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PMT Test @ Univ. of Tokyo

PMT Test @ Univ. of Tokyo. Yasuko HISAMATSU. ICEPP, The University of Tokyo. MEG VRVS meeting Jan. 20th, 2004. PMT Output Deterioration. During the pi0 beam test @PSI, output from some PMTs reduced by 20-30% when beam was ON. (The background was estimated to be ~ 1.5*10^6p.e.)

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PMT Test @ Univ. of Tokyo

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  1. PMT Test @ Univ. of Tokyo Yasuko HISAMATSU ICEPP, The University of Tokyo MEGVRVS meeting Jan. 20th, 2004

  2. PMT Output Deterioration • During the pi0 beam test @PSI, output from some PMTs reduced by 20-30% when beam was ON. (The background was estimated to be ~ 1.5*10^6p.e.) • Similar change was observed under the background simulated using LED pulses -> 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

  3. PMT Test @ Univ. of Tokyo PMT (Al Strip Type) TB0094 TB0102 TB0286 TB0302 (now being analized…) TB0284 TB0568 • Set up Liq. Xe PMT 5.5MeV alpha peak Alpha source(241Am ) LED PMT ADC channel Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting

  4. 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 @ LED OFF • Alpha Run @ LED ON (LED : high rate background) • -Change LED Pulse height, rate and PMT gain Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting

  5. 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

  6. For instance…TB0302 5*e^5 gain peak (LED ON)/peak (LED OFF) 1*e^6 gain peak (LED ON)/peak (LED OFF) 10^7p.e. per sec 1*e^6 gain (peak/sigma @LED ON)/ (peak/sigma @LED OFF)

  7. X: number of photoelectrons per second from LED Y: alpha peak (@LED ON) / alpha peak (@LED OFF) Result TB0094 TB0102 5*e5gain TB0268 TB0302 ? Yasuko HISAMATSU Jan. 20th, 2004 MEG VRVS Meeting

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

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

  10. 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

  11. 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 10^7 p.e. per sec. • No output deterioration so far under background of ~1.5 *10^6p.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

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