Nuclear Interaction of Fast μ Mesons

An experimental study has been made of events in which a fast μ meson interacts with a nucleus to produce at least one evaporation neutron. The experimental results of major importance are σm̅ =(9.1±1.2)×10^-27 cm²/Fe-nucleus; 1.03<m̅ <7.7±2.2; and (1.2±0.4)×10^-27 cm²/Fe-nucleus<σ<(8.8±1.1)×10^-27 cm²/Fe-nucleus, where σ is the cross section for such events and m̅ is the mean multiplicity of evaporation neutrons emitted. These results are in good agreement with the results of calculations based on present information on the nuclear interaction of γ rays, which lead to the prediction of a σ of about 2.4×10^-27 cm²/Fe-nucleus and an m̅ of about 3.3. The surprisingly large cross section and small mean multiplicity of neutrons are shown to be reasonable by calculating that about 90 percent of all μ-meson nuclear interactions result in the transfer to the nucleus of less than 300 Mev.