Measurement of the cross section for the ${}^{13}\mathrm{C}{(\alpha ,n)}^{16}\mathrm{O}$ reaction and determination of the cross section for the ${}^{16}\mathrm{O}{(n,\alpha )}^{13}\mathrm{C}$ reaction

The angular dependence of the differential cross sections for the ${}^{13}\mathrm{C}{\left(\alpha ,n_0\right)}^{16}\mathrm{O}$ reaction was measured in the energy range 2.0–6.2 MeV using the time-of-flight method for separating neutrons corresponding to the ground state of the residual nucleus. The integrated total cross sections were derived from the measured data and the cross sections for the ${}^{16}\mathrm{O}{\left(n,{\alpha }_0\right)}^{13}\mathrm{C}$ reaction were determined using the reciprocity theorem. The cross sections obtained for the reaction ${}^{16}\mathrm{O}{\left(n,{\alpha }_0\right)}^{13}\mathrm{C}$ support the evaluation given in the ENDF/B-VIII.0 library.

Figure 1

The schematic diagram of the experimental setup (not to scale).

Figure 2

The pulse-height spectrum of the charged particles detected at an angle of 150° for the ${}^{13}\mathrm{C}$ target on a gold backing irradiated with deuterons. Dots: experimental values; line: simulation.

Figure 3

Pulse-height spectra of α particles detected by SBD (dots) and results of the simnra simulation (lines). The spectra are given for different time intervals elapsed since the start of the experiment.

Figure 4

Dependence of carbon deposits on the time elapsed since the beginning of the experiment.

Figure 5

Time-of-flight distribution of the neutron pulses, corresponding to the beam energy of 5910 keV and angle of 0°.

Figure 6

Integral time distribution of α particles in a bunch. The distribution is given for the beam energy of 5884 keV.

Figure 7

The intrinsic efficiency of the neutron detector. Open dots: results obtained with a fission chamber as a neutron flux monitor; filled dots: results based on the measurements of the neutron time-of-flight spectra from the ${}^2\mathrm{H}\left(d,n\right){}^3\mathrm{He}$ reaction; solid line: Monte Carlo calculations. The energy range of neutrons detected in the experiment was 3–9 MeV.

Figure 8

Correction factor for multiple neutron scattering for selected α-particle energies. (a) α-particle energy of 2219 keV, (b) 3389 keV, (c) 4709 keV, (d) 5180 keV.

Figure 9

The angular distributions for the ${}^{13}\mathrm{C}{\left(\alpha ,n_0\right)}^{16}\mathrm{O}$ reaction in the α-particle energy range 2090–4807 keV. Dots: experimental data; solid lines: approximation by Legendre polynomials.

Figure 10

The same as in Fig. 9 but for the α-particle energy range 4880–6122 keV.

Figure 11

The comparison of the differential cross sections for the ${}^{13}\mathrm{C}{\left(\alpha ,n_0\right)}^{16}\mathrm{O}$ reaction measured at an angle of 0° in two experimental runs with data from the literature for 2.0–3.5 MeV [39] (a) and 4.75–6.20 MeV [12, 27] (b). The Robb data were multiplied by a factor of 2.25.

Figure 12

The ${}^{16}\mathrm{O}{\left(n,{\alpha }_0\right)}^{13}\mathrm{C}$ reaction cross section in the neutron energy range 4.0–5.2 MeV, obtained via direct (a) and inverse (b) reactions, in comparison with the ENDF/B-VIII.0 and JENDL-4.0/HE evaluations, and other experimental data [4, 7, 8, 9, 11, 13]. The data by Bair are given with the normalization recommended by the authors.

Figure 13

The same as in Fig. 12 but for the neutron energy range 6.0–7.5 MeV. The experimental data are from Refs. [4, 5, 7, 8, 9, 10, 11, 12, 13].