Absolute differential cross sections for the elastic scattering of neutrons in the angular range from 2.5 degrees to 16 degrees have been determined for nitrogen at neutron energies of 7.65, 7.88, 8.11, 10.95, and 14.00 MeV and for oxygen at neutron energies of 10.25, 10.75, 10.95, 11.25 and 14.10 MeV. The measured cross sections are in good agreement with the most recent evaluations by Young and Foster except for oxygen around 11 MeV where the measured differential cross sections are significantly lower than the evaluated ones.

Absolute differential cross sections for the elastic scattering of 7.40, 7.55, 8.00, 8.55, 9.00, and 9.50 MeV neutrons from carbon, nitrogen, and oxygen in the angular range from 2.5 degrees to 15 degrees have been determined. Measurements were made relative to the scattering from lead by use of a special-purpose collimator. The cross section scale was then established by absolute measurements for lead in a ring geometry experiment. The results for nitrogen are consistent with recent measurements at other laboratories which suggest that the discrepancy in previous nitrogen cross section data around 7-8 MeV neutron energy arose from an underestimate of the elastic scattering cross section. The data presented in this report represent the first direct measurements of neutron scattering cross sections for light elements at very small scattering angles. (Author).

The calculation of neutron transport in air requires an accurate knowledge of the neutron cross sections for nitrogen and oxygen. Existing direct measurement of the total elastic cross section for nitrogen is in marked disagreement with the value deduced by taking the difference between the total cross section and the sum of all partial non-elastic cross sections. This discrepancy in the available data indicates an error in the total-elastic measurement of 30% or in the total non-elastic cross section of 50%. A technique to measure differential cross sections for the small-angle (3 degrees to 15 degrees) scattering of fast neutrons has been developed and applied to a study of the scattering of 7.55 and 9.5 MeV neutrons from N, O, and C. Preliminary analysis of measurements obtained thus far show that the forward angle elastic scattering in nitrogen (theta

The calculation of neutron transport in air requires an accurate knowledge of the neutron cross sections for nitrogen and oxygen. Existing direct measurements of the total elastic cross section for nitrogen in the energy range from 6 to 10 MeV are in marked disagreement with the value deduced by taking the difference between the total cross section and the sum of all partial non-elastic cross sections. This discrepancy in the data previously available indicates an error in the total elastic measurement of approximately 30 percent or a 50 percent error in the total non-elastic cross section. A technique to measure differential cross sections for the small-angle (2 degrees to 15 degrees) scattering of fast neutrons has been developed and applied to a study of the scattering of 7.55 and 9.50 MeV neutrons from C, N, and O. The results obtained for nitrogen at 7.55 MeV yield differential cross sections 20 percent to 40 percent higher (at forward angles) than would be inferred from previous measurements and shows that at least 25 percent of the missing cross section should be assigned to the total elastic cross section. (Author).

Neutron cross sections for nitrogen and oxygen that are of primary interest in shielding and transport calculations are compiled in this report. Cross sections for the following processes are compiled for both oxygen and nitrogen: total, elastic scattering, nonelastic collisions, inelastic scattering, differential elastic scattering, (n, alpha) reactions, (n, p) reaction, and (n, d) reaction. The following cross sections are compiled for nitrogen only: gamma-ray production, (n, t) reaction, (n,2n) reaction, and (n,2 alpha) reaction. Cross sec tions of nitrogen for excitation of the various levels of the residual nucleus in the (n, alpha j), and (n, n'j) reactions are also compiled.thor).