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Report on PMT - Summer 1999

K.Furuno, K.Ishihara, T.Mitsui, H.Ogawa, T.Iwamoto, S.Enomoto, F.Suekane and Kengo Nakamura stayed at Kamioka for 10 days to check all PMTs and move some of them to Sendai.

Checking method.

  • Supply +1500 volts to PMT and just see dark pulse.

    Before we left for Kamioka.

  • There were 62 PMTs at Honda-seiki, Sendai.
  • 61 out of 62 PMTs have been checked whether it is working.
  • 16 out of 61 PMTs are dead. (26%)

    During staying at Kamioka.

  • There were 992 PMTs in Kamioka-mozumi mine.
  • 954 PMTs out of 992 have been checked.
  • 149 PMTs out of 954 are dead. (16%)
  • 38 PMTs(=992-954) will not be checked in mine but will be checked at Sendai.
  • About 300 working PMTs out of 805(=992-149) have been moved to Sendai by Honda-seiki.
  • Dead PMTs will be kept in the mine. I have no idea until when?

    Remarks

  • The dark pulse height was around 2-3mV in mine and the signal was clean.
  • pulse height > 10mV ---> the signal was noisy but seemed to be working.
  • The noise might depend on power supply condition, GND condition, etc. It should be studied at Sendai.
  • Current of most dead PMT was greater than 10mA, while about 0.55mA normally.
  • Some discharging PMT were found. Blue/white light around dynodes. These should be sent to Hamamatsu to investigate.

    The difference of dead PMT rate(26% and 16%) could be up to the difference of condition between Sendai and mine. The condition of everything in mine is BAD, while that at Sendai is not bad. In the mine, there hardly was places to walk through, put something down and even sit down. Thus discremination(dead or not) in mine was looser than that at Sendai.

    It was estimated that no more than 820 PMTs are still working. Complete measurements should be done at Sendai.

    The next moving date is not fixed yet.


    Last updated: August 20, 1999
    jamessim@tunl.duke.edu