Proton-Proton Scattering at 7 Mev

Abstract

Scattering experiments have been performed with protons from the cyclotron scattered in hydrogen gas. Photographic plates were used in a camera which recorded simultaneously individual protons scattered at angles from 10.5\ifmmode^\circ\else\textdegree\fi{} to 45\ifmmode^\circ\else\textdegree\fi{}. 5000 tracks were counted in each of nine narrow angular ranges to give good statistical accuracy. An experimentally determined correction was necessary due to proton penetration of the edges of the slits which admitted scattered protons to the photographic plates. The energy of the protons was determined by magnetic deflection and from ionization ranges. Analysis of the results shows an $s$ phase shift somewhat lower than that predicted by extrapolation of the earlier low energy data as analyzed in terms of square well, Gauss, and meson potentials. On the assumption of central $p$ wave scattering the results are fitted by a $p$ phase shift of -0.22\ifmmode^\circ\else\textdegree\fi{} which corresponds to scattering from a repulsive square well with interior Coulomb potential, range ${\mathit{e}}^{2}$/${\mathrm{mc}}^{2}$ and height 2.2 Mev. Extending the Rarita-Schwinger neutron-proton interactions to the proton-proton system for a prediction of tensor $^{3}P$ wave scattering, we find that the experimental results are reconcilable with the "symmetrical" theory and with the "charged" theory as formally constructed by them. The "neutral" theory gives $^{3}P$ scattering in definite disagreement with the experimental results.