Excitation Function and Integral Recoil Properties of theCu65(p,pπ+)Ni65Reaction

The excitation function for the ${\mathrm{Cu}}^{65}(p,p{\pi }^{+}){\mathrm{Ni}}^{65}$ reaction was measured from 0.49 to 28 GeV. With other data, this provides a complete excitation function for this reaction from threshold to 28 GeV. The excitation function is dominated by a broad peak at ∼1.3 GeV which is due to the $(\frac{3}{2},\frac{3}{2}){\pi }^{+}-p$ resonance. Thick-target, integral recoil experiments were performed at 2.8 and 28 GeV. The experimental excitation function and the results of the recoil experiments were compared with the results of an improved version of the calculation of Ericson, Selleri, and Van de Walle. Agreement between the experimental data and the calculations is obtained only when the one-pion-exchange (OPE) theory is used to describe the inelastic $p-p$ interaction occurring in the nucleus. These results indicate that the treatment of the ($p,p{\pi }^{+}$) reaction by Ericson et al. is basically correct and that OPE theory remains valid at energies up to 28 GeV, at least at the low momentum transfers selected by the ($p,p{\pi }^{+}$) reaction. These data also suggest that the exchange of one unit of isotopic spin at very high energies is not greatly suppressed at low momentum transfers.