Proton-Proton Scattering from 1.4 to 2.4 Mev

Differential cross sections for the scattering of protons by protons have been measured at energies of 1.397, 1.855, and 2.425 Mev over an angular range from 12° to 90° in the center-of-mass system. Total uncertainties vary from about ±0.1% at large angles to ±0.3% at the smallest angles. A thorough investigation of sources of error has yielded cross-section values in disagreement with previously published values. A simple phase-shift analysis has been made. Without the inclusion of vacuum polarization contributions, a satisfactory fit is not obtained with only $S$-wave and effective nuclear $P$-wave phase shifts. With their inclusion, the data are fitted well by pure $S$-wave nuclear scattering. An upper limit on the magnitude of the effective nuclear $P$-wave phase shift is estimated at about 0.02° at these energies.