Article

# Collective Excitations and Pairing Effects in Drip-Line Nuclei -- Continuum RPA in Coordinate-Space HFB --

Progress of Theoretical Physics Supplement (Impact Factor: 1.25). 03/2002; DOI: 10.1143/PTPS.146.110

Source: arXiv

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**ABSTRACT:**We investigate the neutron pair transfer modes associated with the low-lying quadrupole states in neutron-rich Sn isotopes by means of the quasiparticle random phase approximation based on the Skyrme-Hartree-Fock-Bogoliubov mean-field model. The transition strength of the quadrupole pair-addition mode feeding the 2â{sup +} state is enhanced in the Sn isotopes with A{>=}132. The transition density of the pair-addition mode has a large spatial extension in the exterior of the nucleus, reaching to râ12-13 fm. The quadrupole pair-addition mode reflects sensitively a possible increase of the effective pairing interaction strength in the surface and exterior regions of neutron-rich nuclei.Physical Review C 08/2010; 82(2):024318-024318. · 3.72 Impact Factor - [Show abstract] [Hide abstract]

**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 $l \gesim 5$, 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.Physical Review C 08/2013; 88(5). · 3.72 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We apply the continuum quasiparticle random phase approximation to calculate the direct neutron capture cross section relevant to the r-process nucleo-synthesis. The electric dipole strength function in an even-even n-rich nucleus is decomposed with respect to the channels of direct neutron decays. Using the detailed balance relation, the partial dipole strengths are converted to obtain the direct neutron-capture cross sections. Numerical examples are given for 142Sn.Journal of Physics Conference Series 07/2013; 445(1):2019-.

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