status of the etl 9125flb photomultiplier tubes
DESCRIPTION
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 - PowerPoint PPT PresentationTRANSCRIPT
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Status of the ETL 9125FLB Photomultiplier Tubes
Steve BacheUNC-Wilmington
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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
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Visual Inspection
• All PMT’s had “frosty” front window
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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
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Set up
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Signal Width
RiseTime
Noise
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Working High Voltage• HV required for average signal ~10mV
High Voltage (kV)
# ofPMT’s
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Signal Widths
• Full signal widths (in ns)
Width (ns)
# ofPMT’s
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Rise Time
• Rise time from 10% to 90%
Rise Time (ns)
# ofPMT’s
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Noise Amplitude• Noise between signals
Noise (mV)
# ofPMT’s
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Coincidence Rates• Coincidence proportions at lowest threshold• Related to ionic feedback, i.e. air leakage
Coincidence / Total count
# ofPMT’s
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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