Energy-differential measurement of the ${}^{\mathrm{nat}}$C(n,p) and ${}^{\mathrm{nat}}$C(n,d) reactions at the n_TOF facility at CERN

Abstract

Energy-differential cross section of the ${}^{\mathrm{nat}}$C(n,p) and ${}^{\mathrm{nat}}$C(n,d) reactions was measured at the neutron time of flight facility n_TOF at CERN. The measurement was performed in the first experimental area (EAR1; flight path of 182.5 m). Two position-sensitive $\hat{I}”E$-$E$ silicon telescopes were used. Two naturally occurring carbon isotopes, ${}^{12}$C and ${}^{13}$C, contribute to the reactions on natural carbon, with the (n,p) reaction threshold at 13.7 MeV and the (n,d) threshold at 14.9 MeV (determined by the ${}^{12}$C isotope for both reactions). This paper provides the details of the analysis leading to the final results published previously as a Letter. The cross section results are reported up to 25 MeV. During the data analysis the population of the excited states in the daughter nuclei ${}^{11}$B, ${}^{12}$B, ${}^{13}$B had to be considered, requiring the adoption of the branching ratios and angular distributions of the emitted particles from an external source of information. TALYS-2.0 calculations were used as the main source and an in-depth analysis of the model-related uncertainties was performed. The n_TOF results are largely inconsistent with the major evaluation libraries. On the other hand, an unexpected agreement is found with TALYS-2.0 calculations. Specifically, the obtained cross section for the (n,p) reaction is significantly higher than in the available evaluations, fully supporting the earlier finding from an integral measurement at n_TOF.

22 pages, 15 figures, 4 tables