Time scales in nuclear giant resonances

TL;DR

This paper introduces a wavelet-based method to analyze fluctuations in nuclear giant resonance cross sections, revealing how decay time scales relate to fragmentation complexity and spreading widths.

Contribution

It presents a novel wavelet analysis approach to extract time scales of nuclear resonance decays and links fragmentation patterns to resonance widths.

Findings

Wavelet analysis successfully extracts decay time scales.

Fragmentation complexity correlates with spreading widths.

Analytic Fourier expansion confirms the relation between spectra and decay times.

Abstract

We propose a general approach to characterise fluctuations of measured cross sections of nuclear giant resonances. Simulated cross sections are obtained from a particular, yet representative self-energy which contains all information about fragmentations. Using a wavelet analysis, we demonstrate the extraction of time scales of cascading decays into configurations of different complexity of the resonance. We argue that the spreading widths of collective excitations in nuclei are determined by the number of fragmentations as seen in the power spectrum. An analytic treatment of the wavelet analysis using a Fourier expansion of the cross section confirms this principle. A simple rule for the relative life times of states associated with hierarchies of different complexity is given.