Problem of ''deformed'' superheavy nuclei

International Nuclear Information System (INIS)

Sobiczewski, A.; Patyk, Z.; Muntian, I.

2000-08-01

Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)

Pauli principle role in the description of collective non-rotational states of deformed nuclei

International Nuclear Information System (INIS)

Solov'ev, V.G.; Shirikova, N.Yu.; Serdyukova, S.I.; Meliev, F.; Nesterenko, V.O.

1981-01-01

The Pauli principle role account for one-phonon and two- phonon states of even-even deformed nuclei sup(160, 164)Dy, sup(230, 232)Th, 154 Gd, 240 Pu, 238 U is performed. With account of isoscalar part of multipole-multipole interaction hamiltonian of a model and basic equations for energy and wave functions of one-phonon and two-phonon states are obtained. The results of calculations of centroids of energies of two-phonon states of the (lambda 1 μ 1 i 1 lambda 2 μ 2 i 2 ) type with and without the Pauli principle are tabulated. The calculations performed have shown that the energy centroids shift of collective two-phonon states with the Pauli-principle account is characteristic for all even-even deformed nuclei. In the authors opinion additional experimental investigations of 154 Cd, 164 Dy, 240 Pu two-phonon nuclei states to confirm theoretical results are necessary [ru

Toroidal and rotating bubble nuclei and the nuclear fragmentation

International Nuclear Information System (INIS)

Royer, G.; Fauchard, C.; Haddad, F.; Jouault, B.

1997-01-01

The energy of rotating bubble and toroidal nuclei predicted to be formed in central heavy ion collisions at intermediate energies is calculated within the generalized rotating liquid drop model. Previously, a one-parameter shape sequence has been defined to describe the path leading to pumpkin-like configurations and toroidal shapes. New analytical expressions for the shape dependent functions have been obtained. The potential barriers standing in these exotic deformation paths are compared with the three-dimensional and plane-fragmentation barriers. Metastable bubble-like minima only appear at very high angular momentum and above the three dimensional fragmentation barriers. In the toroidal deformation path of the heaviest systems exists a large potential pocket localized below the plane-fragmentation barriers. This might allow the temporary survival of heavy nuclear toroids before the final clusterization induced by the surface and proximity tension

Parameterization of rotational spectra

International Nuclear Information System (INIS)

Zhou Chunmei; Liu Tong

1992-01-01

The rotational spectra of the strongly deformed nuclei with low rotational frequencies and weak band mixture are analyzed. The strongly deformed nuclei are commonly encountered in the rare-earth region (e. g., 150 220). A lot of rotational band knowledge are presented

Rotational motion in nuclei

International Nuclear Information System (INIS)

Bohr, A.

1977-01-01

History is surveyed of the development of the theory of rotational states in nuclei. The situation in the 40's when ideas formed of the collective states of a nucleus is evoked. The general rotation theory and the relation between the single-particle and rotational motion are briefly discussed. Future prospects of the rotation theory development are indicated. (I.W.)

Phonon operators in deformed nuclei

International Nuclear Information System (INIS)

Soloviev, V.G.

1981-01-01

For the description of the excited states in deformed nuclei new phonon operators are introduced, which depend on the sign of the angular momentum projection onto the symmetry axis of a deformed nucleus. In the calculations with new phonons the Pauli principle is correctly taken into account in the two-phonon components of the wave functions. There is a difference in comparison with the calculation with phonons independent of the sign of the angular momentum projection. The new phonons should be used in deformed nuclei if the Pauli principle is consistently taken into account and in the calculations with the excited state wave functions having the components with more than one phonon operator [ru

Particle-rotation coupling in atomic nuclei

International Nuclear Information System (INIS)

Almberger, J.

1980-01-01

Recently an increased interest in the rotational nuclei has been spurred by the new experimental high-spin activities and by the possibilities for lower spins to interpret an impressive amount of experimental data by some comparatively simple model calculations. The author discusses the particle modes of excitation for rotational nuclei in the pairing regime where some puzzles in the theoretical description remain to be resolved. A model comparison is made between the particle-rotor and cranking models which have different definitions of the collective rotation. The cranking model is found to imply a smaller value of the quasiparticle spin alignment than the particle-rotor model. Rotational spectra for both even and odd nuclei are investigated with the use of the many-BCS-quasiparticles plus rotor model. This model gives an accurate description of the ground and S-bands in many even-even rare-earth nuclei. However, the discrepancies for odd-A nuclei between theory and experiments point to the importance of additional physical components. Therefore the rotationally induced quadrupole pair field is considered. This field has an effect on the low spin states in odd-A nuclei, but is not sufficient to account for the experimental data. Another topic considered is the interaction matrix element in crossings for given spin between quasiparticle rotational bands. The matrix elements are found to oscillate as a function of the number of particles, thereby influencing the sharpness of the backbending. Finally the low-spin continuation of the S-band is studied and it is shown that such states can be populated selectively by means of one-particle pickup reactions involving high angular momentum transfer. (Auth.)

Some considerations of the energy spectrum of odd-odd deformed nuclei; Quelqes considerations sur le spectre d'energie des noyaux impair-impair deformes

Energy Technology Data Exchange (ETDEWEB)

Alceanu-G, Pinho de; Picard, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

The odd-odd deformed nuclei are described as a rotator plus two odd nucleons moving in orbitals {omega}{sub p} and {omega}{sub n} of the deformed potential. We investigate the energies and wave functions of the various states of the ({omega}{sub p}, {omega}{sub n}) configurations by calculating and numerically diagonalizing the Hamiltonian matrix (with R.P.C. and residual interactions). The Gallagher-Mosskowski coupling rules ana the abnormal K equals 0 rotational bands are discussed. (authors) [French] Les noyaux impair-impairs deformes sont decrits comme un rotateur plus deux nucleons non apparies dans les orbites {omega}{sub p} et {omega}{sub n} du potentiel deforme. Nous etudions le spectre d'energie et les fonctions d'onde des configurations ({omega}{sub p}, {omega}{sub n}) en tenant compte de l'interaction particule-rotation et de la force residuelle entre les deux nucleons celibataires.

Phonon operators for deformed nuclei

International Nuclear Information System (INIS)

Solov'ev, V.G.

1982-01-01

The mathematical formalism with the phonon operators independent of the signature of the angular momentum projection turns out to be inadequate for describing excited states of deformed nuclei. New phonon operators are introduced which depend on the signature of the angular momentum projection on the symmetry axis of a deformed nucleus. It is shown that the calculations with the new phonons take correctly into account the Pauli principle in two-phonon components of wave functions. The results obtained differ from those given by the phonons independent of the signature of the angular momentum projection. The new phonons must be used in deformed nuclei at taking systematically the Pauli principle into account and in calculations involving wave functions of excited states having components with more than one-phonon operator

Some considerations of the energy spectrum of odd-odd deformed nuclei; Quelqes considerations sur le spectre d'energie des noyaux impair-impair deformes

Energy Technology Data Exchange (ETDEWEB)

Alceanu-G, Pinho de; Picard, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

The odd-odd deformed nuclei are described as a rotator plus two odd nucleons moving in orbitals {omega}{sub p} and {omega}{sub n} of the deformed potential. We investigate the energies and wave functions of the various states of the ({omega}{sub p}, {omega}{sub n}) configurations by calculating and numerically diagonalizing the Hamiltonian matrix (with R.P.C. and residual interactions). The Gallagher-Mosskowski coupling rules ana the abnormal K equals 0 rotational bands are discussed. (authors) [French] Les noyaux impair-impairs deformes sont decrits comme un rotateur plus deux nucleons non apparies dans les orbites {omega}{sub p} et {omega}{sub n} du potentiel deforme. Nous etudions le spectre d'energie et les fonctions d'onde des configurations ({omega}{sub p}, {omega}{sub n}) en tenant compte de l'interaction particule-rotation et de la force residuelle entre les deux nucleons celibataires.

Study of high angular momentum phenomena in rotating nuclei

International Nuclear Information System (INIS)

Walus, W.

1982-01-01

Information about rotational bands of deformed Yb nuclei as obtained through in-beam spectroscopic studies is discussed. Routhians and alignments have been extracted from the experimental data. Experimental single-quasineutron routhians have been used to construct two- and three-quasineutron routhians. Residual interaction between excited quasiparticles is obtained from a comparison of the excitation energies of multiple-quasiparticle states constructed from single-quasiparticle states. An odd-even neutron-number dependence of the alignment frequency of the first pair of isub(13/2) quasineutron in rare-earth nuclei is presented. This effect is explained by a reduction of the neutron pairing-correlation parameter for odd-N systems as compared to seniority-zero configurations in even-N nuclei. The signature dependence of the interband-intraband branching ratios as well as of the interband M1/E2 mixing ratios is discussed and compared to the signature dependence of B(M1) transition rates recently suggested by Hamamoto. (author)

Program package for calculation of cross sections of neutron scattering on deformed nuclei by the coupled-channel method

International Nuclear Information System (INIS)

Kloss, Yu.Yu.

1985-01-01

Program package and numerical solution of the problem for a system of coupled equations used in optical model to solve a problem on low and mean energy neutron scattering on deformed nuclei, is considered. With these programs differnet scattering cross sections depending on the incident neutron energy on even-even and even-odd nuclei were obtained. The programm permits to obtain different scattering cross sections (elastic, inelastic), excitation cross sections of the first three energy levels of rotational band depending on the energy, angular distributions and neutron polarizations including excited channels. In the program there is possibility for accounting even-even nuclei octupole deformation

Neutron scattering on deformed nuclei

International Nuclear Information System (INIS)

Hansen, L.F.; Haight, R.C.; Pohl, B.A.; Wong, C.; Lagrange, C.

1984-09-01

Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9 Be, C, 181 Ta, 232 Th, 238 U and 239 Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP

Nuclear elasticity applied to giant resonances of fast rotating nuclei

International Nuclear Information System (INIS)

Jang, S.; Bouyssy, A.

1987-06-01

Isoscalar giant resonances in fast rotating nuclei are investigated within the framework of nuclear elasticity by solving the equation of motion of elastic nuclear medium in a rotating frame of reference. Both Coriolis and centrifugal forces are taken into account. The nuclear rotation removes completely the azimuthal degeneracy of the giant resonance energies. Realistic large values of the angular velocity, which are still small as compared to the giant resonance frequencies, are briefly reviewed in relation to allowed high angular momenta. It is shown that for the A=150 region, the Coriolis force is dominating for small values (< ∼ 0.05) of the ratio of angular velocity to resonance frequency, whereas the centrifugal force plays a prominent part in the shift of the split resonance energies for larger values of the ratio. Typical examples of the resonance energies and their fragmentation due to both rotation and deformation are given

Quantum algebra Uqp(u2) and application to the rotational collective dynamics of the nuclei

International Nuclear Information System (INIS)

Barbier, R.

1995-01-01

This thesis concerns some aspects of new symmetries in Nuclear Physics. It comprises three parts. The first one is devoted to the study of the quantum algebra U qp (u 2 ). More precisely, we develop its Hopf algebraic structure and we study its co-product structure. The bases of the representation theory of U qp (u 2 ) are introduced. On one hand, we construct the finite-dimensional irreducible representations of U qp (u 2 ). On the other hand, we calculate the Clebsch-Gordan coefficients with the projection operator method. To complete our study, we construct some deformed boson mappings of the quantum algebras U qp (u 2 ), U q 2 (su 2 ) and U qp (u 1,1 ). The second part deals with the construction of a new phenomenological model of the non rigid rotator. This model is based on the quantum algebra U qp (u 2 ). The rotational energy and the E2 reduced transition probabilities are obtained. They depend on the two deformation parameters q and p of the quantum algebra. We show how the use of the two-parameter deformation of the algebra U qp (u 2 ) leads to a generalization of the U q (su 2 )-rotator model. We also introduce a new model of the anharmonic oscillator on the basis of the quantum algebra U qp (u 2 ). We show that the system of the U q (su 2 )-rotator and of the anharmonic oscillator can be coupled with the use of the deformation parameters of U qp (u 2 ). A ro-vibration energy formula and expansion 'a la' Dunham are obtained. The aim of the lest part is to apply our non rigid rotator model to the rotational collective dynamics of the superdeformed nuclei of the A∼130 - 150 and A∼190 mass regions and deformed nuclei of the actinide and rare earth series. We adjust the free parameters of our model and compare our results with those arising from four other models of the non rigid rotator. A comparative analysis is given in terms of transition energies. We calculate the dynamical moments of inertia with the fitted parameters. A comparison between the

A microscopic derivation of nuclear collective rotation-vibration model and its application to nuclei

Energy Technology Data Exchange (ETDEWEB)

Gulshani, P., E-mail: matlap@bell.net [NUTECH Services, 3313 Fenwick Crescent, Mississauga, Ontario, L5L 5N1 (Canada)

2016-07-07

We derive a microscopic version of the successful phenomenological hydrodynamic model of Bohr-Davydov-Faessler-Greiner for collective rotation-vibration motion of an axially symmetric deformed nucleus. The derivation is not limited to small oscillation amplitude. The nuclear Schrodinger equation is canonically transformed to collective co-ordinates, which is then linearized using a constrained variational method. The associated constraints are imposed on the wavefunction rather than on the particle co-ordinates. The approach yields three self-consistent, time-reversal invariant, cranking-type Schrodinger equations for the rotation-vibration and intrinsic motions, and a self-consistency equation. For harmonic oscillator mean-field potentials, these equations are solved in closed forms for excitation energy, cut-off angular momentum, and other nuclear properties for the ground-state rotational band in some deformed nuclei. The results are compared with measured data.

On connection of rotation and internal motion in deformed nuclei

International Nuclear Information System (INIS)

Krutov, V.A.

1979-01-01

In the semiphenomenological nuclear madel (SPNM) the problem of ''overestimate of Coriolis interaction'' is shown to be easily solved. The rotation and internal motion coupling operator H(rot/in) is used. Overdetermination of the operator H(rot/in) has been generalized and extended into schemes of strong and weak coupling. In this case both schemes of coupling are transformed from approximate into precise ones and become applicable for any nuclear deformation. As examples of application of the theory considered are the matrix elements of the E2-transitions and inertia parameters of a 235 U nucleus

Deformation and shape transitions in hot rotating neutron deficient Te isotopes

International Nuclear Information System (INIS)

Aggarwal, Mamta; Mazumdar, I.

2009-01-01

Evolution of the nuclear shapes and deformations under the influence of temperature and rotation is investigated in Te isotopes with neutron number ranging from the proton drip line to the stability valley. Spin dependent critical temperatures for the shape transitions in Te nuclei are computed. Shape transitions from prolate at low temperature and spin to oblate via triaxiality are seen with increasing neutron number and spin.

Effective field theory for triaxially deformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Chen, Q.B. [Technische Universitaet Muechen, Physik-Department, Garching (Germany); Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); Kaiser, N. [Technische Universitaet Muechen, Physik-Department, Garching (Germany); Meissner, Ulf G. [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Bonn (Germany); Institute for Advanced Simulation, Institut fuer Kernphysik, Juelich Center for Hadron Physics and JARA-HPC, Forschungszentrum Juelich, Juelich (Germany); Meng, J. [Peking University, State Key Laboratory of Nuclear Physics and Technology, School of Physics, Beijing (China); Beihang University, School of Physics and Nuclear Energy Engineering, Beijing (China); University of Stellenbosch, Department of Physics, Stellenbosch (South Africa)

2017-10-15

Effective field theory is generalized to investigate the rotational motion of triaxially deformed even-even nuclei. The Hamiltonian for the triaxial rotor is obtained up to next-to-leading order within the effective field theory formalism. Its applicability is examined by comparing with a five-dimensional rotor-vibrator Hamiltonian for the description of the energy spectra of the ground state and γ band in Ru isotopes. It is found that by taking into account the next-to-leading order corrections, the ground state band in the whole spin region and the γ band in the low spin region are well described. The deviations for high-spin states in the γ bands point towards the importance of including vibrational degrees of freedom in the effective field theory formulation. (orig.)

Transmission coefficents in strongly deformed nuclei

International Nuclear Information System (INIS)

Aleshin, V.P.

1996-01-01

By using our semiclassical approach to particle evaporation from deformed nuclei developed earlier, we analyze here the heuristic methods of taking into account the effects of shape deformations on particle emission. These methods are based on the 'local' transmission coefficients in which the effective barrier depends on the angle with respect to the symmetry axis. The calculations revealed that the heuristic models are reasonable for particle energy spectra but fail, at large deformations, to describe the angular distributions. In A∼160 nuclei with axis ratio in the vicinity of 2:1 at temperatures of 2-3 MeV, the W (90 )/W(0 ) anisotropies of α particles with respect to the nuclear spin are 1.5 to 3 times larger than our approach predicts. The influence of spin alignment on particle energy spectra is discussed shortly. (orig.)

Woods-Saxon potential parametrization at large deformations for odd-plutonium nuclei

International Nuclear Information System (INIS)

Garcia, F.; Yoneama, M.L.; Arruda Neto, J.D.T.; Mesa, J.; Bringas, F.; Dias, J.F.; Likhachev, V.P.

1997-01-01

The structure of the the single-particle levels in the secondary minima of 237,239,241 Pu fissioning nuclei is analysed with the help of an axially-deformed Woods-Saxon potential. The nuclear shape was parametrized in terms of the Cassinian ovaloids. The parametrization of the spin-orbit part of the potential in the region corresponding to large deformations (second minimum), which depends only on the nuclear surface area, B s , was obtained. With this relation we were able to reproduce successfully the spin (parity) and the energies of the rotational band built on the 8μs isomeric rate in 239 Pu and also to make a spin assignment for both isomer states in 237 Pu and 241 Pu. (author)

Geometry and dynamics of particle emission from strongly deformed nuclei

International Nuclear Information System (INIS)

Aleshin, V.P.

1995-01-01

By using our semiclassical approach to particle evaporation from deformed nuclei, we analyze the heuristic models of particle emission from deformed nuclei which are used in the codes GANES, ALICE, and EVAP. The calculations revealed that the heuristic models are reasonable for particle energy spectra but fail, at large deformations, to describe the angular distributions

Neutron halo in deformed nuclei

International Nuclear Information System (INIS)

Zhou Shangui; Meng Jie; Ring, P.; Zhao Enguang

2010-01-01

Halo phenomena in deformed nuclei are investigated within a deformed relativistic Hartree Bogoliubov (DRHB) theory. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Contributions of the halo, deformation effects, and large spatial extensions of these systems are described in a fully self-consistent way by the DRHB equations in a spherical Woods-Saxon basis with the proper asymptotic behavior at a large distance from the nuclear center. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nucleus 44 Mg. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the occurrence of this decoupling effects are discussed.

Ground state properties of exotic nuclei in deformed medium mass region

International Nuclear Information System (INIS)

Manju; Chatterjee, R.; Singh, Jagjit; Shubhchintak

2017-01-01

The dipole moment, size of the nucleus and other ground state properties of deformed nuclei 37 Mg and 31 Ne are presented. Furthermore with this deformed wave function the electric dipole strength distribution for deformed nuclei 37 Mg and 31 Ne is calculated. This will allow us to investigate the two dimensional scaling phenomenon with two parameters: quadrupole deformation and separation energy

Gamma spectroscopical studies of strongly deformed rotational bands in 73Br and 79Sr

International Nuclear Information System (INIS)

Heese, J.

1989-01-01

In the framework of this thesis the excitation structures of the nuclei 73 Br and 79 Sr were studied. For the population of high-spin states the reactions 40 Ca( 36 Ar,3p) 73 Br, -58 Ni( 24 Mg,2αp) 73 Br and 58 Ni( 24 Mg,2pn) 79 Sr were used. The level scheme of 73 Br could be extended by γγ coincidence measurements by 18 new states up to the spins 45/2 + respectively 45/2 - . DSA lifetime measurements yielded information about the deformations of the observed rotational bands. The conversion coefficients of the low-energetic transitions in the range of the excitation spectrum below 500 keV were determined and allowed the assignments of spins and parities. Furthermore the converted decay of the 27-keV state was observed for the first time, from the measured intensities of the electron line the lifetime of this state was estimated to 1.1 ≤ τ ≤ 9.1 μs. The measurement of the lifetime and the g factor of the isomeric 240-keV state confirmed the already known spin values and allowed statements on the particle structure. Lifetime measurements in 79 Sr were performed up to the states 21/2 + and 17/2 - . They yielded informations on E2 and M1 transition strengthened in the rotational bands. The transition strengths calculated from the lifetimes show that both nuclei are strongly prolate deformed. The sign of the deformation could be concluded in the case of 73 Br from the observed band structure, in 79 Sr it was calculated from E2/M1 mixing ratios. The E2-transition strengths show a reduction in both nuclei in the region of the g 9/2 proton alignment. Alignment effects in the rotational bands were discussed in the framework of the cranked shell model. Microscopical calculations in the Hartree-Fock-Bogolyubov cranking model with a deformed Woods-Saxon potential were performed. (orig./HSI) [de

Isovector giant dipole resonance in hot rotating light nuclei in the calcium region

International Nuclear Information System (INIS)

Shanmugam, G.; Thiagasundaram, M.

1989-01-01

The isovector giant dipole resonances in hot rotating light nuclei in the calcium region are studied using a rotating anisotropic harmonic oscillator potential and a separable dipole-dipole residual interaction. The influence of temperature on the isovector giant dipole resonance is assumed to occur through the change of deformation of the average field only. Calculations are performed for the three nuclei /sup 40,42/Ca and /sup 46/Ti which have spherical, oblate, and prolate ground states, respectively, to see how their shape transitions at higher excited states affect the isovector giant resonance frequencies built on them. It is seen that, while the width fluctuations present at T = 0 vanish at T = 0.5 MeV in /sup 40,42/Ca, they persist up to T = 1.5 MeV in the case of /sup 46/Ti. This behavior brings out the role of temperature on shell effects which in turn affects the isovector giant dipole resonance widths

Systematics of triaxial deformation in Xe, Ba, and Ce nuclei

International Nuclear Information System (INIS)

Yan, J.; Vogel, O.; von Brentano, P.; Gelberg, A.

1993-01-01

The (β,γ) deformation parameters of even-even Xe, Ba, and Ce nuclei have been calculated by using the triaxial rotor model. Deformation parameters calculated, on one hand, from decay properties and, on the other hand, from energies are in good agreement. The smooth dependence of the deformation parameters on Z and N is discussed. The results are compared with those extracted from properties of odd-A nuclei

''Identical'' bands in normally-deformed nuclei

International Nuclear Information System (INIS)

Garrett, J.D.; Baktash, C.; Yu, C.H.

1990-01-01

Gamma-ray transitions energies in neighboring odd- and even-mass nuclei for normally-deformed nuclear configurations are analyzed in a manner similar to recent analyses for superdeformed states. The moment of inertia is shown to depend on pair correlations and the aligned angular momentum of the odd nucleon. The implications of this analysis for ''identical'' super-deformed bands are discussed. 26 refs., 9 figs

The role of quasiparticles in rotating transitional nuclei

International Nuclear Information System (INIS)

Frauendorf, Stefan

1984-01-01

The yrast sequency of nuclei rotating about the symmetry axis is classified in analogy to class I and II superconductors, where the quasiparticles play the role of the quantized flux in metals. The experimental spectra show a class I behaviour. The ω-dependence of the quasiparticle excitation energy in collectively rotating nuclei is used as evidence for magnitude of the pair correlations and the occurrence of triaxial shapes. A transition from triaxial to oblate shape explains the experimental spectra and E2-transition probabilities in the N=88-90 nuclei. (author)

Study of the joining particle rotation in nuclei of 161-167 Er and 235 U

International Nuclear Information System (INIS)

Fernandez L, M.

1996-01-01

The residual quadrupole pairing and spin-spin interactions among the nucleons, in presence of the rotational motion, lead to additional terms in the particle-rotation coupling which attenuate the effects of the Coriolis interaction. These couplings are determined by using the density matrix formalism, under the consideration of the exact conservation of the nuclear angular moment. Finally the energy levels of the rotational bands and the mixing amplitudes of the BE2 transition probabilities are calculated for some odd deformed nuclei. A very good agreement between the theoretical and experimental energies is obtained. The Coriolis attenuation produced by these interactions shows itself as relevant for explaining the experimental results. (Author)

The giant quadrupole resonance in highly excited rotating nuclei

International Nuclear Information System (INIS)

Civitarese, O.; Furui, S.; Ploszajczak, M.; Faessler, A.

1983-01-01

The giant quadrupole resonance in highly excited, fast rotating nuclei is studied as a function of both the nuclear temperature and the nuclear angular momentum. The photo-absorption cross sections for quadrupole radiation in 156 Dy, 160 Er and 164 Er are evaluated within the linear response theory. The strength functions of the γ-ray spectrum obtained from the decay of highly excited nuclear states by deexcitation of the isoscalar quadrupole mode show a fine structure, which depends on the temperature T, the angular momentum I and the deformation of the nucleus β. The splitting of the modes associated with the signature-conserving and signature-changing components of the quadrupole field is discussed. (orig.)

Triaxial energy relation to describe rotational band in 98-112Ru nuclei

International Nuclear Information System (INIS)

Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Varshney, A.K.; Varshney, Mani; Singh, M.; Gupta, D.K.

2010-01-01

In a broader perspective rotation vibration coupling parameter (b) is considered changing with the change in excitation energy (ε 1 ) and is evaluated on fitting experimental energy for 98-112 Ru isotopes in the frame work of general asymmetric rotor model. The moment of inertia parameter (a), common to yrast and quasi-γ band, is calculated from deformation parameter (β) using general empirical relation. The present work is undertaken to suggest some suitable equation for the trajectories which are similar in shape in 98-112 Ru nuclei

Collisions of deformed nuclei and superheavy-element production

International Nuclear Information System (INIS)

Iwamoto, Akira; Moeller, P.; Univ. of Aizu, Fukushima; P. Moller Scientific Computing and Graphics, Inc., Los Alamos, NM; Los Alamos National Lab., NM; Nix, J.R.; Sagawa, Hiroyuki, Sagawa

1995-01-01

A detailed understanding of complete fusion cross sections in heavy-ion collisions requires a consideration of the effects of the deformation of the projectile and target. The aim here is to show that deformation and orientation of the colliding nuclei have a very significant effect on the fusion-barrier height and on the compactness of the touching configuration. To facilitate discussions of fusion configurations of deformed nuclei, the authors develop a classification scheme and introduce a notation convention for these configurations. They discuss particular deformations and orientations that lead to compact touching configurations and to fusion-barrier heights that correspond to fairly low excitation energies of the compound systems. Such configurations should be the most favorable for producing superheavy elements. They analyze a few projectile-target combinations whose deformations allow favorable entrance-channel configurations and whose proton and neutron numbers lead to compound systems in a part of the superheavy region where a half-lives are calculated to be observable, that is, longer than 1 micros

Dynamic deformation theory of spherical and deformed light and heavy nuclei with A = 12-240

International Nuclear Information System (INIS)

Kumar, Krishna.

1979-01-01

Deformation dependent wave functions are calculated for different types of even-even nuclei (spherical, transitional, deformed; light, medium, heavy) without any fitting parameters. These wave functions are employed for the energies, B(E2)'s, quadrupole and magnetic moments of selected nuclei with A = 12-240 (with special emphasis on 56 Fe, 154 Gd), and for neutron cross sections of 148 Sm, 152 Sm

Single particle Schroedinger fluid and moments of inertia of deformed nuclei

International Nuclear Information System (INIS)

Doma, S.B.

2002-01-01

The authors have applied the theory of the single-particle Schroedinger fluid to the nuclear collective motion of axially deformed nuclei. A counter example of an arbitrary number of independent nucleons in the anisotropic harmonic oscillator potential at the equilibrium deformation has been also given. Moreover, the ground states of the doubly even nuclei in the s-d shell 20 Ne, 24 Mg, 28 Si, 32 S and 36 Ar are constructed by filling the single-particle states corresponding to the possible values of the number of quanta of excitations n x , n y and n z . Accordingly, the cranking-model, the rigid-body model and the equilibrium-model moments of inertia of these nuclei are calculated as functions of the oscillator parameters ℎω x , ℎω y and ℎω z which are given in terms of the non deformed value ℎω 0 0 , depending on the mass number A, the number of neutrons N, the number of protons Z, and the deformation parameter β. The calculated values of the cranking-model moments of inertia of these nuclei are in good agreement with the corresponding experiential values and show that the considered axially deformed nuclei may have oblate as well as prolate shapes and that the nucleus 24 Mg is the only one which is highly deformed. The rigid-body model and the equilibrium-model moments of inertia of the two nuclei 20 Ne and 24 Mg are also in good agreement with the corresponding experimental values

General Relativistic Mean Field Theory for rotating nuclei

Energy Technology Data Exchange (ETDEWEB)

Madokoro, Hideki [Kyushu Univ., Fukuoka (Japan). Dept. of Physics; Matsuzaki, Masayuki

1998-03-01

The {sigma}-{omega} model Lagrangian is generalized to an accelerated frame by using the technique of general relativity which is known as tetrad formalism. We apply this model to the description of rotating nuclei within the mean field approximation, which we call General Relativistic Mean Field Theory (GRMFT) for rotating nuclei. The resulting equations of motion coincide with those of Munich group whose formulation was not based on the general relativistic transformation property of the spinor fields. Some numerical results are shown for the yrast states of the Mg isotopes and the superdeformed rotational bands in the A {approx} 60 mass region. (author)

An optical potential for the statically deformed actinide nuclei derived from a global spherical potential

Science.gov (United States)

Al-Rawashdeh, S. M.; Jaghoub, M. I.

2018-04-01

In this work we test the hypothesis that a properly deformed spherical optical potential, used within a channel-coupling scheme, provides a good description for the scattering data corresponding to neutron induced reactions on the heavy, statically deformed actinides and other lighter deformed nuclei. To accomplish our goal, we have deformed the Koning-Delaroche spherical global potential and then used it in a channel-coupling scheme. The ground-state is coupled to a sufficient number of inelastic rotational channels belonging to the ground-state band to ensure convergence. The predicted total cross sections, elastic and inelastic angular distributions are in good agreement with the experimental data. As a further test, we compare our results to those obtained by a global channel-coupled optical model whose parameters were obtained by fitting elastic and inelastic angular distributions in addition to total cross sections. Our results compare quite well with those obtained by the fitted, channel-coupled optical model. Below neutron incident energies of about 1MeV, our results show that scattering into the rotational excited states of the ground-state band plays a significant role in the scattering process and must be explicitly accounted for using a channel-coupling scheme.

Semiclassical approach to giant resonances of rotating nuclei

International Nuclear Information System (INIS)

Winter, J.

1983-01-01

Quadrupole and isovector dipole resonances of rotating nuclei are investigated in the frame-work of Vlasov equations transformed to a rotating system of reference, which are based on the time-dependent Hartree-method for schematic forces. The parameter free model of the self-consistent vibrating harmonic oscillator potential for the quadrupole mode is extended to a coupling to rotation, which also includes large-amplitude behaviour. A generalization to an exactly solvable two-liquid model describing the isovector mode is established; for rotating nuclei Hilton's explicit result for the eigenfrequencies is obtained. The advantage of using the concept of the classical kinetic momentum in a rotating system also in quantum-mechanical descriptions is demonstrated. It completes the standard transformation of density matrices by a time-odd part realized in a phase-factor and permits a more direct interpretation of rotation effects in terms of the classical forces of inertia. (author)

Two-neutron transfer reactions with heavy-deformed nuclei

International Nuclear Information System (INIS)

Price, C.; Landowne, S.; Esbensen, H.

1988-01-01

In a recent communication we pointed out that one can combine the macroscopic model for two-particle transfer reactions on deformed nuclei with the sudden limit approximation for rotational excitation, and thereby obtain a practical method for calculating transfer reactions leading to high-spin states. As an example, we presented results for the reaction 162 Dy( 58 Ni, 60 Ni) 160 Dy populating the ground-state rotational band up to the spin I = 14 + state. We have also tested the validity of the sudden limit for the inelastic excitation of high spin states and we have noted how the macroscopic model may be modified to allow for more microscopic nuclear structure effects in an application to diabolic pair-transfer processes. This paper describes our subsequent work in which we investigated the systematic features of pair-transfer reactions within the macroscopic model by using heavier projectiles to generate higher spins and by decomposing the cross sections according to the multipolarity of the transfer interaction. Particular attention is paid to characteristic structures in the angular distributions for the lower spin states and how they depend on the angular momentum carried by the transferred particles. 11 refs., 3 figs

'Static' octupole deformation at high spin

International Nuclear Information System (INIS)

Nazarewicz, W.

1985-01-01

Rotational bands characterized by spin states of alternating parity p=(-1) I connected by enhanced E1 transitions have recently been observed in several nuclei from the Ra-Th region. They can be interpreted by means of a reflection asymmetric mean field theory. The interplay between octupole deformation and rotation is briefly discussed. For nuclei with ground state octupole deformation a transition to a reflection symmetric shape is expected around I=22. (orig.)

Polarized electric dipole moment of well-deformed reflection asymmetric nuclei

International Nuclear Information System (INIS)

Denisov, V.Yu.

2012-01-01

The expression for polarized electric dipole moment of well-deformed reflection asymmetric nuclei is obtained in the framework of liquid-drop model in the case of geometrically similar proton and neutron surfaces. The expression for polarized electric dipole moment consists of the first and second orders terms. It is shown that the second-order correction terms of the polarized electric dipole moment are important for well-deformed nuclei

The SU(3) structure of rotational states in heavy deformed nuclei

International Nuclear Information System (INIS)

Jarrio, M.; Wood, J.L.; Rowe, D.J.

1991-01-01

The SU(3) coupling scheme provides an informative basis for the expansion of shell-model wave functions and their interpretation in collective-model terms. We show in this paper that it is possible, using the coupled-rotor-vibrator model, to infer averages of the distributions of SU(3) representation labels in heavy rotational nuclei by direct interpretation of physically observed E2 transition rates and quadrupole moments. We find that the distributions of SU(3) representation labels have nearly constant average values for states belonging to some well-defined rotational bands. These are bands of states having B(E2) values and quadrupole moments that follow the predictions of the rotor model. Such bands are interpreted as soft SU(3) bands in parallel with the concept of a soft rotor band with vibrational-shape fluctuations. The concept of a soft SU(3) band and its implications for beta-vibrational excited bands is developed. The average SU(3) representation labels inferred from experiment are interpreted by calculating those implied by the Nilsson model. An analysis of the SU(3) content of Nilsson wave functions also leads to two remarkable predictions. The first is that, in the asymptotic limit, the Nilsson model implies intrinsic states for a rotor band that are beta rigid. The second is that, although the intrinsic Nilsson state is axially symmetric, it generates a sequence of K=0, 2, 4,...bands. (orig.)

Lipkin-Nogami method for rotating nuclei

International Nuclear Information System (INIS)

Magierski, P.

1993-01-01

The extension of Lipkin-Nogami method to the case of rotating nuclei, where the short-range attraction acting between the nucleus (pairing free) plays a significant role for the coupling scheme is discussed. 7 refs, 6 figs

Microscopic mechanism of moments of inertia and odd-even differences for well-deformed actinide nuclei

International Nuclear Information System (INIS)

Yu Lei; Liu Shuxin; Zeng Jinyan

2004-01-01

The microscopic mechanism of the variation with rotational frequency of moments of inertia and their odd-even differences for well-deformed actinide nuclei are analyzed by using the particle-number conserving (PNC) method for treating nuclear pairing interaction. The moments of inertia for bands building on high j intruder orbitals in odd-A nuclei, e.g., the 235 U (ν[743]7/2) band, are found to be much larger than those of ground-state bands in neighboring even-even nuclei. Moreover, there exist large odd-even differences in the ω variation of moments of inertia. All these experimental odd-even differences are reproduced quite well in the PNC calculation, in which the effective monopole and quadrupole pairing interaction strengths are determined by the experimental odd-even differences in binding energies and bandhead moments of inertia, and no free parameter is involved in the PNC calculation

Shapes of non-rotating nuclei

International Nuclear Information System (INIS)

Bengtsson, R.; Krumlinde, J.; Moeller, P.; Nix, J.R.; Zhang, J.

1983-01-01

We study nuclear potential-energy surfaces, ground-state masses and shapes calculated by use of a Yukawa-plus-exponential macroscopic model and a folded-Yukawa single-particle potential for 4023 nuclei ranging from 16 O to 279 112. We discuss extensively the transition from spherical to deformed shapes and study the relation between shape changes and the mass corresponding to the ground-state minimum. The calculated values for the ground-state mass and shape show good agreement with experimental data throughout the periodic system, but some discrepancies remain that deserve further study. We also discuss the effect of deformation on Gamow-Teller #betta#-strength functions

Rotational damping motion in nuclei

International Nuclear Information System (INIS)

Egido, J.L.; Faessler, A.

1991-01-01

The recently proposed model to explain the mechanism of the rotational motion damping in nuclei is exactly solved. When compared with the earlier approximative solution, we find significative differences in the low excitation energy limit (i.e. Γ μ 0 ). For the strength functions we find distributions going from the Wigner semicircle through gaussians to Breit-Wigner shapes. (orig.)

Rotational-mode component of the density of levels of nuclei with A approx-lt 150

International Nuclear Information System (INIS)

Rastopchin, E.M.; Svirin, M.I.; Smirenkin, G.N.

1992-01-01

Some difficulties which arise in the use of the generalized superfluid model to describe the density of levels in the region A approx-lt 150, as the result of an imperfect understanding of collective nuclear excitations, are discussed. One possible way to overcome these difficulties is examined. The idea is to depart from the conventional classification of collective nuclear properties and make use of small static deformations predicted theoretically and a corresponding rotational-mode component of the density of levels of these nuclei

Relativistic extension of the complex scaled Green's function method for resonances in deformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Shi, Min [Anhui University, School of Physics and Materials Science, Hefei (China); RIKEN Nishina Center, Wako (Japan); Shi, Xin-Xing; Guo, Jian-You [Anhui University, School of Physics and Materials Science, Hefei (China); Niu, Zhong-Ming [Anhui University, School of Physics and Materials Science, Hefei (China); Interdisciplinary Theoretical Science Research Group, RIKEN, Wako (Japan); Sun, Ting-Ting [Zhengzhou University, School of Physics and Engineering, Zhengzhou (China)

2017-03-15

We have extended the complex scaled Green's function method to the relativistic framework describing deformed nuclei with the theoretical formalism presented in detail. We have checked the applicability and validity of the present formalism for exploration of the resonances in deformed nuclei. Furthermore, we have studied the dependences of resonances on nuclear deformations and the shape of potential, which are helpful to recognize the evolution of resonant levels from stable nuclei to exotic nuclei with axially quadruple deformations. (orig.)

Collective two-phonon states in deformed nuclei

International Nuclear Information System (INIS)

Solov'ev, V.G.; Shirikova, N.Y.

1982-01-01

The Pauli principle in the two-phonon components of the wave functions is taken into account within the framework of the quasiparticle-phonon model of the nucleus with phonon operators depending on the sign of the projection of the angular momentum. The centroid energies of collective two-phonon states in even-even deformed nuclei are calculated and it is shown that the inclusion of the Pauli principle shifts them by 1--3 MeV to higher energies. The shifts of the three-phonon poles due to the inclusion of the Pauli principle in the three-phonon components of the wave functions are calculated. Strong fragmentation of collective two-phonon states whose energy centroids are 3--5 MeV should be expected. It is concluded that collective two-phonon states need not exist in deformed nuclei. The situation with the 168 Er nucleus and the Th and U isotopes is analyzed

Spin, quadrupole moment, and deformation of the magnetic-rotational band head in Pb193

Science.gov (United States)

Balabanski, D. L.; Ionescu-Bujor, M.; Iordachescu, A.; Bazzacco, D.; Brandolini, F.; Bucurescu, D.; Chmel, S.; Danchev, M.; de Poli, M.; Georgiev, G.; Haas, H.; Hübel, H.; Marginean, N.; Menegazzo, R.; Neyens, G.; Pavan, P.; Rossi Alvarez, C.; Ur, C. A.; Vyvey, K.; Frauendorf, S.

2011-01-01

The spectroscopic quadrupole moment of the T1/2=9.4(5) ns isomer in Pb193 at an excitation energy Eex=(2585+x) keV is measured by the time-differential perturbed angular distribution method as |Qs|=2.6(3) e b. Spin and parity Iπ=27/2- are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the 1i13/2 subshell with the (3s1/2-21h9/21i13/2)11- proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation ɛ2=-0.11, similar to that of the 11-proton intruder states, which nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

Relativistic mean field theory for deformed nuclei with pairing correlations

International Nuclear Information System (INIS)

Geng, Lisheng; Toki, Hiroshi; Sugimoto, Satoru; Meng, Jie

2003-01-01

We develop a relativistic mean field (RMF) description of deformed nuclei with pairing correlations in the BCS approximation. The treatment of the pairing correlations for nuclei whose Fermi surfaces are close to the threshold of unbound states needs special attention. With this in mind, we use a delta function interaction for the pairing interaction to pick up those states whose wave functions are concentrated in the nuclear region and employ the standard BCS approximation for the single-particle states obtained from the BMF theory with deformation. We apply the RMF + BCS method to the Zr isotopes and obtain a good description of the binding energies and the nuclear radii of nuclei from the proton drip line to the neutron drip line. (author)

Electromagnetic transitions in nuclei between states with different deformation for the case H>=Ksub(iota)+Ksub(j)

International Nuclear Information System (INIS)

Kopanets, E.G.; Inopin, E.V.; Korda, L.P.

