Explanation of the seasonal variation of cosmic multiple muon events observed with the NOvA Near Detector

Fuente: arXiv
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Main Author: The NOvA Collaboration
Format: Preprint
Published: 2025
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author The NOvA Collaboration
author_facet The NOvA Collaboration
contents The flux of cosmic ray muons at the Earth's surface exhibits seasonal variations due to changes in the temperature of the atmosphere affecting the production and decay of mesons in the upper atmosphere. Using 1473 live days of data collected by the NuMI Off-axis $ν_e$ Appearance (NOvA) Near Detector during 2018--2022, we studied the seasonal pattern in the multiple-muon event rate. The data confirm an anticorrelation between the multiple-muon event rate and effective atmospheric temperature, consistent across all the years of data. Previous analyses from MINOS and NOvA saw a similar anticorrelation but did not include an explanation. We find that this anticorrelation is driven by altitude--geometry effects as the average muon production height changes with the season. This has been studied with a CORSIKA cosmic ray simulation package by varying atmospheric parameters, and provides an explanation to a longstanding discrepancy between the seasonal phases of single and multiple-muon events.
format Preprint
id arxiv_https___arxiv_org_abs_2508_04434
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Explanation of the seasonal variation of cosmic multiple muon events observed with the NOvA Near Detector
The NOvA Collaboration
High Energy Physics - Experiment
Instrumentation and Detectors
The flux of cosmic ray muons at the Earth's surface exhibits seasonal variations due to changes in the temperature of the atmosphere affecting the production and decay of mesons in the upper atmosphere. Using 1473 live days of data collected by the NuMI Off-axis $ν_e$ Appearance (NOvA) Near Detector during 2018--2022, we studied the seasonal pattern in the multiple-muon event rate. The data confirm an anticorrelation between the multiple-muon event rate and effective atmospheric temperature, consistent across all the years of data. Previous analyses from MINOS and NOvA saw a similar anticorrelation but did not include an explanation. We find that this anticorrelation is driven by altitude--geometry effects as the average muon production height changes with the season. This has been studied with a CORSIKA cosmic ray simulation package by varying atmospheric parameters, and provides an explanation to a longstanding discrepancy between the seasonal phases of single and multiple-muon events.
title Explanation of the seasonal variation of cosmic multiple muon events observed with the NOvA Near Detector
topic High Energy Physics - Experiment
Instrumentation and Detectors
url https://arxiv.org/abs/2508.04434