Neutron width statistics in a realistic resonance-reaction model

Abstract

A recent experiment on s-wave neutron scattering from ${}^{192,194,196}$Pt found that the reduced neutron width distributions deviate significantly from the expected Porter-Thomas distribution (PTD), and several explanations have been proposed within the statistical model of compound nucleus reactions. Here, we study the statistics of reduced neutron widths in the reaction $n{+}^{194}$Pt within a model that combines the standard statistical model with a realistic treatment of the neutron channel. We find that, if the correct secular energy dependence of the average neutron widths is used, then the reduced neutron width distribution is in excellent agreement with the PTD for a reasonable range of the neutron-nucleus coupling strength and depth of the neutron channel potential. Within our parameter range, there can be a near-threshold bound or virtual state of the neutron channel potential that modifies the energy dependence of the average width from the $\sqrt{E}$ dependence, commonly assumed in experimental analysis, in agreement with the proposal of H. A. Weidenmüller [1]. In these cases, the reduced neutron width distributions extracted using the $\sqrt{E}$ dependence are significantly broader than the PTD. We identify a relatively narrow range of parameters where this effect is significant.

5 pages, 4 figures, 1 table, accepted for publication in Phys. Rev. C

References in corpus (5)

• Numerical methods for calculating poles of the scattering matrix with applications in grating theory
• Distribution of Partial Neutron Widths for Nuclei close to a Maximum of the Neutron Strength Function
• Modification of the Porter-Thomas distribution by rank-one interaction
• Resonance width distribution in RMT: Weak coupling regime beyond Porter-Thomas
• Porter-Thomas distribution in unstable many-body systems

Cited by in corpus (6)

• Statistical-model description of $\gamma$ decay from compound-nucleus resonances
• Derivation of K-matrix reaction theory in a discrete basis formalism
• A Model for Scattering with Proliferating Resonances: Many Coupled Square Wells
• Applications of the Modified Hulthén-Kohn Method for Bound and Scattering States
• Coupled-cluster computations of optical potential for medium-mass nuclei
• Test of the Porter-Thomas distribution with the total cross section autocorrelation function