Explanation of the seasonal variation of cosmic multiple muon events observed with the NOvA Near Detector American Physical Society 01/01/2026 10684442 10.1103/6djf-6bn5 Physical Review D 2470-0010 113 1 S AbubakarM A AceroB AcharyaP AdamsonN AnfimovA AntoshkinE Arrieta-DiazL AsquithA AurisanoA BackN BalashovP BaldiB A BambahE F BannisterA BarrosJ BarrowA BatT_J C BezerraV BhatnagarB BhuyanJ BianA C BoothR BowlesB BrahmaC BrombergN BuchananA ButkevichT J CarrollE Catano-MurJ P CesarS ChaudharyR ChircoS ChoateB C ChoudharyO_T K ChowA ChristensenM F CicalaT E CoanT ContrerasA CooleybeckD CoveyouL CremonesiG S DaviesP F DerwentZ DjurcicK DobbsD Dueñas TonguinoE C DukesA DyeR EhrlichE EwartP FilipM J FrankH R GallagherA GiriR A GomesM C GoodmanR GroupE GuanA HabigF HaklJ HartnellR HatcherJ M HaysM HeK HellerV HewesA HimmelT HorohoX HuangA IvanovaI KakorinA KalitkinaD M KaplanA KhanamB KirezliJ KleykampO KlimovL W KoernerL KolupaevaR KralikA KumarC D KuruppuV KusT LackeyK LangJ LesmeisterA ListerJ A LockS MagillW A MannM T ManoharanM Manrique PlataM L MarshakM Martinez-CasalesV MatveevA MedhiB MehtaM D MessierH MeyerT MiaoV MikolaS R MishraR MohantaA MorenA MorozovaW MuL MualemM MuetherC MurthyD MyersJ NachtmanD NaplesJ K NelsonO NeogiR NicholE NinerA NormanA NorrickH OhA OlshevskiyT OlsonA PalJ PaleyL PandaR B PattersonG PawloskiR PettiL R PraisA RafiqueV RajM RajaoalisoaB RamsonB RebelC ReynoldsE RoblesP RoyO SamoylovM C SanchezS Sánchez FaleroP ShanahanP SharmaA SheshukovA ShmakovW ShorrockS ShuklaI SinghP SinghV SinghS Singh ChhibraA SmithJ SmolikP SnopokN SolomeyA SousaK SoustruznikM StraitC SullivanL SuterA SuttonK SuttonS K SwainA SztucN TalukdarP TasT ThakoreJ ThomasE TirasM TitusY TorunD TranJ Trokan-TenorioJ UrheimB UttP VahleZ VallariK J VockerodtA V WaldronM WallbankB WangC WeberM WetsteinD WhittingtonD A WickremasingheJ WolcottS WuW WuY XiaoB YaeggyA YahayaA YankelevichK YoneharaS ZadorozhnyyJ ZalesakR ZwaskaNOvA_Collaboration 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-axisνeAppearance (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.

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