1980-01-01

Calculations of matrix elements of the electromagnetic transitions at the multipolarity L>Ksub(i)+Ksub(f), where Ksub(i) and Ksub(f) are the projections of the total moment of the final and initial states on the nucleus symmetry axis, have been carried out E2transitions between the low-lying levels -/ of the rotational bands of 23 Na, 29 P, 35 Cl and 37 Cl nuclei have been investigated. The ranges of the initial and final state deformation parameters are given at which a coincidence is observed between the calculated and experimental values of the probability of E2-transitions between the ground states of the rotational bands. A conclusion has been made that the theory and experiments can agree only on the assumption that changes in nucleus equilibrium deformation take place not only in the case of single-particle levels but also in the case of the same rotational band. This indicates to breaking the adiabatic approximation due to mixing the states with different K caused by the Coriolis interaction [ru

Spectrum fluctuations from regular and damped rotational structures in {sup 16}`8Yb and {sup 163}Tm nuclei

Energy Technology Data Exchange (ETDEWEB)

Herskind, B; Dossing, T; Ninel, N; Atac, A; Jensen, H J; Hagemann, G B; Lieder, R M; Maj, A; Nyberg, J; Piiparinen, M; Sugawara, M; Virtanen, A [Niels Bohr Inst., Copenhagen (Denmark); Leoni, S; Vigezzi, E; Bosetti, P; Bracco, A; Broglia, R A; Million, B [Milan Univ. (Italy); Matsuo, M [Kyoto Univ., Uji (Japan). Uji Research Center of Yukawa Inst. for Theoretical Physics; Bergstrom, M; Brockstedt, A; Carlsson, H; Ekstrom, P; Nordlund, A; Ryde, H [Lund Univ. (Sweden). Dept. of Physics; Jongman, J [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Ingebretsen, F; Tjom, P O [Oslo Univ. (Norway); Lonnroth, T [Aabo Akademi, Turku (Finland). Dept. of Physics

1992-08-01

A new method has been developed for analyzing fluctuations of count in two-dimensional gamma ray energy coincidence spectra of deformed nuclei formed in heavy ion fusion reactions. Most of the gamma decay cascades flow through regions of high level density, and the method is based upon assumptions about average properties of the excited states. Transition energies along discrete rotational bands are viewed as randomly selected from a continuous distribution of rotational frequencies and moments of inertia. For damped rotational motion, implying a mixing of the rotational bands, a random matrix model is assumed, leading to smooth energy spectra, and strong fluctuations of the transition strengths. The method is illustrated for {sup 168}Yb and {sup 163}Tm. 4 refs., 4 figs.

Anisotropy of favoured alpha transitions producing even-even deformed nuclei

International Nuclear Information System (INIS)

Tavares, O.A.P.

1997-05-01

The anisotropy in favoured alpha transitions which produce even-even deformed nuclei is discussed. A simple, Gamow's-like model which takes into account the quadrupole deformation of the product nucleus has been formulated to calculate the alpha decay half-life. It is assumed that before tunneling into a purely Coulomb potential barrier the two-body system oscillated isotropically, thus giving rise to an equivalent, average preferential polar direction θ 0 (referred to the symmetry axis of the ellipsoidal shape of the product nucleus) for alpha emission in favoured alpha transitions of even-even nuclei. (author)

Deformed configurations, band structures and spectroscopic ...

Indian Academy of Sciences (India)

2014-03-20

Mar 20, 2014 ... The deformed configurations and rotational band structures in =50 Ge and Se nuclei are studied by deformed Hartree–Fock with quadrupole constraint and angular momentum projection. Apart from the `almost' spherical HF solution, a well-deformed configuration occurs at low excitation. A deformed ...

The shape of nuclei

International Nuclear Information System (INIS)

Mackintosh, R.S.

1977-01-01

For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)

Static and dynamic deformations of actinide nuclei

International Nuclear Information System (INIS)

Rozmej, P.

1985-09-01

The zero-point quadrupole-hexadecapole vibrations have been taken into account to calculate dynamical deformations for even-even actinide nuclei. The collective and intrinsic motions are separated according to the Born-Oppenheimer approximation. The collective Hamiltonian is constructed using the macroscopic-microscopic method in the potential energy part and the cranking model in the kinetic energy part. The BCS theory with a modified oscillator potential is applied to describe the intrinsic motion of nucleons. A new set of Nilsson potential parameters, which produces a much better description of the properties of light actinide nuclei, has also been found. (orig.)

Study of ^{14}C Cluster Decay Half-Lives of Heavy Deformed Nuclei

Science.gov (United States)

Shamami, S. Rahimi; Pahlavani, M. R.

2018-01-01

A theoretical model based on deformed Woods-Saxon, Coulomb and centrifugal terms are constructed to evaluate the half-lives for the cluster radioactivity of various super heavy nuclei. Deformation have been applied on all parts of their potential containing nuclear barrier for cluster decay. Also, both parent and daughter nuclei are considered to be deformed. The calculated results of ^{14}C cluster radioactivity half-lives are compared with available experimental data. A satisfactory agreement between theoretical and measured data is achieved. Also, obtained half-lives for each decay family is agreed with Geiger-Nuttall law.

{Delta}I = 2 energy staggering in normal deformed dysprosium nuclei

Energy Technology Data Exchange (ETDEWEB)

Riley, M.A.; Brown, T.B.; Archer, D.E. [Florida State Univ., Tallahassee, FL (United States)] [and others

1996-12-31

Very high spin states (I{ge}50{Dirac_h}) have been observed in {sup 155,156,157}Dy. The long regular band sequences, free from sharp backbending effects, observed in these dysprosium nuclei offer the possibility of investigating the occurence of any {Delta}I = 2 staggering in normal deformed nuclei. Employing the same analysis techniques as used in superdeformed nuclei, certain bands do indeed demonstrate an apparent staggering and this is discussed.

High spin rotations of nuclei with the harmonic oscillator potential

International Nuclear Information System (INIS)

Cerkaski, M.; Szymanski, Z.

1978-01-01

Calculations of the nuclear properties at high angular momentum have been performed recently. They are based on the liquid drop model of a nucleus and/or on the assumption of the single particle shell structure of the nucleonic motion. The calculations are usually complicated and involve long computer codes. In this article we shall discuss general trends in fast rotating nuclei in the approximation of the harmonic oscillator potential. We shall see that using the Bohr Mottelson simplified version of the rigorous solution of Valatin one can perform a rather simple analysis of the rotational bands, structure of the yrast line, moments of inertia etc. in the rotating nucleus. While the precision fit to experimental data in actual nuclei is not the purpose of this paper, one can still hope to reach some general understanding within the model of the simple relations resulting in nuclei at high spin. (author)

High-spin excitations of atomic nuclei

International Nuclear Information System (INIS)

Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing

2004-01-01

The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)

Role of shape and quadrupole deformation of parents in the cluster emission of rare earth nuclei

International Nuclear Information System (INIS)

Girija, K.K.; Joseph, Antony

2014-01-01

The nuclear structure effects on α decay and cluster emission are investigated in the case of even–even rare earth nuclei 150–160 Dy, 150–160 Er, 150–160 Yb, 158,162,166–176 Hf, 160,164–178 W and 162,166,170–180 Os. The role of shape and deformation of parent nuclei in the decay rate is studied by taking the Coulomb and proximity potentials as the interacting barrier for the post scission configuration. The quadrupole deformation of parent nuclei causes a slight change in the half-life of α emissions, but it affects the rate of heavy cluster emissions significantly. Prolate deformation of parents enhances cluster emission, while an oblate deformation slows down the decay. Shape and deformation of parent nuclei causes change in the branching ratio also. A prolate deformation increases the branching ratio, whereas an oblate deformation reduces it. Highest branching ratio is predicted at N ∼ 90. (author)

Strong electric and magnetic dipole excitations in deformed nuclei

International Nuclear Information System (INIS)

Kneissl, U.

1993-01-01

Systematic nuclear resonance fluorescence (NRF) experiments have been performed at the bremsstrahlung facility of the Stutgart dynamitron to investigate the distribution of magnetic and electric dipole excitations in deformed nuclei

Description of deformed nuclei in the sdg boson model

Energy Technology Data Exchange (ETDEWEB)

Li, S.C. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences; Kuyucak, S. [Australian National Univ., Canberra, ACT (Australia). Research School of Physical Sciences

1996-07-15

We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical 1/N expansion techniques. The focus is on the description of high-spin states which have recently become computationally accessible through the use of computer algebra in the 1/N expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei. (orig.).

Description of deformed nuclei in the sdg boson model

Science.gov (United States)

Li, S. C.; Kuyucak, S.

1996-02-01

We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical {1}/{N} expansion techniques. The focus is on the description of high-spin states which have recently become computationally accessible through the use of computer algebra in the {1}/{N} expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei.

Description of deformed nuclei in the sdg boson model

International Nuclear Information System (INIS)

Li, S.C.; Kuyucak, S.

1996-01-01

We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical 1/N expansion techniques. The focus is on the description of high-spin states which have recently become computationally accessible through the use of computer algebra in the 1/N expansion formalism. A systematic study is made of high-spin states in rare-earth and actinide nuclei. (orig.)

Nucleus spectroscopy: extreme masses and deformations

International Nuclear Information System (INIS)

Theisen, Ch.

2009-12-01

The author proposes a synthesis of research activities performed since 1995 in the field of experimental nuclear physics, and more particularly in the investigation of two nucleus extreme states: deformation on the one hand, heavy and very heavy nuclei on the other hand. After a presentation of the context of investigations on deformation, rotation, and heavy nuclei, he gives an overview of developments regarding instruments (gamma spectrometers, detection of fission fragments, and detection at the focal plane of spectrometers or separators) and analysis techniques. Experiments and results are then reported and discussed, concerning super-deformed states with a high angular moment, spectroscopy of neutron-rich nuclei, very heavy nuclei close to nucleus map borders. He finally draws perspectives for middle and long term studies on the heaviest nuclei

Real and complex boson expansions in even-even deformed nuclei

International Nuclear Information System (INIS)

Silvestre-Brac, B.; Piepenbring, R.

1977-01-01

Analysis of real and complex boson expansions of the Kishimoto-Tamura type is performed in a deformed basis in order to allow a further study of the anharmonicities of vibrations in deformed nuclei. It is shown that complex solutions cannot be found in the cases where no real one exists. (Auth.)

IBA in deformed nuclei

International Nuclear Information System (INIS)

Casten, R.F.; Warner, D.D.

1982-01-01

The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168 Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong β → γ transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the β → γ transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ΔK=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics

Pair correlation of super-deformed rotation band

International Nuclear Information System (INIS)

Shimizu, Yoshio

1989-01-01

The effect of pair correlation, one of the most important residual interactions associated with the super-deformed rotation band, is discussed in terms of the characteristics of the rotation band (its effect on the moment of inertia in particular), and the tunneling into an normal deformed state in relation to its effect on the angular momentum dependence of the potential energy plane as a function of the deformation. The characteristics of the rotation band is discussed in terms of the kinematic and dynamic momenta of inertia. It is shown that the pair correlation in a super-deformed rotation band acts to decrease the former and increase the latter momentum mainly due to dynamic pair correlation. A theoretical approach that takes this effect into account can provide results that are consistent with measured momenta, although large differences can occur in some cases. Major conflicts include a large measured kinetic momentum of inertia compared to the theoretical value, and the absence of the abnormality (shape increase) generally seen in low-spin experiments. The former seems likely to be associated with the method of measuring the angular momentum. (N.K.)

Pairing effects in rotating nuclei: a semi classical approach

International Nuclear Information System (INIS)

Durand, M.

1985-10-01

The semi-classical phase-space distribution ρ(r,p) is calculated for rotating superfluid nuclei, taking into account the reaction of the pairing field to the rotational motion. Moments of inertia and current distributions calculated by means of this distribution pass continuously from a rigid to an irrotational behaviour

Nuclear quadrupole-quadrupole interaction in the inelastic scattering of aligned deuterons from deformed nuclei

International Nuclear Information System (INIS)

Clement, H.; Frick, R.; Graw, G.; Schiemenz, P.; Seichert, N.

1983-01-01

The 2 1 + -excitation of deformed nuclei by tensor polarized deuterons provides an alignment of both nuclei and thus a means to study specifically the quadrupole-quadrupole interaction between both nuclei. The tensor analyzing power Asub(xz)(theta) has been measured for the elastic and inelastic scattering on 24 Mg and 28 Si. The coupled channel analysis including a deformed tensor potential reveals a clear signature of the quadrupole-quadrupole part of the nuclear projectile-target interaction. (orig.)

Nuclear squid: Diabolic pair transfer in rotating nuclei

Energy Technology Data Exchange (ETDEWEB)

Nikam, R S; Ring, P; Canto, L F

1987-02-19

A new unexpected behavior of pair transfer matrix elements in superfluid rotating nuclei is predicted. With increasing angular velocity they drop to zero, change their sign and in some cases even oscillate between positive and negative values. This effect is related to diabolical points in rotating quasiparticle spectra and is closely analogous to the DC-Josephson effect in superconductors in the presence of a magnetic field.

Deformed model Sp(4) model for studying pairing correlations in atomic nuclei

CERN Document Server

Georgieva, A I; Sviratcheva, K

2002-01-01

A fermion representation of the compact symplectic sp(4) algebra introduces a theoretical framework for describing pairing correlations in atomic nuclei. The important non-deformed and deformed subalgebras of sp sub ( sub q sub ) (4) and the corresponding reduction chains are explored for the multiple orbit problem. One realization of the u sub ( sub q sub ) (2) subalgebra is associated with the valence isospin, other reductions describe coupling between identical nucleons or proton-neutron pairs. Microscopic non-deformed and deformed Hamiltonians are expressed in terms of the generators of the sp(4) and sp sub q (4) algebras. In both cases eigenvalues of the isospin breaking Hamiltonian are fit to experimental ground state energies. The theory can be used to investigate the origin of the deformation and predict binding energies of nuclei in proton-rich regions. The q-deformation parameter changes the pairing strength and in so doing introduces a non-linear coupling into the collective degree of freedom

Quantum algebra U{sub qp}(u{sub 2}) and application to the rotational collective dynamics of the nuclei; Algebre quantique U{sub qp}(u{sub 2}) et application a la dynamique collective de rotation dans les noyaux

Energy Technology Data Exchange (ETDEWEB)

Barbier, R

1995-09-22

This thesis concerns some aspects of new symmetries in Nuclear Physics. It comprises three parts. The first one is devoted to the study of the quantum algebra U{sub qp}(u{sub 2}). More precisely, we develop its Hopf algebraic structure and we study its co-product structure. The bases of the representation theory of U{sub qp}(u{sub 2}) are introduced. On one hand, we construct the finite-dimensional irreducible representations of U{sub qp}(u{sub 2}). On the other hand, we calculate the Clebsch-Gordan coefficients with the projection operator method. To complete our study, we construct some deformed boson mappings of the quantum algebras U{sub qp}(u{sub 2}), U{sub q{sup 2}}(su{sub 2}) and U{sub qp}(u{sub 1,1}). The second part deals with the construction of a new phenomenological model of the non rigid rotator. This model is based on the quantum algebra U{sub qp}(u{sub 2}). The rotational energy and the E2 reduced transition probabilities are obtained. They depend on the two deformation parameters q and p of the quantum algebra. We show how the use of the two-parameter deformation of the algebra U{sub qp}(u{sub 2}) leads to a generalization of the U{sub q}(su{sub 2})-rotator model. We also introduce a new model of the anharmonic oscillator on the basis of the quantum algebra U{sub qp}(u{sub 2}). We show that the system of the U{sub q}(su{sub 2})-rotator and of the anharmonic oscillator can be coupled with the use of the deformation parameters of U{sub qp}(u{sub 2}). A ro-vibration energy formula and expansion `a la` Dunham are obtained. The aim of the last part is to apply our non rigid rotator model to the rotational collective dynamics of the superdeformed nuclei of the A{approx}130 - 150 and A{approx}190 mass regions and deformed nuclei of the actinide and rare earth series. We adjust the free parameters of our model and compare our results with those from four other models of the non rigid rotator. A comparative analysis is given in terms of transition energies.

Spin, quadrupole moment, and deformation of the magnetic-rotational band head in (193)Pb

CERN Document Server

Balabanski, D L; Iordachescu, A; Bazzacco, D; Brandolini, F; Bucurescu, D; Chmel, S; Danchev, M; De Poli, M; Georgiev, G; Haas, H; Hubel, H; Marginean, N; Menegazzo, R; Neyens, G; Pavan, P; Rossi Alvarez, C; Ur, C A; Vyvey, K; Frauendorf, S

2011-01-01

The spectroscopic quadrupole moment of the T(1/2) = 9.4(5) ns isomer in (193)Pb at an excitation energy E(ex) = (2585 + x) keV is measured by the time-differential perturbed angular distribution method as vertical bar Q(s)vertical bar = 2.6(3) e b. Spin and parity I(pi) = 27/2(-) are assigned to it based on angular distribution measurements. This state is the band head of a magnetic-rotational band, described by the coupling of a neutron hole in the 1i(13/2) subshell with the (3s(1/2)(-2)1h(9/2)1i(13/2))(11-) proton excitation. The pairing-plus-quadrupole tilted-axis cranking calculations reproduce the measured quadrupole moment with a moderate oblate deformation epsilon(2) = -0.11, similar to that of the 11(-)proton intruder states, which occur in the even-even Pb nuclei in the region. This is the first direct measurement of a quadrupole moment and thus of the deformation of a magnetic-rotational band head.

New estimates of quadrupole deformation β of some nearly spherical even Mo nuclei

International Nuclear Information System (INIS)

Singh, Y.; Gupta, K.K.; Singh, M.; Bihari, Chhail; Varshney, A.K.; Gupta, D.K.

2013-01-01

The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. In recent past the sets of deformation parameters (β, γ) have been extracted from both level energies and E2 transition rates in even Xe, Ba and Ce nuclei and Hf, W, Os, Pt and Hg nuclei using rigid triaxial rotor model of Davydov – Filippov

Scissors and unique-parity modes of M1 excitation in deformed nuclei

International Nuclear Information System (INIS)

Otsuka, T.

1989-01-01

In this paper the possible modes of M1 excitation in deformed even-even nuclei are studied in terms of the particle-number-conserved Nilsson + BCS formalism with the standard parameters. The spurious motion with respect to the rotation is removed. In addition to the Scissors mode, the Unique-Parity Spin and Normal-Parity Spin modes are suggested, although the latter may be fragmented to a large extent. The Scissors mode carries most of the orbital strength, while the others the spin strength. The proton Unique-Parity (i.e. Oh 11/12 ) Spin mode for 164 Dy is obtained just below Ex = 3 MeV with B(M1) ∼ 0.2 μ 2 N ) in the sum rule limit. This is in a good agreement to the recent experimental data

Sub-barrier quasifission in heavy element formation reactions with deformed actinide target nuclei

Science.gov (United States)

Hinde, D. J.; Jeung, D. Y.; Prasad, E.; Wakhle, A.; Dasgupta, M.; Evers, M.; Luong, D. H.; du Rietz, R.; Simenel, C.; Simpson, E. C.; Williams, E.

2018-02-01

Background: The formation of superheavy elements (SHEs) by fusion of two massive nuclei is severely inhibited by the competing quasifission process. Low excitation energies favor SHE survival against fusion-fission competition. In "cold" fusion with spherical target nuclei near 208Pb, SHE yields are largest at beam energies significantly below the average capture barrier. In "hot" fusion with statically deformed actinide nuclei, this is not the case. Here the elongated deformation-aligned configurations in sub-barrier capture reactions inhibits fusion (formation of a compact compound nucleus), instead favoring rapid reseparation through quasifission. Purpose: To determine the probabilities of fast and slow quasifission in reactions with prolate statically deformed actinide nuclei, through measurement and quantitative analysis of the dependence of quasifission characteristics at beam energies spanning the average capture barrier energy. Methods: The Australian National University Heavy Ion Accelerator Facility and CUBE fission spectrometer have been used to measure fission and quasifission mass and angle distributions for reactions with projectiles from C to S, bombarding Th and U target nuclei. Results: Mass-asymmetric quasifission occurring on a fast time scale, associated with collisions with the tips of the prolate actinide nuclei, shows a rapid increase in probability with increasing projectile charge, the transition being centered around projectile atomic number ZP=14 . For mass-symmetric fission events, deviations of angular anisotropies from expectations for fusion fission, indicating a component of slower quasifission, suggest a similar transition, but centered around ZP˜8 . Conclusions: Collisions with the tips of statically deformed prolate actinide nuclei show evidence for two distinct quasifission processes of different time scales. Their probabilities both increase rapidly with the projectile charge. The probability of fusion can be severely

Shell effects in the nuclear deformation energy

International Nuclear Information System (INIS)

Ross, C.K.

1973-01-01

A new approach to shell effects in the Strutinsky method for calculating nuclear deformation energy is evaluated and the suggestion of non-conservation of angular momentum in the same method is resolved. Shell effects on the deformation energy in rotational bands of deformed nuclei are discussed. (B.F.G.)

The structure of rotational bands in alpha-cluster nuclei

Directory of Open Access Journals (Sweden)

Bijker Roelof

2015-01-01

Full Text Available In this contribution, I discuss an algebraic treatment of alpha-cluster nuclei based on the introduction of a spectrum generating algebra for the relative motion of the alpha-clusters. Particular attention is paid to the discrete symmetry of the geometric arrangement of the α-particles, and the consequences for the structure of the rotational bands in the 12C and 16O nuclei.

Exotic octupole deformation in proton-rich Z=N nuclei

Energy Technology Data Exchange (ETDEWEB)

Takami, Satoshi; Yabana, K [Niigata Univ. (Japan); Matsuo, M

1998-03-01

We study static non-axial octupole deformations in proton-rich Z=N nuclei, {sup 64}Ge, {sup 68}Se, {sup 72}Kr, {sup 76}Sr, {sup 80}Zr and {sup 84}Mo, by using the Skyrme Hartree-Fock plus BCS method with no restrictions on the nuclear shape. The calculation predicts that the oblate ground state in {sup 68}Se is extremely soft for the Y{sub 33} triangular deformation, and that in {sup 80}Zr the low-lying local minimum state coexisting with the prolate ground state has the Y{sub 32} tetrahedral deformation. (author)

Study of Triaxial deformation variable γ in even - even nuclei

International Nuclear Information System (INIS)

Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Sharma, Aparna; Varshney, A.K.; Singh, M.; Gupta, D.K.; Varshney, Mani; Dhiman, S.K.

2011-01-01

The deformation parameters β and γ of the collective model are basic description of the nuclear equilibrium shape and structure, while values for these variables have been discussed for many nuclei. A systematic study in mass region A = 120-140 and A = 150 -180 can never be less revealing, such study has been presented, in A = 90 -120 for Mo, Ru and Pd nuclei where β and γ both vary strongly

Band-head spectra of low-energy single-particle excitations in some well-deformed, odd-mass heavy nuclei within a microscopic approach

Energy Technology Data Exchange (ETDEWEB)

Koh, Meng-Hock [Universiti Teknologi Malaysia, Skudai, Johor (Malaysia); Univ. Bordeaux, CENBG, UMR5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, Gradignan (France); Duc, Dao Duy [Ton Duc Thang University, Division of Nuclear Physics, Ho Chi Minh City (Viet Nam); Ton Duc Thang University, Faculty of Applied Sciences, Ho Chi Minh City (Viet Nam); Nhan Hao, T.V. [Duy Tan University, Center of Research and Development, Danang (Viet Nam); Hue University, Center for Theoretical and Computational Physics, College of Education, Hue City (Viet Nam); Long, Ha Thuy [Hanoi University of Sciences, Vietnam National University, Hanoi (Viet Nam); Quentin, P. [Universiti Teknologi Malaysia, Skudai, Johor (Malaysia); Univ. Bordeaux, CENBG, UMR5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, Gradignan (France); Ton Duc Thang University, Division of Nuclear Physics, Ho Chi Minh City (Viet Nam); Bonneau, L. [Univ. Bordeaux, CENBG, UMR5797, Gradignan (France); CNRS, IN2P3, CENBG, UMR5797, Gradignan (France)

2016-01-15

In four well-deformed heavy odd nuclei, the energies of low-lying rotational band heads have been determined microscopically within a self-consistent Hartree-Fock-plus-BCS approach with blocking. A Skyrme nucleon-nucleon effective interaction has been used together with a seniority force to describe pairing correlations. Only such states which are phenomenologically deemed to be related to single-particle excitations have been considered. The polarization effects, including those associated with the genuine time-reversal symmetry breaking have been fully taken into account within our model assumptions. The calculated spectra are in reasonably good qualitative agreement with available data for the considered odd-neutron nuclei. This is not so much the case for the odd-proton nuclei. A potential explanation for such a difference in behavior is proposed. (orig.)

Gamma band odd-even staggering in some deformed nuclei

International Nuclear Information System (INIS)

Khairy, M.K.; Talaat, SH.M.; Morsy, M.

2005-01-01

A complete investigation was carried out in studying the odd-even staggering (OES) of gamma bands energy levels in some deformed nuclei up to angular momentum L=13 . With the help of Minkov treatment in the framework of a collective Vector Boson Model (VBM) with broken SU (3) symmetry. The OES behavior of deformed isotopes 162 E r, 164 E r, 166 E r, 156 G d, 170 Y b and 232 T h was studied and discussed

Situation with collective two-phonon states in deformed nuclei

International Nuclear Information System (INIS)

Soloviev, V.G.; Shirikova, N.Yu.

1982-01-01

Within the quasiparticle-phonon nuclear model with the operators of phonons depending on the sign of the angular momentum projection, the Pauli principle is taken into account in the two-phonon components of the wave functions. The centroid energies of the collective two-phonon states in even-even deformed nuclei are calculated. It is shown that the inclusion of the Pauli principle leads to their shift by 1-3 MeV towards high energies. The shifts of three-phonon poles due to the Pauli principle are calculated in the three-phonon components of the wave functions. The collective two-phonon states, the centroid energies of which are 3-5 MeV, are expected to be strongly fragmented. The conclusion is confirmed that the collective two-phonon states should not exist in deformed nuclei. The situation in 168 Er and in the 228 Th isotopes is analysed

The collective model of nuclei and its applications

International Nuclear Information System (INIS)

Frank H, A.; Castanos G, O.H.

1975-01-01

The concepts of collective coordinates, the establishment of Hamiltonian collectives through the model of the drop of liquid or through the symmetry arguments and of the operators in these variables are discussed in this study. The passage of the laboratory system to the principal axis system is discussed thoroughly with the symmetries produced by this transformation, considering a drop in two dimensions. It is also observed that the deformed nuclei have some properties that can be described through the rotation-vibration and symmetric rotor models. The rotation-vibration model concerns the nuclei with axially symmetric deformations in the basic state and its importance is due to the fact that it can predict the nuclear spectrum at low energies. The asymmetric rotor model assumes the existence of triaxial nuclei and considers their collective movements. This model can be modified taking into consideration that vibrations β can also appear. Finally there is a comparison between the two models and the models are also compared with the experiment. (author)

E2 transitions in deformed nuclei and the IBA

International Nuclear Information System (INIS)

Warner, D.D.; Casten, R.F.

1981-01-01

The mechanism which determines the relative E2 strengths in the Interacting Boson Approximation is studied, and the structure of the E2 operator necessary to reproduce the empirical B(E2) values in deformed even-even nuclei in the rate earth region is investigated

Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei

International Nuclear Information System (INIS)

Ibanez-Sandoval, A.; Ortiz, M. E.; Velazquez, V.; Galindo-Uribarri, A.; Hess, P. O.; Sun, Y.

2011-01-01

A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A=130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the 125,127,129,131,133 Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J (2) , kinetic moment of inertia J (1) , the crossing of rotational bands, and backbending effects.

Rare-earth nuclei: Radii, isotope-shifts and deformation properties in the relativistic mean-field theory

International Nuclear Information System (INIS)

Lalazissis, G.A.; Ring, P.

1996-01-01

A systematic study of the ground-state properties of even-even rare earth nuclei has been performed in the framework of the Relativistic Mean-Field (RMF) theory using the parameter set NL-SH. Nuclear radii, isotope shifts and deformation properties of the heavier rare-earth nuclei have been obtained, which encompass atomic numbers ranging from Z=60 to Z=70 and include a large range of isospin. It is shown that RMF theory is able to provide a good and comprehensive description of the empirical binding energies of the isotopic chains. At the same time the quadrupole deformations β 2 obtained in the RMF theory are found to be in good agreement with the available empirical values. The theory predicts a shape transition from prolate to oblate for nuclei at neutron number N=78 in all the chains. A further addition of neutrons up to the magic number 82 brings about the spherical shape. For nuclei above N=82, the RMF theory predicts the well-known onset of prolate deformation at about N=88, which saturates at about N=102. The deformation properties display an identical behaviour for all the nuclear chains. A good description of the above deformation transitions in the RMF theory in all the isotopic chains leads to a successful reproduction of the anomalous behaviour of the empirical isotopic shifts of the rare-earth nuclei. The RMF theory exhibits a remarkable success in providing a unified and microscopic description of various empirical data. (orig.)

Deformation effects in the Si + C and Si + Si reactions

Indian Academy of Sciences (India)

The possible occurrence of highly deformed configurations is investigated in the. ¼ ... Fusion–fission; nuclear deformation; exclusive light charge particle measurements. .... In hot rotating nuclei formed in heavy-ion reactions, the energy level.

The role of cranking frequency in the generation of angular momentum in isospin formalism for nuclei around A=90

International Nuclear Information System (INIS)

Mohamed Akbar, A.; Veeraraghavan, S.; Arunachalam, N.

1998-01-01

The role of cranking frequency in hot rotating deformed nuclei has been studied with reference to the extraction of several nuclear parameters. In this work, the angular momentum degree of freedom is included in the isospin formalism using statistical theory of hot deformed nuclei

Shell structure in superdeformed nuclei at high rotational frequencies

International Nuclear Information System (INIS)

Ploszajczak, M.

1980-01-01

Properties of the shell structure in superdeformed nuclei at high rotational frequencies are discussed. Moreover, stability of the high spin compound nucleus with respect to the fission and the emission of light particles is investigated. (author)

Relativistic quasiparticle random phase approximation in deformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Pena Arteaga, D.

2007-06-25

Covariant density functional theory is used to study the influence of electromagnetic radiation on deformed superfluid nuclei. The relativistic Hartree-Bogolyubov equations and the resulting diagonalization problem of the quasiparticle random phase approximation are solved for axially symmetric systems in a fully self-consistent way by a newly developed parallel code. Three different kinds of high precision energy functionals are investigated and special care is taken for the decoupling of the Goldstone modes. This allows the microscopic investigation of Pygmy and scissor resonances in electric and magnetic dipole fields. Excellent agreement with recent experiments is found and new types of modes are predicted for deformed systems with large neutron excess. (orig.)

Influence of fragment deformation and orientation on compact configuration of odd-Z superheavy nuclei

International Nuclear Information System (INIS)

Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

2016-01-01

The synthesis of heavy and superheavy nuclei is generally carried out by using hot and cold fusion reaction mechanisms. It has been noticed that, the cold fusion reactions occur at relatively low excitation energies (E*_C_N ∼ 10-20 MeV) whereas, the hot fusion reactions occur at excitation energies of E*_C_N ∼ 30- 50 MeV. The fusion mechanism is quite different in both the processes. In the cold fusion process, the interaction of spherical targets (Pb and Bi) with deformed light mass projectiles occurs. On the other hand, the fusion of deformed actinide targets with spherical "4"8Ca projectile characterize the hot interaction processes. Hence the deformations and orientations of targets and projectiles play extremely important role in the superheavy fusion process. The present analysis is carried out to aggrandize the work of which illustrate the role of deformations and orientations on even superheavy nuclei. Here, we extend this analysis for odd superheavy nuclei. It is relevant to note that the temperature and angular momentum effects are not included in the present analysis

Improving the Calculation of The Potential Between Spherical and Deformed Nuclei

International Nuclear Information System (INIS)

Ismail, M.; Ramadan, Kh.A.

2000-01-01

The Heavy Ion (HI) interaction potential between spherical and deformed nuclei is improved by calculating its exchange part using finite range nucleon-nucleon (NN) force. We considered U 238 as a target nucleus and seven projectile nuclei to show the dependence of the HI potential on both the energy and orientation of the deformed target nucleus. The effect of finite range NN force has been found to produce significant changes in the HI potential. The variation of the barrier height V B , its thickness and its position R B due to the use of finite range NN force are significant. Such variation enhance the fusion cross-section at energy values just below the Coulomb barrier by a factor increasing with the mass number of projectile nucleus. (author)

Giant resonances in hot rotating nuclei

International Nuclear Information System (INIS)

Ring, P.

1992-01-01

Present theoretical descriptions of the giant resonances in hot rotating nuclei are reviewed. Mean field theory is used as a basis for the description of the hot compound states. Starting from the static solution at finite temperature and with fixed angular momentum small amplitude collective vibrations are calculated in the frame work of finite temperature random phase approximation for quasi-particles. The effect of pairing at low temperatures as well as the effect of rotations on the position of the resonance maxima are investigated. Microscopic and phenomenological descriptions of the damping mechanisms are reviewed. In particular it turns out that fluctuations play an important role in understanding of the behaviour of the width as a function of the temperature. Motional narrowing is critically discussed. (author). 99 refs., 5 figs

Shapes and alignments at high spin in some rare-earth nuclei

International Nuclear Information System (INIS)

Deleplanque, M.A.; Diamond, R.M.; Stephens, F.S.; Macchiavelli, A.O.; Doessing, T.; Draper, J.E.; Dines, E.L.

1985-01-01

The structure of nuclei at high spins is dominated by an interplay between deformation and alignment effects. Cranking models predict various shapes but at the highest spins, there is a tendency towards large triaxial deformations and sometimes towards very large prolate deformations (superdeformations). Directly involved in the shape changes are aligned orbitals which come down to the Fermi level as the nucleus rotates more rapidly. At a certain frequency, they become populated and cause large alignments. The mechanism of these changes has been explored by looking at a series of rare earth quasirotational nuclei from Dy to W in the transition region around N = 90 neutrons. The continuum spectra, corrected for incomplete population (feeding) of the high spins, are directly proportional to dynamic effective moments of inertia which describe how much spin is generated at each rotational frequency

Effects of high-order deformation on high-K isomers in superheavy nuclei

International Nuclear Information System (INIS)

Liu, H. L.; Bertulani, C. A.; Xu, F. R.; Walker, P. M.

2011-01-01

Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of β 6 deformation, we find remarkable effects of the high-order deformation on the high-K isomers in 254 No, the focus of recent spectroscopy experiments on superheavy nuclei. For shapes with multipolarity six, the isomers are more tightly bound and, microscopically, have enhanced deformed shell gaps at N=152 and Z=100. The inclusion of β 6 deformation significantly improves the description of the very heavy high-K isomers.

SP (4,R) symmetry in light nuclei

International Nuclear Information System (INIS)

Peterson, D.R.

1979-01-01

A classification of nuclear states according to the noncompact sympletic Lie algebras sp(2n,R), n = 1, 2, 3, is investigated. Such a classification has recently been shown to be physically meaningful. This classification scheme is the appropriate generalization fo Elliott's SU 3 model of rotational states in deformed light nuclei to include core excitations. A restricted classification according to the Lie algebra, sp(4,R), is motivated. Truncation of the model space to a single sp(4,R) irreducible representation allows the inclusion of states possessing very high excitation energy. An sp(4,R) model study is performed on S = T = 0 positive-parity rotational bands in the deformed light nuclei 16 O and 24 Mg. States are included in the model space that possess up to 10h ω in excitation energy. Results for the B(E2) transition rates compare favorable with experiment, without resort to effective charges

Macroscopic description of normal quadrupole oscillations and shape of rotating nuclei (spheroids)

International Nuclear Information System (INIS)

Balbutsev, E.B.; Mikhailov, I.N.; Vaishvila, Z.

1981-01-01

The ''distorted-Fermi-surface'' model is generalized to study the rotating nuclei. The mathematical problems of the model are solved with the help of the tensor virial method by Chandrasekhar-Lebovitz. The parameters of a form and characteristic frequencies of the quadrupole oscillations are calculated as a function of angular velocity Ω for the rotating nuclei. The energy of Giant Quadrupole Resonance is in agreement with experiment for Ω=0. There are two low-lying modes of oscillations in the model. The critical angular momenta are calculated. The comparison with the liquid drop model is done [ru

Electric monopole transitions from low energy excitations in nuclei

CERN Document Server

Wood, J L; De Coster, C; Heyde, Kris L G

1999-01-01

Electric monopole (E0) properties are studied across the entire nuclear mass surface. Besides an introductory discussion of various model results (shell model, geometric vibrational and rotational models, algebraic models), we point out that many of the largest E0 transition strengths, $\\rho^2$(E0), are associated with shape mixing. We discuss in detail the manifestation of E0 transitions and present extensive data for~: single-closed shell nuclei, vibrational nuclei, well-deformed nuclei, nuclei that exhibit sudden ground-state changes, and nuclei that exhibit shape coexistence and intruder states. We also give attention to light nuclei, odd-A nuclei, and illustrate a suggested relation between $\\rho^2$(E0) and isotopic shifts.

On the study of level density parameters for some deformed light nuclei

International Nuclear Information System (INIS)

Sonmezoglu, S.

2005-01-01

The nuclear level density, which is the number of energy levels/MeV at an excitation energy Ex , is a characteristic property of every nucleus. Total level densities are among the key quantities in statistical calculations in many fields, such as nuclear physics, astrophysics, spallation s neutrons measurements, and studies of intermediate-energy heavy-ion collisions. The nuclear level density is an important physical quantity both from the fundamental point of view as well as in understanding the particle and gamma ray emission in various reactions. In light and heavy deformed nucleus, the gamma-ray energies drop with decreasing spin in a very regular fashion. The nuclear level density parameters have been usually used in investigation of the nuclear level density. This parameter itself changes with excitation energy depending on both shell effect in the single particle model and different excitation modes in the collective models. In this study, the energy level density parameters of some deformed light nucleus (40 C a, 47 T i, 59 N i, 79 S e, 80 B r) are determined by using energy spectrum of the interest nucleus for different band. In calculation of energy-level density parameters dependent upon excitation energy of nuclei studied, a model was considered which relies on the fact that energy levels of deformed light nuclei, just like those of deformed heavy nuclei, are equidistant and which relies on collective motions of their nucleons. The present calculation results have been compared with the corresponding experimental and theoretical results. The obtained results are in good agreement with the experimental results

Effects of deformations and orientations on neutron-halo structure of light-halo nuclei

International Nuclear Information System (INIS)

Sawhney, Gudveen; Gupta, Raj K.; Sharma, Manoj K.

2013-01-01

The availability of radioactive nuclear beams have enabled to study the structure of nuclei far from the stability line, which in turn led to the discovery of neutron-halo nuclei. These nuclei, located near the neutron drip-line exhibit a high probability of presence of one or two loosely bound neutrons at a large distance from the rest of nucleons. The fragmentation behavior is studied for 13 cases of 1n-halo nuclei, which include 11 Be, 14 B, 15 C, 17 C, 19 C, 22 N, 22 O, 23 O, 24 O, 24 F, 26 F, 29 Ne and 31 Ne, using the cluster-core model (CCM) extended to include the deformations and orientations of nuclei

Slip systems, dislocation boundaries and lattice rotations in deformed metals

DEFF Research Database (Denmark)

Winther, Grethe

2009-01-01

Metals are polycrystals and consist of grains, which are subdivided on a finer scale upon plastic deformation due to formation of dislocation boundaries. The crystallographic alignment of planar dislocation boundaries in face centred cubic metals, like aluminium and copper, deformed to moderate...... of the mechanical anisotropy of rolled sheets. The rotation of the crystallographic lattice in each grain during deformation also exhibits grain orientation dependence, originating from the slip systems. A combined analysis of dislocation boundaries and lattice rotations concludes that the two phenomena are coupled...

Nuclei and models, 2001-2003. DEA fields, particles and matter

International Nuclear Information System (INIS)

Sida, J.L.

2003-01-01

This document gathers a series of 6 lessons dedicated to students in the first year of their thesis (DEA) in fields and particles physics: 1) the extent of nuclear physics, 2) the nucleus as a cluster of interacting fermions, 3) models and deformation, 4) nuclei and rotation, 5) isospin and exotic nuclei, and 6) fission reactions from the saddle point to the scission point

Structure and symmetries of odd-odd triaxial nuclei

Energy Technology Data Exchange (ETDEWEB)

Palit, R. [Tata Institute of Fundamental Research, Department of Nuclear and Atomic Physics, Colaba, Mumbai (India); Bhat, G.H. [University of Kashmir, Department of Physics, Srinagar (India); Govt. Degree College Kulgam, Department of Physics, Kulgam (India); Sheikh, J.A. [University of Kashmir, Department of Physics, Srinagar (India); Cluster University of Srinagar, Srinagar, Jammu and Kashmir (India)

2017-05-15

Rotational spectra of odd-odd Rh and Ag isotopes are investigated with the primary motivation to search for the spontaneous chiral symmetry breaking phenomenon in these nuclei. The experimental results obtained on the degenerate dipole bands of some of these isotopes using a large array of gamma detectors are discussed and studied using the triaxial projected shell (TPSM) approach. It is shown that, first of all, to reproduce the odd-even staggering of the known yrast bands of these nuclei, large triaxial deformation is needed. This large triaxial deformation also gives rise to doublet band structures in many of these studied nuclei. The observed doublet bands in these isotopes are shown to be reproduced reasonably well by the TPSM calculations. Further, the TPSM calculations for neutron-rich nuclei indicate that the ideal manifestation of the chirality can be realised in {sup 106}Rh and {sup 112}Ag, where the doublet bands have similar electromagnetic properties along with small differences in excitation energies. (orig.)

