Modulations of the Cosmic Muon Signal in Ten Years of Borexino Data

Understand

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.