Neutron Resonance Data Exclude Random Matrix Theory

TL;DR

New neutron resonance data and reanalysis of existing datasets challenge the long-standing agreement between random matrix theory and neutron resonance data, suggesting the theory may not universally apply.

Contribution

The paper presents new neutron-width data that contradict RMT and reanalyzes the nuclear data ensemble, revealing flaws and high-confidence exclusions of RMT.

Findings

New neutron-width data disagree with RMT

Reanalysis of NDE shows it is flawed and excludes RMT

Some radiation widths do not align with RMT predictions

Abstract

Almost since the time it was formulated, the overwhelming consensus has been that random matrix theory (RMT) is in excellent agreement with neutron resonance data. However, over the past few years, we have obtained new neutron-width data at Oak Ridge and Los Alamos National Laboratories that are in stark disagreement with this theory. We also have reanalyzed neutron widths in the most famous data set, the nuclear data ensemble (NDE), and found that it is seriously flawed, and, when analyzed carefully, excludes RMT with high confidence. More recently, we carefully examined energy spacings for these same resonances in the NDE using the $\Delta_{3}$ statistic. We conclude that the data can be found to either confirm or refute the theory depending on which nuclides and whether known or suspected p-wave resonances are included in the analysis, in essence confirming results of our neutron-width analysis of the NDE. We also have examined radiation widths resulting from our Oak Ridge and Los Alamos measurements, and find that in some cases they do not agree with RMT. Although these disagreements presently are not understood, they could have broad impact on basic and applied nuclear physics, from nuclear astrophysics to nuclear criticality safety.