Rotational states of odd Z rare earth proton emitter 131Eu

International Nuclear Information System (INIS)

Aggarwal, Mamta

2013-01-01

Recent observation of proton radioactivity and rotational bands in 131 Eu and 141 Ho with large deformations β ≈ 0.3 and γ softness have already proven the study of excited states of deformed proton emitters a source of valuable information on the structure of proton decaying states and response of proton emitters on the stress of rotation. The rare earth nuclei below the N = 82 shell closure form one of the few regions of the nuclear chart where nuclear shapes are expected to change rapidly with coexistence of oblate and prolate shapes in some nuclei. We evaluate shapes and deformation of 131 Eu by combining classical collective properties of the liquid drop model with the quantum corrections due to shell effects via Strutinsky formalism adequately described in. Excited states are treated using statistical theory. Nuclear shapes and deformation are traced by minimizing free energy (F = E-TS) w.r.t. deformation parameters β from 0 to 0.4 in steps of 0.01 and γ from -180° (oblate with symmetry axis parallel to the rotation axis) to -120° (prolate with symmetry axis perpendicular to rotation axis) and then to -60° (oblate collective) to 0° (prolate non-collective)

The multiphonon method as a dynamical approach to octupole correlations in deformed nuclei

International Nuclear Information System (INIS)

Piepenbring, R.

1986-09-01

The octupole correlations in nuclei are studied within the framework of the multiphonon method which is mainly the exact diagonalization of the total Hamiltonian in the space spanned by collective phonons. This treatment takes properly into account the Pauli principle. It is a microscopic approach based on a reflection symmetry of the potential. The spectroscopic properties of double even and odd-mass nuclei are nicely reproduced. The multiphonon method appears as a dynamical approach to octupole correlations in nuclei which can be compared to other models based on stable octupole deformation. 66 refs

The splitting of giant multipole states of deformed nuclei

International Nuclear Information System (INIS)

Suzuki, T.; Rowe, D.J.

1977-01-01

A vibrating potential model is applied to deformed nuclei with a deformed harmonic oscillator potential in order to discuss the splitting of isoscalar giant quadrupole states. Eigenfrequencies of the collective states are estimated to be √2ω(1 - delta/3), √2ω(1 - delta/6) and √2ω(1 + delta/3) for K = 0 + ,1 + and 2 + modes, respectively. The splitting of isovector dipole and isovector quadrupole states is also studied according to a schematic model as proposed by Bohr and Mottelson. It is shown that isovector dipole states are split, as in a hydrodynamic model, while isovector quadrupole states with the same scaling factors as those of isocalar quadrupole modes. (Auth.)

On some aspects of the semiclassical approach to giant resonances of rotating nuclei

International Nuclear Information System (INIS)

Winter, J.

1985-01-01

Quadrupole and isovector dipole resonances of rotating nuclei are investigated in the frame-work of Vlasov equations transformed to a rotating system of reference, which are based on the time-dependent Hartree-method for schematic forces. The parameter free model of the self-consistent vibrating harmonic oscillator potential for the quadrupole mode is extended to a coupling to rotation, which also includes large amplitude behaviour. A generalization to an exactly solvable two-liquid model describing the isovector mode is established; for rotating nuclei Hilton's explicit result for the eigenfrequencies is obtained. - The advantage of using the concept of the classical kinetic momentum in a rotating system also in quantum-mechanical descriptions is demonstrated. It completes the standard transformation of density matrices by a time-odd part realized in a phase-factor and permits a more direct interpretation of rotation effects in terms of the classical forces of inertia. - In its generalization from constant angular velocity to constant angular momentum, our model is used to demonstrate that cranking calculations of rotating giant resonances should be corrected for an oscillation of the cranking parameter to assure angular-momentum conservation. (orig.)

Evolution of the low-lying dipole strength in deformed nuclei with extreme neutron excess with the Relativistic QRPA

International Nuclear Information System (INIS)

Pena Arteaga, D.; Khan, E.; Ring, P.

2009-01-01

Covariant density functional theory, in the framework of self-consistent Relativistic Hartree Bogoliubov (HFB) and Relativistic Quasiparticle Random Phase approximation (RQRPA), is for the first time applied to axially deformed nuclei [1]. The fully self-consistent RHB+RQRPA equations are posed for the case of axial symmetry and different energy functionals, and solved with the help of a new parallel code. As a sample application, the El strength is systematically analyzed in very neutron-rich Sn nuclei, beyond 1 32S n until 1 66S n [2]. The great neutron excess favors the appearance of a deformed ground state for 1 42-162S n. The evolution of the low-lying strength in deformed nuclei is discussed, and in particular its dependence on the interplay of two major and competing factors, isospin asymmetry and deformation.(author)

Interplay between tilted and principal axis rotation

Energy Technology Data Exchange (ETDEWEB)

Datta, Pradip [Ananda Mohan College, 102/1 Raja Rammohan Sarani, Kolkata 700 009 (India); Roy, Santosh; Chattopadhyay, S. [Saha Institute of Nuclear Physics, 1/AF Bidhan Nagar, Kolkata 700 064 (India)

2014-08-14

At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely {sup 109,110}Ag and {sup 108,110}Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay.

Interplay between tilted and principal axis rotation

International Nuclear Information System (INIS)

Datta, Pradip; Roy, Santosh; Chattopadhyay, S.

2014-01-01

At IUAC-INGA, our group has studied four neutron rich nuclei of mass-110 region, namely 109,110 Ag and 108,110 Cd. These nuclei provide the unique platform to study the interplay between Tilted and Principal axis rotation since these are moderately deformed and at the same time, shears structures are present at higher spins. The salient features of the high spin behaviors of these nuclei will be discussed which are the signatures of this interplay

Generalized vibrating potential model for collective excitations in spherical, deformed and superdeformed systems: (1) atomic nuclei, (2) metal clusters

International Nuclear Information System (INIS)

Nesterenko, V.O.; Kleinig, W.

1995-01-01

The self-consistent vibrating potential model (VPM) is extended for description of Eλ collective excitations in atomic nuclei and metal clusters with practically any kind of static deformation. The model is convenient for a qualitative analysis and provides the RPA accuracy of numerical calculations. The VPM is applied to study Eλ giant resonances in spherical metal clusters and deformed and superdeformed nuclei. It is shown that the deformation splitting of superdeformed nuclei results in a very complicated (''jungle-like'') structure of the resonances, which makes the experimental observation of E2 and E3 giant resonances in superdeformed nuclei quite problematic. Calculations of E1 giant resonance in spherical sodium clusters Na 8 , Na 20 and Na 40 are presented, as a test of the VPM in this field. The results are in qualitative agreement with the experimental data. (orig.)

Fragmentation of single-particle states in deformed nuclei

International Nuclear Information System (INIS)

Malov, L.A.; Soloviev, V.G.

1975-01-01

Fragmentation of single-particle states on levels of deformed nuclei is studied on the example of 239 U and 169 Er nuclei in the framework of the model taking into consideration the interaction of quasiparticles with phonons. The dependence of fragmentation on the Fermi surface is considered from the viewpoint of single-particle levels. It is shown that in the distribution of single-particle strength functions a second maximum appears together with the large asymmetry maximum at high-energy excitation, and the distribution has a long ''tail''. A semimicroscopic approach is proposed for calculating the neutron strength functions. The following values of the strength functions are obtained: for sub(239)U-Ssub(0)sup(cal)=1.2x10sup(-4), Ssub(1)sup(cal)=2.7x10sub(-4) and for sub(169)Er-Ssub(0)sup(cal)=1.10sup(-4), Ssub(1)sup(cal)=1.2x10sup(-4)

Low-spin identical bands in rare earth nuclei

International Nuclear Information System (INIS)

Baktash, C.; Winchell, D.F.; Garrett, J.D.; Smith, A.

1992-01-01

A comprehensive study of odd-A rotational bands in normally deformed rare earth nuclei indicates that a large number of seniority-one configurations (21% for odd-Z nuclei) at low spin have moments of inertia nearly identical to that of the seniority-zero configuration of the neighboring even-even nucleus with one less nucleon. It is difficult to reconcile these results with conventional models of nuclear pair correlation, which predict variations of about 15% in the moments of inertia of configurations differing by one unit in seniority

Identical high- K three-quasiparticle rotational bands

Energy Technology Data Exchange (ETDEWEB)

Kaur, Harjeet; Singh, Pardeep [Guru Nanak Dev University, Department of Physics, Amritsar (India)

2016-12-15

A comprehensive study of high-K three-quasiparticle rotational bands in odd-A nuclei indicates the similarity in γ-ray energies and dynamic moment of inertia I{sup (2)}. The extent of the identicality between the rotational bands is evaluated by using the energy factor method. For nuclei pairs exhibiting identical bands, the average relative change in the dynamic moment of inertia I{sup (2)} is also determined. The identical behaviour shown by these bands is attributed to the interplay of nuclear structure parameters: deformation and the pairing correlations. Also, experimental trend of the I(ℎ) vs. ℎω (MeV) plot for these nuclei pairs is shown to be in agreement with Tilted-Axis Cranking (TAC) model calculations. (orig.)

Intruder bands in Z = 51 nuclei

International Nuclear Information System (INIS)

LaFosse, D.R.

1993-01-01

Recent investigations of h 11/2 proton intruder bands in odd 51 Sb nuclei are reported. In addition to experiments performed at SUNY Stony Brook and Chalk River, data from Early Implementation of GAMMASPHERE (analysis in progress) are presented. In particular, the nuclei 109 Sb and 111 Sb are discussed. Rotational bands based on the πh 11/2 orbital coupled to a 2p2h deformed state of the 50 Sn core have been observed. These bands have been observed to high spin, and in the case of 109 Sb to a rotational frequency of 1.4 MeV, the highest frequency observed in a heavy nucleus. The dynamic moments of inertia in these bands decrease slowly with frequency, suggesting a gradual band termination. The systematics of such bands in 109-119 Sb will be discussed

Thouless-Valatin rotational moment of inertia from linear response theory

Science.gov (United States)

Petrík, Kristian; Kortelainen, Markus

2018-03-01

Spontaneous breaking of continuous symmetries of a nuclear many-body system results in the appearance of zero-energy restoration modes. These so-called spurious Nambu-Goldstone modes represent a special case of collective motion and are sources of important information about the Thouless-Valatin inertia. The main purpose of this work is to study the Thouless-Valatin rotational moment of inertia as extracted from the Nambu-Goldstone restoration mode that results from the zero-frequency response to the total-angular-momentum operator. We examine the role and effects of the pairing correlations on the rotational characteristics of heavy deformed nuclei in order to extend our understanding of superfluidity in general. We use the finite-amplitude method of the quasiparticle random-phase approximation on top of the Skyrme energy density functional framework with the Hartree-Fock-Bogoliubov theory. We have successfully extended this formalism and established a practical method for extracting the Thouless-Valatin rotational moment of inertia from the strength function calculated in the symmetry-restoration regime. Our results reveal the relation between the pairing correlations and the moment of inertia of axially deformed nuclei of rare-earth and actinide regions of the nuclear chart. We have also demonstrated the feasibility of the method for obtaining the moment of inertia for collective Hamiltonian models. We conclude that from the numerical and theoretical perspective, the finite-amplitude method can be widely used to effectively study rotational properties of deformed nuclei within modern density functional approaches.

Understanding nuclei in the upper sd - shell

Energy Technology Data Exchange (ETDEWEB)

Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Kshetri, Ritesh [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India and Sidho-Kanho-Birsha University, Purulia - 723101 (India); Sarkar, S. [Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103 (India)

2014-08-14

Nuclei in the upper-sd shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A ≃ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.

Low-lying states of 184W and 184Os nuclei

International Nuclear Information System (INIS)

Sharrad, F.I.; Abdullah, Hewa Y.; Al-Dahan, N.; Umran, N.M.; Okhunov, A.A.; Abu Kassim, H.

2013-01-01

The energy levels, transition energy, B(E2) values, intrinsic quadrupole moment Q 0 and potential energy surface for even-even 184 W and 184 Os nuclei were calculated using IBM-1. The predicted energy levels, transition energy, B(E2) values and intrinsic quadrupole moment Q 0 results are reasonably consistent with the experimental data. A contour plot of the potential energy surfaces shows that two interesting nuclei are deformed and have rotational characters. (authors)

Scattering of particles by deformed non-rotating black holes

International Nuclear Information System (INIS)

Pei, Guancheng; Bambi, Cosimo

2015-01-01

We study the excitation of axial quasi-normal modes of deformed non-rotating black holes by test particles and we compare the associated gravitational wave signal with that expected in general relativity from a Schwarzschild black hole. Deviations from standard predictions are quantified by an effective deformation parameter, which takes into account deviations from both the Schwarzschild metric and the Einstein equations. We show that, at least in the case of non-rotating black holes, it is possible to test the metric around the compact object, in the sense that the measurement of the gravitational wave spectrum can constrain possible deviations from the Schwarzschild solution. (orig.)

A new relation of parameters of Bohr-Mottelson rotational spectra formula

International Nuclear Information System (INIS)

Li Mingliang; Xu Fuxin

2003-01-01

With the first three terms of Harris formula included and Mottelson's method followed, a new relation of the parameters of Bohr-Mottelson rotational spectra formula is brought forward. Superdeformed bands of even-even nuclei and normal deformed bands of nuclei in actinide and rare-earth are fitted with four-parameter Bohr-Mottelson rotational spectra formula. The relations of the parameters A, B, C, D are studied. The result show, for normal deformed bands, the new relation approach the experiment value in the same degree as the relation deduced from ab formula, but for superdeformed bands, the new relation is closer to the experiment than the relation deduced from ab formula. Three-parameter Harris formula may have better convergence than two-parameter Harris formula

Selfconsistent calculations for hyperdeformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D. [Universite Louis Pasteur, Strasbourg (France)

1996-12-31

Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.

On the Orientation Barrier Distribution of the interacting spherical- Deformed Nuclei

International Nuclear Information System (INIS)

Ismail, M.; Seif, W.M.

2009-01-01

The effect of different multipole deformations on the Coulomb barrier distribution in the orientation degrees of freedom is studied. The demonstrated Coulomb barriers are calculated microscopically using the double folding model which is based on realistic density dependent nucleon nucleon interaction. A simple straight forward method, presented in recent work, has been used to predict the distribution of barriers at arbitrary orientations in presence of different deformations far away the complicated numerical calculations. The proposed interpretation is related to the half density radius change of the deformed nucleus involved in interaction where the orientation Coulomb barrier parameters distributions show similar patterns to that of orientation deformed nucleus one. The orientation Coulomb barrier radius distribution follows the same variation of the deformed nucleus radius, while the barrier height distribution is directly proportional to it. This correlation allows a simple evaluation of the orientation barrier distribution which greatly helps us to estimate when the barrier parameters will increase or decrease and at which orientations they will be independent of the deformation. It helps also to estimate the optimum orientations for hot and cold fusion of colliding nuclei.

Semimicroscopic description of the giant quadrupole resonances in deformed nuclei

International Nuclear Information System (INIS)

Kurchev, G.; Malov, L.A.; Nesterenko, V.O.; Soloviev, V.G.

1976-01-01

The calculation results of the giant quadrupole isoscalar and isovector resonances performed within the random phase approximation are represented. The strength functions for E2-transitions are calculated for doubly even deformed nuclei in the regions 150 (<=) A < 190 and 228 (<=) A < 248 in the energy interval (0-40) MeV. The following integral characteristics of giant quadrupole resonances are obtained: the position, widths, the contribution to the energy weighted sum rule and the contribution to the total cross section of photoabsorption. The calculations have shown that giant quadrupole resonances are common for all the considered nuclei. The calculated characteristics of the isoscalar giant quadrupole resonance agree with the available experimental data. The calculations also show that the semimicroscopic theory can be successfully applied for the description of giant multipole resonances

An approximate method for calculating the deformation of rotating nuclei

International Nuclear Information System (INIS)

Lind, P.

1988-01-01

The author presents as a collective model where the potential surface at spin I=0 is calculated in the Nilsson-Strutinsky model, an analytical expression for the moment of inertia is used which depends on the deformation and the pairing gaps for protons and neutrons, and the energy is minimized with respect to these gaps. Calculations in this model are performed for 16 Oyb. (HSI)

Effect of the Pauli principle on the nonrotational states in odd-A deformed nuclei

International Nuclear Information System (INIS)

Bastrukov, S.I.; Nesterenko, V.O.; Soloviev, V.G.

1982-01-01

The commutation relations between the quasiparticle and phonon operators are used to obtain the equations allowing a correct accounting of the Pauli principle for the description of the states of odd-A deformed nuclei. It is shown, that if in the quasiparticle plus phonon component the Pauli principle is not violated or is slightly violated, then a relevant vibrational state may exist in an odd-A deformed nucleus

Signature effects in 2qp bands of doubly even rare-earth nuclei

Energy Technology Data Exchange (ETDEWEB)

Kalra, Kawalpreet [Amity University, AUUP, Department of Physics, Amity Institute of Applied Sciences (AIAS), Noida (India); Goel, Alpana [Amity University, AUUP, Amity Institute of Nuclear Science and Technology (AINST), Noida (India); Jain, A.K. [Indian Institute of Technology (IIT), Department of Physics, Roorkee (India)

2016-12-15

The two-quasiparticle rotational bands in deformed doubly even nuclei in the rare-earth region have been studied in detail. A number of interesting features like odd-even staggering and signature inversion have been observed. The phenomenon of signature inversion/reversal is observed experimentally in {sup 162}{sub 66}Dy, {sup 170}{sub 70}Yb and {sup 170}{sub 74}W in even-even nuclei. Two quasiparticle plus rotor model (TQPRM) calculations are carried out to explain the reverse pattern of signature in {sup 170}{sub 74}W for the rotational band having configuration {(h_1_1_/_2)_p x (d_5_/_2)_p}. (orig.)

Photon strength in spherical and deformed heavy nuclei

International Nuclear Information System (INIS)

Grosse, E.; Junghans, A.; Birgersson, E.; Massarczyk, R.; Schramm, G.; Becvar, F.

2010-01-01

Information on the photon strength in heavy nuclei with mass A>150 will be given and compared to respective data. The photon strength function is a very important ingredient for statistical model calculations - especially when these are used to describe neutron capture. Several schemes for a transmutation of radioactive waste favor nuclear reactions with fast neutrons and these also influence the performance of various reactor types proposed to deliver nuclear energy together with only small quantities of such waste. Reactions with fast neutrons are far less studied as compared to those induced by thermal neutrons. As they are not easily accessible experimentally, reference is often made to calculations using the statistical model. Photon emission probabilities are needed as input to such calculations aiming for predictions on fission to capture ratios. From the favorable comparison of our parameterization to the experimental data for photon induced as well radiative capture processes in nuclei with various shapes and level densities we conclude what follows. First, the giant dipole resonance has very much the same properties in all heavy nuclei when their deformation is properly accounted for and its spreading width varies only smoothly with the resonance energies E k and not with the photon energy E γ . The radiative neutron capture results presented confirm strength data found in the literature. We also learn that our parameterization is at least a good approximation for photon energies below 4 MeV that dominate this process

Signature splitting in nuclear rotational bands: Neutron i13/2 systematics

International Nuclear Information System (INIS)

Mueller, W.F.; Jensen, H.J.; Reviol, W.; Riedinger, L.L.; Yu, C.; Zhang, J.; Nazarewicz, W.; Wyss, R.

1994-01-01

Experimental values of signature splitting in νi 13/2 rotational bands in odd-N even-Z nuclei in the Z=62--78 region are collected and presented. A procedure is introduced to calculate signature splitting within the cranked deformed Woods-Saxon model. In the theoretical treatment, deformation parameters are obtained by minimizing the total Routhians of individual νi 13/2 bands, and the procedure accounts for the possibility that the two signatures have different deformations and pairing gaps. Experimental signature splitting data for νi 13/2 bands in Dy, Er, Yb, Hf, W, and Os nuclei are compared with calculated values. The sensitivity of calculated signature splitting to changes in deformation, pairing, and other model parameters is presented

Relativistic deformed mean-field calculation of binding energy differences of mirror nuclei

International Nuclear Information System (INIS)

Koepf, W.; Barreiro, L.A.

1996-01-01

Binding energy differences of mirror nuclei for A=15, 17, 27, 29, 31, 33, 39 and 41 are calculated in the framework of relativistic deformed mean-field theory. The spatial components of the vector meson fields and the photon are fully taken into account in a self-consistent manner. The calculated binding energy differences are systematically smaller than the experimental values and lend support to the existence of the Okamoto-Nolen-Schiffer anomaly found decades ago in nonrelativistic calculations. For the majority of the nuclei studied, however, the results are such that the anomaly is significantly smaller than the one obtained within state-of-the-art nonrelativistic calculations. (author). 35 refs

Low-spin identical bands in odd-A nuclei

International Nuclear Information System (INIS)

Baktash, C.; Garrett, J.D.; Winchell, D.F.; Smith, A.

1992-01-01

A comprehensive study of odd-A rotational bands in normally-deformed rare-earth nuclei indicates that a large number of seniority-one configurations (30% for odd-Z nuclei) at low spin have moments of inertia nearly identical to that of the seniority-zero configuration of the neighboring even-even nucleus with one less nucleon. It is difficult to reconcile these results with conventional models, based on the traditional picture of nuclear pair correlation in vogue for more than three decades, which predict variations of about 15% in the moments of inertia of configurations differing by one unit in seniority

Experimental estimates of quasiparticle interactions for rotational nuclei

International Nuclear Information System (INIS)

Frauendorf, S.; Riedinger, L.L.

1984-01-01

Previously presented data on rotationally aligned quasiparticle bands in sup(160,161,162,163)Yb are analyzed to give experimental values of the quasiparticle interactions Vsub(μν) as a function of rotational frequency. The measured level energies are converted to the rotating frame of reference and expressed as routhians. The routhian of a multi-quasiparticle band is compared to the sum of the routhians of the component quasiparticles at a given frequency, the difference being the quasiparticle interaction. The experimental spectra of bands in these nuclei are consistent with the assumption of a binary interaction between the rotating quasiparticles, where most of the Vsub(μν) are in the range -0.3 to -0.1 MeV. Analysis of the shift in the observed crossing frequencies for bands of different quasiparticle number yields similar values. The extracted Vsub(μν) are found to have a frequency dependence, which is associated with the loss of alignment of a multi-quasiparticle state. An equidistant-level model is used to estimate the contributions to the quasiparticle interactions by polarization of the collective degrees of freedom. This model yields typical Vsub(μν) values of -0.15 MeV, which is only half of some values extracted from experiment. This suggests that the extracted Vsub(μν) contain a significant amount of nuclear-structure information. (orig.)

Collective properties and shapes of nuclei at very high spins

International Nuclear Information System (INIS)

Johnson, N.R.

1991-01-01

A topic which has been of major interest to us for some years now involves the evolution of nuclear collectivity at high rotational frequencies and the accompanying changes in the shapes of nuclei in these extreme conditions. We carry out these studies by determining the dynamic electromagnetic multipole moments which are a reflection of the collective aspects of the nuclear wave functions. The most direct way to get these multipole moments is by measurements of excited-state lifetimes which provide the transition matrix elements in a fairly straightforward fashion. Although the primary emphasis of this paper is on the collectivity of the high-spin states in 160 Yb and 164 Yb, it is important to review briefly some work we began about ten years ago lifetime studies of moderately high spins in nuclei near N=90 using the recoil-distance (RD) method. These nuclei are just at the onset of permanent deformation and are known to be very soft with respect to deformation changes. This softness is clearly illustrated in contour diagrams of their potential-energy surfaces. For example, the potential energy surface of 160 Yb reveals that the minimum in the potential occurs around var-epsilon ∼ 0.2 and that it is very shallow in the γ degree of freedom. Because of their γ softness, we have studied several nuclei near N=90 to assess to what extent the polarization effects induced by rotation alignment of high-j quasiparticles affect their collectivity

Near-Barrier Fusion of Heavy Nuclei. Coupling of the Channels

CERN Document Server

Zagrebaev, V I

2003-01-01

The problem of quantum description of near-barrier fusion of heavy nuclei taking place under strong coupling of relative motion with rotation of deformed nuclei and with dynamic deformations of their surfaces is studied in the paper. A new effective method is proposed for numerical solution of a set of coupled Schrodinger equations with boundary conditions corresponding to a full absorption of the flux penetrated through the multi-dimensional Coulomb barrier. The method has no limitation on the number of coupled channels and allows one to calculate fusion cross-sections of very heavy nuclei used for synthesis of super-heavy elements. A combined analysis of the multi-dimensional potential energy surface relief and the multi-channel wave function in the vicinity of the Coulomb barrier gives a clear interpretation of near-barrier fusion dynamics. Comparison with experimental data and with semi-empirical model calculations is performed. The computing codes are allocated at the web-server http://nrv.jinr.ru/nrv/ w...

Strength of Coriolis Coupling in actinide nuclei

International Nuclear Information System (INIS)

Peker, L.K.; Rasmussen, J.O.; Hamilton, J.H.

1982-01-01

Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h 2 /J[j (j + 1) -Ω (Ω + 1)]/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (β approx. = 0.22 versus β 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei

Giant monopole resonance in transitional and deformed nuclei

International Nuclear Information System (INIS)

Garg, U.; Bogucki, P.; Bronson, J.D.; Lui, Y.; Youngblood, D.H.

1984-01-01

Small-angle inelastic α-scattering measurements have been made at E/sub α/ = 129 MeV on /sup 144,148/Sm and /sup 142,146,150/Nd to investigate the giant monopole resonance in transitional and deformed nuclei. The experimental data reveal a mixing of L = 0 and L = 2 modes in 148 Sm resulting in almost identical angular distributions for the two components of the giant resonance peaks in the angular range 2 0 --6 0 . A ''splitting'' of the giant monopole resonance is observed in 150 Nd; the extent of this splitting is smaller than that reported for 154 Sm. Comparison is made with the predictions of various theoretical models

Study on rotational bands in odd-odd nuclei 102,l04Nb by using PSM

International Nuclear Information System (INIS)

Dong Yongsheng; Hu Wentao; Feng Youliang; Wang Jinbao; Yu Shaoying; Shen Caiwan

2012-01-01

The Projected Shell Model (PSM) is used to study the low energy scheme of the neutron-rich normal-deformed isotopes of odd-odd nuclei 102,104 Nb. The quasiparticle configuration is assigned. The theoretical calculations of the energy band of 102,104 Nb could well reproduce the experimental data. It is shown that PSM is a valid method for studying the low energy scheme of heavy nuclei. (authors)

SU-E-J-195: Quantification of Rotations and Deformations in Head and Heck Radiotherapy

International Nuclear Information System (INIS)

Kim, J; Liu, C; Kumarasiri, A; Gordon, J; Siddiqui, F; Chetty, I J; Chetvertkov, M

2014-01-01

Purpose: To quantify the magnitude of patient rotations and deformations over the course of head and neck radiotherapy. Methods: 45 CBCT images acquired weekly were selected retrospectively from 5 head and neck cancer patients. CBCT images were registered to the corresponding planning CT images using translation, rigid-body, and cubic B-spline deformable transformations. Elastix ( elastix.isi.uu.nl ), an open-source public domain registration algorithm, was used for all registrations with mutual information as similarity metric and gradient descent as optimization. Four-level multiresolution approach was employed with 2 cm B-spline grid spacing at the finest resolution. Registration qualities were visually verified. Rotational occurrences were quantified from the rigid-body registrations. The magnitude of deformations in planning target volumes (PTV) and organs were quantified from the deformation vector fields with rigid registrations as baseline. Results: The measured rotations (mean±std) were 1.0±1.0 deg, - 0.3±1.0 deg, and 0.1±0.8 deg in the sagittal, coronal, and axial plains respectively. The estimated magnitudes of deformations (mean±std) were 3.4±2.1 mm for PTVs, 2.9±1.2 mm for parotid glands, 2.8±1.2 mm for mandible, and 2.2±1.1 mm for spinal cord. The overall deformation in the body contour was 4.3±4.3 mm. The organ spatial deviation due to rotation was small and approximately 8.4% of that from deformations. Results varied among patients. Conclusion: Rotations occurred about 1.0 deg (1SD) in the H'N area. Daily geometric deviation of target volumes was considerable and mainly from tissue deformation than rotations. Proper safety margin is necessary for adequate target coverage. Online plan adaptation may mitigate the daily differences between the plan and actual patient poses. Partially supported by a grant from Varian Medical Systems, Palo Alto, CA

SU-E-J-195: Quantification of Rotations and Deformations in Head and Heck Radiotherapy

Energy Technology Data Exchange (ETDEWEB)

Kim, J; Liu, C; Kumarasiri, A; Gordon, J; Siddiqui, F; Chetty, I J [Henry Ford Health System, Detroit, MI (United States); Chetvertkov, M [Wayne State University, Detroit, MI (United States)

2014-06-01

Purpose: To quantify the magnitude of patient rotations and deformations over the course of head and neck radiotherapy. Methods: 45 CBCT images acquired weekly were selected retrospectively from 5 head and neck cancer patients. CBCT images were registered to the corresponding planning CT images using translation, rigid-body, and cubic B-spline deformable transformations. Elastix ( elastix.isi.uu.nl ), an open-source public domain registration algorithm, was used for all registrations with mutual information as similarity metric and gradient descent as optimization. Four-level multiresolution approach was employed with 2 cm B-spline grid spacing at the finest resolution. Registration qualities were visually verified. Rotational occurrences were quantified from the rigid-body registrations. The magnitude of deformations in planning target volumes (PTV) and organs were quantified from the deformation vector fields with rigid registrations as baseline. Results: The measured rotations (mean±std) were 1.0±1.0 deg, - 0.3±1.0 deg, and 0.1±0.8 deg in the sagittal, coronal, and axial plains respectively. The estimated magnitudes of deformations (mean±std) were 3.4±2.1 mm for PTVs, 2.9±1.2 mm for parotid glands, 2.8±1.2 mm for mandible, and 2.2±1.1 mm for spinal cord. The overall deformation in the body contour was 4.3±4.3 mm. The organ spatial deviation due to rotation was small and approximately 8.4% of that from deformations. Results varied among patients. Conclusion: Rotations occurred about 1.0 deg (1SD) in the H'N area. Daily geometric deviation of target volumes was considerable and mainly from tissue deformation than rotations. Proper safety margin is necessary for adequate target coverage. Online plan adaptation may mitigate the daily differences between the plan and actual patient poses. Partially supported by a grant from Varian Medical Systems, Palo Alto, CA.

Quadrupole deformation and clusterization in nuclei

International Nuclear Information System (INIS)

Cseh, J.; Algora, A.; Darai, J.; Hess, P.O.

2004-01-01

in the dinuclear system model, or in the local potential approach. On the other hand the treatment of the exclusion- principle has to be done microscopically, there- fore, apart from the light, or simplest heavy nuclei, it gives rise to very big computational difficulties. Due to this fact no systematic studies has been done, and many of the experimentally interesting systems are untouched from this viewpoint. The main point of our work is that we present a method for the approximative treatment of the exclusion principle, which can be applied both to binary and ternary (and even to multi) cluster-configurations, and we combine this microscopic approach with an empirical method of the calculation of the energetic preference. This latter quantity is obtained in a similar way as in the work with a straightforward generalisation for ternary clusterization. In this way both aspects of the clusterization (i.e. energy-minimum and exclusion principles) can be handled, therefore, their interrelation can be studied in specific problems. The exclusion-principle is taken into account by a selection rule, based on the real or effective U(3) symmetry for light and heavy nuclei, respectively. This symmetry-based consideration can also be very involved for heavy nuclei, nevertheless, it seems to be widely applicable. As specific examples we consider binary and ternary cluster-configurations in the ground, superdeformed and hyperdeformed states of the light 36 Ar and heavy 252 Cf nuclei. In case of 36 Ar the superdeformed state has been found experimentally, and a theoretical prediction is available for its hyperdeformed state. In case of 252 Cf the main motivation is provided by the spontaneous fission experiments from its ground state, which indicated several very exotic clusterizations. As for superdeformed and hyperdeformed states of this nucleus, we consider hypothetical states with appropriate deformations (ε = 0.6 and ε = 0.86 respectively). The main conclusions of our

Rotational bands terminating at maximal spin in the valence space

Energy Technology Data Exchange (ETDEWEB)

Ragnarsson, I.; Afanasjev, A.V. [Lund Institute of Technology (Sweden)

1996-12-31

For nuclei with mass A {le} 120, the spin available in {open_quotes}normal deformation configurations{close_quotes} is experimentally accessible with present detector systems. Of special interest are the nuclei which show collective features at low or medium-high spin and where the corresponding rotational bands with increasing spin can be followed in a continuous way to or close to a non-collective terminating state. Some specific features in this context are discussed for nuclei in the A = 80 region and for {sup 117,118}Xe.

Global set of quadrupole deformation parameters for even-even nuclei

International Nuclear Information System (INIS)

Raman, S.; Nestor, C.W. Jr.

1986-01-01

A compilation of experimental results has been completed for the reduced electric quadrupole transition probability [B(E2)up arrow] between the 0 + ground state and the first 2 + state in even-even nuclei. This compilation together with certain simple relationships noted by other authors can be used to make reasonable predictions of unmeasured B(E2)up arrow values. The quadrupole deformation parameter β 2 immediately follows, because β 2 is proportional to [B(E2)up arrow]/sup 1/2/. 8 refs., 7 figs

Charge-exchange QRPA with the Gogny Force for Axially-symmetric Deformed Nuclei

Energy Technology Data Exchange (ETDEWEB)

Martini, M., E-mail: martini.marco@gmail.com [Institut d' Astronomie et d' Astrophysique, Université Libre de Bruxelles, CP-226, 1050 Brussels (Belgium); CEA, DAM, DIF, F-91297 Arpajon (France); Goriely, S. [Institut d' Astronomie et d' Astrophysique, Université Libre de Bruxelles, CP-226, 1050 Brussels (Belgium); Péru, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

2014-06-15

In recent years fully consistent quasiparticle random-phase approximation (QRPA) calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the {sup 238}U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pnQRPA). In particular we focus on the Isobaric Analog and Gamow-Teller resonances. A comparison of the predicted GT strength distribution with existing experimental data is presented. The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist and for specific isotone chains of relevance for the r-process nucleosynthesis.

Hartree-Fock calculations for strongly deformed and highly excited nuclei using the Skyrme force

International Nuclear Information System (INIS)

Zint, P.G.

1975-01-01

It has been shown that in CHF-calculations the Skyrme-force is usefull to describe strongly deformed nuclei with even proton and neutron number till separation. Thereby the eigenfunctions of the two-centre Hamiltonian form an adequate basis. With this procedure, we obtain the correct deformation of the 32 S-system. Induding the spurious energy of relative motion between the 16 O-fragments, the energy curve is a good approximation for the real potential, extracted form scattering experiments. (orig./WL) [de

Properties of Hot and Fast Rotating Atomic Nuclei Studied by Means of Giant Dipole Resonance in Exclusive Experiments

International Nuclear Information System (INIS)

Maj, A.

2000-01-01

This work entitled ''Properties of hot and fast rotating atomic nuclei studied by means of Giant Dipole Resonance in exclusive experiments'', is the habilitation thesis of dr. Adam Maj. It consists of the review (in Polish) of performed research and of attached reprints from 16 original publications (in English) which A. Maj is the main or one of the main authors. All the studies were performed in collaboration with the groups from Milano and Copenhagen, using the HECTOR array equipment (described in chapter V). The Giant Dipole Resonance couples to the quadrupole degrees of freedom of the nucleus, and therefore constitutes a unique probe to test the shapes of atomic nuclei. In addition, the γ decay of the GDR from highly excited nuclei is a very fast process, it can compete with other modes of nuclear decay, and therefore can provide the information on the initial stages of excited nuclei. The presented investigations were concentrated on the following aspects: the shapes and thermal shape fluctuations, the origin of the behaviour of the GDR width, the properties of some exotic nuclei (Jacobi shapes, superdeformation, superheavy nuclei) and on ''entrance channel'' effects. The GDR γ decay was measured for nuclei with very different masses: from light nuclei with A≅45, through A≅110, 145,170,190, up to superheavy nuclei with A≅270. The shapes of hot nuclei are not fixed but fluctuate. The extent of these fluctuations and their influence on the measured quantities (GDR strength function, angular distribution and effective shape) is discussed in chapter VI.1. The observed width of the GDR is found to arise from the interplay of two effects: the thermal shape fluctuations, which are controlled by the nuclear temperature, and the deformation effects, controlled by the angular momentum. The ''collisional damping'' effect, which should influence the intrinsic GDR width, was found to be negligible (chapter VI.2). The GDR γ decay from hot superheavy nucleus 272 Hs

Rotation-vibrational spectra of diatomic molecules and nuclei with Davidson interactions

CERN Document Server

Rowe, D J

1998-01-01

Complete rotation-vibrational spectra and electromagnetic transition rates are obtained for Hamiltonians of diatomic molecules and nuclei with Davidson interactions. Analytical results are derived by dynamical symmetry methods for diatomic molecules and a liquid-drop model of the nucleus. Numerical solutions are obtained for a many-particle nucleus with quadrupole Davidson interactions within the framework of the microscopic symplectic model. (author)

Nuclear structure at high-spin and large-deformation

International Nuclear Information System (INIS)

Shimizu, Yoshifumi R.

2000-01-01

Atomic nucleus is a finite quantal system and shows various marvelous features. One of the purposes of the nuclear structure study is to understand such features from a microscopic viewpoint of nuclear many-body problem. Recently, it is becoming possible to explore nuclear states under 'extreme conditions', which are far different from the usual ground states of stable nuclei, and new aspects of such unstable nuclei attract our interests. In this lecture, I would like to discuss the nuclear structure in the limit of rapid rotation, or the extreme states with very large angular momenta, which became accessible by recent advent of large arrays of gamma-ray detecting system; these devices are extremely useful to measure coincident multiple γ-rays following heavy-ion fusion reactions. Including such experimental aspects as how to detect the nuclear rotational states, I review physics of high-spin states starting from the elementary subjects of nuclear structure study. In would like also to discuss the extreme states with very large nuclear deformation, which are easily realized in rapidly rotating nuclei. (author)

High-lying Gamow-Teller excited states in the deformed nuclei,76Ge,82Se and N = 20 nuclei in the island of inversion by the Deformed QRPA (DQRPA)

Science.gov (United States)

Cheoun, Myung-Ki; Ha, Eunja

2013-07-01

With the advent of high analysis technology in detecting the Gamow-Teller (GT) excited states beyond one nucleon emission threshold, the quenching of the GT strength to the Ikeda sum rule (ISR) seems to be recovered by the high-lying (HL) GT states. We address that these HL GT excited states result from the smearing of the Fermi surface by the increase of the chemical potential owing to the deformation within a framework of the deformed quasi-particle random phase approximation (DQRPA). Detailed mechanism leading to the smearing is discussed, and comparisons to the available experimental data on 76Ge,82Se and N = 20 nuclei are shown to explain the strong peaks on the HL GT excited states.

