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SUMMARY:Studies of anomalously long-delayed afterpulses in vacuum photomul
 tipliers
DTSTART;VALUE=DATE-TIME:20261030T143000Z
DTEND;VALUE=DATE-TIME:20261030T144500Z
DTSTAMP;VALUE=DATE-TIME:20261023T044828Z
UID:indico-contribution-6394@cern.ch
DESCRIPTION:Speakers: Nikita Ushakov (INR RAS)\nWe report a systematic stu
 dy of afterpulses with anomalously long delays in photomultiplier tubes (P
 MTs) with photocathode diameters ranging from 0.75 inch (Philips/HZC XP191
 1) to 20 inch (Hamamatsu R12860 and NNVT N6205). Our studies reveal a clea
 r dependence of the afterpulse delay on the PMT geometry\, specifically on
  the distance between the photocathode and the first dynode\; for the Hama
 matsu R12860\, for instance\, this delay reaches 260 µs. These measuremen
 ts are motivated by large-scale neutrino detectors\, where delayed afterpu
 lses can mimic genuine neutron-capture signals and produce accidental coin
 cidences with preceding positron events\, thereby degrading sensitivity to
  neutrinos.\n\nThe amplitudes of such afterpulses remain at the single-pho
 toelectron level\, and their probability is below 0.1% per photoelectron. 
 The observed delay times and the absence of dependence on the operating vo
 ltage indicate that these afterpulses cannot be satisfactorily explained w
 ithin the standard ion-feedback model. Their characterization is essential
  for reliable background suppression and event reconstruction in large neu
 trino telescopes\, and further studies are needed to clarify their origin.
 \n\nhttps://indico.particle.mephi.ru/event/626/contributions/6394/
LOCATION:Sevastopol Hotel
URL:https://indico.particle.mephi.ru/event/626/contributions/6394/
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