Proton-Proton Scattering: Revision and Analysis of Experimental Measurements from 1.4 to 3.0 MeV

Abstract

Revised experimental values are given for the differential cross section for proton-proton scattering at energies of 1.397, 1.855, 2.425, and 3.037 MeV. These result from the consolidation and re-evaluation of all published and unpublished data obtained in an experiment reported earlier by Knecht et al. Phase-shift analyses have been made. The preferred solutions determine the $S$-wave phase shift ${K}_{0}$ and the central-force ("effective") part $\ensuremath{\gamma}$ of the $P$-wave phase shifts, under the assumption that the noncentralforce parts and all higher angular-momentum phase shifts are known with sufficient accuracy from one-pion-exchange theory; the values of $\ensuremath{\gamma}$ derived in this way are small, with zero not excluded. Other solutions in which noncentral forces range from zero to very large values are given for comparison. The uncertainty in each of the derived phase shifts is calculated and discussed in detail; uncertainties obtained by the usual statistical method are shown to be too small. The polarization implied by each phase-shift solution has been calculated, and it is shown that reported measurements are in disagreement not only with the present data and theoretical predictions but with any combination of central, tensor, and spin-orbit forces.