Azimuthal angle distributions of neutrons emitted from the $^9$Be($\gamma$,$n$) reaction with linearly polarized $\gamma$-rays

TL;DR

This study investigates how the azimuthal angle distributions of neutrons emitted from the $^9$Be($, n$) reaction with linearly polarized gamma rays can reveal nuclear resonances and transition modes, using advanced theoretical models.

Contribution

The paper introduces a theoretical approach combining a three-body model and complex-scaled solutions to analyze neutron emission distributions in polarized gamma-ray reactions.

Findings

Azimuthal neutron distributions are sensitive to nuclear structure.

Distribution patterns can identify resonances not visible in cross sections.

The anisotropy parameter varies with photon energy, indicating transition mode sensitivity.

Abstract

The electromagnetic transitions of $^9$Be with linearly polarized $\gamma$-rays are calculated by using the $\alpha$~+~$\alpha$~+~$n$ three-body model and the complex-scaled solutions of the Lippmann-Schwinger equation; the azimuthal angle distributions of the emitted neutrons are investigated. We calculate the anisotropy parameter as a function of the photon incident energy $E_\gamma$, and discuss how sensitive the anisotropy parameter is to nuclear structure and transition modes. The result suggests that the azimuthal angle distribution of neutrons emitted from the $^9$Be($\gamma$,$n$) reaction with the linearly polarized $\gamma$-rays is useful to identify the resonances in the final states even if it is not clearly observed in the cross section.