Study of muon-induced neutron production, propagation and energy spectrum with the LVD detector at LNGS

High-energy neutrons, generated as a product of cosmic muon interactions in the rock or in the detector materials, represent the most dangerous background for a large list of research topics such as reactor neutrino studies, the search for SN relic neutrinos, solar antineutrinos, dark matter, etc. (see Khalchukov F. F. et al., Nuovo CiTnento Q 6 (1983) 320.) A high-energy neutron can be detected through a double signature: the first pulse is due to the recoil protons from n-p elastic scattering, while the second pulse is due to the thermalized neutron capture by a proton. Up to now there are few measurements of the muon-produced neutron flux at large depth underground. Moreover it is difficult to reproduce the measured data with Monte Carlo simulation because of the large uncertainties in the neutron production and propagation models. The LVD detector, situated at LNGS, has an ideal configuration for studying this kind of events because it is possible to detect both the muon track, using the high-acceptance tracking system, and the neutron interactions in the liquid scintillation detectors. We present here the results of the measurement, reporting the neutron flux at various distances from the muon track and for different neutron energies. Moreover, the analysis of the neutron yield as a function of the muon track length in the detector is described.