Status of the ETL 9125FLB Photomultiplier Tubes Steve Bache UNC-Wilmington
Jan 21, 2016
Status of the ETL 9125FLB Photomultiplier Tubes
Steve BacheUNC-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 – Coincidence related to possible ion feedback*highest importance
Visual Inspection
• All PMT’s had “frosty” front window
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
Set up
Signal Width
RiseTime
Noise
Working High Voltage• HV required for average signal ~10mV
High Voltage (kV)
# ofPMT’s
Signal Widths
• Full signal widths (in ns)
Width (ns)
# ofPMT’s
Rise Time
• Rise time from 10% to 90%
Rise Time (ns)
# ofPMT’s
Noise Amplitude• Noise between signals
Noise (mV)
# ofPMT’s
Coincidence Rates• Coincidence proportions at lowest threshold• Related to ionic feedback, i.e. air leakage
Coincidence / Total count
# ofPMT’s
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