Sensitivity of $^{252}$Cf(sf) Neutron Observables to $\mathtt{FREYA}$ Inputs

Within the framework of the fission event generator $\mathtt{FREYA}$, (Fission Reaction Event Yield Algorithm) we have studied the sensitivity of various neutron observables to the yield distribution $Y(A,Z,{\rm TKE})$ used as input to the code. Concentrating on the spontaneous fission of $^{252}$Cf, we generate a large number of different input yield distributions by performing simultaneous variations in the mass and charge yields as well as the kinetic energy distribution, governed by yield covariance matrices established from experimental data sets. For each of these input yield distributions, we then use $\mathtt{FREYA}$ to generate a large sample of complete fission events from which we extract various neutron observables, in particular the neutron multiplicity distribution, and the neutron spectrum associated with each multiplicity. On this basis, we are able to determine the sensitivity of those observables to the uncertainties in the input yield distribution obtained experimentally. This kind of study can be applied to any other case of interest and the information obtained can help to establish any needs and target accuracies required for further measurements to ensure reliable data validation.