Statistical features of the thermal neutron capture cross sections

TL;DR

This paper investigates the unusually large thermal neutron capture cross sections in various nuclei, proposing a statistical model that links these phenomena to nuclear coherence and nucleosynthesis processes.

Contribution

It introduces the concept of statistical doorways to explain large cross sections and derives a relation between the average number of maxima and the mass correlation width.

Findings

Large cross sections are statistically random and similar to parity violation phenomena.

Derived formula relating maxima density to mass correlation width.

Links nuclear coherence to nucleosynthesis history.

Abstract

We discuss the existence of huge thermal neutron capture cross sections in several nuclei. The values of the cross sections are several orders of magnitude bigger than expected at these very low energies. We lend support to the idea that this phenomenon is random in nature and is similar to what we have learned from the study of parity violation in the actinide region. The idea of statistical doorways is advanced as a unified concept in the delineation of large numbers in the nuclear world. The average number of maxima per unit mass, $<n_A>$ in the capture cross section is calculated and related to the underlying cross section correlation function and found to be $<n_A> = 3/(\pi \sqrt{2}\gamma_{A})$, where $\gamma_{A}$ is a characteristic mass correlation width which designates the degree of remnant coherence in the system. We trace this coherence to nucleosynthesis which produced the nuclei whose neutron capture cross sections are considered here.