Photodisintegration cross section of $^9$Be up to 16 MeV in the $\alpha$ + $\alpha$ + n three-body model

TL;DR

This study investigates the photodisintegration cross section of $^9$Be up to 16 MeV using a three-body model and complex scaling, revealing different dominant processes in low and high energy regions.

Contribution

It introduces a three-body model combined with complex scaling to analyze $^9$Be photodisintegration, clarifying the roles of resonant and continuum states.

Findings

Cross section explained by resonant state transitions below 6 MeV.

Dipole transition into non-resonant continuum dominates from 6 to 16 MeV.

Dipole strength at 8 MeV linked to single-neutron excitation.

Abstract

The photodisintegration of $^9$Be in the energy region lower than $E_\gamma = 16$ MeV is investigated by using the $\alpha$~+~$\alpha$~+~$n$ three-body model and the complex scaling method. The cross section exhibits two aspects in the different two energy regions. In the low energy region up to $E_\gamma = 6$ MeV, the cross section is explained by the transition strengths into the excited resonant states of $^9$Be, while the dipole transition into the non-resonant continuum states of $^8$Be(2$^+$)~+~$n$ dominates the cross section in the energy region of $6 \le E_\gamma \le 16$ MeV. Furthermore, it is shown that the dipole strength at $E_\gamma \sim 8$ MeV is understood to be caused by the single-neutron excitation from the $^8$Be(2$^+$)~$\otimes$~$\nu p_{3/2}$ configuration in the ground state.