242Pu neutron-induced fission cross-section measurement from 1 to 2 MeV neutron energy

Relative values of the neutron-induced fission cross section $\ensuremath{\sigma}(n,f)$ of $^{242}\mathrm{Pu}$ have been measured with respect to the standard $^{1}\mathrm{H}(n,p)$ elastic scattering cross section, at average energies of 1.0, 1.4, and $1.9\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$. The measurements are part of an international effort to reduce uncertainties and provide independent nuclear data relevant for fast-spectrum reactors. The shape of the measured cross section is in good agreement with data from Tovesson et al. [Phys. Rev. C 79, 014613 (2009)] and with the most recent data from Matei et al. [Phys. Rev. C 95, 024606 (2017)], but disagrees with the shapes of ENDF/B-VII.1 and JEFF3.2 evaluations. Absolute values of $\ensuremath{\sigma}(n,f)$, obtained under some assumptions, indicate an overestimation of $\ensuremath{\sigma}(n,f)$ in the evaluated libraries at 1.0 and $1.4\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$, while a good agreement is found with ENDF/B-VII.1 at $1.9\phantom{\rule{4pt}{0ex}}\mathrm{MeV}$. A careful analysis of the impact of scattered neutrons and anisotropy of the fission fragment angular distribution has been performed. The measurement of the neutron flux by means of a proton-recoil detector is discussed. A comprehensive study of corrections applied to the data, of associated uncertainties, and of correlations between the measurements at the different energies is presented.