Neutron Resonance Data Exclude Random Matrix Theory

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.

14 pages, 9 figures, submitted to special issue of Fortschritte Der Physik, Quantum Physics with Non-Hermitian Operators

References in corpus (6)

• Background identification and suppression for the measurement of (n,g) reactions with the DANCE array at LANSCE
• Distribution of Partial Neutron Widths for Nuclei close to a Maximum of the Neutron Strength Function
• Spin measurements for 147Sm+n resonances: Further evidence for non-statistical effects
• Porter-Thomas distribution in unstable many-body systems
• Resonance width distribution for open quantum systems
• Abrupt Change in Radiation-Width Distribution for 147Sm Neutron Resonances

Cited by in corpus (5)

• Power-law random banded matrices and ultrametric matrices: eigenvector distribution in the intermediate regime
• Modification of the Porter-Thomas distribution by rank-one interaction
• Neutron Resonance Widths and the Porter-Thomas Distribution
• Open Problems in Applying Random-Matrix Theory to Nuclear Reactions
• Test of the Porter-Thomas distribution with the total cross section autocorrelation function