Evaluation of Neutron Reactions on Iron Isotopes for CIELO and ENDF/B-VIII.0

TLDR

The low‑energy portion of the 56Fe data is almost entirely based on experimental measurements. The evaluation combines model predictions adjusted to experimental data at higher energies with high‑quality dosimetry from the IRDFF library. A new suite of iron‑isotope evaluations—including updated resonance ranges and elastic angular distributions—was developed, validated in integral experiments, and incorporated into ENDF/B‑VIII.0.

Abstract

A new suite of evaluations for 54,56,57,58Fe has been developed in the framework of the CIELO international collaboration. New resolved resonance ranges were evaluated for 54Fe and 57Fe, while modifications were applied to resonances in 56Fe. The low energy part of the 56Fe file is almost totally based on measurements. At higher energies in 56Fe and in the whole fast neutron range for minor isotopes the evaluation consists of model predictions carefully adjusted to available experimental data. We also make use of the high quality and well experimentally-constrained dosimetry evaluations from the IRDFF library. Special attention was dedicated to the elastic angular distributions, which were found to affect results of the integral benchmarking. The new set of iron evaluations was developed in concert with other CIELO evaluations and they were tested together in the integral experiments before being adopted for the ENDF/B-VIII.0 library.