Angular Distribution ofn−pScattering at 17.9 Mev

Abstract

The angular distribution of protons bombarded by 17.9\ifmmode\pm\else\textpm\fi{}0.1-Mev neutrons was measured at 11 angles from 2.5\ifmmode^\circ\else\textdegree\fi{} to 50\ifmmode^\circ\else\textdegree\fi{} in the laboratory system. At each angle the energy spectrum of protons producing a coincidence of pulses in two proportional counters and a NaI(Tl) crystal was measured in the NaI crystal. Each spectrum has a peak less than 25% wide at half-maximum and a small low-energy tail caused by Coulomb scattering of the protons in the detector. The error in each yield was between 2 and 3% for angles from 2.5\ifmmode^\circ\else\textdegree\fi{} to 45\ifmmode^\circ\else\textdegree\fi{} and 8% at 50\ifmmode^\circ\else\textdegree\fi{}. A least squares fit to the data gives 1.08\ifmmode\pm\else\textpm\fi{}0.03 for the ratio of the $n\ensuremath{-}p$ scattering cross sections at neutron angles 180\ifmmode^\circ\else\textdegree\fi{} and 90\ifmmode^\circ\else\textdegree\fi{} cm.