Test of the Porter-Thomas distribution with the total cross section autocorrelation function

TL;DR

This paper investigates whether the total cross section autocorrelation function can test the Porter-Thomas distribution in compound nucleus reactions, especially in regimes of weakly overlapping resonances, challenging traditional assumptions.

Contribution

It proposes analyzing total cross section data in the overlapping resonance regime to assess deviations from the Porter-Thomas distribution, expanding beyond isolated resonance studies.

Findings

Supports analysis of total cross section data for PTD deviations

Suggests potential deviations from PTD in overlapping resonance regimes

Highlights importance for statistical reaction theory

Abstract

On the basis of experiments conducted in the 1970s and earlier, it is believed that, in a compound nucleus (CN), fluctuations in transition strengths are drawn from a Porter-Thomas distribution (PTD), a $\chi^2$ distribution of one degree of freedom. However, work done post-1990 at the Los Alamos Neutron Science Center (LANSCE) and Oak Ridge Electron Linear Accelerator (ORELA) facilities has yielded instances of neutron resonance data sets of superior quality that are inconsistent with the PTD. In view of the importance of the status of the PTD to the foundations of statistical reaction theory, the question arises whether other data acquired at these facilities can be mined for evidence of deviations from the PTD? To date, the focus has been on data taken in the regime of isolated resonances. In this letter, arguments are put forward in support of the analysis of measurements of the total cross section in the regime where resonances are weakly overlapping.