Measurement and covariance analysis of \( ^{232} {\text{Th}}\left( {{\text{n}},2{\text{n}}} \right)^{231} {\text{Th}} \) reaction cross section

The \( ^{232} {\text{Th}}\left( {{\text{n}},2{\text{n}}} \right)^{231} {\text{Th}} \) reaction cross sections were measured at the neutron energies of 10.49 ± 0.29, 14.46 ± 0.26, 18.36 ± 0.24 MeV and 15.03 ± 0.003 MeV. For the first three energies, \( ^{7} {\text{Li}}\left( {{\text{p}},{\text{n}}} \right) \) reaction as a neutron source at the BARC-TIFR Pelletron accelerator facility was used. For the latter energy, \( ^{3} {\text{H}}\left( {{\text{d}},{\text{n}}} \right) \) neutron source using the PURNIMA neutron generator facility was used. The experiments were carried out using the activation method and off-line \( \upgamma \)-ray spectrometric technique. Covariance information of various attributes of cross section was propagated to obtain the covariance matrix for the reaction cross sections. The experimental resuts obtained with reference to the two different neutron sources are then compared with the values of evaluated nuclear data files such as ENDF/B-VIII.0, JENDL 4.0, JEFF-3.2, ROSFOND-2010, TENDL-2017 and the theoretical values from TALYS-1.9 code.