Phototube response for a multi-element Optical Module

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Phototube response for a multi-element Optical
Module

• A. Mjös
• H. Löhner
• P. Lubberdink
• N. Kalantar
• KVI Groningen
• in collaboration
• with NIKHEF

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Motivation

• Antares 10 PM multi-PM configuration 3 PM
• larger field of view, low noise,
  trigger selectivity

Candidate Photonis XP53x2 (or modification)
produced in large quantities, available
for selection
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Outline
3 XP53X2

• PMT Photonis
• Test Setup
• Light pulser
• Analysis
• Measurements
• Results
• Future investigations

3 XP3330
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Test Setup
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LED Light pulser
light intensity variable by LED supply
voltage, neutral-density filters
previous pulser
present pulser
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charge vs. supply voltage
XP53X2
typ. spread in gain requires selection and
sufficient dynamic range
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surface sensitivity
XP53X2 at max. gain 4 x 106 (1500 V)
?t ? 1 ns
photocathode area
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Time over threshold
sufficient sensitivity
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Charge spectrum
XP53X2 at max. gain 4 x 106 (1500 V)
s.p.e.
dark rate typ. 5 kHz
peak/valley 2.4
charge threshold 0.25 s.p.e.
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electronic noise / base design

• 0.11 mV ? 0.05 mV
• less critical
• 
  threshold setting

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10 stage tube XP3330
XP3330 at gain 4 x 106 (1100 V)
peak/valley 2.1
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Temperature dependence of dark rate
XP3330 at gain 8 x 106 (1200 V)
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Comparison
should be improved
Peak/valley 2.79
0.46 2.4 2.1

Dark Noise (Hz) 1880 1078
5500 3100 ?150
ideal solution XP53X2 with 10 stages can be
realized within 10 weeks (Photonis offer)
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Summary

• Test setup for systematic measurements
• 3 PM XP53X2 sensitive to s.p.e. at maximum gain
• Peak/valley 2.4
• Position and angle-of-incidence dependence
• over cathode area within 10
• Time spread over cathode area within 1 ns
• Time-over-threshold analysis yields 4ns/pC ? 4ns
  / s.p.e.
• Improvement on dark noise
• a) voltage-multiplying base for XP53X2 (9
  stage)
• (in progress at NIKHEF, prototype available)
• b) use 10-stage PM good results with XP3330
  (150 Hz)
• Ideal and viable solution XP53X2(10 stage)