Sensitivity of FREYA to model inputs in simulations of 252Cf(sf)

Employing the complete fission event generator $\mathtt{FREYA}$, we study the sensitivity of neutron observables to the input yield function $Y (A, Z, {\rm TKE})$ [1]. We first perform a statistical analysis of the available fission data to determine the distribution of possible yield functions and construct an ensemble of 15,000 such yield functions. For each of these, $\mathtt{FREYA}$ is used to generate one million fission events, leading to a corresponding ensemble of fission observables, including the neutron multiplicity distribution and its factorial moments, the neutron energy spectrum, and the neutron-neutron angular correlation. Thus we can study the sensitivity of those neutron observables to the uncertainty in the input yields. Particular attention is given to the anti-correlation between the mean neutron multiplicity $\overline \nu$ and the mean total fragment kinetic energy TKE. Because $\overline \nu$ is very well determined, we employ this anti-correlation to derive a significantly stricter tolerance on TKE. We also study the sensitivity to the $\mathtt{FREYA}$ input parameters.\par \noindent [1] J. Randrup, P. Talou and R. Vogt, Phys. Rev. C {\bf 99}, 054619 (2019).