PMT Test @ Univ. of Tokyo

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PMT Test _at_ Univ. of Tokyo

• Yasuko HISAMATSU

ICEPP, The University of Tokyo
MEG VRVS meeting Jan. 20th, 2004
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PMT Output Deterioration

• During the pi0 beam test _at_PSI, output from some
  PMTs reduced by 20-30 when beam was ON.
• (The background was estimated to be
  1.5106p.e.)
• Similar change was observed under the background
  simulated using LED pulses
• -gt The Deterioration of old type PMT output due
  to the high rate background.
• Output from Al Strip Type PMT (new type) needs
  to be tested under the high rate background.

Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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PMT Test _at_ Univ. of Tokyo

• Set up

PMT (Al Strip Type) TB0094 TB0102 TB0286
TB0302 (now being analized) TB0284 TB0568
Liq. Xe
PMT
5.5MeV alpha peak
Alpha source(241Am ) LED
PMT
ADC channel
Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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Condition and Procedure

• alpha source 200Hz,
• LED pulse height 500p.e. 12000p.e. per event
• pulse shape 10nsec
• rate 100Hz 10KHz

• Trigger alpha self trigger (veto by LED driver
  pulse)
• Procedure
• Pedestal Run Gain calibration using LED
• Alpha Run _at_ LED OFF
• Alpha Run _at_ LED ON (LED high rate
  background)
• -Change LED Pulse height, rate and PMT
  gain

Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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Condition and Procedure

• DAQ
• -Alpha run with LED OFF
• -Alpha run with LED ON
• The cause of the change in PMT output
• Breeder current ?
• Deterioration of photocathode?

The change in PMT output?
Low gain run
Peak/Sigma (gain independent)
Ratio of alpha peak with LED ON to one with LED
OFF
Number of photoelectrons from LED per second
Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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For instanceTB0302
5e5 gain peak (LED ON)/peak (LED OFF)
1e6 gain peak (LED ON)/peak (LED OFF)
107p.e. per sec
1e6 gain (peak/sigma _at_LED ON)/ (peak/sigma _at_LED
OFF)
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Result
X number of photoelectrons per second from
LED Y alpha peak (_at_LED ON) / alpha peak (_at_LED
OFF)

• 5e5gain

TB0094
TB0102
TB0268
TB0302
?
Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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Result
X number of photoelectrons per second from
LED Y alpha peak (_at_LED ON) / alpha peak (_at_LED
OFF)
1e6gain
TB0094
TB0102
TB0268
TB0302
Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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Result
X number of photoelectrons per second from
LED Y (peak/sigma _at_LED ON) / (peak/sigma _at_LED
OFF)
1e6gain
TB0102
TB0094
TB0302
TB0268
Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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Schedule

• DAQ
• Jan. 21-22 2PMTs
• Jan. 27-28 2PMTs
• 10 PMTs will be tested and analized before the
  meeting at PSI.

Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting
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Summary

• 4 Al Strip Type PMTs (new type) have been tested
  under the high rate background environment at the
  university of Tokyo.
• So far, for the 4 PMTs, the stability of PMT
  output is better than 10 under the background up
  to 107 p.e. per sec.
• No output deterioration so far under background
  of 1.5 106p.e.
• In order to confirm the stability of PMT
  performance under the high rate background,
  additional 6PMTs are going to be tested.
• The more precise analysis is now going on.

Additional Comments Of the 4 PMTs, the HV of 2
PMTs tripped frequently. The cause of
this HV trip is now being investigated.
Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting