2018/08/31 by The Borexino Collaboration, M. Agostini, K. Altenmüller +121
Physics and Astronomy · #Amplitude #Astrophysics #Astrophysics and Cosmic Phenomena #Atmosphere (unit) #Borexino #COSMIC cancer database #Cosmic ray #Dark Matter and Cosmic Phenomena #Flux (metallurgy) #Meteorology #Muon #Neutrino #Neutrino Physics Research #Neutron #Nuclear physics #Optics #Physics #Pion #Solar neutrino #hep-ex #physics.ins-det
paper · pdf · doi:10.1088/1475-7516/2019/02/046
30 pages, 16 figures, proofreading for publication in JCAP
arxiv created 2019/01/28 · openalex publication_date 2019/02/22 · arxiv updated 2019/03/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We have measured the flux of cosmic muons in the Laboratori Nazionali del Gran Sasso at 3800 m w.e. to be (3.432 ± 0.003)⋅ 10 −4 m −2 s −1 based on ten years of Borexino data acquired between May 2007 and May 2017. A seasonal modulation with a period of (366.3 ± 0.6) d and a relative amplitude of (1.36 ±0.04)% is observed. The phase is measured to be (181.7 ± 0.4) d, corresponding to a maximum at the 1 st of July. Using data inferred from global atmospheric models, we show the muon flux to be positively correlated with the atmospheric temperature and measure the effective temperature coefficient α T = 0.90 ± 0.02. The origin of cosmic muons from pion and kaon decays in the atmosphere allows to interpret the effective temperature coefficient as an indirect measurement of the atmospheric kaon-to-pion production ratio r K /π = 0.11 +0.11 −0.07 for primary energies above 18 TeV. We find evidence for a long-term modulation of the muon flux with a period of ∼ 3000 d and a maximum in June 2012 that is not present in the atmospheric temperature data. A possible correlation between this modulation and the solar activity is investigated. The cosmogenic neutron production rate is found to show a seasonal modulation in phase with the cosmic muon flux but with an increased amplitude of (2.6 ± 0.4)%.