Extensive study of the quality of fission yields from experiment, evaluation and GEF for antineutrino studies and applications

TL;DR

This study couples the GEF fission model with beta-decay data to improve antineutrino spectrum predictions, revealing discrepancies in existing data and demonstrating GEF's predictive accuracy for reactor antineutrino applications.

Contribution

First integration of GEF fission yields with beta-decay data for summation calculations, improving antineutrino spectrum accuracy and evaluating nuclear data quality.

Findings

GEF model predictions show large initial discrepancies with evaluated data.

Combining experimental and model data improves spectrum agreement.

GEF accurately predicts inverse beta-decay yields matching Daya Bay measurements.

Abstract

The understanding of the antineutrino production in fission and the theoretical calculation of their energy spectra in different types of fission reactors rely on the application of the summation method, where the individual contributions from the different radioactive nuclides that undergo a beta decay are estimated and summed up. The most accurate estimation of the independent fission-product yields is essential to this calculation. We have coupled for the first time the predictions of the general fission model GEF for the fission yields to fission-product beta-decay data in a summation calculation of reactor antineutrino energy spectra. The first comparisons performed between the spectra from GEF and those obtained with the evaluated nuclear databases exhibited large discrepancies that highlighted the exigency of the modelisation of the antineutrino spectra and showing their usefulness in the evaluation of nuclear data. Additional constraints for the GEF model were thus needed in order to reach the level of accuracy required. The quality of different sources of information on the fission yields has been investigated with GEF, and the benefit of a combined analysis is demonstrated. The quality of fission yields emerging from different experimental techniques has been analyzed and indications for shortcomings of mass yields for some of the studied fissioning systems were provided. The combination of a careful study of the independent isotopic yields and the adjunction of the LOHENGRIN fission-yield data as additional constraints led to a substantially improved agreement between the antineutrino spectra computed with GEF and with the evaluated data. The comparison of inverse beta-decay yields computed with GEF with those measured by the Daya Bay experiment shows the excellent level of predictiveness of the GEF model for the fundamental or applied antineutrino physics.