Octupole vibrations of deformed nuclei

The octupole vibrations of deformed nuclei are studied. A strong coupling between the harmonic octupole vibrations and the quadrupole ellipsoid is assumed. This interaction gives rise to a splitting of octupole bands with different projection quantum numberK. TheE1-transitions of the octupole states are explained within the frame of the Dynamic Collective Theory ofDanos andGreiner by calculating the Coulomb interaction between octupole vibrations and giant resonances. Furthermore, theE2- andE3-transitions of the octupole states are studied. The spectrum of W¹⁸² is investigated in detail. A fair agreement between theory and experiment is obtained. Predictions for the octupole spectra of Sm¹⁵² and Gd¹⁵⁶ are given.     

On the isoscalar vibrations in axially deformed nuclei

Using the cranking model we show that the normal modes of isoscalar vibrations in axially deformed nuclei are essentially vibrations parallel and orthogonal to the symmetry axis. This leads to the fragmentation of the E0 and E2 giant resonance strengths in these nuclei.     

Reduced probabilities of gamma transitions in even-even deformed nuclei

The reduced probabilities of the E2 intraband and interband transitions in even-even erbium isotopes (A=158–170) andN=94 isotones (A=158–164) are analysed in the frame of the perturbation theory assuming the mixing of the wave functions of ground, beta- and gammavibrational states as well as different values of the intrinsic quadrupole moments of these states.We would like to thank J. Dobe and J. Zvolský for useful discussions.     

Interaction and fusion of deformed nuclei

It is shown that the height of the barrier and its position, as well the depth of the capture well, are highly sensitive to the relative orientation of colliding strongly deformed nuclei. It is found that the fusion/capture cross sections and the nucleus-nucleus potential for heavy nuclear systems depend greatly on the magnitude and sign of the quadrupole deformation of nuclear surfaces. In order to describe correctly the cross section for the capture of heavy strongly deformed nuclei, it is necessary to perform averaging over all three angles that describe their relative orientation. Allowance for a hexadecapole deformation leads to a significant increase in the capture cross section for very heavy nucleus-nucleus systems.     

Photofission of nuclei with allowance for wriggling vibrations of fissioning nuclei

It is confirmed that one source of the large relative orbital momenta L of fragments in spontaneous and stimulated low-energy nuclear fission is quantum transverse zero-point wriggling vibrations of the fissioning system near its scission point. The angular distributions of fragments of low-energy photofission of actinide nuclei, calculated using the quantum theory of fission, are compared. Vibrations are allowed for by using parameter C _w determined by Nix and Swiatecki. Agreement between the experimental and theoretical angular distributions for ²³⁴U, ²³⁶U, ²³⁸U, ²³⁸Pu, ²⁴⁰Pu, ²⁴²Pu nuclei is observed. The strong sensitivity of the theoretical angular distributions for ²³⁸Pu, ²⁴⁰Pu, ²⁴²Pu nuclei toward the choice of parameters of transient fissioning states at the external and internal fission barriers is demonstrated.     

Evidence for hexadecapole vibrations in A ≈ 170 deformed nuclei; New results for 168Yb

Dominating proton structure has been identified in the K^π=3⁺ band of ¹⁶⁸Yb, contrasting with neutron structure in the corresponding band of ¹⁷²Yb. A region of low-lying K^π=3⁺ bands is now established, with N=98?104, Z=68?72. For all stable nuclei in this region, the I^πK=4⁺3 state is excited by inelastic deutron scattering.     

Surface diffuseness of deformed and rotating nuclei

The surface diffuseness of deformed and rotating nuclei has been studied using the energy density formalism. It is shown that the surface diffuseness exhibits an anisotropy. This anisotropy in surface diffuseness can result in an anisotropic charged particle emission from highly spinning nuclei as has been seen in some recent experiments.     

Investigation of deformed nuclei with a new potential combination

We investigate the alpha-decay half-lives of non-spherical nuclei with the Yukawa potential as the prox- imity potential and an angle-dependent term that accounts for the deformation effects and apply the results to Ho, Tb, Lu, Tin, Ta, Hf, Yb, Re, Ir, Pt, Au, Po, etc. as examples. The comparison with the existing data is encouraging.     

Study of giant pairing vibrations with neutron-rich nuclei

We investigate the possible signature of the presence of giant pairing states at an excitation energy of about 10 MeV via two-particle transfer reactions induced by neutron-rich weakly bound projectiles. Performingparticle-particle RPA calculations on ²⁰⁸Pb and BCS + RPA calculations on ¹¹⁶Sn, we obtain the pairing strength distribution for two-particle addition and removal modes. Estimates of two-particle transfer cross sections can be obtained in the framework of the macroscopic model. The weak-binding nature of the projectile kinematically favors transitions to high-lying states. In the case of the (⁶He, ⁴He) reaction, we predict a population of the Giant Pairing Vibration with cross sections of the order of a millibarn, dominating over the mismatched transition to the ground state.     

On the shape of deformed nuclei

Shape observables measuring the intrinsic quadrupole deformation of the nucleus are identified. The consequences of these shape operators for the collective rotational and SU(3) models are derived. The operator measuring the square of the K quantum number is given.     

Regular and chaotic motion of coupled rotators

We consider a classical Hamiltonian H = L_z+M_z+L_xM_x, where the components of L and M satisfy Poisson brackets similar to those of angular momenta. There are three constants of motion: H, L² and M². By studying Poincaré surfaces of section, we find that the motion is regular when L² or M² is very small or very large. It is chaotic when both L² and M² have intermediate values. The interest of this model lies in its quantization, which involves finite matrices only.     

Magnetic properties of odd-odd deformed nuclei

Magnetic moments and Ml transition probabilities depend on the parameters $\text{g}{}_{\mathrm{R}}\text{, g}{}_{\mathrm{\Omega }}{}_{\mathrm{<mtext>p</mtext>}}\text{,}\text{and}\text{g}{}_{\mathrm{\Omega }}{}_{\mathrm{<mtext>n</mtext>}}$ in odd-odd deformed nuclei. The parameter g_R can be obtained from an intraband branching ratio and a magnetic moment. Available data are analyzed and compared with predictions of the unified model.     

gR and gK factors in deformed nuclei

The static and dynamic magnetic dipole moments of odd-mass and even-mass nuclei with 150R and intrinsic g-factors g_K.     

Tilted rotation of weakly deformed and triaxial nuclei

The Tilted Axis Cranking theory is reviewed. It is used to describe the appearance of magnetic rotation in weakly deformed nuclei. The possibility of aplanar solutions and their experimental signature are discussed.     

Relativistic description of deformed rare earth nuclei

Ground state properties of heavy deformed nuclei in the rare earth region are described in the framework of the relativistic Hartree approximation. Both linear and non-linear parameter sets of the lagrangian are used. The non-linear sets reproduce the experimentally observed binding energies, the charge radii and the quadrupole moments, with the same quality as non-relativistic density dependent mean field calculations with Skyrme forces.