Quenching of gamma0 transition results from p-wave neutron inducing doorway mechanism

TL;DR

This paper investigates the quenching of gamma_0 transitions in p-wave neutron resonances of 57Fe, revealing a doorway mechanism that influences gamma-strength functions and has implications for astrophysical neutron capture rates.

Contribution

It introduces the first observation of gamma_0 transition quenching due to a doorway mechanism in 57Fe, linking nuclear reaction mechanisms to astrophysical processes.

Findings

Quenching of gamma_0 transition observed in 57Fe p-wave neutron resonance.

Doorway mechanism activates non-forming 2p-1h states affecting gamma intensities.

Enhanced low-energy gamma-strength function impacts neutron capture cross sections.

Abstract

Gamma-strength function essentially distinguishes the reaction mechanisms of charged particle inelastic and neutron capture reactions, reflecting from the ratios of transition of neutron capture to low-lying states. The extraordinary quenching of gamma_0 transition of p-wave neutron resonance reaction in 3s-region nucleus 57Fe is observed, for the first time, due to the non-forming 2p-1h doorway state activation which raises the strong intensities of gamma_1 and gamma_2. The enhancement of low energy gamma-strength function doesn't emerge in the neutron capture reaction resulting from the population of cascade transitions of low-lying states rather than primary transitions. The astrophysical reaction rates that are extracted from total and partial neutron capture cross sections of 57Fe might be adopted to constrain the abundance of the successive heavier isotopes in s-process.