π- Meson Production by Protons on Nuclei

The meson production cross section for protons incident on nuclei is formulated in terms of two-particle transition rates and the struck nucleon momentum distribution in the nucleus. Three different momentum densities are assumed. They are a modified Chew-Goldberger, a Gaussian, and a Fermi distribution. With these, it is attempted to fit the experimental ${\pi }^{+}$ and ${\pi }^{-}$ meson spectra obtained by bombarding ${\mathrm{C}}^{12}$ with 345-Mev protons. The effect of the exclusion principle is estimated on the basis of a single particle model for the nucleus. Meson reabsorption and scattering, after production, are also taken into account, but only roughly. The calculations show that the gaussian distribution approximates nuclear conditions best, and that the fundamental proton-neutron and proton-proton production transitions matrices are most probably not equal.