Scattering of Neutrons by Carbon from 7 to 9 MeV

Abstract

Differential elastic cross sections for neutrons scattered by carbon were measured for 7.20-, 7.35-, 7.73-, 8.20-, and 9.00-MeV incident neutron energies using the Aerospace Research Laboratory neutron time-of-flight facility. The inelastic differential cross sections for neutrons leaving the residual $^{12}\mathrm{C}$ nucleus in the 4.43-MeV excited state were also measured for 7.73-, 8.20-, and 9.00-MeV incident neutrons. These data have uncertainties relative to the normalizations of 1.5 to 8% for the elastic cross sections and 4 to 18% for the inelastic cross sections. The normalization uncertainty is 4%. The elastic angular distributions are compared to optical-model calculations using the Rosen potential. Neither this potential nor any other with reasonable geometry fits the data. The angle-integrated cross sections combined with previously reported $^{12}\mathrm{C}(n, \ensuremath{\alpha})^{9}\mathrm{Be}$ cross sections are compared to the total neutron cross sections at 7.73, 8.20, and 9.00 MeV. Because of the several strongly over-lapping resonances in the 7-9-MeV energy region, a unique phase-shift analysis of the data is not possible.