J. Kvasil

Description of the dipole giant resonance in heavy and superheavy nuclei within Skyrme random-phase approximation

W. Kleinig, V.O. Nesterenko, J. Kvasil, P.-G. Reinhard and P. Vesely 1 Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna, Moscow region, 141980, Russia∗ 2 Technische Universität Dresden, Inst. für Analysis, D-01062, Dresden, Germany 3 Institute of Particle and Nuclear Physics, Charles University, CZ-18000, Praha 8, Czech Republic and 4 Institut für Theoretische Physik II, Universität Erlangen, D-91058, Erlangen, Germany (Dated: May 30, 2008)

Separable random phase approximation for self-consistent nuclear models

Self-consistent factorization of two-body residual interaction is proposed for arbitrary density- and current-dependent energy functionals. Following this procedure, a separable RPA (SRPA) method is constructed. SRPA considerably simplifies the calculations and demonstrates quick convergence to exact results. The method is tested for SkI3 and SkM* forces.

Octupole deformations in actinides at high spins within the cranking Skyrme-Hartree-Fock approach

The cranked Skyrme III effective Hamiltonian is applied for the analysis of the rotational dependence of the quadrupole and octupole moments in Ra, Th and U isotopes. A comparison of the intrinsic electric dipole moments calculated in the model with available experimental and theoretical values is presented. It is found that the non-axial octupole deformation Y32 becomes favourable at high spins for the actinide nuclei.

Enhanced and quenched B(E1) transition rates between parity doublet bands in 227Ra

Abstract The fast timing βγγ ( t ) method has been used to measure level lifetimes in the parity doublet bands in 227 Ra populated in the β − decay of 227 Fr. In particular T 1 2 = 254(9) ps , 236(30) ps , ⩽41 ps and 16(13) ps have been measured for the 3 2 − and 5 2 − members of the K π = 3 2 − band and for the 1 2 − and 3 2 − members of the K π = 1 2 − band, respectively. These results indicate surprisingly fast B (E1) rates in this octupole transitional nucleus with the average | D 0 | value of ⩾ 0.11 e ·fm for the K π = 1 2 − band and | D 0 |= 0.10 e ·fm for K π = 3 2 − band. The general enhancement (and occasional quenching) of E1 intra-doublet and some enhanced extra-doublet transitions in 227 Ra are interpreted within the quasiparticle-plus-phonon model with the inclusion of Coriolis coupling. Similar calculations, performed for 223 Ra, are found to be in good agreement with the experimental data.

General treatment of vortical, toroidal, and compression modes

The multipole vortical, toroidal, and compression modes are analyzed. Following the vorticity concept of Ravenhall and Wambach, the vortical operator is derived and related in a simple way to the toroidal and compression operators. The strength functions and velocity fields of the modes are analyzed in {sup 208}Pb within the random-phase approximation using the Skyrme force SLy6. Both convection and magnetization nuclear currents are taken into account. It is shown that the isoscalar (isovector) vortical and toroidal modes are dominated by the convection (magnetization) nuclear current while the compression mode is fully convective. The relation between the above concept of the vorticity and the hydrodynamical vorticity is briefly discussed.

Spin-flip M1 giant resonance as a challenge for Skyrme forces

Despite a great success of the Skyrme mean-field approach in the exploration of nuclear dynamics, it seems to fail in the description of the spin-flip M1 giant resonance. The results for different Skyrme parameterizations are contradictory and poorly agree with experiment. In particular, there is no parameterization which simultaneously describes the one-peak gross structure of M1 strength in doubly magic nuclei and two-peak structure in heavy deformed nuclei. The reason of this mismatch could lie in an unsatisfactory treatment of spin correlations and spin–orbit interaction. We discuss the present status of the problem and possible ways of its solution. In particular, we inspect (i) the interplay of the collective shift and spin–orbit splitting, (ii) the isovector M1 response versus isospin-mixed responses and (iii) the role of tensor and isovector spin–orbit interaction.