High-lying Gamow-Teller excited states in the deformed nuclei,76Ge,82Se and N = 20 nuclei in the island of inversion by the Deformed QRPA (DQRPA)

International Nuclear Information System (INIS)

Cheoun, Myung-Ki; Ha, Eunja

2013-01-01

With the advent of high analysis technology in detecting the Gamow-Teller (GT) excited states beyond one nucleon emission threshold, the quenching of the GT strength to the Ikeda sum rule (ISR) seems to be recovered by the high-lying (HL) GT states. We address that these HL GT excited states result from the smearing of the Fermi surface by the increase of the chemical potential owing to the deformation within a framework of the deformed quasi-particle random phase approximation (DQRPA). Detailed mechanism leading to the smearing is discussed, and comparisons to the available experimental data on 76 Ge, 82 Se and N = 20 nuclei are shown to explain the strong peaks on the HL GT excited states

Deformation and clustering in even-Z nuclei up to Mg studied using AMD with the Gogny force

Energy Technology Data Exchange (ETDEWEB)

Kimura, Masaaki; Sugawa, Yoshio; Horiuchi, Hisashi [Kyoto Univ. (Japan). Dept. of Physics

2001-12-01

Employing the Gogny force as an effective force, we study the ground state properties of light nuclei using antisymmetrized molecular dynamics (AMD). In a previous paper, we discussed the nuclear binding energies and nuclear radii of He, Be, C, O, Ne and Mg isotopes. In this paper, we mainly consider the deformation properties and the clustering nature of these isotopes. By comparing the calculated results with the AMD results by use of the Skyrme-III (SIII) force, we investigated the differences and similarities between the SIII force and the Gogny force. We find that the Gogny force yields rather better binding energy and larger deformation than the SIII force. We carry out the parity-projected calculations. Parity projection enhances the parity-violating deformation and the cluster structure of certain nuclei. Shape of the deformation energy surface is also changed by parity projection. This causes a competition between the mean-field-like structure and the cluster-like structure. A modified version of AMD, which employs deformed Gaussian wave packets instead of spherical ones, is shown to give large quadrupole moments in the case of Mg isotopes. (author)

Deformation and clustering in even-Z nuclei up to Mg studied using AMD with the Gogny force

International Nuclear Information System (INIS)

Kimura, Masaaki; Sugawa, Yoshio; Horiuchi, Hisashi

2001-01-01

Employing the Gogny force as an effective force, we study the ground state properties of light nuclei using antisymmetrized molecular dynamics (AMD). In a previous paper, we discussed the nuclear binding energies and nuclear radii of He, Be, C, O, Ne and Mg isotopes. In this paper, we mainly consider the deformation properties and the clustering nature of these isotopes. By comparing the calculated results with the AMD results by use of the Skyrme-III (SIII) force, we investigated the differences and similarities between the SIII force and the Gogny force. We find that the Gogny force yields rather better binding energy and larger deformation than the SIII force. We carry out the parity-projected calculations. Parity projection enhances the parity-violating deformation and the cluster structure of certain nuclei. Shape of the deformation energy surface is also changed by parity projection. This causes a competition between the mean-field-like structure and the cluster-like structure. A modified version of AMD, which employs deformed Gaussian wave packets instead of spherical ones, is shown to give large quadrupole moments in the case of Mg isotopes. (author)

Description of low-lying vibrational Kπ≠0+ states of deformed nuclei in the quasiparticle-phonon nuclear model

International Nuclear Information System (INIS)

Soloviev, V.G.; Shirikova, N.Yu.

1989-01-01

The QPNM equations are derived taking account of p-h and p-p interactions. The calculated quadrupole, octupole and hexadecapole vibrational states in 168 Er, 172 Yb and 178 Hf are found to be in reasonable agreement with experimental data. It is shown that distribution of the Eλ strength in some deformed nuclei differs from the standard one. There are cases when for a given K π the Eλ strength is concentrated not on the first but on higher-lying states. The assertion made earlier about the absence of collective two-phonon states in deformed nuclei is confirmed. (orig.)

Description of low-lying vibrational Kπ ≠ 0+ states of deformed nuclei in the quasiparticle-phonon nuclear model

International Nuclear Information System (INIS)

Solov'ev, V.G.; Shirikova, N.Yu.

1989-01-01

The QPNM equations are derived taking account of p-h and p-p interactions. The calculated quadrupole, octupole and hexadecapole vibrational states in 168 Er, 172 Yb and 178 Hf are found to be reasonale agreement with experimental data. It is shown that distribution of the Eλ strength in some deformed nuclei differs from the standard one. There are cases when for a given K π and Eλ strength is concentrated not on the first but on higher-lying states. The assertion made earlier about the absence of collective two-phonon states in deformed nuclei is confirmed. 44 refs.; 1 fig.; 6 tabs

Dynamic-angle spinning and double rotation of quadrupolar nuclei

International Nuclear Information System (INIS)

Mueller, K.T.; California Univ., Berkeley, CA

1991-07-01

Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines causing crowding and overlap in NMR spectra. Magic- angle spinning, which is routinely used to produce high resolution spectra of spin-1/2 nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids

Dynamic-angle spinning and double rotation of quadrupolar nuclei

Energy Technology Data Exchange (ETDEWEB)

Mueller, K.T. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Chemistry)

1991-07-01

Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines causing crowding and overlap in NMR spectra. Magic- angle spinning, which is routinely used to produce high resolution spectra of spin-{1/2} nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids.

Translation-rotation plasticity as basic mechanism of plastic deformation in macro-, micro- and nanoindentation processes

International Nuclear Information System (INIS)

Grabco, D; Shikimaka, O; Harea, E

2008-01-01

This paper presents a brief review of multilateral examinations for the purpose of detection of interrelation between processes occuring in solids at different levels of action of exterior loading, namely, at macro-, micro- and nanoindentation. Convincing arguments supporting the rotation deformation mechanism alongside the recognized dislocation one are adduced. It has been shown that the decrease in dislocation mobility leads at all scales to the intensification of rotation plasticity and to the involvement of other plastic deformation mechanisms, such as appearance and interaction of disclinations, twinning, phase transition and compression of material. The conversion from translation plasticity to the rotation-translation one means transition to the higher level of plastic deformation, the mesolevel, when the possibilities of the previous microscopic level are exhausted. It was established that the plastic deformation zone in the vicinity of indentations could be separated into two main specific regions: (i) peripheral region predominantly with the dislocation deformation mechanism; otherwise, translation mechanism: microlevel, and (ii) quasidestructured region mainly with the disclination or the intergranular sliding mechanism: rotation mechanism, mesolevel

Low-spin identical bands in odd-A nuclei

Energy Technology Data Exchange (ETDEWEB)

Baktash, C; Garrett, J D; Winchell, D F; Smith, A [Oak Ridge National Lab., TN (United States)

1992-08-01

A comprehensive study of odd-A rotational bands in normally-deformed rare-earth nuclei indicates that a large number of seniority-one configurations (30% for odd-Z nuclei) at low spin have moments of inertia nearly identical to that of the seniority-zero configuration of the neighboring even-even nucleus with one less nucleon. It is difficult to reconcile these results with conventional models, based on the traditional picture of nuclear pair correlation in vogue for more than three decades, which predict variations of about 15% in the moments of inertia of configurations differing by one unit in seniority. (author). 18 refs., 1 tab., 1 fig.

Low-spin identical bands in odd-A nuclei

International Nuclear Information System (INIS)

Baktash, C.; Garrett, J.D.; Winchell, D.F.; Smith, A.

1992-01-01

A comprehensive study of odd-A rotational bands in normally-deformed rare-earth nuclei indicates that a large number of seniority-one configurations (30% for odd-Z nuclei) at low spin have moments of inertia nearly identical to that of the seniority-zero configuration of the neighboring even-even nucleus with one less nucleon. It is difficult to reconcile these results with conventional models, based on the traditional picture of nuclear pair correlation in vogue for more than three decades, which predict variations of about 15% in the moments of inertia of configurations differing by one unit in seniority. (author). 18 refs., 1 tab., 1 fig

Staircase bands in 105,107,109Ag: fingerprint of interplay between shears mechanism and collective rotation

International Nuclear Information System (INIS)

Das, B.; Rather, Niyaz; Datta, P.

2015-01-01

Shears mechanism in weakly deformed nuclei has been firmly established by numerous experimental observations since its inception by S. Fruaendorf in early nineties. On the contrary, the scope of Shears mode of excitation in moderately deformed nuclei is a less explored territory. The Shears mechanism is primarily identified in bands having strong M1 transitions with increasing energies as well as falling B(M1) rates as a function of angular momentum. On the other hand, the presence of M1 energy staggering in odd and odd-odd nuclei indicates that the signature is a good quantum number which corresponds to collective rotation. It is interesting to note that nuclei near Z=50 shell closure are moderately deformed as well as Shears structure develop at higher excitation with quasi-particles alignment. To be specific, the moderately deformed Ag nuclei are good candidates for such study as the high spin states are predominantly generated by the valance neutrons in low-Ω orbitals of h 11/2 and the valance protons in high-Ω orbitals of g 9/2 which forms a Shears structure

Conversion electron spectroscopy in transfermium nuclei

International Nuclear Information System (INIS)

Herzberg, R.D.

2003-01-01

Conversion electron spectroscopy is an essential tool for the spectroscopy of heavy deformed nuclei. The conversion electron spectrometer SACRED has been used in conjunction with the gas-filled recoil separator RITU to study conversion electron cascades in 254 No. The spectra reveal the ground state rotational bands down to low spin. A detailed analysis of the background seen for 254 No shows that approximately 40% of the decay path goes via excited high K bands which may be built on an isomer. (orig.)

Description of rotational excitations of odd nuclei by the method of projection

International Nuclear Information System (INIS)

Mazepus, V.V.

1981-01-01

We have carried out a projection on the angular-momentum operator eigenspace for deformed nuclei. The space of the trial wave functions is chosen to be broader than in the ordinary projection approach. It is shown that this method of projection leads to the particle + rotor model but not to the cranking model. A comparison is made with the method of approximate projection

nuclei

Directory of Open Access Journals (Sweden)

Minkov N.

2016-01-01

Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.

Process of diffractive scattering and disintegration of complex particles by nonspherical deformed nuclei

International Nuclear Information System (INIS)

Evlanov, M.V.

1989-01-01

The differential and integral cross sections of diffractive elastic and inelastic scattering and of the disintegration of complex particles by axial and nonaxial deformed nuclei are investigated depending on the shape, deformability and diffuseness of nuclear boundary as well as on the structure of the incident particles and of the rescattering processes. It is shown that the complicated coincidence experiments and experimnts on inelastic scattering with excitation of the target nucleus collective states are satisfactorily described taking simultaneously into account all factors mentioned above and the final-state interaction between the disintegration products of the incident particle

Calculation of ground state deformation of even-even rare-earth nuclei in sdg interacting boson model

International Nuclear Information System (INIS)

Wang Baolin

1995-01-01

The analytical calculation of the nuclear ground state deformation of the even-even isotopes in the rare-earth region is given by utilizing the intrinsic states of the sdg interacting boson model. It is compared systematically with the reported theoretical and experimental results. It is shown that the sdg interacting boson model is a reasonable scheme for the description of even-even nuclei deformation

Low-spin identical bands in neighboring odd-A and even-even nuclei

International Nuclear Information System (INIS)

Baktash, C.; Winchell, D.F.; Garrett, J.D.; Smith, A.

1992-01-01

A comprehensive study of odd-A rotational bands in normally deformed rare-earth nuclei indicates that a large number of seniority-one configurations (21% for odd-Z nuclei) at low spin have moments of inertia nearly identical to that of the seniority-zero configuration of the neighboring even-even nucleus with one less nucleon. It is difficult to reconcile these results with conventional models of nuclear pair correlation, which predict variations of about 15% in the moments of inertia of configurations differing by one unit in seniority

Evolution of Binary Supermassive Black Holes in Rotating Nuclei

Energy Technology Data Exchange (ETDEWEB)

Rasskazov, Alexander; Merritt, David [School of Physics and Astronomy and Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States)

2017-03-10

The interaction of a binary supermassive black hole with stars in a galactic nucleus can result in changes to all the elements of the binary’s orbit, including the angles that define its orientation. If the nucleus is rotating, the orientation changes can be large, causing large changes in the binary’s orbital eccentricity as well. We present a general treatment of this problem based on the Fokker–Planck equation for f , defined as the probability distribution for the binary’s orbital elements. First- and second-order diffusion coefficients are derived for the orbital elements of the binary using numerical scattering experiments, and analytic approximations are presented for some of these coefficients. Solutions of the Fokker–Planck equation are then derived under various assumptions about the initial rotational state of the nucleus and the binary hardening rate. We find that the evolution of the orbital elements can become qualitatively different when we introduce nuclear rotation: (1) the orientation of the binary’s orbit evolves toward alignment with the plane of rotation of the nucleus and (2) binary orbital eccentricity decreases for aligned binaries and increases for counteraligned ones. We find that the diffusive (random-walk) component of a binary’s evolution is small in nuclei with non-negligible rotation, and we derive the time-evolution equations for the semimajor axis, eccentricity, and inclination in that approximation. The aforementioned effects could influence gravitational wave production as well as the relative orientation of host galaxies and radio jets.

Surface thickness effects and splitting of multipole excitations in deformed nuclei. [Sum rule, hydrodynamic model

Energy Technology Data Exchange (ETDEWEB)

Christillin, P [Scuola Normale Superiore, Pisa (Italy); Lipparini, E; Stringari, S [Dipartimento Matematica e Fisica, Trento, Italy

1978-09-25

A sum-rule approach is used to study the influence of surface thickness upon the splitting of dipole and isoscalar quadrupole energies in deformed nuclei. It is shown that hydrodynamic model results are recovered in the case of a deformed skin thickness. A constant skin thickness leads in the dipole case to slightly different predictions which seem in better agreement with experiments. The splitting of the isoscalar quadrupole mode is not sensitive to the surface thickness shape.

Systematics of Absolute Gamma Ray Transition Probabilities in Deformed Odd-A Nuclei

Energy Technology Data Exchange (ETDEWEB)

Malmskog, S G

1965-11-15

All known experimentally determined absolute gamma ray transition probabilities between different intrinsic states of deformed odd-A nuclei in the rare earth, region (153 < A < 181) and in the actinide region (A {>=} 227) are compared with transition probabilities (Weisskopf and Nilsson estimate). Systematic deviations from the theoretical values are found. Possible explanations for these deviations are given. This discussion includes Coriolis coupling, {delta}K ={+-}2 band-mixing effects and pairing interaction.

A semi-classical approach to signature splitting and signature inversion in odd–odd nuclei

International Nuclear Information System (INIS)

Kumar, Vinod; Kumar, Suresh; Kumar, Sushil; Hasan, Zafrul; Koranga, B.S.; Kumar, Deepak; Negi, D.; Angus, Lee

2011-01-01

The signature inversion observed in rotational bands belonging to high-j configurations of odd–odd deformed nuclei has been analyzed within the framework of an axially symmetric rotor plus two-particle model. The Coriolis and n–p interaction are considered the main cause of energy staggering. However, γ-triaxial deformation and the numbers of valence protons, N p , and neutrons, N n also contribute to the energy staggering between odd- and even-spin states. (author)

Energy correlations for mixed rotational bands

International Nuclear Information System (INIS)

Doessing, T.

1985-01-01

A schematic model for the mixing of rotational bands above the yrast line in well deformed nuclei is considered. Many-particle configurations of a rotating mean field form basis bands, and these are subsequently mixed due to a two body residual interaction. The energy interval over which a basis band is spread out increases with increasing excitation energy above the yrast line. Conversely, the B(E2) matrix element for rotational decay out of one of the mixed band states is spread over an interval which is predicted to become more narrow with increasing excitation energy. Finally, the implication of band mixing for γ-ray energy correlations is briefly discussed. (orig.)

g-factors in deformed nuclei: Annual report, September 1, 1983-August 31, 1984

International Nuclear Information System (INIS)

Krane, K.S.

1984-01-01

This report describes work performed for the period September 1, 1983 to August 31, 1984 under the contract DE-AT06-83ER40109, /open quotes/g-Factors in Deformed Nuclei./close quotes/ The literature survey has been completed and the first stage of the raw data analysis has been accomplished. A preliminary data summary prepared for publication is attached

Mass coefficient systematics in triaxially deformed Xe and Ba nuclei

International Nuclear Information System (INIS)

Singh, Yuvraj; Bihari, Chhail; Singh, M.; Varshney, A.K.; Gupta, K.K.; Gupta, D.K.

2009-01-01

In A ∼ 120-140 region where transition occurs from vibrator like stretching around the neutron closed shell (N = 82) to a region with more rotational character (N = 66) energies and B(E2) values of the low lying states change slowly and smoothly with N and Z indicating the collective nature of the levels. The systematic investigation of such nuclei within an isotopic chain undergoing shape or phase transitions is of particular current interest in nuclear structure physics. Rotation is one of the specific collective motions in finite body systems. When the angular momentum increase, one can observe how the energies of the quantum state change due to the effect of the coriolis and centrifugal forces. Thus in the transition to excited states the axial symmetry of the nucleus is violated even if it existed in the ground state

Theory of hot and rotating nuclei within the static path approximation

International Nuclear Information System (INIS)

Ansari, A.

1995-01-01

For the description of hot and rotating nuclei the static path approximation to the path integral representation of the partition function is at present the best practicable approach incorporating rigorously the statistical fluctuations in nuclear shape degrees of freedom. The paper briefly discusses the method and present a few of the recent results on level densities and GDR (giant dipole resonance) γ-absorption cross sections. (author). 22 refs., 2 figs

The decay from the two-quasiparticle regime in even-even deformed rare earth nuclei

International Nuclear Information System (INIS)

Henriques, A.; Thorstensen, T.F.; Hammaren, E.

1983-06-01

A bump at 1 MeV has been identified in coincidence gamma-ray spectra from the ( 3 He, 4 He) reaction in deformed rare earth nuclei. Particle/gamma-ray angular correlation indicates a dipole character. It is suggested that this bump corresponds to transitions from two-quasiparticle states to the ground state band

Heavy ion interactions of deformed nuclei. Progress report, May 1, 1984-December 31, 1984

International Nuclear Information System (INIS)

Oberacker, V.E.

1984-11-01

This progress report describes the main topics that were investigated during the reporting period: (a) a new microscopic approach to the calculation of heavy ion interaction potentials; (b) the dynamical orientation of deformed heavy nuclei near the distance of closest approach; and (c) the theory of Coulomb fission (project finished in Sept.)

Low-spin identical bands in neighboring odd-A and even-even nuclei

International Nuclear Information System (INIS)

Baktash, C.; Winchell, D.F.; Garrett, J.D.; Smith, A.

1993-01-01

A comprehensive study of odd-A rotational bands in normally deformed rare-earth nuclei indicates that a large number of seniority-one configurations (21 % for odd-Z nuclei) at low spin have moments of inertia nearly identical to that of the seniority-zero configuration of the neighboring even-even nucleus with one less nucleon. It is difficult to reconcile these results with conventional models of nuclear pair correlation, which predict variations of about 15% in the moments of inertia of configurations differing by one unit in seniority. (orig.)

On the role of high multipolarity interactions in deformed nuclei

International Nuclear Information System (INIS)

Solov'ev, V.G.; Sushkov, A.V.

1989-01-01

The influence of interactions with the multipolarity λ=5,6,7 and 9 is studied on the mixing of two-quasineutron and two-quasineutron states with large K in doubly even deformed nuclei. The mixing of the two-quasineutron and two-quasiproton states with the same values of K π , caused by a high multipolarity interaction, is shown to be large in the case of proximity of their energies. Qualitatively correct description of experimental data on the mixing of two-quasineutron and two-quasiproton configurations in 178,176 Hf, 174 Yb, 168 Er and 158 Gd is obtained. 20 refs.; 1 tab

Vibrational motions in rotating nuclei studied by Coulomb excitations

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Yoshifumi R [Kyushu Univ., Fukuoka (Japan). Dept. of Physics

1998-03-01

As is well-known Coulomb excitation is an excellent tool to study the nuclear collective motions. Especially the vibrational excitations in rotating nuclei, which are rather difficult to access by usual heavy-ion fusion reactions, can be investigated in detail. Combined with the famous 8{pi}-Spectrometer, which was one of the best {gamma}-ray detector and had discovered some of superdeformed bands, such Coulomb excitation experiments had been carried out at Chalk River laboratory just before it`s shutdown of physics division. In this meeting some of the experimental data are presented and compared with the results of theoretical investigations. (author)

Alpha Anisotropy Studies of Near-Spherical and Deformed Nuclei

CERN Multimedia

Van Duppen, P

2002-01-01

% IS329 \\\\ \\\\ Although it was the first decay mode to be discovered, the process of $\\alpha$-particle emission is still poorly understood. A few years ago the first systematic study of anisotropic $\\alpha$-decay triggered renewed theoretical interest. Nevertheless, today the theories are still not adequate enough and more experimental data are urgently needed. We therefore measure the $\\alpha$-anisotropies of the favoured transitions of a number of near-spherical Rn and At isotopes, and of deformed nuclei near A=220. As the different models yield contradictory predictions for the transitions that are investigated, the measurements will allow to discern on their validity. They will at the same time provide the necessary basis for further theoretical developments.

New properties of giant resonances in highly excited nuclei

International Nuclear Information System (INIS)

Morsch, H.P.

1991-01-01

Studies on the giant dipole resonance in very hot nuclei investigated in heavy ion-induced particle-γ coincidence experiments are reviewed. A signature is found in the γ-decay of excited nuceli which shows direct decay of the giant dipole resonance. This provides a new dimension in giant resonance studies and the possibility to study the dependence of giant resonance energy, width and sum rule strength on excitation energy and rotation of the system. Further, the fact that the giant resonance splits in deformed nuclei provides a unique way to get information on the shape of hot nuclei. First results are obtained on the following questions: (i)What is the nuclear shape at high temperature (T≥2 MeV)? (ii)Is there a phase transition in the nuclear shape at T∼1.7 MeV? (iii)Does motional narrowing exist in hot nuclei? (author). 19 refs., 11 figs

The effect of rotational deformity on patellofemoral parameters following the treatment of femoral shaft fracture.

Science.gov (United States)

Yildirim, Ahmet Ozgur; Aksahin, Ertuğrul; Sakman, Bulent; Kati, Yusuf Alper; Akti, Sefa; Dogan, Ozgur; Ucaner, Ahmet; Bicimoglu, Ali

2013-05-01

The purpose of this study was to investigate the effect of rotational deformities on patellofemoral alignment using the dynamic magnetic resonance imaging method on patients whose femur fractures were treated with intramedullary locking nails. The dynamic patellofemoral magnetic resonance imaging results of 33 patients (5 females and 28 males) were reviewed. The mean age of the patients was 36.3 (range 19-61) years. The mean follow-up was 30.2 months (range 24-38). All the patients were given Kujala patellofemoral clinical evaluation scores at the latest follow-up. Those with less than 10° of rotational deformity in either direction were classified as Group A, those with more than a 10° of internal rotation deformity as Group B and more than a 10° of external rotation deformity as Group C. The three groups were then compared regarding to clinical scores. Patellofemoral parameters of operated and contralateral side were also compared in each group. There were 14 (42.4 %) patients in Group A, 12 (36.4 %) patients in Group B and 7 (21.2 %) patients in Group C. The mean patella score in Group C (74 ± 7.02) was significantly lower when compared with Group B (87.6 ± 9.9) and group A (90.6 ± 6.1) (p < 0.05). In Group C patients, medial patellar tilt was detected when compared with the intact side. There were no significant changes in patellofemoral position in either Group A or Group B. The results of this study revealed that more than 10° of external rotation deformity could cause a detoriation in the patellofemoral scores. Anatomic reduction of the fracture site should be performed as soon as possible and external rotational deformities should especially be avoided in order to prevent patellofemoral malalignment.

Effect of deformations on the compactness of odd-Z superheavy nuclei formed in cold and hot fusion reactions

Science.gov (United States)

Kaur, Gurjit; Sandhu, Kirandeep; Sharma, Manoj K.

2018-03-01

Using the extended fragmentation theory, the compactness of hot and cold fusion reactions is analyzed for odd-Z nuclei ranging Z = 105- 117. The calculations for the present work are carried out at T = 0MeV and ℓ = 0 ħ, as the temperature and angular momentum effects remain silent while addressing the orientation degree of freedom (i.e. compact angle configuration). In the hot fusion, 48Ca (spherical) + actinide (prolate) reaction, the non-equatorial compact (nec) shape is obtained for Z = 113 nucleus. On the other hand, Z > 113 nuclei favor equatorial compact (ec) configuration. The distribution of barrier height (VB) illustrate that the ec-shape is obtained when the magnitude of quadrupole deformation of the nucleus is higher than the hexadecupole deformation. In other words, negligible or small -ve β4-deformations support ec configurations. On the other hand, large (+ve) magnitude of the β4-deformation suggests that the configuration appears for compact angle θc < 90 °, leading to nec structure. Similar deformation effects are observed for Bi-induced reactions, in which not belly-to-belly compact (nbbc) configurations are seen at θc = 42 °. In addition to the effect of β2 and β4-deformations, the exclusive role of octupole deformations (β3) is also analyzed. The β3-deformations do not follow the reflection symmetry as that of β2 and β4, leading to the possible occurrence of compact configuration within 0° to 180° angular range.

Nuclei and models, 2001-2003. DEA fields, particles and matter; Noyaux et modeles, 2001-2003. DEA champs, particules, matieres

Energy Technology Data Exchange (ETDEWEB)

Sida, J.L

2003-07-01

This document gathers a series of 6 lessons dedicated to students in the first year of their thesis (DEA) in fields and particles physics: 1) the extent of nuclear physics, 2) the nucleus as a cluster of interacting fermions, 3) models and deformation, 4) nuclei and rotation, 5) isospin and exotic nuclei, and 6) fission reactions from the saddle point to the scission point.

Identical bands in (even, odd) nuclei as evidence for spectator nucleons

Energy Technology Data Exchange (ETDEWEB)

Schmeing, N C [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.

1992-08-01

An explanation is sought for ``identical`` moments of inertia for pairs of rotational bands in superdeformed nuclei differing in particle number. The authors postulate that certain nucleons do not participate in the collective rotation. The energy of superdeformed {sup 152}Dy has been calculated using this model with a deformed Woods-Saxon potential and full mixing of oscillator shells. A significant reduction in energy is achieved when the protons and neutron with asymptotic quantum number N < 4 constitute a nonrotating factor, as compared to the conventional prolate nucleus. 9 refs.

Systematic behavior of B(E2) values in the yrast bands of doubly even nuclei

International Nuclear Information System (INIS)

Andrejtscheff, W.; Rutgers - the State Univ., New Brunswick, NJ; Nadjakov, E.; Venkova, T.

1980-01-01

The experimental information on B(E2) transition rates in the yrast bands of doubly even nuclei (126 2 (J: moment of inertia) are plotted versus the rotational frequency squared h/2π 2 ω 2 for each nucleus. In strongly deformed nuclei (N >= 90), the Ssub(exp) curves smoothly increase for low rotational frequencies suggesting that up to spin values I approx. 8 the ratio Q 2 0 /J is nearly constant (Q 0 : quadrupole moment). This is not the case in nuclei with a soft core (N <= 88). In the relevant discussion, the hydrodynamical model as well as the CAP effect are considered. The results in the backbending region are qualitatively discussed in terms of the two-band crossing model. Evidence is found supporting the prediction of an oscillating behavior of the yrast-yrare interaction. (orig.)

Deformations and Rotational Ground Motions Inferred from Downhole Vertical Array Observations

Science.gov (United States)

Graizer, V.

2017-12-01

Only few direct reliable measurements of rotational component of strong earthquake ground motions are obtained so far. In the meantime, high quality data recorded at downhole vertical arrays during a number of earthquakes provide an opportunity to calculate deformations based on the differences in ground motions recorded simultaneously at different depths. More than twenty high resolution strong motion downhole vertical arrays were installed in California with primary goal to study site response of different geologic structures to strong motion. Deformation or simple shear strain with the rate γ is the combination of pure shear strain with the rate γ/2 and rotation with the rate of α=γ/2. Deformations and rotations were inferred from downhole array records of the Mw 6.0 Parkfield 2004, the Mw 7.2 Sierra El Mayor (Mexico) 2010, the Mw 6.5 Ferndale area in N. California 2010 and the two smaller earthquakes in California. Highest amplitude of rotation of 0.60E-03 rad was observed at the Eureka array corresponding to ground velocity of 35 cm/s, and highest rotation rate of 0.55E-02 rad/s associated with the S-wave was observed at a close epicentral distance of 4.3 km from the ML 4.2 event in Southern California at the La Cienega array. Large magnitude Sierra El Mayor earthquake produced long duration rotational motions of up to 1.5E-04 rad and 2.05E-03 rad/s associated with shear and surface waves at the El Centro array at closest fault distance of 33.4km. Rotational motions of such levels, especially tilting can have significant effect on structures. High dynamic range well synchronized and properly oriented instrumentation is necessary for reliable calculation of rotations from vertical array data. Data from the dense Treasure Island array near San Francisco demonstrate consistent change of shape of rotational motion with depth and material. In the frequency range of 1-15 Hz Fourier amplitude spectrum of vertical ground velocity is similar to the scaled tilt

γ-spectroscopy and radioactive beams: search for highly deformed exotic nuclei

International Nuclear Information System (INIS)

Rosse, B.

2006-07-01

This work is devoted to the search for highly deformed nuclei under extreme conditions of isospin, located near the proton drip-line, around A ∼ 130. The experiment was performed at GANIL (Caen) with the SPIRAL radioactive beam facility. The nuclei of interest were produced by fusion-evaporation reactions induced by the neutron deficient Kr 76 radioactive beam (T1/2 = 14.8 h). γ-rays were detected by the EXOGAM array, composed of 11 segmented germanium clover detectors, for which a new segment calibration method has been developed. To extract fusion-evaporation events of a overwhelming background due to the radioactivity of the beam, the EXOGAM array was coupled with the light charged particle detector DIAMANT and the high acceptance VAMOS spectrometer. The latter was used for the first time to detect fusion-evaporation residues. The detailed data analysis allowed us to demonstrate that the EXOGAM + DIAMANT + VAMOS coupling is operational and essential to investigate the structure of these nuclei. Furthermore, the first γ transition was observed in the very exotic odd-odd Pm 130 nucleus. The results have been interpreted with static and dynamic self-consistent microscopic calculations in collaboration with the Theoretical Physicists of the IPN Lyon. (author)

γ-spectroscopy and radioactive beams: search for highly deformed exotic nuclei

International Nuclear Information System (INIS)

Rosse, Bertrand

2006-01-01

This work is devoted to the search for highly deformed nuclei under extreme conditions of isospin, located near the proton drip-line, around A∼130. The experiment was performed at GANIL (Caen) with the SPIRAL radioactive beam facility. The nuclei of interest were produced by fusion-evaporation reactions induced by the neutron deficient 76 Kr radioactive beam (T 1/2 = 14.8 h). γ-rays were detected by the EXOGAM array, composed of 11 segmented germanium clover detectors, for which a new segment calibration method has been developed. To extract fusion-evaporation events of a overwhelming background due to the radioactivity of the beam, the EXOGAM array was coupled with the light charged particle detector DIAMANT and the high acceptance VAMOS spectrometer. The latter was used for the first time to detect fusion-evaporation residues. The detailed data analysis allowed us to demonstrate that the EXOGAM + DIAMANT + VAMOS coupling is operational and essential to investigate the structure of these nuclei. Furthermore, the first γ transition was observed in the very exotic odd-odd 130 Pm nucleus. The results have been interpreted with static and dynamic self-consistent microscopic calculations in collaboration with the Theoretical Physicists of the IPN Lyon. (author)

Survey of odd-odd deformed nuclear spectroscopy

International Nuclear Information System (INIS)

Hoff, R.W.

1993-01-01

In this paper, we survey the current experimental data that support assignment of rotational bands in odd-odd deformed nuclear in the rare earth and actinide regions. We present the results of a new study of 170 Mt nuclear structure. In a comparing experimental and calculated Gallagher-Moszkowski matrix elements for rare earth-region nuclei, we have developed a new approach to the systematics of these matrix elements

Influence of Axisymmetrically Deformed Explosions in Type II Supernovae on the Reproduction of the Solar System Abundances

Science.gov (United States)

Nagataki, Shigehiro

1999-01-01

We have tried to reproduce the solar system abundances using the nucleosynthesis products of Type Ia and Type II supernovae. In particular, we examined the effects of axisymmetrically deformed explosions in Type II supernovae. 44Ca and 47,48Ti are enhanced considerably in axisymmetrically deformed explosion models because of the active alpha-rich freezeout. The enhancement of nuclei around A=45 is a welcome result since it solves the problem of the nuclei shortage. Moreover, 59Co, 63,65Cu, and 66Zn are enhanced enough to reproduce the solar system abundances. The enhancement of Cu and Zn means the possibility that these nuclei, which have been said to be produced by the slow process, can be synthesized fairly well during the explosive nucleosynthesis. To discuss their origin quantitatively, the position of the mass cut is a very important parameter that is very difficult to determine numerically at present. We also stress that an axisymmetrically deformed explosion of Type II supernovae of the degree that is considered in this analysis is not excluded by the results of calculations of explosive nucleosynthesis, that is, the nucleosynthesis products are not extremely disturbed and the solar system abundances can be reproduced fairly well by the axisymmetrically deformed explosion models. This conclusion will be good for the theory of core collapse including the rotation of an iron core, magnetic field, and axisymmetrically modified neutrino radiation from a rotating protoneutron star, which possibly can cause an axisymmetrically deformed explosion.

E2 and M1 transition strengths in heavy deformed nuclei revisited

International Nuclear Information System (INIS)

Draayer, J.P.; Popa, G.; Hirsch, J.G.; Vargas, C.E.

2003-01-01

An update on the status of pseudo-SU(3) shell-model calculations in strongly deformed nuclei in the rare earth region is presented. Representative results for energy levels as well as E2 (quadrupole) and M1 (scissors) transitions strengths in 162 Dy (even-even) and 163 Dy (odd-mass) are given. The calculations use realistic single-particle energies and quadrupole-quadrupole and pairing interaction strengths fixed from systematics. The strengths of rotor-like terms included in the Hamiltonian- all small relative to the other terms in the interaction were adjusted to give an overall best fit to the energy spectra. The results present a paradox: for even-even nuclei (integer angular momentum) non-zero pseudo-spin configurations seems to be unimportant while for the odd-mass systems (half-integer angular momentum) pseudo-spin mixing is essential as spin-flip couplings appear to dominate the M1 transition strengths. (Author)

A brief review of intruder rotational bands and magnetic rotation in the A = 110 mass region

Science.gov (United States)

Banerjee, P.

2018-05-01

Nuclei in the A ∼ 110 mass region exhibit interesting structural features. One of these relates to the process by which specific configurations, built on the excitation of one or more protons across the Z = 50 shell-gap, manifest as collective rotational bands at intermediate spins and gradually lose their collectivity with increase in spin and terminate in a non-collective state at the maximum spin which the configuration can support. These bands are called terminating bands that co-exist with spherical states. Some of these bands are said to terminate smoothly underlining the continuous character of the process by which the band evolves from significant collectivity at low spin to a pure particle-hole non-collective state at the highest spin. The neutron-deficient A ∼ 110 mass region provides the best examples of smoothly terminating bands. The present experimental and theoretical status of such bands in several nuclei with 48 ≤ Z ≤ 52 spanning the 106 ≤ A ≤ 119 mass region have been reviewed in this article. The other noteworthy feature of nuclei in the A ∼ 110 mass region is the observation of regular rotation-like sequences of strongly enhanced magnetic dipole transitions in near-spherical nuclei. These bands, unlike the well-studied rotational sequences in deformed nuclei, arise from a spontaneous symmetry breaking by the anisotropic currents of a few high-j excited particles and holes. This mode of excitation is called magnetic rotation and was first reported in the Pb region. Evidence in favor of the existence of such structures, also called shears bands, are reported in the literature for a large number of Cd, In, Sn and Sb isotope with A ∼ 110. The present article provides a general overview of these reported structures across this mass region. The review also discusses antimagnetic rotation bands and a few cases of octupole correlations in the A = 110 mass region.

Diffraction scattering and disintegration of complex particles by nonspherical deformable nuclei

International Nuclear Information System (INIS)

Evlanov, M.V.; Isupov, V.Y.; Tartakovskii, V.K.

1989-01-01

We study the dependence of the differential and integrated cross sections for diffraction scattering and disintegration of complex particles by axially symmetric and non-axially-symmetric nuclei on the shape, deformability, and diffuseness of the nuclear surface, and also on the structure of the incident particles and rescattering processes. It is shown that when all of these factors are taken into account, as well as the interaction in the final state between the disintegration products of the incident particle, a satisfactory description of complicated coincidence experiments can be obtained, and also inelastic scattering experiments with excitation of collective states of the target nucleus

Influence of Rotator Cuff Tear Size and Repair Technique on the Creation and Management of Dog Ear Deformities in a Transosseous-Equivalent Rotator Cuff Repair Model

Science.gov (United States)

Redler, Lauren H.; Byram, Ian R.; Luchetti, Timothy J.; Tsui, Ying Lai; Moen, Todd C.; Gardner, Thomas R.; Ahmad, Christopher S.

2014-01-01

Background: Redundancies in the rotator cuff tissue, commonly referred to as “dog ear” deformities, are frequently encountered during rotator cuff repair. Knowledge of how these deformities are created and their impact on rotator cuff footprint restoration is limited. Purpose: The goals of this study were to assess the impact of tear size and repair method on the creation and management of dog ear deformities in a human cadaveric model. Study Design: Controlled laboratory study. Methods: Crescent-shaped tears were systematically created in the supraspinatus tendon of 7 cadaveric shoulders with increasing medial to lateral widths (0.5, 1.0, and 1.5 cm). Repair of the 1.5-cm tear was performed on each shoulder with 3 methods in a randomized order: suture bridge, double-row repair with 2-mm fiber tape, and fiber tape with peripheral No. 2 nonabsorbable looped sutures. Resulting dog ear deformities were injected with an acrylic resin mixture, digitized 3-dimensionally (3D), and photographed perpendicular to the footprint with calibration. The volume, height, and width of the rotator cuff tissue not in contact with the greater tuberosity footprint were calculated using the volume injected, 3D reconstructions, and calibrated photographs. Comparisons were made between tear size, dog ear measurement technique, and repair method utilizing 2-way analysis of variance and Student-Newman-Keuls multiple-comparison tests. Results: Utilizing 3D digitized and injection-derived volumes and dimensions, anterior dog ear volume, height, and width were significantly smaller for rotator cuff repair with peripheral looped sutures compared with a suture bridge (P repair with 2-mm fiber tape alone (P repair with looped peripheral sutures compared with a suture bridge (P repair technique, peripheral No. 2 nonabsorbable looped sutures significantly decreased the volume, height, and width of dog ear deformities, better restoring the anatomic footprint of the rotator cuff. Clinical

Gamow-Teller strength in deformed nuclei within self-consistent pnQRPA with the Gogny force

Directory of Open Access Journals (Sweden)

Martini M.

2014-03-01

Full Text Available In recent years fully consistent quasiparticle random-phase approximation (QRPA calculations using finite range Gogny force have been performed to study electromagnetic excitations of several axially-symmetric deformed nuclei up to the 238U. Here we present the extension of this approach to the charge-exchange nuclear excitations (pn-QRPA. In particular we focus on the Gamow-Teller (GT excitations. A comparison of the predicted GT strength distribution with existing experimental data is presented The role of nuclear deformation is shown. Special attention is paid to β-decay half-lives calculations for which experimental data exist.

High-spin states in the transitional odd-odd nuclei 150Eu and 152Tb

International Nuclear Information System (INIS)

Barneoud, D.; Foin, C.; Pinston, J.A.; Monnand, E.

1983-06-01

The ( 7 Li, 5n) and ( 11 B, 5n) reactions have been used to study the high-spin states in the two odd-odd nuclei 150 Eu and 152 Tb. Three decoupled bands have been evidenced in each nucleus belonging to the same configurations [f 7/2]sub(n) [h 11/2]sub(p), [h 9/2]sub(n) [h 11/2 ]sub(p) and [i 13/2]sub(n) [h 11/2]sub(p). The latter one is well developped and improves our knowledge of this system between the spherical and deformed region. The analysis of the collective moment of inertia and transition ratios strongly suggests an increase of the deformation when the rotational frequency increases in these two transitional nuclei 150 Eu and 152 Tb

One- and two-phonon excitations in strongly deformed triaxial nuclei

International Nuclear Information System (INIS)

Hagemann, G.B.

2003-01-01

The wobbling mode is uniquely related to triaxiality and introduces a series of bands with increasing wobbling phonon number, n ω , and a characteristic large Δ nω =1 E2 strength between the bands. The pattern of γ-transitions between the wobbling excitations will be influenced by the presence of an aligned particle. Evidence for the wobbling mode was obtained recently, and even a two-phonon wobbling excitation has now been identified in 163 Lu. The similarity of the data in 163 Lu to new strongly deformed triaxial bands and connecting transitions in the neighbouring nuclei, 165 Lu and 167 Lu, establishes wobbling as a more general phenomenon in this region. (author)

A united phenomenological description of quadrupole excitations in even-even nuclei

International Nuclear Information System (INIS)

Lipas, P.O.; Haapakoski, P.; Honkaranta, T.

