Angular distributions of the recoil nuclei from the ${\mathrm{Cu}}^{65}(p,p{\pi }^{+}){\mathrm{Ni}}^{65}$ reaction were measured at incident-proton energies of 1.0 and 2.8 GeV. Kinetic-energy spectra of the recoil nuclei were obtained for angles of 15° and 45° at 1.0 GeV. These energy spectra are directly related to the effective mass of all the outgoing particles, and prominent peaks corresponding to production of the $\Delta \mathrm{}\left(1236\right)\mathrm{}$ isobar were observed. The experimental data were compared with the results of calculations based on the model of Ericson, Selleri, and Van de Walle, and reasonably good agreement was obtained.

• Received 19 June 1969

DOI:https://doi.org/10.1103/PhysRev.188.1698