Scattering of Neutrons by Carbon from 3 to 7 MeV

Abstract

Angular distributions of neutrons elastically scattered from natural carbon have been measured at 32 neutron energies between 3 and 7 MeV with energy spreads ranging from 37 to 165 keV. The angular distributions of neutrons inelastically scattered from $^{12}\mathrm{C}$ have also been measured at the nine highest neutron energies. A phase-shift analysis of the elastic scattering cross sections yields the following spin and parity assignments for the excited states of $^{13}\mathrm{C} ({E}_{x},J): 8.3 \mathrm{MeV},{\frac{3}{2}}^{+}; 8.88 \mathrm{MeV},{\frac{1}{2}}^{\ensuremath{-}}; 9.50 \mathrm{MeV},{(\frac{1}{2},\frac{3}{2})}^{\ensuremath{-}}; 9.90 \mathrm{MeV},{\frac{3}{2}}^{\ensuremath{-}}; 10.75 \mathrm{MeV},{\frac{7}{2}}^{\ensuremath{-}}; 11.00 \mathrm{MeV},({\frac{1}{2}}^{+})$. Neutron polarizations calculated from the extracted phase shifts agree fairly well with most of the available polarization measurements. A polarization contour map is given showing that carbon may be useful as a polarization analyzer between 4.5 and 7 MeV.