1975-05-01

A phenomenological model is developed for the collective quadrupole properties of all even-even nuclei. Rotational, vibrational, and transitional nuclei are included in the model on an equal footing. A Bohr-type intrinsic Hamiltonian for harmonic quadrupole vibrations about an axially deformed shape is solved exactly. States of good angular momentum are projected out of the intrinsic states, and they are made orthogonal by a Schmidt scheme. The angular-momentum and phonon-number composition of the states is analyzed at various stages; states with K=1 are found spurious. Excitation energies for the ground, β and γ bands are calculated as expectation values of a radically simplified nuclear Hamiltonian in our projected and orthogonalized states. With increasing deformation the calculated energies evolve smoothly from the evenly spaced phonon spectrum to the Bohr-Mottelson rotational-vibrational spectrum according to the scheme of Sheline and Sakai. The basic model contains only two parameters (deformation d and energy scale) to fix the entire quadrupole spectrum of a nucleus. The results are given in the form of graphs suitable for immediate application; numerical results are readily produced by our computer code. The ground bands are fitted comparably to the VMI model, while the β and γ bands are reproduced qualitatively. The nuclei 152 Sm, 152 Gd, and 114 Cd are used as test cases. Quadrupole moments and E2 transition rates are also calculated. Intra-ground-band transition ratios and branching ratios from the β and γ bands are given in terms of the single parameter d. The results are applied to 152 Sm, with fair success. Finally the model to include two more parameters (anisotropy) is extended. The improvement over the basic model is modest in view of added parameters and computational effort. (author)

Spin dependence of rotational damping by the rotational plane mapping method

Energy Technology Data Exchange (ETDEWEB)

Leoni, S; Bracco, A; Million, B [Milan Univ. (Italy). Ist. di Fisica; Herskind, B; Dossing, T; Rasmussen, P [Niels Bohr Inst., Copenhagen (Denmark); Bergstrom, M; Brockstedt, A; Carlsson, H; Ekstrom, P; Nordlund, A; Ryde, H [Lund Univ. (Sweden). Dept. of Physics; Ingebretsen, F; Tjom, P O [Oslo Univ. (Norway); Lonnroth, T [Aabo Akademi, Turku (Finland). Dept. of Physics

1992-08-01

In the study of deformed nuclei by gamma spectroscopy, the large quadrupole transition strength known from rotational bands at high excitation energy may be distributed over all final states of a given parity within an interval defined as the rotational damping width {Gamma}{sub rot} The method of rotational plane mapping extracts a value of {Gamma}{sub rot} from the width of valleys in certain planes in the grid plots of triple gamma coincidence data sets. The method was applied to a high spin triple data set on {sup 162,163}Tm taken with NORDBALL at the tandem accelerator of the Niels Bohr Institute, and formed in the reaction {sup 37}Cl + {sup 130}Te. The value {Gamma}{sub rot} = 85 keV was obtained. Generally, experimental values seem to be lower than theoretical predictions, although the only calculation made was for {sup 168}Yb. 6 refs., 3 figs.

Compound nuclei at high angular momentum. High-spin γ-ray spectroscopy: past successes, future hopes

International Nuclear Information System (INIS)

Diamond, R.M.

1984-01-01

The addition of angular momentum to a nucleus presents a whole new dimension, a new coordinate axis, along which to study changes in nuclear behavior and structure. Nuclei can carry angular momentum in two principal ways: by the collective rotation of a deformed nucleus as a whole and by the alignment along the rotation axis of individual high-j nucleons. For spherical (or near-spherical) nuclei, the latter mode is the only one possible. The levels of 212 Rn illustrate a scheme of particle alignment; it is quite irregular with transitions of a variety of electromagnetic types and with little pattern to the level spacing. On the left, the yrast band of 238 U is shown, a predominantly rotational scheme with only strongly enhanced electric quadrupole transitions and a level spacing that approximates that of a rigid rotor, E = I(I + 1)h 2 /2 J and E/sub γ/ = (4I - 2)h 2 /2 J, where J is the moment of inertia. Most nuclei, however, combine both types of motion, and it is this interplay between collective and single-particle motion that makes the behavior of nuclei along the angular momentum coordinate so fascinating and so rich in variety. Data are shown for Yb isotopes, and Er isotopes are discussed

Generalized Michailov plot analysis of inband E2 transitions of deformed nuclei

International Nuclear Information System (INIS)

Long, G.L.; Zhang, W.L.; Ji, H.Y.; Gao, J.F.

1998-01-01

Intraband E2 transitions of some 30 deformed nuclei are analysed using a generalized Michailov plot, based on an E2 transition formula in the SU(3) limit of the sdg interacting boson model. The general E2 transition formula in the sdg-IBM has an L(L+3) term in addition to the usual SU(3) model result. It is found that the general E2 formula can describe the inband transitions well. Comparisons with other models are made. The implications of the results are also discussed. (author)

One-phonon states in deformed nuclei for isoscalar and isovector interactions

International Nuclear Information System (INIS)

Malov, L.A.; Nesterenko, V.O.; Solov'ev, V.G.

1977-01-01

Extension of the formulas describing the one-phonon states of compound even-even deformed nuclei to the case when the isoscalar and isovector multipole-multipole forces are taken into account, is given. The formalism presented makes it possible to obtain an unified description of the low-lying states and gigantic multipole resonances. Procedure is developed which makes it possible to write down the reduced probability and energetically weighted sum rule in the form of force functions averaged over certain interval of energies. The procedure simplifies the calculations significantly and makes it possible to avoid solving the secular equation for energies of one-phonon states

Hyperdeformed nuclei and the residual pseudo-SU(3) symmetry

International Nuclear Information System (INIS)

Dudek, J.; Werner, T.

1988-01-01

The author discusses superdeformed and hypothetical hyperdeformed nuclei. Quadrupole deformations characteristic of these types of nuclei are defined. Symmetry features are also discussed. The characteristic cycle dependence of shell structures as functions of the deformation gives rise to chains of the deformed shell closures. Such a chain structure applies to moderately-, super- and hyper-deformed nuclei as well. The resulting total energy calculations give a systematic variation of super- and hyperdeformations with, e.g., increasing N at fixed Z, thus predicting the way nuclei deviate from the simple a:b = 2:1 and a:b = 3:1 symmetries

Time-odd mean fields in covariant density functional theory: Rotating systems

International Nuclear Information System (INIS)

Afanasjev, A. V.; Abusara, H.

2010-01-01

Time-odd mean fields (nuclear magnetism) and their impact on physical observables in rotating nuclei are studied in the framework of covariant density functional theory (CDFT). It is shown that they have profound effect on the dynamic and kinematic moments of inertia. Particle number, configuration, and rotational frequency dependencies of their impact on the moments of inertia have been analyzed in a systematic way. Nuclear magnetism can also considerably modify the band crossing features such as crossing frequencies and the properties of the kinematic and dynamic moments of inertia in the band crossing region. The impact of time-odd mean fields on the moments of inertia in the regions away from band crossing only weakly depends on the relativistic mean-field parametrization, reflecting good localization of the properties of time-odd mean fields in CDFT. The moments of inertia of normal-deformed nuclei considerably deviate from the rigid-body value. On the contrary, superdeformed and hyperdeformed nuclei have the moments of inertia which are close to rigid-body value. The structure of the currents in rotating frame, their microscopic origin, and the relations to the moments of inertia have been systematically analyzed. The phenomenon of signature separation in odd-odd nuclei, induced by time-odd mean fields, has been analyzed in detail.

Protonic decay of oriented nuclei

International Nuclear Information System (INIS)

Kadmensky, S.G.

2002-01-01

On the basis of the multiparticle theory of protonic decay, the angular distributions of protons emitted by oriented spherical and deformed nuclei in the laboratory frame and in the internal coordinate frame of deformed parent nuclei are constructed with allowance for symmetry with respect to time inversion. It is shown that, because of the deep-subbarrier character of protonic decay, the adiabatic approximation is not applicable to describing the angular distributions of protons emitted by oriented deformed nuclei and that the angular distribution of protons in the laboratory frame does not coincide with that in the internal coordinate frame. It is demonstrated that these angular distributions coincide only if the adiabatic and the semiclassical approximation are simultaneously valid

Nuclear masses, deformations and shell effects

International Nuclear Information System (INIS)

Hirsch, Jorge G; Barbero, César A; Mariano, Alejandro E

2011-01-01

We show that the Liquid Drop Model is best suited to describe the masses of prolate deformed nuclei than of spherical nuclei. To this end three Liquid Drop Mass formulas are employed to describe nuclear masses of eight sets of nuclei with similar quadrupole deformations. It is shown that they are able to fit the measured masses of prolate deformed nuclei with an RMS smaller than 750 keV, while for the spherical nuclei the RMS is, in the three cases, larger than 2000 keV. The RMS of the best fit of the masses of semi-magic nuclei is also larger than 2000 keV. The parameters of the three models are studied, showing that the surface symmetry term is the one which varies the most from one group of nuclei to another. In one model, isospin dependent terms are also found to exhibit strong changes. The inclusion of shell effects allows for better fits, which continue to be better in the prolate deformed nuclei region.

Drop deformation and breakup in a partially filled horizontal rotating cylinder

Science.gov (United States)

White, Andrew; Pereira, Caroline; Hyacinthe, Hyaquino; Ward, Thomas

2014-11-01

Drop deformation and breakup due to shear flow has been studied extensively in Couette devices as well as in gravity-driven flows. In these cases shear is generated either by the moving wall or the drop's motion. For such flows the drop shape remains unperturbed at low capillary number (Ca), deforms at moderate Ca , and can experience breakup as Ca --> 1 and larger. Here single drops of NaOH(aq) will be placed in a horizontal cylindrical rotating tank partially filled with vegetable oil resulting in 10-2 saponification, can yield lower minimum surface tensions and faster adsorption than non-reactive surfactant systems. Oil films between the wall and drop as well as drop shape will be observed as rotation rates and NaOH(aq) concentration are varied. Results will be presented in the context of previous work on bubble and drop shapes and breakup. NSF CBET #1262718.

Covariant density functional theory beyond mean field and applications for nuclei far from stability

International Nuclear Information System (INIS)

Ring, P

2010-01-01

Density functional theory provides a very powerful tool for a unified microscopic description of nuclei all over the periodic table. It is not only successful in reproducing bulk properties of nuclear ground states such as binding energies, radii, or deformation parameters, but it also allows the investigation of collective phenomena, such as giant resonances and rotational excitations. However, it is based on the mean field concept and therefore it has its limits. We discuss here two methods based based on covariant density functional theory going beyond the mean field concept, (i) models with an energy dependent self energy allowing the coupling to complex configurations and a quantitative description of the width of giant resonances and (ii) methods of configuration mixing between Slater determinants with different deformation and orientation providing are very successful description of transitional nuclei and quantum phase transitions.

Microscopic properties of superdeformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Karlsson, Lennart B

1999-04-01

Many high spin rotational bands in superdeformed nuclei have been found in the A 140 - 150 region, but so far no linking transitions to known normal-deformed states have been found in these nuclei. Therefore, configuration and spin assignments have to be based on indirect spectroscopic information. Identical bands were first discovered in this region of superdeformed states. At present, some identical bands have also been found at normal deformation, but such bands are more common at superdeformation. Recently lifetime measurements have given relative quadrupole moments with high accuracy. Spectroscopic quantities are calculated using the configuration constrained cranked Nilsson-Strutinsky model with the modified oscillator potential. In a statistical study the occurrence of identical bands is tested. Comparing superdeformed and normal deformed nuclei, the higher possibility for identical bands at superdeformation is understood from calculated reduced widths of the E{sub {gamma}} and J{sup (2)} distributions. The importance of high-N orbitals for identical bands is also discussed. Additivity of electric quadrupole moment contributions in the superdeformed A - 150 region is discussed with the nucleus {sup 152}Dy as a `core`. In analytic harmonic oscillator calculations, the effective electric quadrupole moment q{sub eff}, i.e. the change in the total quadrupole moment caused by the added particle, is expressed as a simple function of the single-particle mass, quadrupole moment q{sub {nu}}. Also in realistic calculations, simple relations between q{sub eff} and q{sub {nu}} can be used to estimate the total electric quadrupole moment, e.g. for the nucleus {sup 142}Sm, by adding the effect of 10 holes, to the total electric quadrupole moment of {sup 152}Dy. Furthermore, tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A - 150 region. For the superdeformed region around {sup 143}Eu, configuration and spin assignments

Transitional nuclei near shell closures

Energy Technology Data Exchange (ETDEWEB)

Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)

2014-08-14

High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.

Identicity in high-K three quasiparticle rotational bands: a theoretical approach

International Nuclear Information System (INIS)

Kaur, Harjeet; Singh, Pardeep; Malik, Sham S

2015-01-01

The systematics are studied for the identical band phenomenon in high-K three quasiparticle rotational bands. The identical rotational bands based on the same bandhead spin are analyzed on the basis of similarities in γ-ray energies, dynamic moment of inertia and kinematic moment of inertia in particular, which is a function of deformation degrees of freedom, pairing strengths and Nilsson orbitals in nuclei. It is established that a combined effect of all these parameters decides the identicity of the moment of inertia in high-K three quasiparticle rotational bands as the systematics are backed by the Tilted Axis Cranking model calculations. (paper)

Disappearance of neutron magic numbers and deformation coexistence

International Nuclear Information System (INIS)

Kimura, Masaaki

2014-01-01

The disappearance of N=8, 20 and 28 magic numbers in the neutron excess nuclei is a representative example of the special features of the unstable nuclei. In this lecture of summer school, the problems of the magic number disappearance are presented. And the appearance of the deformation coexistence and the anomalous cluster structure come into the problem with them. At the begging the Antisymmetrized Molecular Dynamic (AMD) framework is explained with finite range two body central force and Gorgny DIS force composed of the zero range spin-orbit force and saturability. Island of inversion is explained in the nuclear chart shown in the figure and energy curves of the nuclei near 32 Mg and the excitation level schemes of 32 Mg are shown in the serial figures. As one of the extreme example of the nuclear structure the deformation of 19 F is picked up. The level schemes and structures of 21 F are shown as well. The molecule-like structure in the island of inversion is clear. The rotational band energy of fluorine isotopes are shown up to 29 F. As a new deformation area, disappearance of N=28 magic number is in the spotlight recently. In this case it is characteristic properties that the parities of the orbits to form the gap must be the same but the angular momenta should be different by 2. According to the AMD research, it is shown that deformations of prolate, three-axis asymmetric and oblate characters coexist in the very low excitation energy region accompanying the disappearance of N=28 gap. The concept of magic numbers has been very fundamental in nuclear physics since the success of shell model. At present its disappearance in the unstable nuclei is one of the most challenging problems in the understanding of the nuclear many body problems. (S. Funahashi)

Highly-distorted and doubly-decoupled rotational bands in odd-odd nuclei

International Nuclear Information System (INIS)

McHarris, W.C.; Olivier, W.A.; Rios, A.; Hampton, C.; Chou, Wentsae; Aryaeinejad, R.

1991-01-01

Heavy-ion reactions induce large amounts of angular momentum; hence, they selectively populate rotationally-aligned particle states in compound nuclei. Such states tend to deexcite through similar states connected by large coriolis matrix elements, resulting in relatively few - but highly distorted - bands in the lower-energy portions of odd-odd spectra. The extreme cases of this are doubly-decoupled, K ∼ 1 (π 1/2 x ν 1/2) bands, whose γ transitions are the most intense in spectra from many light Re and Ir nuclei. The authors made a two-pronged assault on such bands, studying them via different HI reactions at different laboratories and using interacting-boson (IBFFA) calculations to aid in sorting them out. The authors are beginning to understand the types of (primarily coriolis) distortions involved and hope to grasp a handle on aspects of the p-n residual interaction, although the coriolis distortions are large enough to mask much of the latter. They also discuss similar but complementary effects in the light Pr region

Decay and fission of the oriented nuclei

CERN Document Server

Kadmenskij, S G

2002-01-01

The fragment angular distributions for binary decay of oriented spherical and deformed nuclei with taking into account the correct transformational properties of wave functions under time inversion have been investigated. It has been shown that for description of fragment angular distributions the adiabatic approximation for collective rotational nuclear degrees of freedom is not correct. It has been demonstrated that this approximation is valid for description of spontaneous and induced low-energy nuclear fission. The dependence of partial fission widths on the orientation of the internal axes spins, projections of spins, and relative angular moments of fission fragments has been analyzed. It has been shown that the adiabatic approximation results in coherent interference of wave functions of fragments relative movement. This interference forms fragments the universal angular distributions of fission fragments for oriented nuclei. For these distributions the deviations from A. Bohr's formula have been invest...

Low-energy E1 transitions and octupole softness in odd-A deformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Hagemann, G B [Niels Bohr Inst., Copenhagen (Denmark); Hamamoto, I [Lund Univ. (Sweden). Dept. of Mathematical Physics; Kownacki, J; Satula, W [Warsaw Univ. (Poland)

1992-08-01

It is found that B(E1) values for yrast spectroscopy of deformed odd-A rare-earth nuclei calculated by using a model in which one quasiparticle is coupled to a rotor are more than an order of magnitude too small. Therefore, measured B(E1) values for {sup 169}Lu were analyzed by introducing parameters which effectively took octupole softness into account. Some preliminary results of the theoretical analysis which are presented in this paper still give do not agree completely with experiment. 4 refs., 1 tab., 5 figs.

Gamow-Teller decay of T = 1 nuclei to odd-odd N = Z nuclei

Energy Technology Data Exchange (ETDEWEB)

Lisetskiy, A F [National Superconducting Cyclotron Laboratory, MSU, East Lansing, MI 48824 (United States); Gelberg, A [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany); Institute of Physical and Chemical Reasearch (RIKEN), Wako, 351-0198 (Japan); Brentano, P von [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany)

2005-01-01

Transition strengths of Gamow-Teller decay of T{sub z} = {+-}1 nuclei to N = Z odd-odd nuclei have been calculated in a two-nucleon approximation for spherical and deformed nuclei. The results obtained for the latter are quite close to the values obtained by full-space shell-model calculations and to the experiment.

Cold transfer between deformed, Coulomb excited nuclei

International Nuclear Information System (INIS)

Bauer, H.

1998-01-01

The scattering system 162 Dy → 116 Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high γ-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in 162 Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)

Lifetime of spherical and deformed states in 1f7/2 nuclei

International Nuclear Information System (INIS)

Medina, N.H.; Ribas, R.V.; Oliveira, J.R.B.; Brandolini, F.; Lenzi, S.M.; Ur, C.A.; Bazzacco, D.; Menegazzo, R.; Pavan, P.; Rossi A, C.; Napoli, D.R.; Marginean, N.; Angelis, G. De; Poli, M. De; Martinez, T.; Algora P, A.; Gadea, A.; Farnea, E.; Bucurescu, D.; Ionescu B, M.; Iordachescu, A.; Cameron, J.A.; Kasemann, S.; Schneider, I.; Espino, J.M.; Poves, A.; Sanchez S, J.

2001-01-01

Full text: An extensive experimental study of the structure of the N ≅ Z 1f 7/2 shell nuclei is going on at LNL, using the GASP gamma-spectrometer. An essential part of this program is aimed at the determination of good quality electromagnetic moments for monitoring rotational collectivity and single particle properties. For this purpose precise DSAM lifetimes were deduced for many levels with the new procedure named Narrow Gate on Transition Below, which avoids the influence of side feeding. In this contribution we report, in particular, lifetime measurements in the N ≅ Z nuclei 46 48 V, and 46 Ti. The data were obtained from the reactions: 28 Si on 28 Si, and 28 Si on 24 Mg at 115 MeV. The targets consisted of a layer of about 0.8 mg/cm 2 backed with Au or Pb. The experimental results for levels with natural parity agree very well with Shell Model (SM) calculations in the full f p configuration space with respect to energies B(E2) and B(E1) values of all observed levels. Big efforts have been made to interpret SM in terms of collective models, developing new tools and approaches. Another well described feature is the loss of collectivity when approaching band termination in the 1f 7/2 shell. The N=Z 46 V nuclei is very peculiar because of the coexistence at low excitation energy of natural parity T=1 states with T=0 and unnatural parity states. Some new transitions have been observed, and lifetime values could be obtained for about 15 transitions. The yrast structure for the 48 V nucleus can be classified as a K = 4 + band, obtained by a parallel coupling of the π[321]3/2 - and υ[312]5/2 - . The strong variation in signature splitting in this band may indicate a change of triaxiality. The low lying negative parity levels can be grouped in two strongly coupled rotational bands with K = 4 - and K = 1 - , which are given by parallel and antiparallel coupling of π [203]3/2 - and υ [312]5/2 - orbitals, respectively. Life times have been determined for 24

Contribution to the study of deformed heavy nuclei by means of nuclear reactions; Contribution a l'etude des noyaux lourds deformes au moyen de reactions nucleaires

Energy Technology Data Exchange (ETDEWEB)

Gastebois, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-06-01

The experimental results obtained in the study of the (d,p) reactions, at E{sub d} = 12 MeV, on the three even-even deformed nuclei {sup 170}Yb, {sup 172}Yb and {sup 174}Yb have been analysed in terms of DWBA calculations. The spectroscopic information relative to the odd final nuclei have been compared with the predictions of the collective model and of the Nilsson's model. The effect of various parameters used in the DWBA analysis (form factors, optical wave functions) has been carefully studied. The observed differences between the three final nuclei are qualitatively reproduced in the experimental study of resonances, seen in excitation functions of elastically and inelastically scattered protons on the same target nuclei, and corresponding to analogue states in the three nuclei {sup 171}Lu, {sup 173}Lu and {sup 175}Lu. (author) [French] Les resultats experimentaux de l'etude des reactions (d.p) a E{sub d} = 12 MeV, sur les noyaux deformes pairs-pairs {sup 170}Yb, {sup 172}Yb et {sup 174}Yb ont ete interpretes dans le cadre de l'approximation de Born des ondes deformees. Les informations spectroscopiques relatives aux noyaux impairs finals ont ete comparees aux predictions du modele collectif et du modele de Nilsson, apres avoir examine avec soin l'influence des differents parametres (facteurs de forme, fonctions d'onde 'optiques') utilises lors de l'analyse. Les differences observees entre les trois noyaux finals sont qualitativement reproduites par les resultats experimentaux de l'etude de resonances dans les fonctions d'excitation de diffusion elastique et inelastique de protons sur les memes noyaux-cibles, lors de la recherche d'etats analogues dans les noyaux {sup 171}Lu, {sup 173}Lu et {sup 175}Lu. (auteur)

Tunneling from super- to normal-deformed minima in nuclei

International Nuclear Information System (INIS)

Khoo, T. L.

1998-01-01

An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The γ spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in ΔI = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters

Tunneling from super- to normal-deformed minima in nuclei.

Energy Technology Data Exchange (ETDEWEB)

Khoo, T. L.

1998-01-08

An excited minimum, or false vacuum, gives rise to a highly elongated superdeformed (SD) nucleus. A brief review of superdeformation is given, with emphasis on the tunneling from the false to the true vacuum, which occurs in the feeding and decay of SD bands. During the feeding process the tunneling is between hot states, while in the decay it is from a cold to a hot state. The {gamma} spectra connecting SD and normal-deformed (ND) states provide information on several physics issues: the decay mechanism; the spin/parity quantum numbers, energies and microscopic structures of SD bands; the origin of identical SD bands; the quenching of pairing with excitation energy; and the chaoticity of excited ND states at 2.5-5 MeV. Other examples of tunneling in nuclei, which are briefly described, include the possible role of tunneling in {Delta}I = 4 bifurcation in SD bands, sub-barrier fusion and proton emitters.

Critical-point nuclei

International Nuclear Information System (INIS)

Clark, R.M.

2004-01-01

It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested

GOE-TYPE ENERGY-LEVEL STATISTICS AND REGULAR CLASSICAL DYNAMICS FOR ROTATIONAL NUCLEI IN THE INTERACTING BOSON MODEL

NARCIS (Netherlands)

PAAR, [No Value; VORKAPIC, D; DIERPERINK, AEL

1992-01-01

We study the fluctuation properties of 0+ levels in rotational nuclei using the framework of SU(3) dynamical symmetry of the interacting boson model. Computations of Poincare sections for SU(3) dynamical symmetry and its breaking confirm the expected relation between dynamical symmetry and classical

The fate of ultrahigh energy nuclei in the immediate environment of young fast-rotating pulsars

Energy Technology Data Exchange (ETDEWEB)

Kotera, Kumiko [Institut d' Astrophysique de Paris UMR7095—CNRS, Université Pierre and Marie Curie, 98 bis boulevard Arago, Paris, F-75014 France (France); Amato, Elena; Blasi, Pasquale, E-mail: kotera@iap.fr, E-mail: amato@arcetri.astro.it, E-mail: blasi@arcetri.astro.it [INAF/Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, Firenze, I-50125 Italy (Italy)

2015-08-01

Young, fast-rotating neutron stars are promising candidate sources for the production of ultrahigh energy cosmic rays (UHECRs). The interest in this model has recently been boosted by the latest chemical composition measurements of cosmic rays, that seem to show the presence of a heavy nuclear component at the highest energies. Neutrons stars, with their metal-rich surfaces, are potentially interesting sources of such nuclei, but some open issues remain: 1) is it possible to extract these nuclei from the star's surface? 2) Do the nuclei survive the severe conditions present in the magnetosphere of the neutron star? 3) What happens to the surviving nuclei once they enter the wind that is launched outside the light cylinder? In this paper we address these issues in a quantitative way, proving that for the most reasonable range of neutron star surface temperatures (T<10{sup 7} K), a large fraction of heavy nuclei survive photo-disintegration losses. These processes, together with curvature losses and acceleration in the star's electric potential, lead to injection of nuclei with a chemical composition that is mixed, even if only iron is extracted from the surface. We show that under certain conditions the chemical composition injected into the wind region is compatible with that required in previous work based on purely phenomenological arguments (typically ∼50% protons, ∼30% CNO and ∼20% Fe), and provides a reasonable explanation of the mass abundance inferred from ultra high energy data.

The fate of ultrahigh energy nuclei in the immediate environment of young fast-rotating pulsars

International Nuclear Information System (INIS)

Kotera, Kumiko; Amato, Elena; Blasi, Pasquale

2015-01-01

Young, fast-rotating neutron stars are promising candidate sources for the production of ultrahigh energy cosmic rays (UHECRs). The interest in this model has recently been boosted by the latest chemical composition measurements of cosmic rays, that seem to show the presence of a heavy nuclear component at the highest energies. Neutrons stars, with their metal-rich surfaces, are potentially interesting sources of such nuclei, but some open issues remain: 1) is it possible to extract these nuclei from the star's surface? 2) Do the nuclei survive the severe conditions present in the magnetosphere of the neutron star? 3) What happens to the surviving nuclei once they enter the wind that is launched outside the light cylinder? In this paper we address these issues in a quantitative way, proving that for the most reasonable range of neutron star surface temperatures (T<10 7 K), a large fraction of heavy nuclei survive photo-disintegration losses. These processes, together with curvature losses and acceleration in the star's electric potential, lead to injection of nuclei with a chemical composition that is mixed, even if only iron is extracted from the surface. We show that under certain conditions the chemical composition injected into the wind region is compatible with that required in previous work based on purely phenomenological arguments (typically ∼50% protons, ∼30% CNO and ∼20% Fe), and provides a reasonable explanation of the mass abundance inferred from ultra high energy data

Structures of exotic nuclei

International Nuclear Information System (INIS)

Hamilton, J.H.

1987-01-01

Discoveries of many different types of nuclear shape coexistence are being found at both low and high excitation energies throughout the periodic table, as documented in recent reviews. Many new types of shape coexistence have been observed at low excitation energies, for examples bands on more than four different overlapping and coexisting shapes are observed in 185 Au, and competing triaxial and prolate shapes in 71 Se and 176 Pt. Discrete states in super-deformed bands with deformations β 2 ∼ 0.4-0.6, coexisting with other shapes, have been seen to high spin up to 60ℎ in 152 Dy, 132 Ce and 135 Nd. Super-deformed nuclei with N and Z both around 38 and around Z = 38, N ≥ 60. These data led to the discovery of new shell gaps and magic numbers of 38 for N and Z and 60 for N but now for deformed shapes. Marked differences in structure are observed at spins of 6 to 20 in nuclei in this region, which differ by only two protons; for example, 68 Ge and 70 Se. The differences are thought to be related to the competing shell gaps in these nuclei

A new spin on nuclei

International Nuclear Information System (INIS)

Clark, R.; Wadsworth, B.

1998-01-01

Magnetic rotation is a new phenomenon that is forcing physicists to rethink their understanding of what goes on inside the nucleus The rotation of quantum objects has a long and distinguished history in physics. In 1912 the Danish scientist Niels Bjerrum was the first to recognize that the rotation of molecules is quantized. In 1938 Edward Teller and John Wheeler observed similar features in the spectra of excited nuclei, and suggested that this was caused by the nucleus rotating. But a more complete explanation had to wait until 1951, when Aage Bohr (the son of Niels) pointed out that rotation was a consequence of the nucleus deforming from its spherical shape. We owe much of our current understanding of nuclear rotation to the work of Bohr and Ben Mottelson, who shared the 1975 Nobel Prize for Physics with James Rainwater for developing a model of the nucleus that combined the individual and collective motions of the neutrons and protons inside the nucleus. What makes it possible for a nucleus to rotate? Quantum mechanically, a perfect sphere cannot rotate because it appears the same when viewed from any direction and there is no point of reference against which its change in position can be detected. To see the rotation the spherical symmetry must be broken to allow an orientation in space to be defined. For example, a diatomic molecule, which has a dumbbell shape, can rotate about the two axes perpendicular to its axis of symmetry. A quantum mechanical treatment of a diatomic molecule leads to a very simple relationship between rotational energy, E, and angular momentum. This energy is found to be proportional to J(J + 1), where J is the angular momentum quantum number. The molecule also has a magnetic moment that is proportional to J. These concepts can be applied to the atomic nucleus. If the distribution of mass and/or charge inside the nucleus becomes non-spherical then the nucleus will be able to rotate. The rotation is termed ''collective'' because many

Quasiequilibrium models for triaxially deformed rotating compact stars

International Nuclear Information System (INIS)

Huang Xing; Markakis, Charalampos; Sugiyama, Noriyuki; Uryu, Koji

2008-01-01

Quasiequilibrium models of rapidly rotating triaxially deformed stars are computed in general relativistic gravity, assuming a conformally flat spatial geometry (Isenberg-Wilson-Mathews formulation) and a polytropic equation of state. Highly deformed solutions are calculated on the initial slice covered by spherical coordinate grids, centered at the source, in all angular directions up to a large truncation radius. Constant rest mass sequences are calculated from nearly axisymmetric to maximally deformed triaxial configurations. Selected parameters are to model (proto-) neutron stars; the compactness is M/R=0.001, 0.1, 0.14, and 0.2 for polytropic index n=0.3 and M/R=0.001, 0.1, 0.12, and 0.14 for n=0.5, where M/R refers to that of a nonrotating spherical star having the same rest mass. We confirmed that the triaxial solutions exist for these parameters as in the case of Newtonian polytropes. However, it is also found that the triaxial sequences become shorter for higher compactness, and those disappear at a certain large compactness for the n=0.5 case. In the scenario of the contraction of proto-neutron stars being subject to strong viscosity and rapid cooling, it is plausible that, once the viscosity driven secular instability sets in during the contraction, the proto-neutron stars are always maximally deformed triaxial configurations, as long as the compactness and the equation of state parameters allow such triaxial sequences. Detection of gravitational waves from such sources may be used as another probe for the nuclear equation of state.

The moments of inertia of a rotational band 3/2- [521] isotones odd nuclei

International Nuclear Information System (INIS)

Karahodjaev, A.K.; Kuyjonov, H.

2003-01-01

The moments of inertia are received from experimental data from the following expression for energy of a level with spin I: E I = E 0 +ℎ 2 /2j·I(I+1), K≠l/2. The characteristics of low statuses of a rotational band 3/2 - [521] and inertial parameters 1.75A 1 keV ( A-1=ℎ 2 /2j) for nuclei 155 Dy and 155 Gd are given. The values of inertial parameters 1.75A1 keV for odd nuclei with N = 89, 91, 93, 95, 97, 99, 101 and 103 are presented. At quantity of neutrons N = 89 with increase of mass number of a nucleus the moment of inertia rather quickly grows. In nuclei with quantity of neutrons equal 91 and 93, with increase of mass number the moment of inertia of nuclei slowly changes and since A=159 and A=163, accordingly, begins sharply to grow. In isotones with N = 95, 97 and 99 moments of inertia decrease with increase of quantity neutrons in a nucleus. The reason of various dependence of the moment of inertia from mass number is, the coriolis interaction of an odd particle with even-even kernel and change of parameter of pair correlation because of presence of an odd particle above a kernel

Hartree-Fock theory for the equilibrium shape of light nuclei; Theorie Hartree-Fock de la forme d'equilibre des noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Ripka, G [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

1968-09-01

Most of the content of this thesis is published in english in Advances In Nuclear Physics, Vol. 1 (Editors: Baranger and Vogt - Plenum Press). The Hartree- Fock equations are derived. The expansions of the orbits and the possible symmetries of the Hartree-Fock field are discussed. Wavefunctions of even-even N = Z nuclei are given for 12 {<=} A {<=} 40. The role of the monopole, quadrupole and exchange components of the force are discussed. The multiplicity of the solutions and the effect of the spin-orbit interaction are discussed. Exact angular momentum projection is used to generate rotational bands. The validity of the adiabatic rotational model in light nuclei is discussed. Hartree-Fock calculations are extended to include major-shell mixing in order to obtain quadrupole deformations without the use of effective charge. The incompressibility, of nuclei is discussed and the compatibility between the Hartree-Fock solutions, the Mottelson model of quadrupole deformations and the SU3 states of J.P. Elliott and M. Moshinsky is established. (author) [French] La theorie de Hartree-Fock est appliquee au calcul des fonctions d'onde des noyaux legers deformes. Les equations de Hartree-Fock, les symetries permises et le choix du developpement des orbites sont discutes. Les fonctions d'onde des noyaux pair-pairs N = Z (12 {<=} A {<=} 40) sont tabulees. Les contributions des composantes monopolaires et quadrupolaires ainsi que des termes d'echange de la force nucleon-nucleon sont discutees. La methode de projection de moment cinetique est utilisee pour engendrer les bandes de rotation. La validite du modele rotationnel adiabatique est discutee. Les calculs de Hartree-Fock qui tiennent compte du melange de plusieurs couches majeures dans chaque orbite sont appliques au calcul des deformations quadrupolaires sans l'utilisation de charge effective. L'incompressibilite des noyaux et la compatibilite des fonctions d'onde de Hartree- Fock avec les fonctions d'onde SU3 de J

Reflection asymmetric shapes in nuclei

International Nuclear Information System (INIS)

Ahmad, I.; Carpenter, M.P.; Emling, H.

1989-01-01

Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N∼134, Z∼88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin ∼8ℎ. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin ∼7ℎ. The nuclei which exhibit octupole deformation in this mass region are 144 Ba, 146 Ba and 146 Ce; 142 Ba, 148 Ce, 150 Ce and 142 Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab

Symmetries of the nuclear average field hamiltonian and a search for possible exotic equilibrium deformations in superdeformed nuclei

Energy Technology Data Exchange (ETDEWEB)

Li Xunjun; Dudek, J.; Romain, P. (Centre de Recherches Nucleaires, IN2P3-CNRS, Univ. Louis Pasteur, 67 - Strasbourg (France))

1991-11-21

Symmetry properties of the general average-field hamiltonian-matrix resulting from the geometrical symmetries of the hamiltonian itself are derived and discussed. The corresponding numerical algorithms are constructed. Total energy calculations for superdeformed nuclei are then extended to include the usually neglected deformation modes {alpha}{sub {lambda}=3{mu}{ne}0} in the expansion of the nuclear surface expression R({theta}, {phi}; {l brace}{alpha}{r brace})=c({l brace}{alpha}{r brace})R{sub 0}(1+{Sigma}{sub {lambda}} {Sigma}{sub {mu}=-{lambda}}{sup {lambda}} {alpha}{sub {lambda}{mu}}{sup *}{Upsilon}{sub {lambda}{mu}}({theta}, {phi})). The general trends in the shell-energy dependence on {alpha}{sub {lambda}=3{mu}} and the implied instabilities in the superdeformed configurations of the rare earth nuclei are studied using the Strutinsky formula with the macroscopic part taken in the form of the folded-Yukawa plus exponential interaction. A possibility of new (double superdeformed minimum) structures coexisting in some nuclei and resulting from the proton shell effects is predicted and illustrated. No significant neutron effects are found in the rare earth superdeformed nuclei considered. (orig.).

Nuclei and quantum worlds

International Nuclear Information System (INIS)

Chomaz, Ph.

2000-01-01

This document gathers the slides and their commentaries that have been presented at the conference 'physics and fundamental questions' by P. Chomaz. The author reviews the different quantum aspects of nuclei: tunnel effect, symmetries, magic numbers, wave functions, size, shapes and deformations. The author shows that nuclei are quantum objects of great complexity, their structures are not yet well understood and the study of exotic nuclei will continue bringing valuable information

Gravitational convergence, shear deformation and rotation of magnetic forcelines

Science.gov (United States)

Giantsos, Vangelis; Tsagas, Christos G.

2017-11-01

We consider the 'kinematics' of space-like congruences and apply them to a family of self-gravitating magnetic forcelines. Our aim is to investigate the convergence and the possible focusing of these lines, as well as their rotation and shear deformation. In so doing, we introduce a covariant 1+2 splitting of the 3-D space, parallel and orthogonal to the direction of the field lines. The convergence, or not, of the latter is monitored by a specific version of the Raychaudhuri equation, obtained after propagating the spatial divergence of the unit magnetic vector along its own direction. The resulting expression shows that, although the convergence of the magnetic forcelines is affected by the gravitational pull of all the other sources, it is unaffected by the field's own gravity, irrespective of how strong the latter is. This rather counterintuitive result is entirely due to the magnetic tension, namely to the negative pressure the field exerts parallel to its lines of force. In particular, the magnetic tension always cancels out the field's energy-density input to the Raychaudhuri equation, leaving the latter free of any direct magnetic-energy contribution. Similarly, the rotation and the shear deformation of the aforementioned forcelines are also unaffected by the magnetic input to the total gravitational energy. In a sense, the magnetic lines do not seem to 'feel' their own gravitational field no matter how strong the latter may be.

Shape of 44Ar: Onset of deformation in neutron-rich nuclei near 48Ca

International Nuclear Information System (INIS)

Zielinska, M.; Goergen, A.; Clement, E.; Korten, W.; Dossat, C.; Ljungvall, J.; Obertelli, A.; Theisen, Ch.; Delaroche, J.-P.; Girod, M.; Buerger, A.; Catford, W.; Iwanicki, J.; Napiorkowski, P. J.; Srebrny, J.; Wrzosek, K.; Libert, J.; PiePtak, D.; Rodriguez-Guzman, R.; Sletten, G.

2009-01-01

The development of deformation and shape coexistence in the vicinity of doubly magic 48 Ca, related to the weakening of the N=28 shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive 44 Ar beam from the SPIRAL facility at GANIL. The 2 1 + and 2 2 + states in 44 Ar were excited on 208 Pb and 109 Ag targets at two different beam energies. B(E2) values between all observed states and the spectroscopic quadrupole moment of the 2 1 + state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the 44 Ar nucleus and giving evidence of an onset of deformation already two protons and two neutrons away from doubly magic 48 Ca. New Hartree-Fock-Bogoliubov based configuration mixing calculations have been performed with the Gogny D1S interaction for 44 Ar and neighboring nuclei using two different approaches: the angular momentum projected generator coordinate method considering axial quadrupole deformations and a five-dimensional approach including the triaxial degree of freedom. The experimental values and new calculations are furthermore compared to shell-model calculations and to relativistic mean-field calculations. The new results give insight into the weakening of the N=28 shell closure and the development of deformation in this neutron-rich region of the nuclear chart.

Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei

International Nuclear Information System (INIS)

Khalfallah, F.

