Coriolis coupling and electromagnetic properties of rotational bands in odd-A Yb nuclei

Influence of a Coriolis coupling on the properties of¹⁷³Yb has been studied using the quasi-particle-phonon model of Soloviev. The energy and structure of the rotational levels, reduced E 2 and M 1 transition probabilities and E 2/M 1 multipole mixing ratios have been calculated. A comparison between theory and experiment is on the whole successful.     

Compound and rotational damping in warm deformed rare-earth nuclei

The gamma decay in the quasicontinuum from selected configurations of the rotational nucleus 163Er has been measured with the EUROBALL array. A new analysis technique has allowed for the first time to directly measure the compound and rotational damping widths Gamma (micro) and Gamma (rot). Values of Gamma (micro) approximately 20 keV and Gamma (rot) approximately 200 keV are obtained in the spin region I approximately 30-40 variant Planck's over 2pi, in good agreement with microscopic cranked shell model calculations. A dependence of Gamma (micro) and Gamma (rot) on the K-quantum number of the nuclear states is also presented.     

An analysis of odd-mass rare-earth nuclei using angular momentum projection

A systematic analysis of positive-parity rotational states in odd-mass rare-earth nuclei is presented. The theory used is microscopic in the true sense and conserves both the angular momentum and the particle number as the projection technique is applied. The hamiltonian contains the quadrupole pairing interaction (in addition to the conventional (monopole) pairing and Q · Q forces) which plays an essential role in odd-mass as well as in doubly-even nuclei. Agreement between theory and experimental data is excellent.     

Microscopic study of odd-A nuclei

The odd-proton nucleus¹⁵⁵Tb and odd-neutron nucleus¹⁵⁵Dy are studied along with doubly-even nucleus¹⁵⁶Dy using microscopic method of variation after projection of angular momentum and conservation of nucleon number in each projected state. The calculated energies of the ground band in¹⁵⁶Dy and the ground and excited bands in¹⁵⁵Dy and¹⁵⁵Tb are in good agreement with the corresponding experimental data. The role played by thei _13/2 neutron pair in these nuclei is discussed.     

Study of weakly-bound odd-A nuclei with quasiparticle blocking

The coordinate-space Hartree-Fock-Bogoliubov(HFB) approach with quasiparticle blocking has been applied to study the odd-A weakly bound nuclei ~(17,19)B and ~(37)Mg,in which halo structures have been reported in experiments.The Skyrme nuclear forces SLy4 and UNEDF1 have been adopted in our calculations.The results with and without blocking have been compared to demonstrate the emergence of deformed halo structures due to blocking effects.In our calculations,~(19)B and ~(37)Mg have remarkable features of deformed halos.     

Algebraic realization of the quantum rotor — odd-A nuclei

An algebraic realization of the quantum rotor for non-zero spin values (integer as well as half-integer) is established by constructing a model Hamiltonian out of rotationally invariant functions of the generators ofSU(3). The eigenvalues of this Hamiltonian in the leading normal-SU(3) symmetry for²⁵Mg and the so-called leading pseudo-SU(3) symmetries for¹⁵⁹Dy and¹⁶⁵Er are compared with the corresponding rotor results. For spinfree systems the internal symmetry group of the rotor and itsSU(3) realization are known to be D₂, the Vierergruppe. This symmetry extends to integral spin values, while for half-integer spins the rotor and itsSU (3) realization are shown to display an internal quaternion group symmetry. The theory points to a microscopic (many-particle shell-model) picture of nuclear rotational motion with spin degrees of freedom taken fully into account. An algebraic realization of the many-particle Nilsson model for odd-A nuclei, with the orbit-orbit and spin-orbit terms included, is given and applied to²³Na.     

Variation of interband interaction strength in odd-A nuclei

Bandcrossing in 31 rotational bands of 25 different odd-A nuclei in the rare-earth region has been analysed by using a two-band mixing formalism with a constant band interaction within the framework of the effective decoupling picture. The interband interaction strengthV between the one-quasiparticle band and the three-quasiparticle band exhibits a variation with the neutron number which is not different from the oscillatory behaviour observed in even-even nuclei and does not show signs of any appreciable phase shifting as predicted by theory. However, the overall range of variation ofV is greater than that observed in even-even systems.     

Deformation properties of the neutron-deficient odd-A Pt and Hg nuclei

Nuclear and atomic spectroscopy measurements have provided a great number of data on the neutron-deficient Pt and Hg nuclei. The odd-A Pt and Hg with A<186 have a prolate shape, and the even-even isotopes have a triaxial shape, while the nuclear shape of the odd-A Pt and Hg with A>186 is still an open question. The energy of the low-lying levels and the nuclear moments have been calculated in the framework of a semimicroscopic “axial-rotor + 1 quasiparticle” coupling model. The predictions are compared with the experimental data and discussed. The results strongly suggest a prolate shape for the negative-parity low-lying states of the odd-A ^187–191Pt and ^187–193Hg isotopes.     

