The DAMA/LIBRA experiment at LNGS reported the observation of an approximately annual variation in the number of events observed in the 2-6 keV energy range with a combined significance of approximately 9.3 σ. If the observed signal modulation is to be explained by the elastic scattering of dark matter particles, it would require that the interaction cross-section of dark matter with nucleons, and the mass of dark matter particles, to be within values that are already excluded by other experiments.
One mechanism that has been proposed in order to explain the DAMA signal modulation is the production of neutrons due to the scattering of cosmogenic muons in the material surrounding the detector. The cosmogenic muon-induced-neutron flux Φμn is expected to have an annual variation related to the mean air temperature above the surface of the Earth that affects the muon flux at the surface, and hence underground.
These explanations have been disputed for a number of reasons, which I will discuss. I will go on to describe a full simulation of the muon-induced background at the DAMA/LIBRA experiment, which conclusively shows that the DAMA signal cannot be explained by known cosmogenic sources.