2007-08-01

Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No 256 et Rf 256 for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa 223 . The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)

{gamma}-spectroscopy and radioactive beams: search for highly deformed exotic nuclei; Detection {gamma} et faisceaux radioactifs: recherche de noyaux exotiques tres deformes

Energy Technology Data Exchange (ETDEWEB)

Rosse, B

2006-07-15

This work is devoted to the search for highly deformed nuclei under extreme conditions of isospin, located near the proton drip-line, around A {approx} 130. The experiment was performed at GANIL (Caen) with the SPIRAL radioactive beam facility. The nuclei of interest were produced by fusion-evaporation reactions induced by the neutron deficient Kr{sup 76} radioactive beam (T1/2 = 14.8 h). {gamma}-rays were detected by the EXOGAM array, composed of 11 segmented germanium clover detectors, for which a new segment calibration method has been developed. To extract fusion-evaporation events of a overwhelming background due to the radioactivity of the beam, the EXOGAM array was coupled with the light charged particle detector DIAMANT and the high acceptance VAMOS spectrometer. The latter was used for the first time to detect fusion-evaporation residues. The detailed data analysis allowed us to demonstrate that the EXOGAM + DIAMANT + VAMOS coupling is operational and essential to investigate the structure of these nuclei. Furthermore, the first {gamma} transition was observed in the very exotic odd-odd Pm{sup 130} nucleus. The results have been interpreted with static and dynamic self-consistent microscopic calculations in collaboration with the Theoretical Physicists of the IPN Lyon. (author)

Hartree-Fock theory for the equilibrium shape of light nuclei; Theorie Hartree-Fock de la forme d'equilibre des noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Ripka, G. [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires

1968-09-01

Most of the content of this thesis is published in english in Advances In Nuclear Physics, Vol. 1 (Editors: Baranger and Vogt - Plenum Press). The Hartree- Fock equations are derived. The expansions of the orbits and the possible symmetries of the Hartree-Fock field are discussed. Wavefunctions of even-even N = Z nuclei are given for 12 {<=} A {<=} 40. The role of the monopole, quadrupole and exchange components of the force are discussed. The multiplicity of the solutions and the effect of the spin-orbit interaction are discussed. Exact angular momentum projection is used to generate rotational bands. The validity of the adiabatic rotational model in light nuclei is discussed. Hartree-Fock calculations are extended to include major-shell mixing in order to obtain quadrupole deformations without the use of effective charge. The incompressibility, of nuclei is discussed and the compatibility between the Hartree-Fock solutions, the Mottelson model of quadrupole deformations and the SU3 states of J.P. Elliott and M. Moshinsky is established. (author) [French] La theorie de Hartree-Fock est appliquee au calcul des fonctions d'onde des noyaux legers deformes. Les equations de Hartree-Fock, les symetries permises et le choix du developpement des orbites sont discutes. Les fonctions d'onde des noyaux pair-pairs N = Z (12 {<=} A {<=} 40) sont tabulees. Les contributions des composantes monopolaires et quadrupolaires ainsi que des termes d'echange de la force nucleon-nucleon sont discutees. La methode de projection de moment cinetique est utilisee pour engendrer les bandes de rotation. La validite du modele rotationnel adiabatique est discutee. Les calculs de Hartree-Fock qui tiennent compte du melange de plusieurs couches majeures dans chaque orbite sont appliques au calcul des deformations quadrupolaires sans l'utilisation de charge effective. L'incompressibilite des noyaux et la compatibilite des fonctions d'onde de Hartree- Fock avec les

Giant dipole resonance in hot rotating nuclei

Energy Technology Data Exchange (ETDEWEB)

Chakrabarty, D.R. [Bhabha Atomic Research Centre, Nuclear Physics Division, Mumbai (India); Dinh Dang, N. [RIKEN, Nishina Centre for Accelerator-based Science, Saitama (Japan); VINATOM, Institute of Nuclear Science and Technique, Hanoi (Viet Nam); Datar, V.M. [Tata Institute of Fundamental Research, INO Cell, Mumbai (India)

2016-05-15

Over the last several decades, extensive experimental and theoretical work has been done on the giant dipole resonance (GDR) in excited nuclei covering a wide range of temperature (T), angular momentum (J) and nuclear mass. A reasonable stability of the GDR centroid energy and an increase of the GDR width with T (in the range∝1-3 MeV) and J are the two well-established results. Some experiments have indicated the saturation of the GDR width at high T. The gradual disappearance of the GDR vibration at much higher T has been observed. Experiments on the Jacobi transition and the GDR built on superdeformed shapes at high rotational frequencies have been reported in a few cases. Theoretical calculations on the damping of the collective dipole vibration, characterised by the GDR width, have been carried out within various models such as the thermal shape fluctuation model and the phonon damping model. These models offer different interpretations of the variation of the GDR width with T and J and have met with varying degrees of success in explaining the experimental data. In this review, the present experimental and theoretical status in this field is discussed along with the future outlook. The interesting phenomenon of the pre-equilibrium GDR excitation in nuclear reactions is briefly addressed. (orig.)

Introduction of the deformed base AMD and application to the stable and unstable nuclei

International Nuclear Information System (INIS)

Kimura, M.; Horiuchi, H.

2003-01-01

A new theoretical framework named as deformed base antisymmetrized molecular dynamics is presented. The theoretical framework enables us to describe sufficiently well the deforemd mean-field structure, cluster structure and their mixed structure within the same framework. Indeed the coexistence and mixture of the deformed mean-field structure and the cluster structure in the low-lying rotational bands of 20 Ne are described well. The possible existence of the cluster core + valance neutron structure in the K π =0 3 + band of 30 Ne is shown as well as the reasonable description of the observed properties of the ground bands of 30 Ne and 32 Mg

Description of rotating N=Z nuclei in terms of isovector pairing

International Nuclear Information System (INIS)

Afanasjev, A.V.; Frauendorf, S.

2005-01-01

A systematic investigation of the rotating N=Z even-even nuclei in the mass A=68-80 region has been performed within the frameworks of the cranked relativistic mean field, cranked relativistic Hartree-Bogoliubov theories, and cranked Nilsson-Strutinsky approach. Most of the experimental data are well accounted for in the calculations. The present study suggests the presence of strong isovector np pair field at low spin, whose strength is defined by the isospin symmetry. At high spin, the isovector pair field is destroyed and the data are well described by the calculations assuming zero pairing. No clear evidence for the existence of the isoscalar t=0 np pairing has been obtained in the present investigation performed at the mean field level

On the origin of deformation-induced rotation patterns below nanoindents

International Nuclear Information System (INIS)

Zaafarani, N.; Raabe, D.; Roters, F.; Zaefferer, S.

2008-01-01

This study is about the origin of systematic deformation-induced crystallographic orientation patterns around nanoindents (here of single crystalline copper; conical indenter) using the following approach: first, the rotation pattern is investigated in three-dimensions (3D) using a high-resolution 3D electron backscattered diffraction (EBSD) technique (EBSD tomography) which works by a serial sectioning and EBSD mapping procedure in a scanning electron microscopy-focused ion beam cross-beam set-up. Second, the problem is modeled using a crystal plasticity finite element method which is based on a dislocation density-based constitutive model. Third, the results were discussed in terms of a geometrical model which simplifies the boundary conditions during indentation in terms of a compressive state normal to the local tangent of the indent shape. This simplification helps to identify the dominant slip systems and the resulting lattice rotations, thereby allowing us to reveal the basic mechanism of the formation of the rotation patterns. The finite element simulations also predict the pile-up patterning around the indents, which can be related to the dislocation density evolution

Microscopic description of low-lying M1 excitations in odd-mass actinide nuclei

Energy Technology Data Exchange (ETDEWEB)

Tabar, Emre, E-mail: etabar@sakarya.edu.tr [Physics Department, Sakarya University, 54187 Sakarya (Turkey); Biomedical, Magnetic and Semiconductor Materials Research Center (BIMAS-RC), Sakarya University, 54187 Sakarya (Turkey); Yakut, Hakan, E-mail: hyakut@sakarya.edu.tr [Physics Department, Sakarya University, 54187 Sakarya (Turkey); Biomedical, Magnetic and Semiconductor Materials Research Center (BIMAS-RC), Sakarya University, 54187 Sakarya (Turkey); Kuliev, Ali Akbar [Azerbaijan National Academy of Aviation, Baku (Azerbaijan)

2017-01-15

A restoration method of a broken symmetry which allows self-consistent determination of the separable effective restoration forces is now adapted to odd-mass nuclei in order to restore violated rotational invariance (RI-) of the Quasiparticle Phonon Nuclear Model (QPNM) Hamiltonian. Because of the self-consistency of the method, these effective forces contain no arbitrary parameters. Within RI-QPNM, the properties of the low-lying magnetic dipole excitations in odd-mass deformed {sup 229–233}Th and {sup 233–239}U nuclei have been investigated for the first time. It has been shown that computed fragmentation of the M1 strengths below 4 MeV in these nuclei is much stronger than that in neighboring doubly even {sup 228–232}Th and {sup 232–238}U nuclei. For {sup 235}U the summed M1 strength in the energy range 1.5–2.8 MeV is in agreement with the relevant experimental data where the missing strength was extracted by means of a fluctuation analysis.

Comparison with Tilted Axis Cranking and particle rotor model for triaxial nuclei

Energy Technology Data Exchange (ETDEWEB)

Ohtsubo, Shin-ichi; Shimizu, Yoshifumi R [Kyushu Univ., Fukuoka (Japan). Dept. of Physics

1998-03-01

An extension of the cranking model in such a way to allow a rotation axis to deviate from the principal axes of the deformed mean-field is a promising tool for the spectroscopic study of rapidly rotating nuclei. We have applied such a `Tilted Axis Cranking` (TAC) method to a simple system of one-quasiparticle coupled to a triaxial rotor and compared it with a particle-rotor coupling calculation in order to check whether the spin-orientation degrees of freedom can be well described within the mean-field approximation. The result shows that the TAC method gives a good approximation to observable quantities and it is a suitable method to understand the dynamical interplay between the collective and single-particle angular momenta. (author)

Nuclei in high forms

International Nuclear Information System (INIS)

Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.

1991-01-01

The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters

Recent developments in high-spin calculations in atomic nuclei

International Nuclear Information System (INIS)

Szymanski, Z.

1980-01-01

A brief introduction to the recent achievements in the high-spin domain in nuclear physics is given. Results of the calculations in highly developed rotational bands in deformed nuclei, as well as the calculations in the structure of the yrast isomers are presented. The calculations fail in two aspects: local minima in the yrast line are not confirmed experimentally, the overall slope of the yrast line in 152 Dy is considerably overestimated. The calculations of the yrast line with new Woods-Saxon parameters are now in progress. The parameters are chosen to reproduce the large gap in the levels at proton number Z=64. (M.H.)

Collective and non-collective structures in nuclei of mass region A ≈ 125

International Nuclear Information System (INIS)

Singh, A. K.

2014-01-01

Generation of angular momentum in nuclei is a key question in nuclear structure studies. In single particle model, it is due to alignment of spin of individual nucleon available in the valence space, whereas coherent motion of nucleons are assumed in the collective model. The nuclei near the closed shell at Z = 50 with mass number A ≈ 120-125 represent ideal cases to explore the interplay between these competing mechanisms and the transition from non-collective to collective behavior or vice versa. Recent spectroscopic studies of nuclei in this region reveal several non-collective maximally aligned states representing the first kind of excitation mechanism, where 8-12 particles above the 114 Sn align their spins to generate these states. Deformed rotational bands feeding the non-collective states in the spin range I=20-25 and excitation energies around 10 MeV have also been observed. Structure of the collective and non-collective states are discussed in the framework of Cranked-Nilsson-Strutinsky model

Parsec-scale Faraday rotation and polarization of 20 active galactic nuclei jets

Science.gov (United States)

Kravchenko, E. V.; Kovalev, Y. Y.; Sokolovsky, K. V.

2017-05-01

We perform polarimetry analysis of 20 active galactic nuclei jets using the very long baseline array at 1.4, 1.6, 2.2, 2.4, 4.6, 5.0, 8.1, 8.4 and 15.4 GHz. The study allowed us to investigate linearly polarized properties of the jets at parsec scales: distribution of the Faraday rotation measure (RM) and fractional polarization along the jets, Faraday effects and structure of Faraday-corrected polarization images. Wavelength dependence of the fractional polarization and polarization angle is consistent with external Faraday rotation, while some sources show internal rotation. The RM changes along the jets, systematically increasing its value towards synchrotron self-absorbed cores at shorter wavelengths. The highest core RM reaches 16 900 rad m-2 in the source rest frame for the quasar 0952+179, suggesting the presence of highly magnetized, dense media in these regions. The typical RM of transparent jet regions has values of an order of a hundred rad m-2. Significant transverse RM gradients are observed in seven sources. The magnetic field in the Faraday screen has no preferred orientation, and is observed to be random or regular from source to source. Half of the sources show evidence for the helical magnetic fields in their rotating magneto-ionic media. At the same time jets themselves contain large-scale, ordered magnetic fields and tend to align its direction with the jet flow. The observed variety of polarized signatures can be explained by a model of spine-sheath jet structure.

Spin-dependent γ softness or triaxiality in even-even 132-138Nd nuclei

Science.gov (United States)

Chai, Qing-Zhen; Wang, Hua-Lei; Yang, Qiong; Liu, Min-Liang

2015-02-01

The properties of γ instability in rapidly rotating even-even 132-138Nd isotopes have been investigated using the pairing-deformation self-consistent total-Routhian-surface calculations in a deformation space of (β2, γ, β4). It is found that even-even 134-138Nd nuclei exhibit triaxiality in both ground and excited states, even up to high-spin states. The lightest isotope possesses a well-deformed prolate shape without a γ deformation component. The current numerical results are compared with previous calculations and available observables such as quadrupole deformation β2 and the feature of γ-band levels, showing basically a general agreement with the observed trend of γ correlations (e.g. the pattern of the odd-even energy staggering of the γ band). The existing differences between theory and experiment are analyzed and discussed briefly. Supported by National Natural Science Foundation of China (10805040,11175217), Foundation and Advanced Technology Research Program of Henan Province(132300410125) and S & T Research Key Program of Henan Province Education Department (13A140667)

Rotational bands on few-particle excitations of very high spin

International Nuclear Information System (INIS)

Andersson, C.G.; Krumlinde, J.; Leander, G.; Szymanski, Z.

1980-01-01

An RPA formalism is developed to investigate the existence and properties of slow collective rotation around a non-symmetry axis, when there already exists a large angular momentum K along the symmetry axis built up by aligned single-particle spins. It is found necessary to distinguish between the collectivity and the repeatability of the rotational excitations. First the formalism is applied to bands on hihg-K isomers in the well-deformed nucleus 176 Hf, where the rotational-model picture is reproduced for intermediate K-values in agreement with experiment. At high K there is a suppression of the collectivity corresponding to the diminishing vector-coupling coefficient of the rotational model, but the repeatability actually improves. The moment of inertia is predicted to remain substantially smaller than the rigid-body value so the bands slope up steeply from the yrast line at spins where pairing effects are gone. A second application is to the initially spherical nucleus 212 Rn, which is believed to acquire an oblate deformation that increases steadily with K due to the oblate shape of the aligned orbitals. In this case the repeatable excitations come higher above the yrast line than in 176 Hf, even at comparable deformations. Some collective states may occur very close to yrast, but these are more like dressed singleparticle excitations. The main differences between the two nuclei studied is interpreted as a general consequence of their different shell structure. (author)

Systematics of triaxial moment of inertia and deformation parameters (β, γ) in even-even nuclei of mass region A = 90-120

International Nuclear Information System (INIS)

Singh, Yuvraj; Gupta, D.K.; Singh, M.; Gupta, K.K.; Bihari, Chhail; Varshney, A.K.; Dhiman, S.K.

2012-01-01

The deformation parameter β and γ of the collective model of Bohr and Mottelson are basic descriptors of the nuclear equilibrium shape and structure. In recent past the sets of deformation parameters ((β, γ) have been extracted from both level energies and E2 transition rates in even Xe, Ba and Ce nuclei (A∼120-140) and Hf, W, Os, Pt and Hg nuclei (A∼160-200) using rigid triaxial rotor model of Davydov-Filippov (DF). Researcher have found that the values of β obtained separately from energy and transition rate (β e and β b respectively), though, are found almost equal in heavy mass region (A ∼160-200) but, not so in medium mass (A∼120-140) nuclei. This observation puts a question mark whether the ββ dependence of moment of inertia in hydrodynamic model is reliable. The purpose of the present work is to study a relatively lighter mass region (A∼90-120) where the gap between values of two sets of β may further increase. To improve the calculations for extracting β e , the use of Grodzins rule will be made along with uncertainties, since only through this rule the E2 1 + is related with β G (value of β for symmetric nucleus and evaluated using Grodzins rule)

An Analytical Model for Rotation Stiffness and Deformation of an Antiloosening Nut under Locking Force

Directory of Open Access Journals (Sweden)

X. J. Jiang

2014-01-01

Full Text Available Screw fasteners are undoubtedly one of the most important machine elements due to their outstanding characteristic to provide a high clamping force just with a simplified design. However, the loosen vibration is their inherent and inevitable fault. The friction locking approach is one of the basic locking fastener categories by enhancing the bearing load on the contact surface of thread by applying a locking force on an antiloosening nut. This locking force may cause more severe deformation in the nut. The contact stress distribution on the nut would be changed and that can cause the variation of the friction torque for the bolt joint. However, there exists no established design calculation procedure that accounts for the rotation deformation and its stiffness of the antiloosening nut under the locking force. The main objective of the work is to develop an analytical solution to the rotation deformation problem encountered in the antiloosening nut. The proposed model is supported by comparison with numerical finite element analysis of different sizes of joint elements and different applied forces.

The contour deformation method in momentum space and effective interactions for weakly bound nuclei

International Nuclear Information System (INIS)

Hagen, Gaute

2005-01-01

The main purpose of this thesis has been to investigate and develop methods suitable for study of resonance phenomena in nuclear and subatomic physics. Emphasis has been on the momentum space formulation of the Schrodinger equation. It has been shown; starting from the integral formulation of the Schrodinger equation, that an efficient way of obtaining a complete set of states including bound- antibound and resonant states is through the Contour Deformation Method. The strength of the Contour Deformation Method has been illustrated by studying a wide range of different cases in subatomic physics where resonance phenomena appear. These applications ranges from the case of a single-particle moving in a spherically symmetric field to the case of strong deformations of the field. Further, it has been studied how resonances may be solved for in complex potentials which models absorptive and emittive processes, using the Contour Deformation Method. The results obtained in these specific applications, strongly favour the Contour Deformation Method in comparison with other methods such as complex coordinate scaling and analytic continuation in the coupling strength. The most appealing feature of CD-NI is that not only does it give accurate results for resonances and anti-bound states, but in addition it provides us with a complete set of states which may be used in many different eigenfunction expansions. The only limitation of CDM is that the analytic structure of the potential has to be known, since the choice of contour is dictated by the singularity structure of the potential. The revival and study of CDM applied to nuclear physics, may be considered the main issue of the first part of this thesis, and is also the topic of Paper 1. In the second part of this thesis, the focus was directed towards the issue of how resonance phenomena may be understood in nuclei, when several valence particles are present. The newly developed Gamow Shell Model is a promising approach in

Octupole shapes in heavy nuclei

International Nuclear Information System (INIS)

Ahmad, I.

1994-01-01

Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets

Deformation and shell effects in nuclear mass formulas

International Nuclear Information System (INIS)

Barbero, César; Hirsch, Jorge G.; Mariano, Alejandro E.

2012-01-01

We analyze the ability of three different Liquid Drop Mass (LDM) formulas to describe nuclear masses for nuclei in various deformation regions. Separating the 2149 measured nuclear species into eight sets with similar quadrupole deformations, we show that the masses of prolate deformed nuclei are better described than those of spherical ones. In fact, the prolate deformed nuclei are fitted with an RMS smaller than 750 keV, while for spherical and semi-magic species the RMS is always larger than 2000 keV. These results are found to be independent of pairing. It is also shown that the macroscopic sector of the Duflo–Zuker (DZ) mass model reproduces shell effects, while most of the deformation dependence is lost and the RMS is larger than in any LDM. Adding to the LDM the microscopically motivated DZ master terms introduces the shell effects, allowing for a significant reduction in the RMS of the fit but still exhibiting a better description of prolate deformed nuclei. The inclusion of shell effects following the Interacting Boson Model's ideas produces similar results.

Deformation and shell effects in nuclear mass formulas

Energy Technology Data Exchange (ETDEWEB)

Barbero, Cesar [Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina); Hirsch, Jorge G., E-mail: hirsch@nucleares.unam.mx [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, 04510 Mexico D.F. (Mexico); Mariano, Alejandro E. [Departamento de Fisica, Universidad Nacional de La Plata, C.C. 67, 1900 La Plata (Argentina); Instituto de Fisica La Plata, CONICET, 1900 La Plata (Argentina)

2012-01-15

We analyze the ability of three different Liquid Drop Mass (LDM) formulas to describe nuclear masses for nuclei in various deformation regions. Separating the 2149 measured nuclear species into eight sets with similar quadrupole deformations, we show that the masses of prolate deformed nuclei are better described than those of spherical ones. In fact, the prolate deformed nuclei are fitted with an RMS smaller than 750 keV, while for spherical and semi-magic species the RMS is always larger than 2000 keV. These results are found to be independent of pairing. It is also shown that the macroscopic sector of the Duflo-Zuker (DZ) mass model reproduces shell effects, while most of the deformation dependence is lost and the RMS is larger than in any LDM. Adding to the LDM the microscopically motivated DZ master terms introduces the shell effects, allowing for a significant reduction in the RMS of the fit but still exhibiting a better description of prolate deformed nuclei. The inclusion of shell effects following the Interacting Boson Model's ideas produces similar results.

Kπ=1+ pairing interaction and moments of inertia of superdeformed rotational bands in atomic nuclei

International Nuclear Information System (INIS)

Hamamoto, I.; Nazarewicz, W.

1994-01-01

The effect of the pairing interaction coming from the rotationally induced K π =1 + pair-density on the nuclear moments of inertia is studied. It is pointed out that, contrary to the situation at normal deformations, the inclusion of the K π =1 + pairing may appreciably modify the frequency dependence of the moments of inertia at superdeformed shapes

Fast electric dipole transitions in Ra-Ac nuclei

International Nuclear Information System (INIS)

Ahmad, I.

1985-01-01

Lifetime of levels in 225 Ra, 225 Ac, and 227 Ac have been measured by delayed coincidence techniques and these have been used to determine the E1 gamma-ray transition probabilities. The reduced E1 transition probabilities. The reduced E1 transition probabilities in 225 Ra and 225 Ac are about two orders of magnitude larger than the values in mid-actinide nuclei. On the other hand, the E1 rate in 227 Ac is similar to those measured in heavier actinides. Previous studies suggest the presence of octupole deformation in all the three nuclei. The present investigation indicates that fast E1 transitions occur for nuclei with octupole deformation. However, the studies also show that there is no one-to-one correspondence between E1 rate and octupole deformation. 13 refs., 4 figs

Calculation of gaint Elambda-resonances of high multipolarity in deformed nuclei

International Nuclear Information System (INIS)

Kiselev, M.A.; Malov, L.A.; Nesterenko, V.O.; Solov'ev, V.G.

1978-01-01

High-miltipole ( lambda=4-7 ) single-phonon states and strength functions of Elambda(0sup(+) → lambdasup(π))-transitions from the ground states to the excited Isup(π)K states with I=lambda in deformed nuclei are calculated. Possible existance of high-multipole ( lambda >= 4 ) giant Elambda-resonances is considered. Magnitudes of isoscalar and isovector constants of multipole-multipole interaction, required for a description of phonons as quasiparticles of the phonon model, are discussed. All the calculations have been carried out in the random-phase approximation of the general semimicroscopic approach. There is a tendency towards broadening resonances and shifting the maxima into the region of high excitation energies as lambda increases. Broad isoscalar resonances at energies of 10-17 MeV, 10-25 MeV, 15-25 MeV and 10-40 MeV for lambda=4, 5, 6 and 7 respectively. Isovector resonances at lambda=4, 5, 6 and 7 show up themselves as well sufficiently clearly

Heavy-ion interactions of deformed nuclei. Progress report and final report, January 1, 1985-December 31, 1985

International Nuclear Information System (INIS)

Oberacker, V.E.

1985-09-01

This Progress Report describes the main topics that were investigated during the reporting period: (1) a new microscopic approach (many-body theory with two-center shell model basis) to the calculation of heavy-ion interaction potentials, primarily for heavy systems; (2) dynamic alignment of deformed nuclei during heavy-ion collisions; (3) the role of shell effects, static deformation and dynamic alignment in heavy-ion fusion reactions; (4) giant nuclear quasimolecules and the positron problem. The proposed research has direct relevance to experimental programs supported by DOE, e.g. the Holifield Heavy-Ion Research Facility (HHIRF) at Oak Ridge, the ATLAS accelerator at Argonne National Laboratory, the Double MP Tandem at Brookhaven and some of the smaller University-based accelerators. A discussion of a review article on Coulomb fission is presented. 36 refs., 7 figs

A study of Gamow-Teller transitions for N = Z nuclei, {sup 24}Mg, {sup 28}Si, and {sup 32}S, by a deformed QRPA

Energy Technology Data Exchange (ETDEWEB)

Ha, Eunja; Cheoun, Myung-Ki [Soongsil University, Origin of Matter and Evolution of Galaxy Institute and Department of Physics, Seoul (Korea, Republic of)

2017-02-15

We investigated Gamow-Teller (GT) transitions and strength distributions of s-d shell N = Z nuclei, {sup 24}Mg, {sup 28}Si, and {sup 32}S, by a deformed quasi-particle random phase approximation (DQRPA). In the DQRPA, we included particle model space up to p-f shell and considered explicitly the deformation as well as the like- and unlike-pairing correlations. Shell evolution by deformation and attractive force by unlike-pairing correlations turned out to play vital roles to reproduce the experimental GT data. Correlations between the deformation and the pairing correlations are also discussed with the comparison to the experimental data shape. (orig.)

Studies of pear-shaped nuclei using accelerated radioactive beams

CERN Document Server

Gaffney, L P; Scheck, M; Hayes, A B; Wenander, F; Albers, M; Bastin, B; Bauer, C; Blazhev, A; Bonig, S; Bree, N; Cederkall, J; Chupp, T; Cline, D; Cocolios, T E; Davinson, T; DeWitte, H; Diriken, J; Grahn, T; Herzan, A; Huyse, M; Jenkins, D G; Joss, D T; Kesteloot, N; Konki, J; Kowalczyk, M; Kroll, Th; Kwan, E; Lutter, R; Moschner, K; Napiorkowski, P; Pakarinen, J; Pfeiffer, M; Radeck, D; Reiter, P; Reynders, K; Rigby, S V; Robledo, L M; Rudigier, M; Sambi, S; Seidlitz, M; Siebeck, B; Stora, T; Thoele, P; Van Duppen, P; Vermeulen, M J; von Schmid, M; Voulot, D; Warr, N; Wimmer, K; Wrzosek-Lipska, K; Wu, C Y; Zielinska, M

2013-01-01

There is strong circumstantial evidence that certain heavy, unstable atomic nuclei are ‘octupole deformed’, that is, distorted into a pear shape. This contrasts with the more prevalent rugby-ball shape of nuclei with reflection-symmetric, quadrupole deformations. The elusive octupole deformed nuclei are of importance for nuclear structure theory, and also in searches for physics beyond the standard model; any measurable electric-dipole moment (a signature of the latter) is expected to be amplified in such nuclei. Here we determine electric octupole transition strengths (a direct measure of octupole correlations) for short-lived isotopes of radon and radium. Coulomb excitation experiments were performed using accelerated beams of heavy, radioactive ions. Our data on and $^{224}$Ra show clear evidence for stronger octupole deformation in the latter. The results enable discrimination between differing theoretical approaches to octupole correlations, and help to constrain suitable candidates for experimental...

Using nuclear structure to study the vaporization of hot nuclei

International Nuclear Information System (INIS)

Broglia, R.A.

1985-01-01

Many experiments on the gamma decay of highly excited nuclei show the persistence of the giant dipole resonance as a collective mode even under rather extreme conditions. The theory of these resonances predicts that they should essentially retain the properties they have in the ground state to quite high excitation. The average resonance energy may be studied in mean-field theory and is found to change less than 5% for temperatures as high as approx.1.5 MeV. The spreading of the resonance has recently been calculated for nuclei at finite temperatures and rotational frequencies. The damping is found to increase by an insignificant amount in the measured temperature range, except when the nucleus changes deformation. The authors argue here that the stability of the dipole may be used to advantage in the study of other properties of nuclei at high excitation. For example, given that a compound nucleus is formed in a heavy-ion reaction, the dipole branching ratio is very sensitive to the statistical properties of the nucleus. The branching ratio allows a more sensitive measurement of the level density parameter at high excitation than would be otherwise available

The rotational mobility of spin labels in wool creatine depending on temperature, humidity and deformation

International Nuclear Information System (INIS)

Bobodzhanov, P.Kh.; Yusupov, I.Kh.; Marupov, R.

2001-01-01

Present article is devoted to study of rotational mobility of spin labels in wool creatine depending on temperature, humidity and deformation. The experimental data of study of structure and molecular mobility of wool creatine modified by spin labels was considered.

Effect of the Pauli principle on the excited states of doubly-even deformed nuclei

International Nuclear Information System (INIS)

Jolos, R.V.; Molina, J.L.; Soloviev, V.G.

1980-01-01

It is shown that the commutation relations between the quasiparticles forming phonons can correctly be taken into account within the quasiparticle-phonon nuclear model. The doubly-even deformed nuclei with the isoscalar and isovector multipole-multipole forces are studied. The exact and approximate secular equations are derived. It is shown that the two-phonon poles in the secular equation are shifted due to the Pauli principle. These shifts are large for the two identical collective phonons. In some cases pronounced shifts are found for the poles composed of a low-lying collective phonon and a collective phonon forming the giant resonance. In other cases the shifts are not large, as a rule. (orig.) 891 FKS/orig. 892 MB

Gamma bands in doubly odd rhenium and iridium nuclei

Directory of Open Access Journals (Sweden)

Balodis M.

2015-01-01

Full Text Available Structure of the |K ± 2| bands in doubly-odd nuclei belonging to the transitional deformation region at A∼190 is discussed. Relation of these quasi gamma-bands with the non-axial deformation of the parent two-quasiparticle configurations is studied. Using available experimental information, new tentative |K ± 2| bands are proposed in 188Re, and 192,194Ir nuclei. Coexistence of two-quasiparticle states with different deformation modes is considered in the case of 188Re and 194Ir.

Simple description of odd-A nuclei around the critical point of the spherical to axially deformed shape phase transition

International Nuclear Information System (INIS)

Zhang Yu; Pan Feng; Liu Yuxin; Luo Yanan; Draayer, J. P.

2011-01-01

An analytically solvable model, X(3/2j+1), is proposed to describe odd-A nuclei near the X(3) critical point. The model is constructed based on a collective core described by the X(3) critical point symmetry coupled to a spin-j particle. A detailed analysis of the spectral patterns for cases j=1/2 and j=3/2 is provided to illustrate dynamical features of the model. By comparing theory with experimental data and results of other models, it is found that the X(3/2j+1) model can be taken as a simple yet very effective scheme to describe those odd-A nuclei with an even-even core at the critical point of the spherical to axially deformed shape phase transition.

Coriolis force and nuclear deformation: cadmium and lead isotopes results with the EUROBALL gamma multidetector

International Nuclear Information System (INIS)

Buforn, Nadege

2001-01-01

This work is devoted to the study of the nuclear matter at high rotational frequency. Thanks to the new generation of γ-ray multidetector array, as EUROGAM then EUROBALL, we propose to identify two sorts of nuclei belonging to two different mass region. Their identification is based on the detection of their γ-rays of des-excitation. We will follow the evolution of the influence of the Coriolis force at the microscopic scale. The cadmium nuclei 113-116 Cd have been populated using heavy-ion induced fission reaction ( 28 Si+ 176 Yb at 145 MeV). Decoupled bands have been identified in odd-nuclei, produced for the first time at high spin. As they were considered as the best example of vibrational nuclei during their studies by radioactivity, they exhibit a small prolate deformation, confirmed by our microscopic calculations performed for even-even nuclei. The odd superdeformed nucleus 197 Pb have been studied via a fusion-evaporation reaction ( 18 O+ 186 W at 117 MeV). We have established the cross-talk transitions between the two signature partners. The experimental measurement of the branching ratio B(M1)/B(E2) allows us to extract the magnetic properties of the superdeformed matter, conforming the lack of quenching for the neutrons. The Coriolis force depends on the nuclei deformation and on the individual configuration. In cadmium nuclei, the single neutron νh 11/2 , Ω=1/2 is decoupled from the motion of the core, whereas in superdeformed nuclei, the Coriolis effect is much weaker on the νj 15/2 , Ω = 5/2 neutron. (author)

Comparison between the harris and ab expressions for the description of nuclear superdeformed rotational bands

International Nuclear Information System (INIS)

Hu Zuoxian; Zeng Jinyan

1998-01-01

The superdeformed rotational bands in the A ≅3D 190 region are systematically analyzed using the Harris two-parameter formula and the ab expression, respectively. Similar to the situations in normally deformed nuclei, there exist obvious and systematic deviation of Harris formula from the experiments. In contrast, the prediction of ab formula is very close to experiments, and can be conveniently used for the description of nuclear superdeformed bands

Effective interactions and coupling schemes in nuclei

International Nuclear Information System (INIS)

Talmi, I.

1994-01-01

Eigenstates of the shell model are obtained by diagonalization of the Hamiltonian submatrix defined by a given shell model subspace. Matrix elements of the effective nuclear interaction can be determined from experiment in a consistent way. This approach was introduced in 1956 with the 38 Cl- 40 K spectra, has been applied in many cases and its latest success is in the s, d shell. This way, general features of the effective interaction have been determined. The T=1 interaction is diagonal in the seniority scheme as clearly demonstrated in proton 1g 9/2 n and 1h 11/2 n configurations and in the description of semimagic nuclei by generalized seniority. Apart from a strong and attractive pairing term, T=1 interactions are repulsive on the average. The T=0 interaction is attractive and is the origin of the central potential well in which nucleons are bound. It breaks seniority in a major way leading to deformed nuclei and rotational spectra. Such an interaction may be approximated by a quadrupole-quadrupole interaction which is the basis of the interacting boson model. Identical nucleons with pairing and quadrupole interactions cannot be models of actual nuclei. Symmetry properties of states with maximum T are very different from those of ground states of actual nuclei. The T=1 interaction between identical nucleons cannot be approximated by pairing and quadrupole interactions. The rich variety of nuclear spectra is due to the competition between seniority conserving T=1 interactions and the T=0 quadrupole interaction between protons and neutrons. (orig.)

Possible Deformed States in 115In and 117ln

International Nuclear Information System (INIS)

Baecklin, A.; Fogelberg, B.; Malmskog, S.G.

1967-01-01

Levels and transitions in 115 In and 117 In have been studied from the beta decay of 2.3-day 115g Cd and 2.5-h 117g Cd. Using a Ge(Li) detector and a double focussing beta spectrometer energies, intensities, conversion coefficients and multipolarities were obtained for the following transitions (energies in keV and multipolarities are given): 115 In: 35.63 (97.0 % M1 + 3.0 % E2), 231.47 (E1), 260.80 (M1), 267, 336. 23 (M4 + 117 In: 71.0, 89.80 (E2 + 115 In and for 3 levels in 117 In. Energies, spins, parities and half lives are given for the following levels: In: 597.03, 3/2 - ; 828.39, 3/2 + , 5.4 ns; 863.95, l/2 + or 3/2 + , 1.1 ns. 117 In: 588.59, 3/2 - ; 0.20 ns; 659.56, 3/2 + , 58.7 ns; 749.37, 1/2 + or 3/2 + , 4.3 ns. Reduced transition probabilities are given for several transitions in both nuclei. The E2 transition rates between the two excited positive parity states in both nuclei were found to be about 100 s. p. u. indicating a possible deformation of these states. The energy spacing and transition rates between these states can be well accounted for within the Nilsson model assuming the states to form a K = 1/2 + rotational band. A deformation δ of about 0.20 is obtained for both nuclei

On the semiclassical description of rotating nuclei

International Nuclear Information System (INIS)

Durand, M.; Kunz, J.; Schuck, P.

1983-01-01

The technique of partial h-resummation is used to obtain semiclassical, i.e. average current distributions in the body fixed system of heavy nuclei. It thereby turns out that this average intrinsic current only flows in the nuclear surface. A Strutinsky smoothing of the current is also performed and gives nice agreement with the semiclassical results. We also show how one can incorporate superfluidity into the semiclassical treatment. To lowest order in h we find that the moment of inertia of superfluid nuclei is zero. The same result is obtained by a quantum mechanical calculation if the gap goes to infinity. The importance of including n-corrections is pointed out

Magnetic dipole moments of deformed odd-A nuclei

Energy Technology Data Exchange (ETDEWEB)

Garg, V P; Sharma, S D; Mahesh, P S [Punjabi Univ., Patiala (India). Dept. of Physics

1976-12-01

Using an extended version of A S Davydov and G F Filippov's model (1958), B E Chi and J P Davidson have calculated magnetic moments of odd-A nuclei in 2s-ld shell, diagonalizing the state matrices for a set of parameters giving the best fit for nuclear spectra (1966). To study the failure of this model in case of nuclear moments, instead of diagonalizing an attempt has been made to simplify the expression for magnetic dipole moment for single nucleonic states without configuration mixing. The model takes care of the proper sign of spin projections. On replacing the total angular momentum j of odd particle (proton or neutron) by its projection ..cap omega.., the expression reduces to that of Mottelson and Nilsson for spin-up nuclei. The Coriolis coupling calculations also have been performed for those odd-A nuclei with K = 1/2. The results are found in better agreement with experimental report in comparison with those of other models.

A systematic fast-timing study of even-even nuclei in the well deformed A 170-180 region

Energy Technology Data Exchange (ETDEWEB)

Jolie, J.; Regis, J.M.; Dannhoff, M.; Gerst, R.B.; Karayonchev, V.; Mueller-Gatermann, C.; Saed-Samii, N.; Stegemann, S.; Blazhev, A. [Institut fuer Kernphysik, Universitaet zu Koeln (Germany); Rudigier, M. [Institut fuer Kernphysik, Universitaet zu Koeln (Germany); Department of Physics, University of Surrey (United Kingdom)

2016-07-01

At the Cologne Tandem accelerator we are performing a systematic study of lifetimes in the ground state bands of well deformed even-even nuclei in order to increase the precision of the ns-ps lifetimes and to solve inconsistencies in the literature. The measurements are done using Orange spectrometers, LaBr{sub 3}(Ce) scintillators and Ge detectors. The data are analyzed using the slope and the generalized centroid difference method. The latter allows the measurement of lifetimes down to 5 ps. First results on Yb, Hf and W isotopes are presented.

New quantum mechanisms exhibited by superdeformed nuclei and their interpretations in terms of mean field and further; Nouveaux mecanismes quantiques manifestes par les noyaux superdeformes et leurs interpretations en terme de champ moyen et au-dela

Energy Technology Data Exchange (ETDEWEB)

El Aouad, N

1994-06-01

Identical superdeformed bands and quantized alignments have been investigated using the deformed Woods-Saxon mean field and a method of solving `exactly` the nuclear many-body problem with rotation. With the first formalism, an analysis method have been developed to find nucleonic configurations for bands in nuclei {sup 151}Tb, for the first three bands in nuclei {sup 149}Gd and for the bands in {sup 132}Ce. This method includes the calculation of incremental alignment which was performed for the first time. Such an approach allows to reproduce the experimental results and give an argument that the nuclear structure employed is correct. With the second formalism, it is shown that the deformed standard average-field plus pairing Hamiltonian with an induced rotation term employed for long time in literature, generates numerous twinned bands. The appearance of the twinned bands is shown to be often accompanied by the quantized incremental alignment. (author) 57 figs., 20 tabs., 66 refs.

High-spin rotational states in {sup 179}Os

Energy Technology Data Exchange (ETDEWEB)

Burde, J [Lawrence Berkeley Lab., CA (United States); [Hebrew Univ., Jerusalem (Israel). Racah Inst. of Physics; Deleplanque, M A; Diamond, R M; Macchiavelli, A O; Stephens, F S; Beausang, C W [Lawrence Berkeley Lab., CA (United States)

1992-08-01

The rotational bands of the osmium isotopes display very interesting properties that vary with the neutron number. On the one hand the yrast bands of {sup 182,184,186}Os display a sudden and rather strong gain in aligned angular momentum,, whereas the lighter osmium nuclei such as {sup 176,178,180}Os show a more gradual increase of alignment characteristic of strongly interacting bands. In addition, an unusual rotational band has been found in {sup 178}Os. It consists of seven regularly spaced transitions about 36 keV apart which correspond closely to the spacing of the superdeformed band in {sup 152}Dy after an A{sup 5/3} normalization. this band populates the yrast band directly, and the moment of inertia J{sup (1)} is found to be much smaller than J{sup (2)}. The most likely interpretation of this is a band with large deformation which is undergoing systematic changes in deformation, pairing and/or alignment. This latter finding in particular motivated us to carry out research on the higher spin states in {sup 179}Os. Dracoulis et al. have published their results on 5 rotational bands in {sup 179}Os. In the present work we found six new bands and extended appreciably the spin limits in the other five. (author). 5 refs., 3 figs.

The role of nuclear shapes in nuclear structure (from the perspective of the Daresbury Tandem)

International Nuclear Information System (INIS)

Nazarewicz, W.

1993-01-01

In specific regions of the nuclear periodic chart, large multipole moments are observed and the low-lying excitations have a rotational character. These features are understood if the nuclei in question are assumed to have a stable deformation, i.e., a non-spherical distribution of the nuclear matter. In other (transitional) regions the quasi-rotational bands are present; they are strongly coupled to low-lying vibrational modes. Those nuclei are best understood in terms of small static deformations but large dynamic fluctuations around local equilibria. As a matter of fact, the vast majority of nuclei are deformed; even in those which are spherical or almost spherical, the dynamical couplings to shape vibrations are crucial. The issue of nuclear deformation is many-faceted. If the nuclear shape (nuclear mean field) is deformed, characteristic excitation modes are present, such as rotations and vibrations built upon the non-spherical equilibrium. Through the particle-core coupling, nuclear deformations can dramatically influence the single-particle properties of nucleons moving in the average nuclear potential. Many experimental investigations using the Daresbury Tandem were related in one way or another to the physics of nuclear shapes. Fundamental discoveries from Daresbury include the observation of superdeformed structures in rapidly rotating nuclei, the observation of identical (open-quotes twinnedclose quotes) rotational bands, various studies of structural changes induced by very fast rotation (band-crossings, band-terminations), the observation of the oblate-deformed open-quotes dipoleclose quotes bands, studies of reflection-asymmetric shapes, studies of (quasimolecular) cluster configurations in light nuclei, and many, many others. The author reviews the forefront research at Daresbury from the global perspective; the common denominator being the nuclear shape deformation

Role of rotational energy and deformations in the dynamics of {sup 6}Li+{sup 90}Zr reaction

Energy Technology Data Exchange (ETDEWEB)

Kaur, Gurvinder; Grover, Neha; Sandhu, Kirandeep; Sharma, Manoj K., E-mail: msharma@thapar.edu

2014-07-15

In reference to recent experimental data, the dynamical cluster-decay model (DCM) has been applied to study the neutron evaporation residue (ER) cross sections of intermediate mass nucleus {sup 96}Tc{sup ⁎} spread over a wide range of incident energy across the Coulomb barrier. In order to analyze the effect of rotational energy in the dynamics of {sup 6}Li+{sup 90}Zr reaction, the cross sections have been calculated using the sticking (I{sub S}) and the non-sticking (I{sub NS}) limits of moment of inertia with inclusion of quadrupole (β{sub 2}) deformation within optimum orientation approach. The effect of either of the two approaches on the angular momentum, and hence the rotational energy associated with it, is assessed through the fragment mass distribution, preformation factor and the barrier penetrability. Also, the role of deformations is studied through a comparative analysis of decay path for spherical and β{sub 2} deformed fragmentation. The calculated evaporation residue cross sections show excellent agreement with the reported data at all incident energies for both spherical and β{sub 2}-deformed approach. Finally, the incomplete fusion (ICF) process observed due to loosely bound projectile {sup 6}Li is addressed within the framework of DCM.

