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

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.

Comments: 17 pages, 6 figures, 3 tables, submitted to PRC