Modulations of the Cosmic Muon Signal in Ten Years of Borexino Data
Creators: name: The Borexino Collaboration
name: Agostini, M.
name: Altenmüller, K.
name: Appel, S.
name: Atroshchenko, V.
name: Bagdasarian, Z.
name: Basilico, D.
name: Bellini, G.
name: Benziger, J.
name: Bick, D.
name: Bolognino, I.
name: Bonfini, G.
name: Bravo, D.
name: Caccianiga, B.
name: Calaprice, F.
name: Caminata, A.
name: Caprioli, S.
name: Carlini, M.
name: Cavalcante, P.
name: Cavanna, F.
name: Chepurnov, A.
name: Choi, K.
name: Collica, L.
name: D'Angelo, D.
name: Davini, S.
name: Derbin, A.
name: Ding, X. F.
name: Di Ludovico, A.
name: Di Noto, L.
name: Drachnev, I.
name: Fomenko, K.
name: Formozov, A.
name: Franco, D.
name: Gabriele, F.
name: Galbiati, C.
name: Gschwender, M.
name: Ghiano, C.
name: Giammarchi, M.
name: Goretti, A.
name: Gromov, M.
name: Guffanti, D.
name: Hagner, C.
name: Houdy, T.
name: Hungerford, E.
name: Ianni, Aldo
name: Ianni, Andrea
name: Jany, A.
name: Jeschke, D.
name: Kobychev, V.
name: Korablev, D.
name: Korga, G.
name: Kudryavtsev, V. A.
name: Kumaran, S.
name: Lachenmaier, T.
name: Laubenstein, M.
name: Litvinovich, E.
name: Lombardi, F.
name: Lombardi, P.
name: Ludhova, L.
name: Lukyanchenko, G.
name: Lukyanchenko, L.
name: Machulin, I.
name: Manuzio, G.
name: Marcocci, S.
name: Maricic, J.
name: Martyn, J.
name: Meighen-Berger, S.
name: Meroni, E.
name: Meyer, M.
name: Miramonti, L.
name: Misiaszek, M.
name: Muratova, V.
name: Neumair, B.
name: Nieslony, M.
name: Oberauer, L.
name: Opitz, B.
name: Orekhov, V.
name: Ortica, F.
name: Pallavicini, M.
name: Papp, L.
name: Penek, Ö.
name: Pietrofaccia, L.
name: Pilipenko, N.
name: Pocar, A.
name: Porcelli, A.
name: Raikov, G.
name: Ranucci, G.
name: Razeto, A.
name: Re, A.
name: Redchuk, M.
name: Romani, A.
name: Rossi, N.
name: Rottenanger, S.
name: Schönert, S.
name: Semenov, D.
name: Skorokhvatov, M.
name: Smirnov, O.
name: Sotnikov, A.
name: Stokes, L. F. F.
name: Suvorov, Y.
name: Tartaglia, R.
name: Testera, G.
name: Thurn, J.
name: Toropova, M.
name: Unzhakov, E.
name: Vishneva, A.
name: Vogelaar, R. B.
name: von Feilitzsch, F.
name: Weinz, S.
name: Wojcik, M.
name: Wurm, M.
name: Yokley, Z.
name: Zaimidoroga, O.
name: Zavatarelli, S.
name: Zuber, K.
name: Zuzel, G.
Publisher: name: arXiv
Year: 2018
Subjects: subject: High Energy Physics - Experiment (hep-ex)
subject: Instrumentation and Detectors (physics.ins-det)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We have measured the flux of cosmic muons in the Laboratori Nazionali del Gran Sasso at 3800\,m\,w.e. to be $(3.432 \pm 0.003)\cdot 10^{-4}\,\mathrm{{m^{-2}s^{-1}}}$ based on ten years of Borexino data acquired between May 2007 and May 2017. A seasonal modulation with a period of $(366.3 \pm 0.6)\,\mathrm{d}$ and a relative amplitude of $(1.36 \pm0.04)\%$ is observed. The phase is measured to be $(181.7 \pm 0.4)\,\mathrm{d}$, corresponding to a maximum at the 1$^\mathrm{st}$ 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 $α_\mathrm{T} = 0.90 \pm 0.02$. 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 $r_{\mathrm{K}/π} = 0.11^{+0.11}_{-0.07}$ for primary energies above $18\,\mathrm{TeV}$. We find evidence for a long-term modulation of the muon flux with a period of $\sim 3000\,\mathrm{d}$ 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 $(2.6 \pm 0.4)\%$.
description: 30 pages, 16 figures, proofreading for publication in JCAP