Magnetic Fluid-Based Squeeze Film Behaviour in Curved Porous-Rotating Rough Annular Plates and Elastic Deformation Effect

Directory of Open Access Journals (Sweden)

M. E. Shimpi

2012-01-01

Full Text Available Efforts have been directed to study and analyze the squeeze film performance between rotating transversely rough curved porous annular plates in the presence of a magnetic fluid lubricant considering the effect of elastic deformation. A stochastic random variable with nonzero mean, variance, and skewness characterizes the random roughness of the bearing surfaces. With the aid of suitable boundary conditions, the associated stochastically averaged Reynolds' equation is solved to obtain the pressure distribution in turn, which results in the calculation of the load-carrying capacity. The graphical representations establish that the transverse roughness, in general, adversely affects the performance characteristics. However, the magnetization registers a relatively improved performance. It is found that the deformation causes reduced load-carrying capacity which gets further decreased by the porosity. This investigation tends to indicate that the adverse effect of porosity, standard deviation and deformation can be compensated to certain extent by the positive effect of the magnetic fluid lubricant in the case of negatively skewed roughness by choosing the rotational inertia and the aspect ratio, especially for suitable ratio of curvature parameters.

Possible existence of backbending in actinide nuclei

International Nuclear Information System (INIS)

Dudek, J.; Nazarewicz, W.; Szymanski, Z.

1982-01-01

The possibilities for the backbending effect to occur in actinide nuclei are studied using the pairing-self-consistent independent quasiparticle method. The Hamiltonian used is that of the deformed Woods-Saxon potential plus monopole pairing term. The results of the calculations explain why there is no backbending in most actinide nuclei and simultaneously suggest that in some light neutron deficient nuclei around Th and 22 Ra a backbending effect may occur

Statistical fission parameters for nuclei at high excitation and angular momenta

International Nuclear Information System (INIS)

Blann, M.; Komoto, T.A.

1982-01-01

Experimental fusion/fission excitation functions are analyzed by the statistical model with modified rotating liquid drop model barriers and with single particle level densities modeled for deformation for ground state (a/sub ν/) and saddle point nuclei (a/sub f/). Values are estimated for the errors in rotating liquid drop model barriers for the different systems analyzed. These results are found to correlate well with the trends predicted by the finite range model of Krappe, Nix, and Sierk, although the discrepancies seem to be approximately 1 MeV greater than the finite range model predictions over the limited range tested. The a priori values calculated for a/sub f/ and a/sub ν/ are within +- 2% of optimum free parameter values. Analyses for barrier decrements explore the importance of collective enhancement on level densities and of nuclear deformation in calculating transmission coefficients. A calculation is performed for the 97 Rh nucleus for which a first order angular momentum scaling is used for the J = 0 finite range corrections. An excellent fit is found for the fission excitation function in this approach. Results are compared in which rotating liquid drop model barriers are decremented by a constant energy, or alternatively multiplied by a constant factor. Either parametrization is shown to be capable of satisfactorily reproducing the data although their J = 0 extrapolated values differ markedly from one another. This underscores the dangers inherent in arbitrary barrier extrapolations

Determination of shell energies. Nuclear deformations and fission barriers

International Nuclear Information System (INIS)

Koura, Hiroyuki; Tachibana, Takahiro; Uno, Masahiro; Yamada, Masami.

1996-01-01

We have been studying a method of determining nuclear shell energies and incorporating them into a mass formula. The main feature of this method lies in estimating shell energies of deformed nuclei from spherical shell energies. We adopt three assumptions, from which the shell energy of a deformed nucleus is deduced to be a weighted sum of spherical shell energies of its neighboring nuclei. This shell energy should be called intrinsic shell energy since the average deformation energy also acts as an effective shell energy. The ground-state shell energy of a deformed nucleus and its equilibrium shape can be obtained by minimizing the sum of these two energies with respect to variation of deformation parameters. In addition, we investigate the existence of fission isomers for heavy nuclei with use of the obtained shell energies. (author)

Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

Directory of Open Access Journals (Sweden)

Ramazan-Ali Jafari-Talookolaei

2015-09-01

Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

Collective states of nonspherical deformable even--even nuclei

International Nuclear Information System (INIS)

Tartakovskii, V.K.

1989-01-01

A more correct method, as compared with some earlier studies, of finding the wave functions and corresponding energies of longitudinal quadrupole vibrations of nonspherical even--even nuclei is proposed. The wave functions and energies of collective motions in nuclei have been obtained in explicit form for a number of dependences of the potential energy of longitudinal vibrations V(β), including the dependence V(β), not previously used, of the most general form. Explicit dependences of the potential energy of transverse vibrations and the corresponding wave functions and eigenvalues for nuclear states with zero spins are proposed

Development of a Rotation Drickamer Apparatus for Deformation Studies Under High Pressure and High Temperature: Applications to magnesiowustite and Wadsleyite

Science.gov (United States)

Xu, Y.; Karato, S.

2002-12-01

Well-controlled high-pressure deformation experiments are critical for understanding the dynamics of Earth's interior. Most of the previous works on ultrahigh-pressure (P>10 GPa) deformation experiments have two limitations. (1) The mode of deformation is "stress-relaxation", in which stress changes with time in a given experiment, and (2) the magnitude of stress is limited (press combined with a rotation actuator involving an ac servo-motor. After the desired pressure and temperature are reached, torsional stress can be applied to a sample with a constant rotation rate. The advantage of this design is that the direction of shear deformation is normal to that of compression and therefore compression and deformation can be separated. A sample (typically ~1.8 mm diameter and ~0.2 mm thickness) is sandwiched between two zirconia plates and two heater plates made of TiC + diamond. Thin foils of W3%Re and W25%Re are inserted between two halves of samples which act as a thermocouple as well as strain markers. We have conducted a preliminary test on MgO at ~12 GPa and ~1470 K to the strain up to ~3. Deformation experiments on wadsleyite are underway to investigate the fabric development and rheology in this mineral.

Intrinsic states and rotational bands in 177Pt

International Nuclear Information System (INIS)

Dracoulis, G.D.; Fabricius, B.; Bark, R.A.; Stuchbery, A.E.; Popescu, D.G.; Kibedi, T.

1989-11-01

The 149 Sm ( 32 S,4n) 177 Pt reaction has been used to populate excited states in the neutron-deficient nucleus 177 Pt. Rotational bands based on intrinsic states assigned to the 1/2-[521], 5/2-[521] and (mixed) 7/2+ [633] Nilsson configurations have been observed. In contrast to the neighbou-ring even isotope 176 Pt, anomalies attributed to shape co-existence at low spin have not been observed. Implications for the deformation of 177 Pt are discussed together with the systematics of intrinsic states in this region, and alignments and other properties of N=99 nuclei. 37 refs., 15 figs., 3 tabs

Investigations of collective and single-particle aspects of excitation in 1fsub(7/2) shell nuclei

International Nuclear Information System (INIS)

Styczen, J.

1976-01-01

Experimental data are presented which were obtained in spectroscopic studies on 1fsub(7/2) shell nuclei in the following reactions: 30 Si( 16 0,pn) 44 Sc, 44 Ca(p,n) 44 Sc, 42 Ca(α,p) 45 Sc, 42 Ca(α,n) 45 Sc, 45 Sc(α,pn) 47 Ti, 46 Ti(α,p) 49 V, 47 Ti(α,pn) 49 V, and 49 Ti(p,n) 49 V. Experimental reduced transition probabilities B(M1) and B(E2) have been systematically compared for inband transitions of Ksup(π)=3/2 + bands in sup(43,45,47)Sc, 45 Ti and sup(47,49)V nuclei. In the framework of the pure rotational model, intrinsic quadrupole moments |Qsub(o)| and |gsub(K)-gsub(R)| ratios have been derived. Band mixing calculations in a strong coupling model treating more correctly the j 2 term in the hamiltonian and hole excitations, have been indertaken on properties of negativeparity states in the cross-conjugate nuclei 47 Ti- 49 V and V 47 - 49 Dr. There is an overall good agreement between the experimental data and the theoretical predictions. The strong coupling model has been also used to study possible regions of stable deformation for the positive parity states of the odd nuclei in the 1fsub(7/2) shell. Band mixing calculations performed for these states have shown that the experimental data are well reproduced in the calculations with a deformation parameter corresponding to a minimum of the static potential energy. (author)

Two-particle spatial correlations in superfluid nuclei

International Nuclear Information System (INIS)

Pillet, N.; Berger, J.-F.; Sandulescu, N.; Schuck, P.

2010-01-01

We discuss the effect of pairing on two-neutron space correlations in deformed nuclei. The spatial correlations are described by the pairing tensor in coordinate space calculated in the HFB approach. Calculations are done using the D1S Gogny force. We show that the pairing tensor has a rather small extension in the relative coordinate, a feature observed earlier in spherical nuclei. It is pointed out that in deformed nuclei the coherence length corresponding to the pairing tensor has a pattern similar to what we have found previously in spherical nuclei; that is, it is maximal in the interior of the nucleus and then it decreases rather rapidly in the surface region, where it reaches a minimal value of about 2 fm. This minimal value of the coherence length in the surface is essentially determined by the finite size properties of single-particle states in the vicinity of the chemical potential and has little to do with enhanced pairing correlations in the nuclear surface. It is shown that in nuclei the coherence length is not a good indicator of the intensity of pairing correlations. This feature is contrasted with the situation in infinite matter.

Simultaneous projection of particle-number and angular momentum BCS wave-functions in the rare-earth nuclei

International Nuclear Information System (INIS)

Oudih, M.R.; Fellah, M.; Allal, N.H.; Benhamouda, N.

1999-01-01

It is well established that the BCS wave-functions are neither eigen-functions of the particle-number operator nor of the angular momentum operator. In a previous paper, we have developed a particle-number projection before variation method (of FBCS type). This discrete projection method is based on the SBCS wave-function. The aim of the present contribution is to perform a subsequent angular momentum projection by means of the Peierls-Yoccoz method. The general expression of the system energy, after the double projection, is established in the case of axial symmetry. For practical calculations, an approximation method is introduced. It leads to a semi-classical form of the rotational energy. The rotational spectra have been evaluated numerically for some even-even rare-earth nuclei. The single-particle energies and eigen-states are those of a deformed Woods-Saxon mean field. The obtained results are compared on one hand, to the experimental data, and on the other hand, to the theoretical spectra evaluated by a particle-number projection after variation method (of PBCS type). For all studied nuclei, the spectra determined by the FBCS method reproduce the experimental data better than those of the PBCS method. However, even if the present method is satisfying for low angular momenta, the agreement with the experimental data is lesser for I ≥ 8, particularly for the lighter studied nuclei. (authors)

Electro-magnetic properties of heavy nuclei

International Nuclear Information System (INIS)

Otsuka, Takaharu

1989-01-01

Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)

Nuclear pairing reduction due to rotation and blocking

International Nuclear Information System (INIS)

Wu Xi; Zhang Zhenhua; Lei Yi'an; Zeng Jinyan

2010-01-01

Nuclear pairing gaps of well-deformed and superdeformed nuclei are investigated using the particle-number conserving (PNC) formalism for the cranked shell model, in which the blocking effects are treated exactly and no spurious states appear. Both the rotational frequency ω-dependence and seniority ν-dependence of the pairing gap Δ-bar are addressed. For the ground-state bands of even-even nuclei, PNC calculations show that in general Δ-bar decreases with increasing ω, but the ω-dependence is much weaker than that calculated by the number-projected Hartree-Fock-Bogolyubov (NHFB) approach. For the multi quasiparticle bands (seniority ν > 2), the pairing gaps keep almost ω-independent. As a function of the seniority ν, the bandhead pairing gaps Δ-bar (ν, ω = 0) decrease slowly with increasing ν. Even for the highest seniority ν bands identified so far, Δ-bar (ν, ω = 0) keep 70% larger than Δ-bar (ν = 0, ω = 0). (authors)

Nuclear pairing reduction due to rotation and blocking

International Nuclear Information System (INIS)

Wu, X.; Zhang, Z. H.; Zeng, J. Y.; Lei, Y. A.

2011-01-01

Nuclear pairing gaps of normally deformed and superdeformed nuclei are investigated using the particle-number-conserving (PNC) formalism for the cranked shell model, in which the blocking effects are treated exactly. Both rotational frequency ω dependence and seniority (number of unpaired particles) ν dependence of the pairing gap Δ-tilde are investigated. For the ground-state bands of even-even nuclei, PNC calculations show that, in general, Δ-tilde decreases with increasing ω, but the ω dependence is much weaker than that calculated by the number-projected Hartree-Fock-Bogolyubov approach. For the multiquasiparticle bands (seniority ν>2), the pairing gaps stay almost ω independent. As a function of the seniority ν, the bandhead pairing gaps Δ-tilde(ν,ω=0) decrease slowly with increasing ν. Even for the highest seniority ν bands identified so far, Δ-tilde(ν,ω=0) remains greater than 70% of Δ-tilde(ν=0,ω=0).

First and second-order corrections to the eikonal phase shifts for the interactions of two deformed nuclei

International Nuclear Information System (INIS)

Metawei, Z.

2000-01-01

We present the first and second - order corrections to the eikonal phase shifts for the interactions of two deformed nuclei. The elastic scattering differential cross-section has been calculated for both the interactions of I2 C- 12 C system (at energies 1016, 1449 and 2400 MeV) and 16 O- 12 C system (at energy 1503 MeV). The calculated results corrections seems to improve the agreement with the experimental data.The deflection function, the S-matrix,the near-side and the far-side decompositions of the scattering amplitude has been calculated using the same corrections

High-spin {gamma}-ray spectroscopy of {sup 124}Ba, {sup 124}Xe and {sup 125}Xe

Energy Technology Data Exchange (ETDEWEB)

Al-Khatib, Ali

2008-08-18

Rotational spectra had been observed for the first time in excited atomic nuclei in 1938. This observation was attributed to the deviation from spherical shape. In quantum mechanics, when a perfectly spherical system rotates, it appears identical when it is viewed from any direction and no point of reference exists to which the change in position can be identified. Therefore, rotation cannot be defined for spherical nuclei. If the shape deviates from spherical symmetry, the nucleus can rotate and rotational spectra are observed. Many nucleons contribute to the rotation which is referred to as collective excitation. Depending on the mass region, nuclei have different deformations and, therefore, different shapes. Many nuclei show larger deformation with increasing excitation energy. Transitional nuclei between spherical and strongly deformed regions of the nuclear chart are usually soft with respect to deformation changes. In the mass region around A{proportional_to}125, which is the subject of this thesis, nuclei are predicted to be soft with respect to deformation. Rotational motion leads to Coriolis-induced alignments of high-j nucleons, which are in this mass region predominantly protons and neutrons from the h{sub 11/2} unique-parity intruder subshells. The proton Fermi level lies in the lower part of the h{sub 11/2} subshell which favours prolate shape whereas the neutron Fermi level lies in the upper part of the h{sub 11/2} subshell which favours oblate shape. According to the opposite shape-driving forces of protons and neutrons, shape co-existence is expected and the interplay between the h{sub 11/2} proton and neutron orbitals is of great interest for spectroscopic investigations. In addition, superdeformation has been established in this mass region. An interesting observation in this mass region is that nuclei undergo a shape-change from collective prolate to non-collective oblate states at high spins. In this spin range the transitions within the

Nuclei quadrupole coupling constants in diatomic molecule

International Nuclear Information System (INIS)

Ivanov, A.I.; Rebane, T.K.

1993-01-01

An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab

Study of a new magnetic dipole mode in the heavy deformed nuclei 154Sm, 156Gd, 158Gd, 164Dy, 168Er, and 174Yb by high-resolution electron spectroscopy

International Nuclear Information System (INIS)

Bohle, D.

1985-01-01

By inelastic electron scattering with high energy resolution a new magnetic dipole mode in heavy, deformed nuclei could be detected. For this the nuclei 154 Sm, 156 Gd, 158 Gd, 164 Dy, 168 Er, and 174 Yb were studied at the Darmstadt electron linear accelerator (DALINAC) at small momentum transfer q ≤ 0.6 fm -1 and low excitation energies. A collective magnetic dipole excitation could be discovered in all nuclei at an excitation energy of E x ≅ 66 δA -1/3 MeV whereby δ means the mass deformation. The transition strength extends in the mean to B(M1)↑ ≅ 1.3 μ N 2 . A systematic study of the nucleus 156 Gd yielded hints to a strong fragmentation of the magnetic dipole strength. A comparison of electron scattering, proton scattering, and nuclear resonance fluorescence experiments shows that the new mode is a pure orbital mode. (orig./HSI) [de

Search for the characters of chiral rotation in excited bands for the idea chiral nuclei with A ∼ 130

International Nuclear Information System (INIS)

Chen Qibo; Yao Jiangming; Meng Jie; Zhang Shuangquan; Qi Bin

2010-01-01

Since the occurrence of chirality was originally suggested in 1997 by Frauendorf and Meng [1] and experimentally observed in 2001 [2] , the investigation of chiral symmetry in atomic nuclei becomes one of the most important topics in nuclear physics. More and more chiral doublet bands [3-7] in atomic nuclei [8] have been reported. There are also many discussions about the fingerprints of chirality. In the pioneer paper [1] , the two lowest near degenerate bands given by the particle-rotor model (PRM) are interpreted as chiral doublet bands. If the nucleus has chiral geometry with proper configuration, the character of chiral rotation may appear not only in the two lowest bands, but also in the other bands. Therefore, it is interesting to search for the character of chiral rotation, Based on the PRM model with configuration corresponding to A ∼ 130 mass region, we examine the theoretical spectroscopy of higher excited bands (band3, band4, band5 and band6) beyond the two lowest bands (bandl and band2), including energies, spin-alignments, projection of total angular momentum and electromagnetic transition probabilities. The results show that band3 and band4 have characters of chirality in some spin region. (authors)

The quest for novel modes of excitation in exotic nuclei

Science.gov (United States)

Paar, N.

2010-06-01

This paper provides an insight into several open problems in the quest for novel modes of excitation in nuclei with isospin asymmetry, deformation and finite-temperature characteristics in stellar environments. Major unsolved problems include the nature of pygmy dipole resonances, the quest for various multipole and spin-isospin excitations both in neutron-rich and proton drip-line nuclei mainly driven by loosely bound nucleons, excitations in unstable deformed nuclei and evolution of their properties with the shape phase transition. Exotic modes of excitation in nuclei at finite temperatures characteristic of supernova evolution present open problems with a possible impact in modeling astrophysically relevant weak interaction rates. All these issues challenge self-consistent many-body theory frameworks at the frontiers of on-going research, including nuclear energy density functionals, both phenomenological and constrained by the strong interaction physics of QCD, models based on low-momentum two-nucleon interaction Vlow-k and correlated realistic nucleon-nucleon interaction VUCOM, supplemented by three-body force, as well as two-nucleon and three-nucleon interactions derived from the chiral effective field theory. Joined theoretical and experimental efforts, including research with radioactive isotope beams, are needed to provide insight into dynamical properties of nuclei away from the valley of stability, involving the interplay of isospin asymmetry, deformation and finite temperature.

Collective motions and band structures in A = 60 to 80, even--even nuclei

International Nuclear Information System (INIS)

Hamilton, J.H.; Robinson, R.L.; Ramayya, A.V.

1978-01-01

Evidence for and the theoretical understanding of the richness of the collective band structures as illustrated by at least seven bands seen in levels of 68 Ge, 74 Se are reviewed. The experimental data on even-even nuclei in the A = 60 to 80 region have now revealed a wide variety of collective bands with different structures. The even parity yrast cascades alone are seen to involve multiple collective structures. In addition to the ground-state bands, strong evidence is presented for both neutron and proton rotation-aligned bands built on the same orbital, (g 9 / 2 ) 2 , in one nucleus. Several other nuclei also show the crossing of RAL bands around the 8 + level in this region. Evidence continues to be strong experimentally and supported theoretically that there is some type of shape transition and shape coexistence occurring now both in the Ge and Se isotopes around N = 40. Negative parity bands with odd and even spins with very collective nature are seen in several nuclei to high spin. These bands seem best understood in the RAL model. Very collective bands with ΔI = 1, extending from 2 + to 9 + are seen with no rotation-alignment. The purity of these bands and their persistence to such high spin establish them as an independent collective mode which is best described as a gamma-type vibration band in a deformed nucleus. In addition to all of the above bands, new bands are seen in 76 Kr and 74 Se. The nature of these bands is not presently known. 56 references

Enhanced T-odd, P-odd electromagnetic moments in reflection asymmetric nuclei

International Nuclear Information System (INIS)

Spevak, V.; Auerbach, N.; Flambaum, V.V.

1997-01-01

Collective P- and T-odd moments produced by parity and time invariance violating forces in reflection asymmetric nuclei are considered. The enhanced collective Schiff, electric dipole, and octupole moments appear due to the mixing of rotational levels of opposite parity. These moments can exceed single-particle moments by more than 2 orders of magnitude. The enhancement is due to the collective nature of the intrinsic moments and the small energy separation between members of parity doublets. In turn these nuclear moments induce enhanced T- and P-odd effects in atoms and molecules. A simple estimate is given and a detailed theoretical treatment of the collective T-, P-odd electric moments in reflection asymmetric, odd-mass nuclei is presented. In the present work we improve on the simple liquid drop model by evaluating the Strutinsky shell correction and include corrections due to pairing. Calculations are performed for octupole deformed long-lived odd-mass isotopes of Rn, Fr, Ra, Ac, and Pa and the corresponding atoms. Experiments with such atoms may improve substantially the limits on time reversal violation. copyright 1997 The American Physical Society

Collective models of transition nuclei Pt. 2

International Nuclear Information System (INIS)

Dombradi, Zs.

1982-01-01

The models describing the even-odd and odd-odd transition nuclei (nuclei of moderate ground state deformation) are reviewed. The nuclear core is described by models of even-even nuclei, and the interaction of a single particle and the core is added. Different models of particle-core coupling (phenomenological models, collective models, nuclear field theory, interacting boson-fermion model, vibration nucleon cluster model) and their results are discussed. New developments like dynamical supersymmetry and new research trends are summarized. (D.Gy.)

Fission barriers of light nuclei

International Nuclear Information System (INIS)

Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.

1989-01-01

Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems

Toward yrast spectroscopy in soft vibrational nuclei

International Nuclear Information System (INIS)

Marumori, Toshio; Kuriyama, Atsushi; Sakata, Fumihiko.

1979-10-01

In a formally parallel way with that exciting progress has been recently achieved in understanding the yrast spectra of the rotational nuclei in terms of the quasi-particle motion in the rotating frame, an attempt to understand the yrast spectra of the vibrational nuclei in terms of the quasi-particle motion is proposed. The essential idea is to introduce the quasi-particle motion in a generalized vibrating frame, which can be regarded as a rotating frame in the gauge space of ''physical'' phonons where the number of the physical phonons plays the role of the angular momentum. On the basis of a simple fundamental principle called as the ''invariance principle of the Schroedinger equation'', which leads us to the ''maximal decoupling'' between the physical phonon and the intrinsic modes, it is shown that the vibrational frame as well as the physical-phonon-number operator represented by the quasi-particles can be self-consistently determined. A new scope toward the yrast spectroscopy of the vibrational nuclei in terms of the quasi-particle motion is discussed. (author)

Toward yrast spectroscopy in soft vibrational nuclei. A microscopic theory of the large amplitude collective motion of soft nuclei

International Nuclear Information System (INIS)

Marumori, Toshio; Kuriyama, Atsushi; Sakata, Fumihiko

1980-01-01

In a formally parallel way with that exciting progress has been recently achieved in understanding the yrast spectra of the rotational nuclei in terms of the quasi-particle motion in the rotating frame, an attempt to understand the yrast spectra of the vibrational nuclei in terms of the quasi-particle motion is proposed. The essential idea is to introduce the quasi-particle motion in a generalized vibrating frame, which can be regarded as a rotating frame in the gauge space of 'physical' phonons where the number of the physical phonons plays the role of the angular momentum. On the basis of a simple fundamental principle called as the 'invariance principle of the Schroedinger equation', which leads us to the 'maximal decoupling' between the physical phonon and the intrinsic modes, it is shown that the vibrational frame as well as the physical-phonon-number operator represented by the quasi-particles can be self-consistently determined. A new scope toward the yrast spectroscopy of the vibrational nuclei in terms of the quasi-particle motion is discussed

Calculation of the total potential between two deformed heavy ion nuclei using the Monte Carlo method and M3Y nucleon-nucleon forces

International Nuclear Information System (INIS)

Ghodsi, O. N.; Zanganeh, V.

2009-01-01

In the current study, a simulation technique has been employed to calculate the total potential between two deformed nuclei. It has been shown that this simulation technique is an efficient one for calculating the total potential for all possible orientations between the symmetry axes of the interacting nuclei using the realistic nuclear matter density and the M3Y nucleon-nucleon effective forces. The analysis of the results obtained for the 48 Ca+ 238 U, 46 Ti+ 46 Ti, and 27 Al+ 70 Ge reactions reveal that considering the density dependent effects in the M3Y forces causes the nuclear potential to drop by an amount of 0.4 MeV.

The surfaces of compact systems: from nuclei to stars

Science.gov (United States)

Broglia, R. A.

2002-03-01

While providing information from worlds separated by five-to-six orders of magnitude in dimensions and in energy, the pairing properties (electrical resistance and viscosity), the electromagnetic response (spectrum of colours), the resilience to stress (elasticity), the ability to deform (plasticity), etc., associated with clusters of atoms and with atomic nuclei have surprisingly similar properties, once the proper scalings are done, and demonstrate the many analogies that can be drawn between different finite many-body systems. These analogies can be further extended to cosmic and to customer tailored nanometre materials. Femtometre materials, like the inner crust of a neutron star (pulsar), are made out of the same protons and neutrons which make infinite nuclear matter. However in pulsars, protons and neutrons are arranged in the form of finite nuclei immersed in a sea of free neutrons. This is the reason why these celestial objects rotate, conduct heat, emit neutrinos, etc., very differently from infinite nuclear matter. In fact, these phenomena reflect the properties of the corresponding atomic nuclei which form the pulsar. Among these properties, those associated with the nuclear surface are most important. Nanostructured materials are made out of atoms as their more common forms, but the atoms are arranged in nanometre or sub-nanometre-size clusters, which become the constituent grains, or building blocks, of new materials like, e.g., C60 fullerene. Because these tiny grains respond to light, mechanical stress and electricity quite differently from micron- or millimetre-sized grains, nanostructured materials display an array of novel attributes. At the basis of the new phenomena we find again the surface of the building blocks used to produce the new materials. A proper understanding of the interweaving of the single-particle motion with the static and dynamic deformations of the surface of finite many-body systems is likely to provide the key to open a

High spin spectroscopy for A ∼ 160 nuclei

International Nuclear Information System (INIS)

Yu, C.-H.

1989-01-01

Experimental routhians, alignments, band crossing frequencies, and the B(M1)/B(E2) ratios of the N = 90 isotopes and several light Lu (N = 90--96) isotopes are summarized and discussed in terms of shape changes. These systematic analyses show a neutron and proton number dependent deformations (both quadruple and γ deformations) for these light rare earth nuclei. The stability of the nuclear deformation with respect to β and γ is also found to be particle number dependent. Such particle number dependent shapes can be attributed to the different locations of the proton and neutron Fermi levels in the Nilsson diagrams. Configurations dependent shapes are discussed specially concerned the deformation difference between the proton h 9/2 1/2 - [541] and the high-K h 11/2 configurations. The observed large neutron band crossing frequencies in the h 9/2 1/2 - [541] configuration support the predicted large deformation of this configuration but can be reproduced by the cranked shell model calculation according to the predicted deformations. Lifetime measurement for 157 Ho, one of the nuclei that show a large ℎω c in the 1/2 - [541] band, indicates that deformation difference can only account for 20% of such shift in ℎω c . 55 refs., 12 figs

Properties of rotational bands at the spin limit in A {approximately} 50, A {approximately} 65 and A {approximately} 110 nuclei

Energy Technology Data Exchange (ETDEWEB)

Janzen, V.P.; Andrews, H.R.; Ball, G.C. [Chalk River Labs., Ontario (Canada)] [and others

1996-12-31

There is now widespread evidence for the smooth termination of rotational bands in A {approx_equal} 110 nuclei at spins of 40-to-50{Dirac_h}s. The characteristics of these bands are compared to those of bands recently observed to high spin in {sup 64}Zn and {sup 48}Cr, studied with the 8{pi} {gamma}-ray spectrometer coupled to the Chalk River miniball charged-particle-detector array.

Hot rotating fp shell Fe isotopes near proton drip line

International Nuclear Information System (INIS)

Aggarwal, Mamta

2003-01-01

F p shell 44-58 Fe nuclei have been investigated in highly excited state using the statistical theory of hot rotating nucleus. Effects of thermal and rotational excitation at drip line nuclei are studied

A version of the Quasiparticle-Phonon Nuclear Model for doubly-even well-deformed nuclei

International Nuclear Information System (INIS)

Soloviev, V.G.

1992-06-01

The basic assumptions concerning the Quasiparticle-Phonon Nuclear Model are formulated and the mathematical apparatus is developed. The Hamiltonian, containing a finite-rank separable isoscalar and isovector multipole, a spin-multipole and a tensor particle-hole as well as particle-particle interactions transforms to a form containing quasiparticle, phonon and quasiparticle-phonon interactions. The general RPA equation is derived and the particular cases are discussed. The very complex interaction does not complicate the description of the fragmentation one-phonon states. It is shown that the three-phonon terms added to the one- and two-phonon terms in the wave function lead to an additional small shift of the two-phonon poles in the secular equation. The influence of the density-dependent separable interaction on the vibrational states is small. A common description of the collective, weakly collective and two-quasiparticle states in doubly-even well-deformed nuclei is obtained. (author)

Understanding Nuclei in the upper sd - shell

OpenAIRE

Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.

2013-01-01

Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array...

Shell-model Monte Carlo studies of nuclei

International Nuclear Information System (INIS)

Dean, D.J.

1997-01-01

The pair content and structure of nuclei near N = Z are described in the frwnework of shell-model Monte Carlo (SMMC) calculations. Results include the enhancement of J=0 T=1 proton-neutron pairing at N=Z nuclei, and the maxked difference of thermal properties between even-even and odd-odd N=Z nuclei. Additionally, a study of the rotational properties of the T=1 (ground state), and T=0 band mixing seen in 74 Rb is presented

Modified suture-bridge technique to prevent a marginal dog-ear deformity improves structural integrity after rotator cuff repair.

Science.gov (United States)

Ryu, Keun Jung; Kim, Bang Hyun; Lee, Yohan; Lee, Yoon Seok; Kim, Jae Hwa

2015-03-01

The arthroscopic suture-bridge technique has proved to provide biomechanically firm fixation of the torn rotator cuff to the tuberosity by increasing the footprint contact area and pressure. However, a marginal dog-ear deformity is encountered not infrequently when this technique is used, impeding full restoration of the torn cuff. To evaluate the structural and functional outcomes of the use of a modified suture-bridge technique to prevent a marginal dog-ear deformity compared with a conventional suture-bridge method in rotator cuff repair. Cohort study; Level of evidence 2. A consecutive series of 71 patients aged 50 to 65 years who underwent arthroscopic rotator cuff repair for full-thickness medium-sized to massive tears was evaluated. Patients were divided into 2 groups according to repair technique: a conventional suture-bridge technique (34 patients; group A) versus a modified suture-bridge technique to prevent a marginal dog-ear deformity (37 patients; group B). Radiographic evaluations included postoperative cuff integrity using MRI. Functional evaluations included pre- and postoperative range of motion (ROM), pain visual analog scale (VAS), the University of California, Los Angeles (UCLA) shoulder rating scale, the Constant score, and the American Shoulder and Elbow Surgeons (ASES) score. All patients were followed up clinically at a minimum of 1 year. When the 2 surgical techniques were compared, postoperative structural integrity by Sugaya classification showed the distribution of types I:II:III:IV:V to be 4:20:2:4:4 in group A and 20:12:4:0:1 in group B. More subjects in group B had a favorable Sugaya type compared with group A (P bridge technique repairs were found in the retear group (P = .03). There were significant differences between healed and retear groups in functional outcome scores, with worse results in the retear group. A modified suture-bridge technique to prevent a marginal dog-ear deformity provided better structural outcomes than a

Studies of Stable Octupole Deformations in the Radium Region

CERN Multimedia

2002-01-01

The purpose of the present project is to locate and identify states in the atomic nuclei possessing stable pearshaped octupole deformation. Such states, formally related to the structures known in molecular physics, manifest themselves as families of parity doublets in odd nuclei.\\\\ \\\\ The best possibilities for observing stable octupole deformations are offered in the Ra-region. Both theoretical calculations and experimental indications support such expectations. Such indications are the non-observation of two-phonon octupole vibrational states in the ISOLDE studies of the even-even radium nuclei, and the reversed sign of the decoupling factor of the ground state band in |2|2|5Ra observed in the single-neutron transfer reactions. In order to establish the predicted strong E1 and E3-transitions between the parity doublets in odd nuclei with stable octupole deformations it is proposed to study conversion electrons in odd-mass francium radium and radon isotopes following the @b-decay of francium and astatine. \\...

High spin states and the competition of spherical and strongly deformed shapes in the A = 70 to 80 region

International Nuclear Information System (INIS)

Hamilton, J.H.; Ramayya, A.V.; Piercey, R.B.

1982-01-01

A wide variety of collective band structures are seen in Ge to Sr nuclei to make this an important new testing ground for nuclear models. These include bands built on coexisting and competing near-spherical and deformed shapes, γ vibrational bands and multiple positive and negative parity bands. Ground state bands in Ge and Kr but not 78 80 Sr are crossed at the 8 + to 12 + levels. Gaps in the Nilsson levels for both N and Z = 38 at large deformation lead to large ground state deformation in Kr and Sr around N = 38. The crossing of rotation aligned bands based on (g/sub 9/2/) 2 configuration are correlated with the ground state deformations. A second high spin crossing is seen in 74 Kr. Measured g factors in 68 Ge yield a two-quasineutron structure for the 8 2 + state. 30 references

α decay chains in 271-294115 superheavy nuclei

International Nuclear Information System (INIS)

Santhosh, K. P.; Priyanka, B.; Joseph, Jayesh George; Sahadevan, Sabina

2011-01-01

α decay of 271-294 115 superheavy nuclei is studied using the Coulomb and proximity potential model for deformed nuclei (CPPMDN). The predicted α half-lives of 287 115 and 288 115 nuclei and their decay products are in good agreement with experimental values. Comparison of α and spontaneous fission half-lives predicts four-α chains and three-α chains, respectively, from 287 115 and 288 115 nuclei and are in agreement with experimental observation. Our study predicts two-α chains from 273,274,289 115, three-α chains from 275 115, and four-α chains consistently from 284,285,286 115 nuclei. These observations will be useful for further experimental investigation in this region.

Stability of the spherical form of nuclei

International Nuclear Information System (INIS)

Sabry, A.A.

1976-08-01

An extension of the mass formula for a spherical nucleus in the drop model to include a largely deformed nucleus of different forms is investigated. It is found that although the spherical form is stable under small deformations from equilibrium, there exists for heavier nuclei another more favourable stable form, which can be approximated by two, or three touching prolate ellipsoids of revolution

Nucleation of recrystallization at selected sites in deformed fcc metals

DEFF Research Database (Denmark)

Xu, Chaoling

The objective of this thesis is to explore nucleation of recrystallization at selected sites in selected face-centered-cubic (FCC) metals, namely cold rolled columnar-grained nickel and high purity aluminum further deformed by indenting. Various techniques, including, optical microscopy, electron...... backscattered diffraction (EBSD), electron channeling contrast (ECC) and synchrotron X-ray technique, differential-aperture X-ray microscopy (DAXM), were used to characterize the microstructures, to explore nucleation sites, orientation relationships between nuclei and deformed microstructures, and nucleation...... mechanisms. In the cold rolled nickel samples, the preference of triple junctions (TJs) and grain boundaries (GBs) as nucleation sites is observed. The majorities of the nuclei have the same orientations as the surrounding matrix or are twin-related to a surrounding deformed grain. Only a few nuclei...

Lifetime measurements in the yrast band of the gamma-soft nuclei ...

Indian Academy of Sciences (India)

2016-06-15

Jun 15, 2016 ... ... J. Phys. (2016) 87: 7 c Indian Academy of Sciences ... +j. 1. Introduction. Shape deformations in nuclei are related to the gen- eral phenomenon of ... properties of various orbitals in which the nucleons move. Nuclei in the ...

Probing the Large Faraday Rotation Measure Environment of Compact Active Galactic Nuclei

Directory of Open Access Journals (Sweden)

Alice Pasetto

2018-03-01

Full Text Available Knowing how the ambient medium in the vicinity of active galactic nuclei (AGNs is shaped is crucial to understanding generally the evolution of such cosmic giants as well as AGN jet formation and launching. Thanks to the new broadband capability now available at the Jansky Very Large Array (JVLA, we can study changes in polarization properties, fractional polarization, and polarization angles, together with the total intensity spectra of a sample of 14 AGNs, within a frequency range from 1 to 12 GHz. Depolarization modeling has been performed by means of so-called “qu-fitting” to the polarized data, and a synchrotron self absorption model has been used for fitting to the total intensity data. We found complex behavior both in the polarization spectra and in the total intensity spectra, and several Faraday components with a large rotation measure (RM and several synchrotron components were needed to represent these spectra. Here, results for three targets are shown. This new method of analyzing broadband polarization data through qu-fitting successfully maps the complex surroundings of unresolved objects.

Direct non-destructive observation of bulk nucleation in 30% deformed aluminum

DEFF Research Database (Denmark)

West, Stine; Schmidt, Søren; Sørensen, Henning Osholm

2009-01-01

A 30% deformed aluminum sample was mapped non-destructively using three-dimensional X-ray diffraction (3DXRD) before and after annealing to nucleation of recrystallization. Nuclei appeared in the bulk of the sample. Their positions and volumes were determined, and the crystallographic orientations...... were compared with the orientations of the deformed grains. It was found that nuclei with new orientations can form and their orientations have been related to the dislocation structure in the deformed grains....

Fine structure in deformed proton emitting nuclei

International Nuclear Information System (INIS)

Sonzogni, A. A.; Davids, C. N.; Woods, P. J.; Seweryniak, D.; Carpenter, M. P.; Ressler, J. J.; Schwartz, J.; Uusitalo, J.; Walters, W. B.

1999-01-01

In a recent experiment to study the proton radioactivity of the highly deformed 131 Eu nucleus, two proton lines were detected. The higher energy one was assigned to the ground-state to ground-state decay, while the lower energy, to the ground-state to the 2 + state decay. This constitutes the first observation of fine structure in proton radioactivity. With these four measured quantities, proton energies, half-life and branching ratio, it is possible to determine the Nilsson configuration of the ground state of the proton emitting nucleus as well as the 2 + energy and nuclear deformation of the daughter nucleus. These results will be presented and discussed

Grain rotation and lattice deformation during photoinduced chemical reactions revealed by in situ X-ray nanodiffraction.

Science.gov (United States)

Huang, Zhifeng; Bartels, Matthias; Xu, Rui; Osterhoff, Markus; Kalbfleisch, Sebastian; Sprung, Michael; Suzuki, Akihiro; Takahashi, Yukio; Blanton, Thomas N; Salditt, Tim; Miao, Jianwei

2015-07-01

In situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) have been used to investigate many physical science phenomena, ranging from phase transitions, chemical reactions and crystal growth to grain boundary dynamics. A major limitation of in situ XRD and TEM is a compromise that has to be made between spatial and temporal resolution. Here, we report the development of in situ X-ray nanodiffraction to measure high-resolution diffraction patterns from single grains with up to 5 ms temporal resolution. We observed, for the first time, grain rotation and lattice deformation in chemical reactions induced by X-ray photons: Br(-) + hv → Br + e(-) and e(-) + Ag(+) → Ag(0). The grain rotation and lattice deformation associated with the chemical reactions were quantified to be as fast as 3.25 rad s(-1) and as large as 0.5 Å, respectively. The ability to measure high-resolution diffraction patterns from individual grains with a temporal resolution of several milliseconds is expected to find broad applications in materials science, physics, chemistry and nanoscience.

Stability of superheavy nuclei

Science.gov (United States)

Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.

2018-03-01

The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.

