Proton-Proton Scattering at 40 Mev

Abstract

Differential cross sections have been measured for the scattering of 39.4-Mev protons by hydrogen gas at angles from 45\ifmmode^\circ\else\textdegree\fi{} to 4\ifmmode^\circ\else\textdegree\fi{} in the laboratory system, with \ifmmode\pm\else\textpm\fi{}\textonehalf{}\ifmmode^\circ\else\textdegree\fi{} angular resolution at small angles. Data are given for every half degree near the interference minimum. The relative and absolute probable errors given are respectively \ifmmode\pm\else\textpm\fi{}0.5% and \ifmmode\pm\else\textpm\fi{}0.8% from 45\ifmmode^\circ\else\textdegree\fi{} to 8\ifmmode^\circ\else\textdegree\fi{}. The corresponding probable errors at 4\ifmmode^\circ\else\textdegree\fi{} are \ifmmode\pm\else\textpm\fi{}4.0% and \ifmmode\pm\else\textpm\fi{}4.1%. The cross-section curve is essentially flat at 11.15 millibarns from 90\ifmmode^\circ\else\textdegree\fi{} to 55\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system. It falls to a minimum of 9.80 millibarns at 21\ifmmode^\circ\else\textdegree\fi{}, and rises rapidly to 104 millibarns at 8\ifmmode^\circ\else\textdegree\fi{}. A typical but not unique set of phase shifts which fit the data is: $^{1}S_{0}$, 40\ifmmode^\circ\else\textdegree\fi{}; $^{3}P_{0}$, 16.90\ifmmode^\circ\else\textdegree\fi{}; $^{3}P_{1}$, -6.93\ifmmode^\circ\else\textdegree\fi{}; $^{3}P_{2}$, 3.04\ifmmode^\circ\else\textdegree\fi{}; $^{1}D_{2}$, 2.16\ifmmode^\circ\else\textdegree\fi{}; coupling parameter between $^{3}P_{2}$ and $^{3}F_{2}$ as defined by Stapp, -2.21\ifmmode^\circ\else\textdegree\fi{}.