Mean-field approach to superdeformed high-spin states in 40Ca and neutron-rich 50S regions

With the use of the symmetry-unrestricted cranked SHF method in the 3D coordinate-mesh representation, a systematic search for the SD and HD rotational bands in the N=Z nuclei from 32S to 48Cr has been done, and SD and HD solutions have been found in 32S, 36Ar, 40Ca, 44Ti, and in 36Ar, 40Ca, 44Ti, 48Cr, respectively. The SD band in 40Ca is found to be extremely soft against both the axially symmetric (Y30) and asymmetric (Y31) octupole deformations. Possible presense of SD states in neutron-rich sulfur isotopes from 46S to 52S has also been investigated, and deformation properties of neutron skins both in the ground and SD states are discussed.Comment: 10 pages including 9 ps figures, Talk at International Symposium on "Frontiers of Collective Motion 2002", November 6-9, 2002, Univ. of Aizu, Japa

Superdeformed bands in neutron-rich Sulfur isotopes suggested by cranked Skyrme-Hartree-Fock calculations

On the basis of the cranked Skyrme-Hartree-Fock calculations in the three-dimensional coordinate-mesh representation, we suggest that, in addition to the well-known candidate 32S, the neutron-rich nucleus 36S and the drip-line nuclei,48S and 50S, are also good candidates for finding superdeformed rotational bands in Sulfur isotopes. Calculated density distributions for the superdeformed states in 48S and 50S exhibit superdeformed neutron skinsComment: 18 pages including 10 ps figure

Pairing and continuum effects on low-frequency quadrupole vibrations in deformed Mg isotopes close to the neutron drip line

Low-frequency quadrupole vibrational modes in deformed $^{36,38,40}$Mg close to the neutron drip line are studied by means of the quasiparticle-random-phase approximation based on the coordinate-space Hartree-Fock-Bogoliubov formalism. Strongly collective $K^{\pi}=0^{+}$ and $2^{+}$ excitation modes carrying 10-20 Weisskopf units in the intrinsic isoscalar quadrupole transition strengths are obtained at about 3 MeV. There are two reasons for the enhancement of the transition strengths. First, the quasiparticle wave functions generating these modes possess spatially very extended structure. The asymptotic selection rules characterizing the $\beta$ and $\gamma$ vibrations in stable deformed nuclei are thus strongly violated. Second, the dynamic pairing effects act strongly to enhance the collectivity of these modes. It is suggested that the lowest $K^{\pi}=0^{+}$ collective mode is a particularly sensitive indicator of the nature of pairing correlations in deformed nuclei close to the neutron drip line.Comment: 23 pages including 11 figures and 8 tables. Submitted to NP

Mixed Representation RPA Calculation for Octupole Excitations on Superdeformed Sates in the 40Ca and Neutron-Rich Sulfur Regions

By means of the mixed representation RPA based on the Skyrme-Hartree-Fock mean field, we investigate low-frequency octupole excitations built on the superdeformed (SD) states in the N=Z nuclei around 40Ca and the neutron-rich Sulfur isotopes. The RPA calculation is carried out fully self-consistently on the three-dimensional Cartesian mesh in a box, and yields a number of low-frequency octupole vibrations built on the SD states in 32S, 36Ar, 40Ca and 44Ti. In particular, a strongly collective K^\pi=1^- octupole vibration is suggested to appear on top of the SD state in 40Ca. For 48,50S close to the neutron drip line, we find that the low-lying state created by the excitation of a single neutron from a loosely bound low Omega level to a high Omega resonance level acquires an extremely strong octupole transition strength due to the spatially very extended structure of the particle-hole wave functions.Comment: 22 pages, 7 figure