MINOS Document 941-v1

Tests of Anomalous PMT Singles Rates due to MINOS Fibers

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John Urish
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John Urish
Document Created:
16 Jul 2003, 12:00
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16 Jul 2003, 12:00
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16 Jul 2003, 12:00
Actually Revised:
08 Sep 2006, 21:17
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We summarize results of tests conducted in Austin to measure the anomalous
rates in photomultipliers when they are coupled to wavelength-shifting
(green) fibers used in the MINOS detectors. Our observations are consistent
with the effect at the far detector. After 260 days of testing, the anomalous
rates are at the level of about 100~Hz per meter of green fiber when glued
in a scintillator strip and decrease with time exponentially with a decay
time constant of about 100 days, which is in rough agreement with the measurements
at the far detector in the Soudan Mine. The source of these unexpected rates,
which dominate the singles noise in the MINOS detectors, is still speculative.
We have also studied the rates in PMTs due to clear fibers and found rates
consistent with the intrinsic dark noise of the M16 PMTs.

This is a Postscript document
This is revision # 1
Posted by Karol Lang

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Jing Liu, Patricia Vahle, Mike Kordosky, Marek Proga and Karol Lang
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