Shell-model calculations for two-neutron transfer near the N=20 island of inversion

We have performed shell-model calculations of two-neutron amplitudes (TNA) relevant for the two-neutron transfer reactions ²⁸Mg(t,p)³⁰Mg and ³⁰Mg(t,p)³²Mg. The neutron-rich isotopes of Mg are central to the understanding of intruder configurations responsible for the “Island of Inversion” at N=20. Of particular interest are 0⁺ states populated in (t,p) reactions as shown by early studies more than 10 years ago [1]. With coming radioactive-beam facilities, new experiments are planned for similar studies. We use shell-model calculations with two interactions, SDPF-MU and SDPF-M, to illustrate how different nuclear structure leads to different predictions for observables in the 2n transfer reactions ^28,30Mg(t,p)^30,32Mg. Reaction strengths were obtained using calculated Two Neutron Amplitudes (TNA) as input to Distorted-Wave Born Approximation cross-section calculations. The shell-model calculations were performed using the code “KSHELL” [2] and ran on the High-Performance Computing Facility at the University of Connecticut. The results of the calculations and the implications for future studies of two-neutron transfer in the Mg region will be discussed.

[1] K. Wimmer et al., Phys. Rev. Lett. 105, 252501 (2010).

[2] N. Shimizu et al., Comp. Phys. Comm. 244, 372 (2019).