Scattering of 14.1-Mev Neutrons in Helium, Hydrogen, and Nitrogen

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Abstract
Cloud-chamber studies have been made of the scattering of 14.1-Mev neutrons in helium, hydrogen, and nitrogen. For each of these gases the angular distribution of the elastically scattered neutrons has been obtained. The angular distribution in helium shows a minimum at about 110° in the center-of-mass system, with a large maximum representing forward scattering and a smaller maximum for backscattering. The hydrogen angular distribution is isotropic. Elastic scattering in nitrogen resembles diffraction scattering, showing a strong forward scattering maximum and smaller maxima at 70° and 180°, with minima close to 60° and 130°. Inelastic scattering in nitrogen does not depart from spherical symmetry by more than a factor of two. The elastic scattering cross section for nitrogen is 0.82 barn and the inelastic scattering cross section is 0.48 barn. Cross sections for two- and three-particle disintegrations are 270 and 16 millibarns, respectively.