Proton and neutron correlations in ¹⁰B

Abstract

We investigate positive-parity states of ¹⁰B with the calculation of antisymmetrized molecular dynamics focusing on pn pair correlations. We discuss effects of the spin-orbit interaction on energy spectra and pn correlations of the J^πT = 1<inf>1</inf>⁺0, 3<inf>1</inf>⁺0, and 0<inf>1</inf>⁺1 states. The 1<inf>1</inf>⁺0 state has almost no energy gain of the spin-orbit interaction, whereas the 3<inf>1</inf>⁺0 state gains the spin-orbit interaction energy largely to come down to the ground state. We analyze the spin-orbit interaction dependence of the ¹⁰B spectra and find that the ordering of the 3<inf>1</inf>⁺0 and 1<inf>1</inf>⁺0 states is sensitive to the spin-orbit interaction. We also apply a 2α + pn model to discuss effects of the spin-orbit interaction on T = 0 and T = 1 pn pairs around the 2α core. In the spin-aligned JπT = 3⁺0 state, the spin-orbit interaction affects the (ST) = (10) pair attractively and keeps the pair close to the core, whereas, in the 1⁺0 state, it gives a minor effect to the (ST) = (10) pair. In the 0⁺1 state, the (ST) = (01) pair is somewhat dissociated by the spin-orbit interaction.