Low-energy magnetic radiation: deviations from GOE

TL;DR

This paper uses Shell Model calculations to identify a low-energy spike in magnetic radiation strength functions, explaining experimental enhancements and predicting effects on r-process nucleosynthesis, with deviations from random matrix theory.

Contribution

It reveals a low-energy magnetic radiation phenomenon (LEMAR) originating from complex state transitions, which deviates from GOE predictions and impacts astrophysical reaction rates.

Findings

Identifies a low-energy spike in magnetic radiation strength functions.

Predicts LEMAR's impact on r-process nucleosynthesis.

Finds deviations from GOE in strength function behavior.

Abstract

A pronounced spike at low energy in the strength function for magnetic radiation (LEMAR) is found by means of Shell Model calculations, which explains the experimentally observed enhancement of the dipole strength. LEMAR originates from statistical low-energy M1-transitions between many excited complex states. Re-coupling of the proton and neutron high-j orbitals generates the strong magnetic radiation. LEMAR is closely related to Magnetic Rotation. LEMAR is predicted for nuclides participating in the r-process of element synthesis and is expected to change the reaction rates. An exponential decrease of the strength function and a power law for the size distribution of the $B(M1)$ values are found, which strongly deviate from the ones of the GOE of random matrices, which is commonly used to represent complex compound states.