Di-neutron correlation in monopole two-neutron transfer modes in the 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 vibrational 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 > ∼ 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.

New isomer found inSb8951140: Sphericity and shell evolution betweenN=82andNLozeva1, Naïdja2, Nowacki3 et al. 2016Phys. Rev. C25190View full textAdd to dashboardCite

“…Within the SM framework and empirical interactions an effect of sub-shell gap was suggested in [30] between the νf 7/2 and the νp 3/2 orbitals at N =90. According to an independent Hartree Fock Bogoliubov MF calculation within a neutron Cooper-pair transfer formalism in [31], a structural change may be expected in 140 Sn. It could, however, be very localized and with almost equidistant spacing between these νf 7/2 and the νp 3/2 orbitals at 142 Sn.…”

Two-neutron transfer in Sn isotopes beyond theN=82shell closure

“…[13], where both pair-addition and pair-removal transitions were considered, although most of the attention was focused on the former. However, in [14] a microscopic analysis of the predictions reported in the study of Ref. [13] was performed, showing that a large number of both weakly bound and unbound states is responsible for the obtained results.…”

“…This choice is motivated by the possibility to have a comparison with the results of Refs. [12][13][14]. In these studies only transfers of nucleonic pairs to low-lying 0 + states were investigated, with the aim of exploring the properties of the pairing force for neutron-rich nuclei.…”

“…This is a subject of great current interest, especially with regard to the latter reaction, which is likely to be performed in the near future employing a 134 Sn RIB impinging on a tritium gas target. Recently, the two-neutron transfer mode in neutron-rich Sn isotopes beyond N = 82 has been studied [12][13][14] with emphasis put on the character of pairing correlations. In these studies, microscopic nuclear structure calculations have been performed within the Hartree-Fock-Bogoliubov (HFB) plus quasiparticle random phase approximation (QRPA) approach.…”

Collective inertia of the Nambu-Goldstone mode from linear response theory

“…V D, translational symmetry is not an exact symmetry of the system if the single-particle states are expressed in a finite harmonic oscillator basis, and the strength function is approximated by Eq. (56). Therefore the value of the strength function at ω = 0 is finite, and there is a lowenergy pole that corresponds to a spurious excitation of the center of mass mode.…”