Proton-Proton Scattering at 970 MeV

Abstract

Proton-proton scattering has been studied at 970 MeV using the Birmingham University 1-BeV synchrotron and a 9-in.-diam liquid-hydrogen bubble chamber; 3945 events have been analyzed and cross sections determined for the various reactions. The elastic scattering cross section of 24.8±0.9 mb is significantly higher than the result of Dowell et al. using counters. The two experiments agree on the shape of the angular distribution, but not on its normalization; possible reasons for this are discussed. The elastic scattering angular distribution is peaked strongly forward, but does not agree quantitively with pure diffraction. Polarization effects observed in the elastic scattering agree with previous and more accurate counter experiments. Inelastic scattering is strongly influenced by the ($\frac{3}{2},\frac{3}{2}$) ${\pi }^{+}p$ resonance and the peripheral mechanism. Theoretical predictions based on the single-pion exchange model are compared in detail with the experimental results and good quantitative agreement is obtained for small momentum transfers, particularly for the reaction $p+p\to n+p+{\pi }^{+}$. Even for small momentum transfers, asymmetries in the Treiman-Yang test and departure from the expected $(1+3\mathrm{} {cos}^2\theta ) {\pi }^{+}-P$ angular distribution indicate that other mechanisms may be important. The cross section for double-pion production at 970 MeV is less than 0.2 mb.