Subthreshold ? production on nuclei by protons

A simple expression for the inclusive cross section of η production on light nuclei by protons has been obtained in the first collision approximation in the framework of the intranuclear cascade approach. An intranuclear cascade model which takes into account η production by primary proton and secondary pion, elastic scattering of η on intranuclear nucleons and absorption of η in nuclear matter has been developed. The calculated cross sections are found to be in satisfactory agreement with the experimental data.