Skyrme-QRPA calculations for low-lying excitation modes in deformed neutron-rich nuclei

Kenichi Yoshida

doi:10.1140/epja/i2008-10742-y

EPJ

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2023 Impact factor 2.6

Hadrons and Nuclei

Eur. Phys. J. A (2009) 42: 583-590
https://doi.org/10.1140/epja/i2008-10742-y

Regular Article - Theoretical Physics

Skyrme-QRPA calculations for low-lying excitation modes in deformed neutron-rich nuclei

Kenichi Yoshida^*

Nishina Center for Accelerator-Based Science, RIKEN, 351-0198, Wako, Saitama, Japan

^* e-mail: Kenichi.Yoshida@riken.jp

Received: 8 December 2008
Revised: 13 January 2009
Accepted: 6 February 2009
Published online: 17 March 2009

Abstract

Low-frequency modes of excitation in deformed neutron-rich nuclei are studied by means of the quasiparticle random-phase approximation on the Skyrme-Hartree-Fock-Bogoliubov mean field. We investigate the microscopic structure of the soft $\ensuremath K^{\pi} = 0^{+}$ modes systematically in neutron-rich magnesium isotopes with N = 22, 24, 26 and 28 close to the drip line, and it is found that the strong collectivity in ³⁴Mg and ⁴⁰Mg is acquired due to the coherent coupling between the $\beta$ vibration and the pairing vibration of neutrons. Microscopic structure of the $\ensuremath K^{\pi} = 2^{+}$ modes changes gradually associated with the location of the Fermi level of neutrons, and it is found that the proton particle-hole excitation generating the $\gamma$ -vibrational mode in ²⁴Mg continues to play a key role in the near-drip-line nucleus ⁴⁰Mg . The low-frequency octupole excitations are also investigated and the microscopic mechanism for the enhancement of transition strengths is discussed.