Di-neutron correlation in monopole two-neutron transfer modes in Sn isotope chain

Abstract

We study microscopic structures of monopole pair vibrational modes and associated two-neutron transfer amplitudes in neutron-rich Sn isotopes by means of the linear response formalism of the quasiparticle random phase approximation(QRPA). For this purpose we introduce a method to decompose the transfer amplitudes with respect to two-quasiparticle components of the QRPA eigen mode. It is found that pair-addition ibrational modes in neutron-rich ${}^{132-140}$Sn and the pair rotational modes in ${}^{142-150}$Sn are commonly characterized by coherent contributions of quasaiparticle states having high orbital angular momenta $l\text{gesim}5$, which suggests transfer of a spatially correlated neutron pair. The calculation also predicts a high-lying pair vibration, the giant pair vibration, emerging near the one-neutron separation energy in ${}^{110-130}$Sn, and we find that they have the same di-neutron characters as that of the low-lying pair vibration in ${}^{132-140}$Sn.

Comments: 30 pages, 10 figures