Very Late Afterpulses and Search for the Neutron Echo in IceCube

Fuente: arXiv
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Main Authors: Dutta, Kaustav, Böser, Sebastian, Rongen, Martin
Format: Preprint
Published: 2025
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author Dutta, Kaustav
Böser, Sebastian
Rongen, Martin
author_facet Dutta, Kaustav
Böser, Sebastian
Rongen, Martin
contents While high-energy astrophysical neutrinos are well-established, their flavor composition remains relatively unconstrained. In IceCube, long muon tracks from $ν_μ$ charged-current interactions are easily identified but the detector geometry does not allow sufficient resolution to distinguish cascade-type events. The Neutron Echo - a delayed light signal in the detector from neutron capture and de-excitation - can probe the shower's hadronic content and thus the underlying interaction. A significant background arises from late PMT afterpulses, which are temporally coincident with the physics signal. The traditional IceCube data acquisition system has a limited readout window with significant deadtime between triggers, which is insufficient to capture the late pulses. A recently developed deadtime-free readout mode, with an extended window, enables their detection. An observed excess in the delayed time spectrum over the background would be compatible with the Neutron Echo hypothesis. In this contribution, we summarize the physics scope of delayed signals, discuss the timing spectrum of signal and PMT background, highlight the capabilities of the new system for recording late pulses, and emphasize the potential of IceCube for particle identification through delayed signals.
format Preprint
id arxiv_https___arxiv_org_abs_2507_07042
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Very Late Afterpulses and Search for the Neutron Echo in IceCube
Dutta, Kaustav
Böser, Sebastian
Rongen, Martin
High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
High Energy Physics - Experiment
While high-energy astrophysical neutrinos are well-established, their flavor composition remains relatively unconstrained. In IceCube, long muon tracks from $ν_μ$ charged-current interactions are easily identified but the detector geometry does not allow sufficient resolution to distinguish cascade-type events. The Neutron Echo - a delayed light signal in the detector from neutron capture and de-excitation - can probe the shower's hadronic content and thus the underlying interaction. A significant background arises from late PMT afterpulses, which are temporally coincident with the physics signal. The traditional IceCube data acquisition system has a limited readout window with significant deadtime between triggers, which is insufficient to capture the late pulses. A recently developed deadtime-free readout mode, with an extended window, enables their detection. An observed excess in the delayed time spectrum over the background would be compatible with the Neutron Echo hypothesis. In this contribution, we summarize the physics scope of delayed signals, discuss the timing spectrum of signal and PMT background, highlight the capabilities of the new system for recording late pulses, and emphasize the potential of IceCube for particle identification through delayed signals.
title Very Late Afterpulses and Search for the Neutron Echo in IceCube
topic High Energy Astrophysical Phenomena
Instrumentation and Methods for Astrophysics
High Energy Physics - Experiment
url https://arxiv.org/abs/2507.07042