Phenomenology of muon-induced neutron yield

Abstract

The cosmogenic neutron yield $Y_n$ characterizes the matter ability to produce neutrons under the effect of cosmic ray muons with spectrum and average energy corresponding to an observation depth. The yield is the basic characteristic of cosmogenic neutrons. The neutron production rate and neutron flux both are derivatives of the yield. The constancy of the exponents $\alpha$ and $\beta$ in the known dependences of the yield on energy $Y_n {\propto} E_{\mu}^\alpha$ and the atomic weight $Y_n {\propto} A^\beta$ allows to combine these dependences in a single formula and to connect the yield with muon energy loss in the matter. As a result, the phenomenological formulas for the yield of muon-induced charged pions and neutrons can be obtained. These expressions both are associated with nuclear loss of the ultrarelativistic muons, which provides the main contribution to the total neutron yield. The total yield can be described by a universal formula, which is the best fit of experimental data.