Systematid study on the Even-Even nuclei and odd-A nuclei calculating error with Relativistic Mean-Field Theory

The ground state properties of the four isotope chains, ²⁸Ni,⁵⁴Xe,⁷⁸Pt,⁹⁴Pu are studied in the relativistic mean-field theory by using two sets of parameters, NL-3 and NL-Z. We find that the binding energies of odd-A nuclei are even closer to the corresponding experimental results, compared with those of the even-even nuclei. Our results indicate that it is reliable to neglect the space component of the vector meson fields in calculating binding energies of odd-A nuclei in the relativistic mean-field theory.     

A composite chiral pair of rotational bands in the odd-A nucleus 135Nd

High-spin states in 135Nd were populated with the 110Pd(30Si,5n)135Nd reaction at a 30Si bombarding energy of 133 MeV. Two DeltaI=1 bands with close excitation energies and the same parity were observed. These bands are directly linked by DeltaI=1 and DeltaI=2 transitions. The chiral nature of these two bands is confirmed by comparison with three-dimensional tilted axis cranking calculations. This is the first observation of a three-quasiparticle chiral structure and establishes the primarily geometric nature of this phenomenon.     

Rotational motion of triaxial shape in unfavoured-signature states of odd-A nuclei

In the region of the angular momentum where the intrinsic energy (namely, the odd-quasiparticle energy) plays a more important role than the collective rotational energy, we point out that the way of rotation in unfavoured-signature states of odd-A nuclei, which is clearly different from that in the usual cranking approximation, can be realized for triaxial intrinsic shape and leads to a peculiar signature dependence of B(E2;I→I - 1) values.     

Study of the inertial functions for rare-earth nuclei

Vibrational (B_ββ, B_βγ, B_γγ) and rotational (B_x, B_y, B_z) inertial functions of Bohr's collective Hamiltonian are studied microscopically as functions of deformation. The study is extended to the inertial functions of the Hamiltonian appropriate for the phonon expansion treatment. The cranking approximation is used. The results are compared with those of the pairing-plus-quadrupole model. Non-adiabatic effects are discussed.     

Collective properties of A = 117−127 odd-A I nuclei

Systematic ΔJ = 2 bands have been observed on the $\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$, $\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ and $\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ quasi-proton states in A = 117?127 odd-I nuclei. The ΔJ = 2 energy spacings decrease (relative to the Te cores) as A decreases for the $\text{h}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ band but not for the others. Also ΔJ = 1 bands on unsually low-lying $\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ proton-hole states exist.     

Influence of the pairing parameter rotation dependence on signature splitting in odd-A nuclei

The influence of the rotation dependence of the pairing correlations on the signature splitting is analysed in terms of the core quasiparticle coupling model. The quenching of the pairing parameter with increasing the rotational angular momentum, and the different rotational structures of the favoured and unfavoured states cause a rising of the signature splitting. An additional growth of the signature splitting results from the different particle-hole structures of the favoured and unfavoured states and from the fact that theA?1 andA+1 cores, to which the quasiparticle is coupled in the odd-A nucleus, have different moments of inertia. The calculated results are in agreement with experiment.     

The structure of the odd-A nuclei withA≈130 and the problem ofγ-softness

The negative parity states in the^{123, 125, 131}Cs and the¹³¹La nuclei are described in the framework of the particle-core coupling model. In order to study the problem of gamma softness, the following two core models are used:(1) the rigid triaxial rotor model, and(2) theγ-unstable model withγ-dependent inertial functions. The properties of the odd-A nuclei with rigid and soft cores are compared with the experimental data. The results do not allow to draw a definite conclusion about the softness. When seeking properties which could help to distinguish between soft and rigid nuclei it has been found that some spectroscopic factors for the proton stripping reaction are sensitive to the gamma softness.     

An angular momentum projected quasiparticle approach to rotational states in nuclei

An attempt is made to take into account single particle degrees of freedom in angular momentum projected HFB-calculations via the explicit inclusion of two quasiparticle states. For this purpose a formalism is used which, though being rather general, nevertheless is rather suitable for numerical applications even in realistic model spaces. As a first test the method is applied in thei _13/2-shell, where exact shell model solutions are available. Though using only a rather truncated quasiparticle space we obtain almost perfect agreement with these exact solutions.