Structure of 14C via elastic and inelastic neutron scattering from 13C: Measurement, R-matrix analysis, and shell model calculations

The specific purpose of this work is to provide a better understanding of the 14C level structure: the general purpose is to provide the details for using shell model calculations in R-matrix analyses. Using the TOF facilities of the Ohio University Accelerator Laboratory, the elastic and first 3 inelastic differential scattering cross sections for 13C + n were measured at 69 energies for 4.5 ≤ En ≤ 11 MeV. A multiple scattering code was developed which provided a simulation of the experimental scattering process allowing accurate corrections to the small inelastic data. The integrated 13C(n,α)10Be cross section is estimated. The sequential 2n-decay of 14C states populated by 13C + n was observed. A shell model code was developed. Normal and non-normal parity calculations were made for the lithium isotopes using a new two-body interaction. The results for 5Li predict the 2s1/2 and 1d5/2 single-particle states to be located below the 3/2+ (Ex = 16.66 MeV) state. Similar calculations were made for 13C, 13N, and 14C. Shell model calculations generated the R-matrix parameters for the elastic and first 3 inelastic channels of 13C + n. After adjusting some energies, the predicted structure generally agrees with experiment for En < 4 MeV. The procedure for using shell model calculations in R-matrix analyses is given. New and more consistent 14C level information is obtained