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High Energy Physics - Experiment, hep-ex, Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM, Physics, Atmospheric and Oceanic Physics, physics.ao-ph
Abstract:
We have measured the muon flux at the underground Gran Sasso National
Laboratory (3800 m w.e.) to be (3.41 \pm 0.01) \times 10-4m-2s-1 using four
years of Borexino data. A modulation of this signal is observed with a period
of (366\pm3) days and a relative amplitude of (1.29 \pm 0.07)%. The measured
phase is (179 \pm 6) days, corresponding to a maximum on the 28th of June.
Using the most complete atmospheric data models available, muon rate
fluctuations are shown to be positively correlated with atmospheric
temperature, with an effective coefficient {\alpha}T = 0.93 \pm 0.04. This
result represents the most precise study of the muon flux modulation for this
site and is in good agreement with expectations.
