedestal, ~300 is max of pedestal

  10. Threshold analysis • Decide to use ~300 to reject/accept TGC signals • Previous example was for one channel; each channel has individually computed threshold

  11. TGC efficiency • Determine geometry of scintillator cross-section • Determine how many scintillator double coincidences we expect to see in the TGC • Computed to be about 16.5% • Using VME, measured to be about 15.1% • No uncertainty known yet, but estimate these are within experimental uncertainty

  12. Positive Voltage problem • Due to VME hardware, cannot accept voltages higher than ~30mv • These are seen once in a while due to spikes in TGC • Must find a way to get rid of these to avoid damaging VME hardware

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