The influence of phonon admixture and non-adiabatic effects in the even-even core on the coriolis mixing of odd nuclei states

Some generalizations of the model for odd nuclei suggested by Kerman are considered. The effects of phonon admixtures on matrix elements of Coriolis interaction are studied. Several schemes are considered for studying the role of non-adiabatic effects in the even-even core.

TDDFT with Skyrme forces: Effect of time-odd densities on electric giant resonances

Time-odd densities and their effect on electric giant resonances are investigated within the self-consistent separable random-phase-approximation (SRPA) for a variety of Skyrme forces (SkT6, SkO, SkM*, SIII, SGII, SLy4, SLy6, SkI3). Time-odd densities are essential for maintaining the Galilean invariance of the Skyrme functional. Their contribution is determined by the values and signs of the isovector and isoscalar effective-mass parameters of the force. In even-even nuclei these densities are not active in the ground state but can affect the dynamics. As a particular case, we explore the role of the current density in the description of isovector E1 and isoscalar E2 giant resonances in a chain of spherical and deformed Nd isotopes with A=134-158. The relation of the current to the effective masses and relevant parameters of the Skyrme functional is analyzed. It is shown that the current contributes substantially to E1 and E2 and the contribution is the same for all the isotopes along the chain, i.e. for both standard and exotic nuclei.

The Nuclear Structure of 229Th

E. Ruchowska,1,∗ W. A. Plociennik,1,† J. Żylicz,2 H. Mach,3 J. Kvasil,4 A. Algora,5 N. Amzal,6 T. Back,7 M. G. Borge,8 R. Boutami,8 P. A. Butler,6 J. Cederkall,9 B. Cederwall,7 B. Fogelberg,3 L. M. Fraile,9,‡ H. O. U. Fynbo,9 E. Hagebo,10 P. Hoff,10 H. Gausemel,10 A. Jungclaus,8 R. Kaczarowski,1 A. Kerek,7 W. Kurcewicz,2 K. Lagergren,7 E. Nacher,5 B. Rubio,5 A. Syntfeld,1 O. Tengblad,8 A. A. Wasilewski,1 and L. Weissman9 1The Andrzej Soltan Institute for Nuclear Studies, PL 05-400 Świerk, Poland 2Institute of Experimental Physics, University of Warsaw, PL 00-681 Warsaw, Poland 3Department of Radiation Sciences, University of Uppsala, SE-751 21 Uppsala, Sweden 4Department of Nuclear Physics, Charles University, CZ-18000 Prague 8, Czech Republic 5Instituto de Fizica Corpuscular, CSIC-University Valencia, E-46100 Burjassot, Spain 6Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 3BX, United Kingdom 7Physics Department, Royal Institute of Technology, SE-106 91 Stockholm, Sweden 8Instituto de Estructura de la Materia, CSIC, E-28006 Madrid, Spain 9ISOLDE, CERN, CH-1211 Geneva 23, Switzerland 10Department of Chemistry, University of Oslo, Post Office Box 1033 Blindern, N-0315 Oslo, Norway (Received 28 December 2005; published 26 April 2006)

Octupole correlations in 229Ra

Abstract The structure of 229 Ra has been studied in the β − decay of 229 Fr. Spins and parities have been determined from the conversion electron measurements, while half-lives for the 137.5, 142.7, 168.8, 213.0 and 479.0 keV levels have been measured in the ps and ns ranges via the fast timing βγγ ( t ) method. Our data confirm the previous results and enrich the knowledge of the structure of this nucleus by 25 new states and several strong transitions. Structural similarities are established between 229 Ra and its N = 141 isotone 231 Th. The experimental results are compared with the theoretical predictions of the quasiparticle-phonon model with inclusion of Coriolis coupling. The reduced transition probabilities, and especially the moderately fast B (E1) rate for the 137.5 keV transition connecting the band-heads of the K π = 5 2 ± parity doublet bands, reveal the presence of significant octupole correlations in 229 Ra.