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Status of the ETL 9125FLB Photomultiplier Tubes

Status of the ETL 9125FLB Photomultiplier Tubes. Steve Bache UNC-Wilmington. Parameters. Hall D Pair Spectrometer requires 20 PMT’s (16 for detector, 4 spare) 45 out of ~3000 I have checked so far *Visual inspection *Working High Voltage Signal width *Rise time Noise

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Status of the ETL 9125FLB Photomultiplier Tubes

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  1. Status of the ETL 9125FLB Photomultiplier Tubes Steve Bache UNC-Wilmington

  2. Parameters • Hall D Pair Spectrometer requires 20 PMT’s (16 for detector, 4 spare) • 45 out of ~3000 I have checked so far • *Visual inspection • *Working High Voltage • Signal width • *Rise time • Noise • Coincidence related to possible ion feedback *highest importance

  3. Visual Inspection • All PMT’s had “frosty” front window

  4. Set-up • High voltage was applied to 4 PMT’s at a time in a covered, black box • No additional source and scintillator are attached • Used oscilloscope for all timing measurements • Checked coincidence rate at lowest threshold, also on scalars

  5. Set up

  6. Noise Signal Width Rise Time

  7. Working High Voltage • HV required for average signal ~10mV # of PMT’s High Voltage (kV)

  8. Signal Widths • Full signal widths (in ns) # of PMT’s Width (ns)

  9. Rise Time • Rise time from 10% to 90% # of PMT’s Rise Time (ns)

  10. Noise Amplitude • Noise between signals # of PMT’s Noise (mV)

  11. Coincidence Rates • Coincidence proportions at lowest threshold • Related to ionic feedback, i.e. air leakage # of PMT’s Coincidence / Total count

  12. Initial Conclusions: • Consistent rise time (~2ns) • working HV ~1.15kV • Signal width~12 ns • Out of 45 tested, found one with no signal and 1 unusable due to noise • Original experiment was designed for Cherenkov radiation (few photoelectron detection) • Frosty PMT front window • Require positive HV Next: Develop a streamlined procedure for testing up to 16 PMT’s at a time, more results

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