Band Structures of 182^{182} Os Studied by GCM based on 3D-CHFB

Band structure properties of $^{182}$Os are investigated through a particle number and angular momentum constrained generator coordinate(GCM) calculation based on self-consistent three-dimensional cranking solutions. From the analysis of the wave function of the lowest GCM solution, we confirm that this nucleus shows a tilted rotational motion in its yrast states, at least with the present set of force parameters of the pairing-plus-quadrupole interaction Hamiltonian. A close examination of behavior of other GCM solutions reveals a sign of a possible occurrence of multi-band crossing in the nucleus. Furthermore, in the course of calculations, we have also found a new potential curve along the prime meridian on the globe of the $J=18\hbar$ sphere. Along this new solution the characters of proton and neutron gap parameters get interchanged. Namely, $\Delta_p$ almost vanishes while $\Delta_n$ grows to a finite value close to the one corresponding to the principal axis rotation(PAR). A state in the new solution curve at the PAR point turns out to have almost the same characteristic features of an yrare $s$-band state which gets located just above the $g$-band in our calculation. This fact suggests a new type of seesaw vibrational mode of the proton and the neutron pairing, occurring through a wobbling motion. The mode is considered to bridge the $g$-band states and the $s$-band states in the backbending region.Comment: LaTeX 19 pages; 14 ps figures; 1 table; submitted to Nucl.Phys.

Band Crossing studied by GCM with 3D-CHFB

We solved the constrained Hill-Wheeler Equation, and found several signatures of multi-band crossing in 182 Os.Comment: LaTeX 3 pages, 3 eps figures; Contribution to International Conference, Nuclear Structure at the extreme,Lewes, UK, (1998) Jun.17-1

Wobbling motion in the multi-bands crossing region

The backbending in the A=180 mass region is expected to be caused by multi-bands crossing between low-K (g- and s-bands) and high-K bands. % We analyze a mechanism of coupling of these bands in terms of a dynamical treatment for nuclear rotations, i.e., the wobbling motion. The wobbling states are produced through the generator coordinate method after angular momentum projection, in which the intrinsic states are constructed through the 2d-cranked HFB calculations.Comment: 9 pages, 3 PS figures: to appear in Phys.Lett.

Signature and Angular Momentum in 3d-Cranked HFB states

In terms of the exaxt angular momentum projection, properties of the three dimensional cranked HFB (3d-CHFB) states are analyzed quantitatively in the context of the relation between the signature of an intrinsic symmetry and the parity of angular momentum, (-1)^I. We found that the tilted states have favorable features to describe states involved with high-K quantum number and/or odd total angular momentum. This implies that 3d-CHFB can describe properly the backbending phenomena like a "t-band and g-band" crossing, which is suggested in N=106 isotopes.Comment: 10 pages, 2 figure

Restoration of the Broken D2-Symmetry in the Mean Field Description of Rotating Nuclei

Signature effects observed in rotational bands are a consequence of an inherent D2-symmetry. This symmetry is naturally broken by the mean field cranking approximation when a tilted (non-principal) axis orientation of the nuclear spin becomes stable. The possible tunneling forth and back between the two symmetry-related minima in the double-humped potential-energy surface appears as a typical bifurcation of the rotational band. We describe this many-body process in which all nucleons participate by diagonalizing the nuclear Hamiltonian within a selected set of tilted and non-tilted cranking quasiparticle states. This microscopic approach is able to restore the broken D2 symmetry and reproduce the quantum fluctuations between symmetry- related HFB states which emerge as splitting of the band energies and in parallel staggering in intraband M1 transitions.Comment: 9 pages, 4 figure

Stability of s-band states in the tilting calculation of 182Os

We carried out the three-dimensional cranking calculations for osmium 182Os within the Hartree-Fock-Bogoliubov framework. It turned out that the state in the g-band is stable (unstable) with respect to the tilt angle of the cranking axis when the angular momentum is below (above) a critical value. However, the states in the s-band with the angular momentum below 30[h-bar] are unstable everywhere along the band. In our model calculations, the wobbling motion does not exist on top of the s-band state characterized by the component of two aligned particles

Symposium on the biology of cells modified by viruses or antigens. II.: On the Analysis of Antibody Synthesis at the Cellular Level

The title of this symposium implies a similarity which is not obvious between the cellular responses to virus infection and to antigenic stimulation. In fact, no analogy between these two types of cellular response is apparent either from a consideration of the natures of the stimuli, a specific nucleotide sequence on the one hand and almost any foreign chemical configuration on the other, or from an examination of the products of the response, identical units in the case of the virus and complementary antibody units in the case of the antigen

Three-dimensional rotation of even-even triaxial nuclei

With the self-consistent three-dimensional cranked Hartree-Fock-Bogoliubov (3d-cranked HFB) method, various types of rotational motion near the yrast line are investigated in an even-even nucleus in the $A\simeq 130$ mass region ($^{134}_{58}$Ce$_{76}$). The possibilities of chiral rotations, tilted-rotations, and dynamical aspects of these rotations are discussed through the analysis of the 3d-cranked HFB solutions. Although a stable planar solution of the chiral rotation is obtained, an aplanar chiral configuration is found to be unstable when triaxial deformation is treated self-consistently.Comment: 4 pages, 3 figures; accepted for publication in Phys. Lett.