Relativistic and Non-Relativistic Mean Field Investigation of the Superdeformed Bands in 62^{62}Zn

Following the discovery of the superdeformed(SD) band in $^{62}$Zn, we calculate several low-lying SD bands in $^{62}$Zn using Relativistic Mean Field and Skyrme-Hartree-Fock models. Both models predict similar results, but still we can see some qualitative differences in the results of these two models, which are coming from the difference of the detail of single-particle levels.Comment: 17 pages, 4 eps figures included, uses REVTeX, discussion on other Zn isotopes than $^{62}$Zn is omitted, considerable modifications are don

Importance of Prolate Neutrino Radiation in Core-Collapse Supernovae: The Reason for the Prolate Geometry of SN1987A?

We have carried out 2-D simulations of core-collapse supernova explosions. The local neutrino radiation field is assumed to have its maximum value either at the symmetry (polar) axis or on the equatorial plane. These lead to the prolate and oblate explosions, respectively. We find that the gain of the explosion energy in the prolate explosion evolves more predominately than that in the oblate one when the total neutrino luminosity is given. Namely, the prolate explosion is more energetic than the oblate one. One of the authors (Shimizu et al. 2001) showed for the first time that globally anisotropic neutrino radiation produces more powerful explosion than the spherical neutrino radiation does. In our previous study (Madokoro et al. 2003), we improved the numerical code of Shimizu et al. and demonstrated that the globally anisotropic neutrino radiation yields more energetic explosion than spatially-fluctuated neutrino radiation does. Together with the result of this paper, we conclude that the globally anisotropic (prolate) neutrino radiation is the most effective way of increasing the explosion energy among various types of explosions investigated in these studies. We discuss the reason for this. Our result is suggestive of the fact that the expanding materials of SN1987A is observed to have a prolate geometry.Comment: 15 pages, including 7 figures, to appear in PAS

Relativistic mean field description for the shears band mechanism in 84^{84}Rb

For the first time, the Relativistic Mean Field (RMF) model is applied to the shears band recently observed in $_{37}^{84}$Rb. Signals of the appearance of the shears mechanism, such as smooth decreases of the shears angle and of the $B$(M1)/$B$(E2) ratio with keeping the nearly constant tilt angle, are well reproduced. Thus it is shown that the microscopic RMF model can nicely describe the shears band in this nucleus.Comment: 5 pages, 6 eps figures included, uses REVTeX and epsf.sty, to appear in Phys. Rev.

Core-Collapse Supernovae Induced by Anisotropic Neutrino Radiation

We demonstrate the important role of anisotropic neutrino radiation on the mechanism of core-collapse supernova explosions. Through a new parameter study with a fixed radiation field of neutrinos, we show that prolate explosions caused by globally anisotropic neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given. This is suggestive of the fact that the expanding materials of SN 1987A has a prolate geometry.Comment: in Proceedings of Int. conf. in hohour of the 60th birthday of Marcel Arnould, The Future Astronuclear Physics, From microscopic puzzles to macroscopic nightmares, Eds. H.M.J. Boffin et al., EAS Publication Series, EDP Sciences, in press (2004

Global Anisotropy Versus Small-Scale Fluctuations in Neutrino Flux in Core-Collapse Supernova Explosions

Effects of small-scale fluctuations in the neutrino radiation on core-collapse supernova explosions are examined. Through a parameter study with a fixed radiation field of neutrinos, we find substantial differences between the results of globally anisotropic neutrino radiation and those with fluctuations. As the number of modes of fluctuations increases, the shock positions, entropy distributions, and explosion energies approach those of spherical explosion. We conclude that global anisotropy of the neutrino radiation is the most effective mechanism of increasing the explosion energy when the total neutrino luminosity is given. This supports the previous statement on the explosion mechanism by Shimizu and coworkers.Comment: 14 pages, including 12 figures. To be published in the Astrophysical Journa

General Relativistic Mean Field Theory for Rotating Nuclei

We formulate a general relativistic mean field theory for rotating nuclei starting from the special relativistic $\sigma - \omega$ model Lagrangian. The tetrad formalism is adopted to generalize the model to the accelerated frame.Comment: 13 pages, REVTeX, no figures, submitted to Phys. Rev. Lett., the word `curved' is replaced by `non-inertial' or `accelerated' in several places to clarify the physical situation interested, some references are added, more detail discussions are given with omitting some redundant sentence