Complementary Time- and Distance-Based Methods for Cosmogenic 9Li/8He Background Estimation
Abstract
Cosmogenic 9Li and 8He isotopes constitute an important correlated background in low-energy neutrino experiments because their β-delayed neutron decay signatures can mimic inverse beta decay signals. Conventional estimates based on the time since the last muon become challenging at high muon rates, while muon-related vetoes further reduce the residual isotope statistics. We extend the conventional time fit to an event-level muon-categorized joint time (J-MuCAT) fit, which uses the time to the most recent preceding muon in each energy-loss category. A complementary estimate is obtained from the candidate-to-muon-track distance distribution (TraDiTS). The muon-uncorrelated component is determined from the far-distance region and subtracted. This estimate is then used to constrain the J-MuCAT fit, defining the distance-constrained J-MuCAT (DCJ-MuCAT) fit. In detector-level simulation with successive cosmogenic-background vetoes, DCJ-MuCAT reduces the statistical uncertainty by more than 40% relative to J-MuCAT and by more than 10% relative to the TraDiTS. The fitted results remain consistent with the simulation truth. Applicability studies further show good performance over a broad range of muon rates and isotope fractions. The proposed framework provides a practical approach for estimating residual 9Li/8He backgrounds in large neutrino detectors.
Related
- Full-Stokes response to a stochastic gravitational-wave background in pulsar timing arrays: Fully analytic overlap reduction functions at finite distance and coherence of close pulsar pairs
- Optimal Diamond Distance Estimation for Unitary Channels
- A machine-learning method for the estimation of the background from jets misidentified as hadronic tau lepton decays
- Cosmogenic neutrinos from FRII galaxies as potential origin of the ultra-high-energy KM3-230213A event
- Probing Lorentz Invariance Violation in Cosmogenic Neutrino Propagation with KM3-230213A
BibTeX
@misc{jiang2026complementary,
title = {{Complementary Time- and Distance-Based Methods for Cosmogenic $^9$Li/$^8$He Background Estimation}},
author = {Cailian Jiang and Qishan Liu and Liangjian Wen and Gaosong Li and Zeyuan Yu and Wanlei Guo and Lei Zhang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26538},
eprint = {2609.26538},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26538},
}
RIS
TY - UNPB
TI - Complementary Time- and Distance-Based Methods for Cosmogenic ^9Li/^8He Background Estimation
AU - Cailian Jiang
AU - Qishan Liu
AU - Liangjian Wen
AU - Gaosong Li
AU - Zeyuan Yu
AU - Wanlei Guo
AU - Lei Zhang
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2609.26538
UR - https://arxiv.org/abs/2609.26538
AB - Cosmogenic ^9Li and ^8He isotopes constitute an important correlated background in low-energy neutrino experiments because their β-delayed neutron decay signatures can mimic inverse beta decay signals. Conventional estimates based on the time since the last muon become challenging at high muon rates, while muon-related vetoes further reduce the residual isotope statistics. We extend the conventional time fit to an event-level muon-categorized joint time (J-MuCAT) fit, which uses the time to the most recent preceding muon in each energy-loss category. A complementary estimate is obtained from the candidate-to-muon-track distance distribution (TraDiTS). The muon-uncorrelated component is determined from the far-distance region and subtracted. This estimate is then used to constrain the J-MuCAT fit, defining the distance-constrained J-MuCAT (DCJ-MuCAT) fit. In detector-level simulation with successive cosmogenic-background vetoes, DCJ-MuCAT reduces the statistical uncertainty by more than 40% relative to J-MuCAT and by more than 10% relative to the TraDiTS. The fitted results remain consistent with the simulation truth. Applicability studies further show good performance over a broad range of muon rates and isotope fractions. The proposed framework provides a practical approach for estimating residual ^9Li/^8He backgrounds in large neutrino detectors.
ER -