Nuclear Interaction of FastμMesons

An experimental study has been made of events in which a fast $\mu$ meson interacts with a nucleus to produce at least one evaporation neutron. The experimental results of major importance are $\sigma \overline{m}=(9.1\mathrm{}\pm 1.2)\times {10}^{-27\mathrm{}}$ ${\mathrm{cm}}^2$/Fe-nucleus; $1.03<\mathrm{}\overline{m}<7.7\mathrm{}\pm 2.2$; and $(1.2\mathrm{}\pm 0.4)\times {10}^{-27\mathrm{}} {\mathrm{cm}}^2/\mathrm{F}\mathrm{e}-\mathrm{n}\mathrm{u}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{u}\mathrm{s}<\sigma <(8.8\mathrm{}\pm 1.1)\times {10}^{-27\mathrm{}} {\mathrm{cm}}^2/\mathrm{F}\mathrm{e}-\mathrm{n}\mathrm{u}\mathrm{c}\mathrm{l}\mathrm{e}\mathrm{u}\mathrm{s}$, where $\sigma$ is the cross section for such events and $\overline{m}$ 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 $\gamma$ rays, which lead to the prediction of a $\sigma$ of about 2.4×${10}^{-27\mathrm{}}$ ${\mathrm{cm}}^2$/Fe-nucleus and an $\overline{m}$ 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 $\mu$-meson nuclear interactions result in the transfer to the nucleus of less than 300 Mev.