Tagging Spallation Backgrounds with Showers in Water-Cherenkov Detectors

Abstract

Cosmic-ray muons and especially their secondaries break apart nuclei ("spallation") and produce fast neutrons and beta-decay isotopes, which are backgrounds for low-energy experiments. In Super-Kamiokande, these beta decays are the dominant background in 6--18 MeV, relevant for solar neutrinos and the diffuse supernova neutrino background. In a previous paper, we showed that these spallation isotopes are produced primarily in showers, instead of in isolation. This explains an empirical spatial correlation between a peak in the muon Cherenkov light profile and the spallation decay, which Super-Kamiokande used to develop a new spallation cut. However, the muon light profiles that Super-Kamiokande measured are grossly inconsistent with shower physics. We show how to resolve this discrepancy and how to reconstruct accurate profiles of muons and their showers from their Cherenkov light. We propose a new spallation cut based on these improved profiles and quantify its effects. Our results can significantly benefit low-energy studies in Super-Kamiokande, and will be especially important for detectors at shallower depths, like the proposed Hyper-Kamiokande.

17 pages, 11 figures, comments are welcome; minor changes; version accepted for publication in Phys. Rev. D

References in corpus (11)

• Phenomenology with Massive Neutrinos
• Solar neutrino measurements in Super-Kamiokande-II
• Supernova Neutrino Detection
• The Diffuse Supernova Neutrino Background
• Supernova Relic Neutrino Search with Neutron Tagging at Super-Kamiokande-IV
• Muon Simulations for Super-Kamiokande, KamLAND and CHOOZ
• First Indication of Terrestrial Matter Effects on Solar Neutrino Oscillation
• First calculation of cosmic-ray muon spallation backgrounds for MeV astrophysical neutrino signals in Super-Kamiokande
• Study of TeV Neutrinos with Upward Showering Muons in Super-Kamiokande
• Letter of Intent: The Accelerator Neutrino Neutron Interaction Experiment (ANNIE)
• Showering Cosmogenic Muons in A Large Liquid Scintillator

Cited by in corpus (31)

• Search for the Majorana Nature of Neutrinos in the Inverted Mass Ordering Region with KamLAND-Zen
• Measurement of electron antineutrino oscillation based on 1230 days of operation of the Daya Bay experiment
• DUNE as the Next-Generation Solar Neutrino Experiment
• Strong New Limits on Light Dark Matter from Neutrino Experiments
• Diffuse Supernova Neutrino Background Search at Super-Kamiokande
• Exciting Prospects for Detecting Late-Time Neutrinos from Core-Collapse Supernovae
• Diffuse Supernova Neutrino Background from extensive core-collapse simulations of $8$-$100{\mathrm{M}}_{\odot }$ progenitors
• First measurement of radioactive isotope production through cosmic-ray muon spallation in Super-Kamiokande IV
• Developing the MeV potential of DUNE: Detailed considerations of muon-induced spallation and other backgrounds
• Detectability of thermal neutrinos from binary-neutron-star mergers and implication to neutrino physics
• Solar neutrino measurements using the full data period of Super-Kamiokande-IV
• Echo Technique to Distinguish Flavors of Astrophysical Neutrinos
• Sensitivity of Super-Kamiokande with Gadolinium to Low Energy Anti-neutrinos from Pre-supernova Emission
• Physics potential of searching for $0\nu \beta \beta$ decays in JUNO
• Searching for Sub-GeV Dark Matter in the Galactic Centre using Hyper-Kamiokande
• Search for Majorana Neutrinos with the Complete KamLAND-Zen Dataset
• Neutral-current background induced by atmospheric neutrinos at large liquid-scintillator detectors: I. model predictions
• Measurement of neutrino-oxygen neutral-current quasi-elastic cross section using atmospheric neutrinos at Super-Kamiokande
• Search for supernova bursts in Super-Kamiokande IV
• Prospects for the detection of the Diffuse Supernova Neutrino Background with the experiments SK-Gd and JUNO
• Water-based Liquid Scintillator Detector as a New Technology Testbed for Neutrino Studies in Turkey
• Feasibility and physics potential of detecting ${}^8$B solar neutrinos at JUNO
• Large Energy Singles at JUNO from Atmospheric Neutrinos and Dark Matter
• Dark Matter Pollution in the Diffuse Supernova Neutrino Background
• Distinctive nuclear signatures of low-energy atmospheric neutrinos
• Reactor Antineutrino Oscillations at Super-Kamiokande
• First Detailed Calculation of Atmospheric Neutrino Foregrounds to the Diffuse Supernova Neutrino Background in Super-Kamiokande
• Neutron Tagging Can Greatly Reduce Spallation Backgrounds in Super-Kamiokande
• Identification of the cosmogenic ${}^{11}$C background in large volumes of liquid scintillators with Borexino
• New Spallation Background Rejection Techniques to Greatly Improve the Solar Neutrino Sensitivity of JUNO
• Towards First Detection of the Solar MSW Transition With JUNO