Studies of high-K isomers in hafnium nuclei

International Nuclear Information System (INIS)

Sletten, G.; Gjoerup, N.L.

1991-01-01

K-isomeric states built on high-Ω Nilsson orbitals from deformation-aligned high-j levels near the Fermi surface are found to cluster in the neutron rich Hf, W and Os nuclei. It has been shown that some of the high seniority states of this type have decay properties that indicate strong mixing of configurations and that in Osmium nuclei γ-softness cause strong deviations from the well established K-selection rule. Also in the Hafnium nuclei is the expected forbiddenness in isomeric decays an order of magnitude smaller than expected from the K-selection rule. A new 9 quasiparticle isomer has been discovered in 175 Hf at I=57/2. This isomer has the anomalous decay as the dominant mode. Other lower seniority states are also identified. At spin 35/2 and 45/2 the deformation aligned states become yrast, but the structure of the yrast line to even higher spins is not yet understood. (author)

Critical and shape-unstable nuclei

CERN Document Server

Cailliau, M; Husson, J P; Letessier, J; Mang, H J

1973-01-01

The authors' experimental work on the decay of neutron deficient mercury osmium nuclei, some other studies at ISOLDE (CERN) and their first theoretical analysis show that the nuclei around /sup 186/Pt (Z=78, N=108) are at the limit of spherical, oblate, prolate nuclei, have (the even one) their first 0/sup +/ excited states at very low energy; quasi- rotational bands are associated to these states. The energy of this O/sup +/ state in /sup 186-/Pt deviate from the Kumar value: angular shape instability is not enough to explain this result. The authors look at radial shape and pairing fluctuations. The position of the 4p-4n state must also be known. (0 refs).

Shape transition in Pt-nuclei with mass A ∼190

International Nuclear Information System (INIS)

Chamoli, S.K.

2017-01-01

The nuclei in mass region A ∼190 are well known for the prolate-oblate shape co-existence/transition phenomena. The shape coexistence phenomena has been observed in nuclei like Hg and Tl of this mass region. The calculations done for Pt nuclei in indicate a smooth shape change from prolate deformed "1"8"6Pt to nearly spherical "2"0"2"-"2"0"4 Pt through the region of triaxially deformed "1"8"8"-"1"9"8Pt and slightly oblate "2"0"0Pt. In these calculations, a change of shape from prolate to oblate is expected at A = 188. In recent high spin spectroscopic investigations, significant amount of reduced prolate collectivity has been observed in "1"8"8Pt. The level lifetimes provide valuable information about the nuclear shape and also the shape change with increase in spin along a band. So, to get clear signature of prolate to oblate shape inversion in Pt nuclei near A = 190, it is required to perform lifetime measurements. With this objective, the RDM lifetime measurements of high spin states have been done for various even-even Pt isotopes with masss A ≤ 186 over the years. The results obtained in these measurements are very encouraging and do indicate changing nuclear structure for Pt-isotopes with increasing mass at low spins. A gradual increase in B(E2) values upto 4"+ state and near constant nature there after in "1"8"8Pt, contrary to the other light neighboring Pt nuclei tends to indicate the volatile nature of deformation in Pt nuclei near A ∼ 190 which needs further theoretical investigations. (author)

Nuclear moments of inertia and wobbling motions in triaxial superdeformed nuclei

International Nuclear Information System (INIS)

Matsuzaki, Masayuki; Shimizu, Yoshifumi R.; Matsuyanagi, Kenichi

2004-01-01

The wobbling motion excited on triaxial superdeformed nuclei is studied in terms of the cranked shell model plus random phase approximation. First, by calculating at a low rotational frequency the γ dependence of the three moments of inertia associated with the wobbling motion, the mechanism of the appearance of the wobbling motion in positive-γ nuclei is clarified theoretically--the rotational alignment of the πi 13/2 quasiparticle(s) is the essential condition. This indicates that the wobbling motion is a collective motion that is sensitive to the single-particle alignment. Second, we prove that the observed unexpected rotational-frequency dependence of the wobbling frequency is an outcome of the rotational-frequency dependent dynamical moments of inertia

Superdeformed nuclei

International Nuclear Information System (INIS)

Janssens, R.V.F.; Khoo, T.L.

1991-01-01

Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states

A review of experimental evidence for octupole deformation

International Nuclear Information System (INIS)

Zylicz, J.

1986-08-01

Experimental evidence for octupole correlations, which lead to octupole instability and octupole deformation of some nuclei, is illustrated through typical examples. Data are considered for both the 220< A<230 region and for a few medium mass nuclei. (orig.)

Validity of single term energy expression for ground state rotational band of even-even nuclei

International Nuclear Information System (INIS)

Sharma, S.; Kumar, R.; Gupta, J.B.

2005-01-01

Full text: There are large numbers of empirical studies of gs band of even-even nuclei in various mass regions. The Bohr-Mottelson's energy expression is E(I) = AX + BX 2 +CX 3 +... where X = I(I+1). The anharmonic vibrator energy expression is: E(I) = al + bl 2 + cl 3 SF model with energy expression: E(I)= pX + qI + rXI... where the terms represents the rotational, vibrational and R-V interaction energy, respectively. The validity f the various energy expressions with two terms had been tested by Sharma for light, medium and heavy mass regions using R I s. R 4 plots (where, spin I=6, 8, 10, 12), which are parameter independent. It was also noted, that of the goodness of energy expression can be judged with the minimum input of energies (i.e. only 2 parameters) and predictability's of the model p to high spins. Recently, Gupta et. al proposed a single term energy expression (SSTE) which was applied for rare earth region. This proposed power law reflected the unity of rotation - vibration in a different way and was successful in explaining the structure of gs-band. It will be useful for test the single term energy expression for light and heavy mass region. The single term expression for energy of ground state band can be written as: E I =axI b , where the index b and the coefficient a are the constant for the band. The values of b+1 and a 1 are as follows: b 1 =log(R 1 )/log(I/2) and a 1 =E I /I b ... The following results were gained: 1) The sharp variation in the value of index b at given spin will be an indication of the change in the shape of the nucleus; 2) The value of E I /I b is fairly constant with spin below back-bending, which reflects the stability of shape with spin; 3) This proposed power law is successful in explaining the structure of gs-band of nuclei

Study of transitional Erbium nuclei (N=86) at very high spin. Highlight of dipolar transitions and medium livetimes in the continuum

International Nuclear Information System (INIS)

Bogaert, G.

1984-01-01

Average lifetimes and multipolarities of unresolved transitions deexciting very high spin states of the light Rare Earth nuclei (N approximately 86) have been determined by a measure of Doppler shift attenuation and their anisotropy. The spin selection is provided by the total energy spectrometer technique; great care was taken of the existence of many long lived isomeric states in the studied nuclei. The N approximately 86 nuclei have been formed in the 84 Kr(340 MeV) + 74 Ge → 158 Er* reactions using the 84 Kr beam of the Orsay ALICE facilities and targets of 74 Ge built at the PARIS Isotope separator of the CSNSM. NaI γ spectra have been thoroughly cleared of the discrete lines contribution through a carefull subtraction procedure synthetising NaI spectra from the Ge ones. At very high spin the continuum γ rays feed two well separated bumps with Esub(γ) approximately .65 MeV and Esub(γ) approximately 1.3 MeV. The 1.3 MeV transitions appear at I > 30 h and their energy does not vary with the increasing spin like expected in the rotational case of the well deformed nuclei; they are strongly collectively enhanced with B(E2) > 130 W.u. Below 1 MeV the anisotropy of transitions is R approximately 0.7, indicating their stretched dipole nature. Recent calculations of nuclear shape deformation (following Strutinsky shell correction method) reproduce the two bumps shape of the experimental spectra and the origin of the excitation is explained in terms of nuclear vibration (γ-vibration, wobbling motion) [fr

Octupole Deformed Nuclei in the Actinide Region

CERN Multimedia

Thorsteinsen, T; Rubio barroso, B; Simpson, J; Gulda, K; Sanchez-vega, M; Cocks, J; Nybo, K; Garcia borge, M; Aas, A; Fogelberg, B; Honsi, J; Smith, G; Naumann, R; Grant, I

2002-01-01

The aim of the present study is to investigate the limits of the "island" of octupole deformation in the mass region A=225. It is of particular importance to demonstrate experimentally the sudden disappearance of the stable octupole deformation in the presence of a well developed quadrupole field. \\\\ \\\\In order to establish the upper border line the $\\beta$ -decay chains of $^{227}$Rn $\\rightarrow ^{227}$Fr $\\rightarrow ^{227}$Ra and $^{231}$Fr $\\rightarrow ^{231}$Ra $\\rightarrow ^{231}$Ac were studied at PSB-ISOLDE using advanced fast timing and $\\gamma$-ray spectroscopy techniques. The lifetimes of the excited states have been measured in the picosecond range using the time-delayed $\\beta\\gamma\\gamma$(t) method.

Hot nuclei: high temperatures, high angular momenta

International Nuclear Information System (INIS)

Guerreau, D.

1991-01-01

A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs

Dominant Modes in Light Nuclei - Ab Initio View of Emergent Symmetries

International Nuclear Information System (INIS)

Draayer, J P; Dytrych, T; Launey, K D; Dreyfuss, A C; Langr, D

2015-01-01

An innovative symmetry-guided concept is discussed with a focus on emergent symmetry patterns in complex nuclei. In particular, the ab initio symmetry-adapted no-core shell model (SA-NCSM), which capitalizes on exact as well as partial symmetries that underpin the structure of nuclei, provides remarkable insight into how simple symmetry patterns emerge in the many-body nuclear dynamics from first principles. This ab initio view is complemented by a fully microscopic no-core symplectic shell-model framework (NCSpM), which, in turn, informs key features of the primary physics responsible for the emergent phenomena of large deformation and alpha-cluster substructures in studies of the challenging Hoyle state in Carbon-12 and enhanced collectivity in intermediate-mass nuclei. Furthermore, by recognizing that deformed configurations often dominate the low-energy regime, the SA-NCSM provides a strategy for determining the nature of bound states of nuclei in terms of a relatively small subspace of the symmetry-reorganized complete model space, which opens new domains of nuclei for ab initio investigations, namely, the intermediate-mass region, including isotopes of Ne, Mg, and Si

Theory of two-step two-proton decays of nuclei

International Nuclear Information System (INIS)

Kadmensky, S. G.; Ivankov, Yu. V.

2014-01-01

A general theory of many-body diagonal and nondiagonal one-proton decays of spherical and deformed nuclei is developed on the basis of an approach not employing R-matrix theory in describing deep-subbarrier alpha and one-proton decays of nuclei but relying on integral formulas for the widths with respect to these decays. With the aid of this theory and by means of a diagram technique, a formalism is developed for describing two-step two-proton decays of a (Z, A) parent nucleus, which proceed as two successive time-separated one-proton decays of the parent and intermediate [(Z − 1, A − 1)] nuclei, these decays being related by the Green’s function for the intermediate nucleus, G(Z − 1, A − 1). It is shown that, upon taking into account, in this Green’s function, intermediate-nucleus states that are on- and off-shell states for the decaying system, there arise, respectively, sequential and virtual two-proton decays of parent nuclei. Expressions for the widths with respect to sequential and virtual two-proton decays from the ground and excited states of spherical and deformed nuclei and for the angular and energy distributions of emitted protons are obtained

Breakdown of NpNn scheme in very heavy nuclei

International Nuclear Information System (INIS)

Varshney, A.K.; Singh, M.; Kumar, Rajesh; Gupta, K.K.; Gupta, D.K.

2016-01-01

The proton neutron interaction has been considered the key ingredient in the development of configuration mixing, collectivity and ultimately deformation in atomic nuclei for over five decades. Phenomenologically, the correlation of the integrated valance p - n interaction with the onset of collectivity and deformation has been described in terms of NpNn scheme

Deformation inside and outside the nuclear molecules

International Nuclear Information System (INIS)

Cseh, J.; Algora, A.; Antonenko, N.V.; Jolos, R.V.; Hess, P.O.

2006-01-01

Complete text of publication follows. Clusterization is an important phenomenon both in light and in heavy nuclei. The two basic natural laws governing the clusterization (just like the composition of nuclei from nucleons) are the energy-minimum principle, and the Pauli-exclusion principle. In a fully microscopic description of clusterization both aspects are taken into account. This kind of description, however, is limited to the territory of light nuclei. Many interesting aspects of the clusterization, like e.g. the appearance of exotic cluster configurations, show up only in heavy nuclei. Phenomenologic approaches are applied both to light and to heavy nuclei, on an equal footing, but these models do not really contain the effects of the antisymmetrization, or it is not under control, what aspects of the exclusion principle is incorporated. Recently we have developed an approach, which involves both the energetic preference and the exclusion principle [?]. The antisymmetrization is not carried out explicitly, it is treated in an approximate way, but it is done microscopically in a well-controlled manner, and consistency-check measures, how effective it is. We calculate the energetic preference of different clusterizations both on the basis of simple binding-energy-arguments [?], and from the Dinuclear System Model (DNS) [?], including Coulomb as well as nuclear interactions. The potential energy is calculated both for the usual pole-to-pole configuration, and for those more compact configurations, which turn out to be allowed from the microscopic viewpoint. The exclusion principle is treated by the application of a selection rule, related to the microscopic structure. For light nuclei it is based on the real U(3) symmetry [?], and it is exact to the extent to which the leading term representation is valid. In heavy nuclei it is based on the quasidynamical, or effective U(3) symmetry [?]. Its validity is shown by the consistency of the quadrupole deformation of

Three-dimensional deformation of orthodontic brackets

Science.gov (United States)

Melenka, Garrett W; Nobes, David S; Major, Paul W

2013-01-01

Braces are used by orthodontists to correct the misalignment of teeth in the mouth. Archwire rotation is a particular procedure used to correct tooth inclination. Wire rotation can result in deformation to the orthodontic brackets, and an orthodontic torque simulator has been designed to examine this wire–bracket interaction. An optical technique has been employed to measure the deformation due to size and geometric constraints of the orthodontic brackets. Images of orthodontic brackets are collected using a stereo microscope and two charge-coupled device cameras, and deformation of orthodontic brackets is measured using a three-dimensional digital image correlation technique. The three-dimensional deformation of orthodontic brackets will be evaluated. The repeatability of the three-dimensional digital image correlation measurement method was evaluated by performing 30 archwire rotation tests using the same bracket and archwire. Finally, five Damon 3MX and five In-Ovation R self-ligating brackets will be compared using this technique to demonstrate the effect of archwire rotation on bracket design. PMID:23762201

Three-dimensional deformation of orthodontic brackets.

Science.gov (United States)

Melenka, Garrett W; Nobes, David S; Major, Paul W; Carey, Jason P

2013-01-01

Braces are used by orthodontists to correct the misalignment of teeth in the mouth. Archwire rotation is a particular procedure used to correct tooth inclination. Wire rotation can result in deformation to the orthodontic brackets, and an orthodontic torque simulator has been designed to examine this wire-bracket interaction. An optical technique has been employed to measure the deformation due to size and geometric constraints of the orthodontic brackets. Images of orthodontic brackets are collected using a stereo microscope and two charge-coupled device cameras, and deformation of orthodontic brackets is measured using a three-dimensional digital image correlation technique. The three-dimensional deformation of orthodontic brackets will be evaluated. The repeatability of the three-dimensional digital image correlation measurement method was evaluated by performing 30 archwire rotation tests using the same bracket and archwire. Finally, five Damon 3MX and five In-Ovation R self-ligating brackets will be compared using this technique to demonstrate the effect of archwire rotation on bracket design.

Study of 148-152Sm nuclei employing γ - derived from B(E2) values and level energies

International Nuclear Information System (INIS)

Sharma, Aparna; Varshney, A.K.; Singh, M.; Gupta, D.K.; Singh, Yuvraj; Gupta, K.K.; Bihari, Chhail; Varshney, Mani

2011-01-01

The study of samarium nuclei has been a challenging theoretical problem, since they lie in the range from near spherical to well deformed shapes. 148 Sm was believed to be basically spherical while 154 Sm is thought to be well deformed nucleus and 150-15 '2Sm are transitional nuclei

Theoretical study on rotational bands and shape coexistence of 183,185,187Tl in the particle-triaxial-rotor model

International Nuclear Information System (INIS)

Chen Guojie; Cao Hui; Liu Yuxin; Song Huichao

2006-01-01

By taking the particle-triaxial-rotor model with variable moment of inertia, we systematically investigate the energy spectra, deformations, and single-particle configurations of the nuclei 183,185,187 Tl. The calculated energy spectra agree quite well with experimental data. The obtained results indicate that the rotation-aligned bands observed in 183,185,187 Tl originate from one of the [530](1/2) - ,[532](3/2) - ,[660](1/2) + proton configurations coupled to a prolate deformed core. Furthermore, the negative parity bands built upon the (9/2) - isomeric states in 183,185,187 Tl are formed by a proton with the [505](9/2) - configuration coupled to a core with triaxial oblate deformation, and the positive parity band on the (13/2) + isomeric state in 187 Tl is generated by a proton with configuration [606](13/2) + coupled to a triaxial oblate core

Electron scattering and collective excitations in nuclei

International Nuclear Information System (INIS)

Goutte, D.

1989-01-01

Nuclear collective degrees of freedom are investigated through the study of the radial dependance of their wave function. Inelastic electron scattering is shown to be the appropriate tool to extract such a detailed information. Some recent results on spherical as well as deformed nuclei are discussed and the most recent extensions to the mean field approach are compared to these data in order to clarify the present status of our understanding of the dynamical properties of complex nuclei

Collective dipole rotational bands in the A {approx} 200 region

Energy Technology Data Exchange (ETDEWEB)

Clark, R M; Wadsworth, R; Regan, P H [York Univ. (United Kingdom). Dept. of Physics; Paul, E S; Beausang, C W; Ali, I; Cullen, D M; Dagnall, P J; Fallon, P; Joyce, M J; Sharpey-Schafer, J F [Liverpool Univ. (United Kingdom). Oliver Lodge Lab.; Astier, A; Meyer, M; Redon, N [Lyon-1 Univ., 69 - Villeurbanne (France). Inst. de Physique Nucleaire; Nazakewicz, W; Wyss, R [Joint Inst. for Heavy Ion Research, Oak Ridge, TN (United States)

1992-08-01

Rotational oblate bands consisting of regular sequences of magnetic dipole transitions have recently been identified in {sup 196-200}Pb. Their observation indicates a drastic change in the high-spin configurations between the Hg, Tl and {sup 194}Pb nuclei, in which SD bands are clearly observed, and the heavier Pb isotopes, where these weakly deformed oblate structures see to dominate. Angular correlation ratios show the transitions to be dipoles. Their magnetic nature can be deduced from intensity measurements, and they are characterized by small dynamic moments of inertia. Several of the bands have been interpreted as being built on high-K two-proton configurations coupled to an aligned pair of i{sub 13/2} neutrons in the even A nuclei, and to either one or three i{sub 13/2} neutrons in the odd A nuclei. Cranked shell model calculations predict the alignment of a pair of i{sub 13/2} neutrons (the AB crossing) at {omega} {approx} 0.18 MeV{Dirac_h}{sub -1}. The higher frequency crossing at {omega} {approx} 0.4 MeV{Dirac_h}{sub -1} may be due to the alignment of f{sub 5/2} neutrons, h{sub 11/2} protons, or both. 17 refs., 4 figs.

Shell and isotopic effects in neutron interaction with nuclei. [Optical model and nucleus asymmetry correlations

Energy Technology Data Exchange (ETDEWEB)

Pasechnik, M V

1978-01-01

Major results of investigations into the shell structure of deformed nuclei with the number of neutrons of approximately 100, as well as new isotopic effects in the inelastic scattering of fast neutrons with nuclei are reported. The experiments conducted at the WWR-M research reactor have shown a substantial dependence of the nuclear excited energy-level density on the mass number and the number of neutrons. The fact resulted in a conclusion that the deformed nuclei possess filled shells, that was an incentive to revise the whole nuclear shell concept. In particular it was established that the property of magicity rests not only on the sphericity of nuclei but it may be also observed in strongly deformed nuclei. The isotope-spin dependence of the nuclear potential was studied at the AG-5 pulse electrostatic generator. The parameters of the potential were determined by comparing the experimental data on inelastic scattering and polarization of fast neutrons by nuclei from /sup 48/Ti to /sup 209/Bi with the calculations in terms of the optical model. Simple correlations were established between the optical potential and the nucleus asymmetry parameter ..cap alpha..=N-Z/A in wide ranges of mass numbers and neutron energy.

Superheavy Nuclei in the Quark-Meson-Coupling Model

Directory of Open Access Journals (Sweden)

Stone Jirina

2017-01-01

Full Text Available We present a selection of the first results obtained in a comprehensive calculation of ground state properties of even-even superheavy nuclei in the region of 96 < Z < 136 and 118 < N < 320 from the Quark-Meson-Coupling model (QMC. Ground state binding energies, the neutron and proton number dependence of quadrupole deformations and Qα values are reported for even-even nuclei with 100 < Z < 136 and compared with available experimental data and predictions of macro-microscopic models. Predictions of properties of nuclei, including Qα values, relevant for planning future experiments are presented.

Classically dynamical behaviour of a nucleon in heavy nuclei

International Nuclear Information System (INIS)

Gu Jianzhong; Zhao Enguang; Zong Hongshi; Zhuo Yizhong; Wu Xizhen

1998-01-01

Within the framework of the two-center shell model the classically dynamical behaviour of a nucleon in heavy nuclei is investigated systematically with the change of nuclear shape parameters for the first time. It is found that as long as the nucleonic energy 0is appreciably higher than the height of the potential barrier there is a good quantum-classical correspondence of nucleonic regular (chaotic) motion. Thus, Bohigas, Giannoni and Schmit conjecture is confirmed once again. We find that the difference between the potential barrier for prolate nuclei and that for oblate ones is reponsible for the energy-dependence difference between the nucleonic chaotic dynamics for prolate nuclei and that for oblate ones. In addition, it is suggested that nuclear dissipation is shape-dependent, and strong nuclear dissipation can be expected for medium or large separations in the presence of a considerable neck deformation built on a pronounced octupole-like deformation, which provides us a dynamical understanding of nuclear shape dependence of nuclear dissipation. (orig.)

Underlying physics of identical odd- and even-mass bands in normally deformed rare-earth nuclei

International Nuclear Information System (INIS)

Yu Lei; Liu Shuxin; Lei Yian; Zeng Jinyan

2001-01-01

The microscopic mechanism of the identical odd- and even-mass number nuclear bands in normally deformed rare-earth nuclei was investigated using the particle-number conserving (PNC) method for treating nuclear pairing correlation. It was found that the odd particle of an odd-A identical band always occupied a cranked low j and high Ω Nilsson orbital (e.g. proton [404]7/2, [402]5/2. On the contrary, if the odd particle occupies an intruder high j orbital (e.g. neutron [633]7/2, proton[514]9/2), the moment of inertia of the odd-A band was much larger than that of neighboring even-even ground state band. The observed variation of moment of inertia (below band crossing) was reproduced quite well by the PNC calculation, in which no free parameter was involved. The strengths of monopole and Y 20 quadrupole interactions were determined by the experimental odd-even differences in binding energy and band head moment of inertia

How do nuclei really vibrate or rotate

International Nuclear Information System (INIS)

Andresen, H.G.; Kunz, J.; Mosel, U.; Mueller, M.; Schuh, A.; Wust, U.

1983-01-01

By means of the adiabatic cranking model the properties of the current and velocity fields of nuclear quadrupole vibrations for even-even nuclei in the rare-earth region are investigated. BCS correlated wave functions based on the Nilsson single particle Hamiltonian have been used. The current fields are analyzed in terms of vector spherical harmonics. The realistic microscopic currents show a vortex structure not present in the classical irrotational flow. The microscopic origin of the vortex structure is investigated

Coupled SU(3) models of rotational states in nuclei and quasi-dynamical symmetry

International Nuclear Information System (INIS)

Thiamova, G.; Rowe, D. J.

2007-01-01

This contribution reports a first step towards the development of a model of low-lying nuclear collective states based on the progression from weak to strong coupling of a combination of systems in multiple SU(3) irreps. The motivation for such a model comes partly from the remarkable persistence of rotational structure observed experimentally and in many model calculations. This work considers the spectra obtainable by coupling just two SU(3) irreps by means of a quadrupole-quadrupole interaction. For a particular value of this interaction, the two irreps combine to form strongly-coupled irreps while for zero interaction the weakly-coupled results are mixtures of many such strongly-coupled irreps. A notable result is the persistence of the rotor character of the low-energy states for a wide range of the interaction strength. Also notable is the fact that, for very weak interaction strengths, the energy levels of the yrast band resemble those of a vibrational sequence while the B(E2) transition strengths remain close to those of an axially symmetric rotor, as observed in many nuclei. (Author)

The investigation of the decay of the deformed 167Yb, 164Tm, 225Ac, 221Fr nuclei. Beta-spectrograph with positional-sensitive detector

International Nuclear Information System (INIS)

Butabaev, Yu.S.

1994-01-01

The decay of the deformed 167 Yb, 164 Tm, 225 Ac, 221 Fr nuclei is investigated in this work. For 167 Yb and 164 Tm decays the specters of the conversion electrons were measured. 32 γ-transitions were found for 167 Yb decay, 6 of which were found for the first time. The multipolarities for 9 γ-transitions were found. For 164 Tm decay 23 new γ-transitions were found. The theoretical investigations of the collective states in the nucleus were carried out. Octupole-rotatory line with k=1 - was found in the measurement of conversion electrons specters of the short-life nuclei. Device' nonlinearity was 0,04%. Resolution was Δβρ/βρ 0,11%. Effective light yield was 1-2 %. The decay of 225 Ac and 221 Fr nuclei were investigated. The investigations of α-γ -coincidence, α-γ - rays were carried out. 24 new γ -transitions for 225 Ac and 13 ones for 221 Fr were found. The new levels and their intensities were defined more precisely. Intensity balance calculations were carried out and the full populations of the nuclear levels were calculated. (author). 3 tabs.; 10 figs

Systematics in p-n interaction vs deformation

International Nuclear Information System (INIS)

Singh, M.; Singh, Yuvraj; Kumar, Rajesh; Vrshney, A.K.; Gupta, K.K.

2017-01-01

The correlation of integrated valance p-n interaction in the onset of collectivity and deformation has been described phenomenologically in terms of N p N n scheme. L. Esser et al. presented the graphs between N p N n and deformation β and γ for some heavy nuclei

Deep inelastic reactions and isomers in neutron-rich nuclei across the perimeter of the A = 180 - 190 deformed region

International Nuclear Information System (INIS)

Dracoulis, G.D.; Lane, G.J.; Byrne, A.P.; Watanabe, H.; Hughes, R.O.; Kondev, F.G.; Carpenter, M.P.; Janssens, R.V.F.; Lauritsen, T.; Lister, C.J.; Seweryniak, D.; Zhu, S.; Chowdhury, P.; Shi, Y.; Xu, F.R.

2014-01-01

Recent results on high-spin isomers populated in deep-inelastic reactions in the transitional tungsten-osmium region are outlined with a focus on 190 Os, 192 Os and 194 Os. As well as the characterization of several two-quasineutron isomers, the 12 + and 20 + isomers in 192 Os are interpreted as manifestations of maximal rotation alignment within the neutron i(13/2) and possibly proton h(11/2) shells at oblate deformation. (authors)

Fission dynamics of superheavy nuclei formed in uranium induced reactions

International Nuclear Information System (INIS)

Gurjit Kaur; Sandhu, Kirandeep; Sharma, Manoj K.

2017-01-01

The compound nuclear system follows symmetric fission if the competing processes such as quasi-elastic, deep inelastic, quasi-fission etc are absent. The contribution of quasi fission events towards the fusion-fission mechanism depends on the entrance channel asymmetry of reaction partners, deformations and orientations of colliding nuclei beside the dependence on energy and angular momentum. Usually the 209 Bi and 208 Pb targets are opted for the production of superheavy nuclei with Z CN =104-113. The nuclei in same mass/charge range can also be synthesized using actinide targets + light projectiles (i.e. asymmetric reaction partners) via hot fusion interactions. These actinide targets are prolate deformed which prefer the compact configurations at above barrier energies, indicating the occurrence of symmetric fission events. Here an attempt is made to address the dynamics of light superheavy system (Z CN =104-106), formed via hot fusion interactions involving actinide targets

Spectroscopical study of the yrast and yrare structure in far-from-stability nuclei; Etude spectroscopique de la structure yrast et yrare de noyaux loin de la stabilite

Energy Technology Data Exchange (ETDEWEB)

Hoellinger Fabien [Institut de Recherches Subatomiques, 23, Rue du Loess, BP 28, 67037 Strasbourg Cedex 2 (France)]|[Universite Louis Pasteur, 67 - Strasbourg (France)

1999-01-13

The nuclear structure study of neutron-rich nuclei was realized with the EUROGAM II array in two different experiments. The first study consisted in the analysis of the product of spontaneous fission of {sup 248}Cm. Three neutron-rich cerium isotopes {sup 147,149,151}Ce were analyzed. A level scheme for {sup 151}Ce is presented for the first time. The yrast structure of the three nuclei does not show alternative parity bands as expected in this region of octupole deformations. We studied the rotational structure of the bands and this leads to suggest Nilsson configurations to some of them. The aim of this second experiment was the study of the nuclei {sup 99}Mo, {sup 101}Tc, {sup 103}Ru. The three nuclei are situated on the neutron-rich side of the nuclear chart and are produced as fission fragments of a heavy-ion induced reaction. Some bands are extended to higher spins and some new bands are observed. The structure of the rotational bands is interpreted by means of the Hartree-Fock-Bogolyubov model. A last experiment intended to study the structure of the proton-rich nucleus {sup 223}Pa has been achieved with the JURO+RITU array located at Jyvaeskylae (Finland). In this proton-rich actinide region, the nuclei develop octupole features around Z{approx_equal}88, N{approx_equal}132. The analysis of this experiment leads to the first assignment of gamma transitions to the {sup 223}Pa. (author) 91 refs., 78 figs., 16 tabs.

Multi-quasiparticle high-K isomeric states in deformed nuclei

Directory of Open Access Journals (Sweden)

Xu F. R.

2016-01-01

Full Text Available In the past years, we have made many theoretical investigations on multi-quasiparticle high-K isomeric states. A deformation-pairing-configuration self-consistent calculation has been developed by calculating a configuration-constrained multi-quasiparticle potential energy surface (PES. The specific single-particle orbits that define the high-K configuration are identified and tracked (adiabatically blocked by calculating the average Nilsson numbers. The deformed Woods-Saxon potential was taken to give single-particle orbits. The configuration-constrained PES takes into account the shape polarization effect. Such calculations give good results on excitation energies, deformations and other structure information about multi-quasiparticle high-K isomeric states. Many different mass regions have been investigated.

Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei; Spectroscopie de noyaux tres lourds en vue de l'etude des noyaux super-lourds

Energy Technology Data Exchange (ETDEWEB)

Khalfallah, F

2007-08-15

Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No{sup 256} et Rf{sup 256} for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa{sup 223}. The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)

Hybrid theory and calculation of e-N2 scattering. [quantum mechanics - nuclei (nuclear physics)

Science.gov (United States)

Chandra, N.; Temkin, A.

1975-01-01

A theory of electron-molecule scattering was developed which was a synthesis of close coupling and adiabatic-nuclei theories. The theory is shown to be a close coupling theory with respect to vibrational degrees of freedom but is a adiabatic-nuclei theory with respect to rotation. It can be applied to any number of partial waves required, and the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations and not on experiment can be given as to which partial waves and energy domains require the various approximations. The theory allows all cross sections (i.e., pure rotational, vibrational, simultaneous vibration-rotation, differential and total) to be calculated. Explicit formulae for all the cross sections are presented.

Dynamical pairing correlations in rotating nuclei

International Nuclear Information System (INIS)

Szymanski, Z.

1985-01-01

When the atomic nucleus rotates fast enough the static pair correlations may be destroyed. In this situation the pair-vibrations become an important manifestation of the short-range attractive pairing force. The influence of this effect on nuclear properties at high spin is discussed. (orig.)

The rotational spectrum of IBr

International Nuclear Information System (INIS)

Tiemann, E.; Moeller, T.

1975-01-01

The microwave spectrum of IBr was measured in the low rotational transition J = 3 → 2 in order to resolve the hyperfine structure as completely as possible. Rotational constants and quadrupole coupling constants were derived for both nuclei. The observation of the rotational spectrum in different vibrational states yields the vibrational dependence of the rotational constants as well as of the hyperfine parameters. The Dunham potential coefficients α 0 , α 1 , α 2 , α 3 are given. (orig.) [de

Possible isomers in nuclei beyond the drip line

International Nuclear Information System (INIS)

Ogawa, K.

1986-12-01

To search a new decay model which is not observed in nuclei near stability line such as beta-delayed proton emission or direct proton emission provides us a wealth of knowledge on nuclear stability. Besides study of the nuclear decay modes, study of nuclear structures reveals us new aspect of nuclei like new deformed regions or new magic numbers. In these respects the study of a nucleus 100 Sn and its closest neighbours has a special role. (author)

The structure of nuclei far from stability

International Nuclear Information System (INIS)

Zganjar, E.F.

1993-01-01

Studies on nuclei near Z=82 contributed to the establishment of a new region of nuclear deformation and a new class of nuclear structure at closed shells. A important aspect of this work is the establishment of the connection between low-lying 0 + states in even endash even nuclei and the occurrence of shape coexistence in the odd-mass neighbors (E0 transitions in 185 Pt, shape coexistence in 184 Pt and 187 Au). A new type of picosecond lifetime measurement system capable of measuring the lifetime of states that decay only by internal conversion was developed and applied to the 186,188 Tl decay to determine the lifetime of the 0 2 + and 2 2 + deformed states in 186,188 Hg. A search for the population of superdeformed states in 192 Hg by the radioactive decay of 192 Tl was accomplished by using a prototype internal pair formation spectrometer

Nuclear sub-structure in 112–122Ba nuclei within relativistic mean field theory

International Nuclear Information System (INIS)

Bhuyan, M.; Patra, S.K.; Arumugam, P.; Gupta, Raj K.

2011-01-01

Working within the framework of relativistic mean field theory, we study for the first time the clustering structure (nuclear sub-structure) of 112–122 Ba nuclei in an axially deformed cylindrical coordinate. We calculate the individual neutrons and protons density distributions for Ba-isotopes. From the analysis of the clustering configurations in total (neutrons-plus-protons) density distributions for various shapes of both the ground and excited states, we find different sub-structures inside the Ba nuclei considered here. The important step, carried out here for the first time, is the counting of number of protons and neutrons present in the clustering region(s). 12 C is shown to constitute the cluster configuration in prolate-deformed ground-states of 112–116 Ba and oblate-deformed first excited states of 118–122 Ba nuclei. Presence of other lighter clusters such as 2 H, 3 H and nuclei in the neighborhood of N = Z, 14 N, 34–36 Cl, 36 Ar and 42 Ca are also indicated in the ground and excited states of these nuclei. Cases with no cluster configuration are shown for 112–116 Ba in their first and second excited states. All these results are of interest for the observed intermediate-mass-fragments and fusion–fission processes, and the so far unobserved evaporation residues from the decaying Ba* compound nuclei formed in heavy ion reactions. (author)

Field-substance interaction and collective oscillation of nuclei

International Nuclear Information System (INIS)

Shermatov, E.N.; Choriev, M.

2004-01-01

Full text: In this work a mechanism of formation of collective excitation in a set of particles, including atomic nuclei, is proposed. According to [1] the energy density of cosmic vacuum significantly exceeds the energy density of an atomic nucleus. In [2] the process of formation of the physical vacuum in surrounding cosmic space was considered. We considered the behavior of a system of particles, which possesses transversal and longitudinal oscillation with frequency ω 0 in the physical or cosmic vacuum. The oscillating influence on the physical vacuum and surrounding particles on a single particle leads to inducing the spins with various directions and magnitudes. This process leads to the formation of oscillating response wave function (RWF) of particles. As a result of a phase coherency among RWF of particles an oscillating self-coordinated field in a set of particles is formed. As a result of realization of the phase coherency among harmonics of RWF of particles there occurs a deformation of the character of distribution of the energy structure of the self-coordinated field, which, finally, transforms into a resonant line. At this occurs a collapse of the RWF of particles there. In terms of these ideas we explained the observed regularities in the self-coordinated field in a set of particles, including the atomic nuclei. It was shown that the giant resonance in spectra of atomic nuclei is a result of manifestation of the self-coordinated field of atomic nuclei. As a result of realization of the phase coherency among harmonics of RWF of atomic nuclei there occurs a collapse of the RWF of particles, and the energy structure of the self-coordinated field of nuclei gains a resonant form, and it is manifested as the giant resonance. In deformable nuclei the RWF of particles possesses two oscillation modes, and that is why in the energy spectrum of the self-coordinated field of nuclei they are manifested as two maximum

Nature of the identical bands in atomic nuclei

International Nuclear Information System (INIS)

Szymanski, Z.

1995-01-01

Single-nucleon spectra in the fast rotating nuclei are shown to exhibit some special orbits that appear to be insensitive to nuclear rotation. It is suggested that the special orbits play an essential role in explaining the appearance and structure of the identical bands discovered in the superdeformed region. It is suggested that identical bands appear whenever the nucleonic orbit approaches the separatrix, i.e., a line dividing regions of different coupling schemes in a rotating mean field

Helical modes generate antimagnetic rotational spectra in nuclei

Science.gov (United States)

Malik, Sham S.

2018-03-01

A systematic analysis of the antimagnetic rotation band using r -helicity formalism is carried out for the first time. The observed octupole correlation in a nucleus is likely to play a role in establishing the antimagnetic spectrum. Such octupole correlations are explained within the helical orbits. In a rotating field, two identical fermions (generally protons) with paired spins generate these helical orbits in such a way that its positive (i.e., up) spin along the axis of quantization refers to one helicity (right-handedness) while negative (down) spin along the same quantization-axis decides another helicity (left-handedness). Since the helicity remains invariant under rotation, therefore, the quantum state of a fermion is represented by definite angular momentum and helicity. These helicity represented states support a pear-shaped structure of a rotating system having z axis as the symmetry axis. A combined operation of parity, time-reversal, and signature symmetries ensures an absence of one of the signature partner band from the observed antimagnetic spectrum. This formalism has also been tested for the recently observed negative parity Δ I =2 antimagnetic spectrum in odd-A 101Pd nucleus and explains nicely its energy spectrum as well as the B (E 2 ) values. Further, this formalism is found to be fully consistent with twin-shears mechanism popularly known for such type of rotational bands. It also provides significant clue for extending these experiments in various mass regions spread over the nuclear chart.

Coupling of collective and single-particle degrees of freedom in atomic nuclei (commentary to thesis qualifying for assistant-professorship)

International Nuclear Information System (INIS)

Chlebowska, D.

1992-11-01

The analysis of the spectroscopic properties of the spherical and transitional nuclei is performed from the point of view of the relation between the single-particle and collective degrees of freedom on the ground of the core-particle coupling model with the total angular momentum conserved and without any unphysical parameters (such as the attenuation parameter). A new definition of the rotational alignment is given. The staggering effect is interpreted as a manifestation of the vibrational structure. The rotational dependence of the energy gap parameter is shown to have an influence on the energy spectra of the transitional nuclei. The nuclei with A 130 are shown to have a tendency to be rather rigid. The vibrational and rotational structures, and the magnitude of the rotation-particle coupling in the considered nuclei are determined. 18 figs., 9 tabs., 66 refs. (author)

Polarization electric dipole moment in nonaxial nuclei

International Nuclear Information System (INIS)

Denisov, V.Yu.; Davidovskaya, O.I.

1996-01-01

An expression for the macroscopic polarization electric dipole moment is obtained for nonaxial nuclei whose radii of the proton and neutron surfaces are related by a linear equation. Dipole transitions associated with the polarization electric dipole moment are analyzed for static and dynamical multipole deformations

Where is the Scissors Mode Strength in Odd-Mass Nuclei?

International Nuclear Information System (INIS)

Enders, J.; Huxel, N.; von Neumann-Cosel, P.; Richter, A.

1997-01-01

It is demonstrated by a fluctuation analysis based on the assumption of a Wigner distribution for the nuclear level spacings and of a Porter-Thomas distribution for the transition strengths that significant parts of the dipole strength excited in photon scattering experiments in heavy, deformed odd-mass nuclei are hidden in the background of the experimental spectra. With this additional strength, the heretofore claimed severe reduction of the B(M1) scissors mode strength in odd-mass nuclei compared to the one in neighboring even-even nuclei disappears. copyright 1997 The American Physical Society

Symmetry energy and surface properties of neutron-rich exotic nuclei

Energy Technology Data Exchange (ETDEWEB)

Gaidarov, M. K.; Antonov, A. N. [Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Sofia 1784 (Bulgaria); Sarriguren, P. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Moya de Guerra, E. [Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain)

2014-07-23

The symmetry energy, the neutron pressure and the asymmetric compressibility of spherical Ni, Sn, and Pb and deformed Kr and Sm neutron-rich even-even nuclei are calculated within the coherent density fluctuation model using the symmetry energy as a function of density within the Brueckner energy-density functional. The correlation between the thickness of the neutron skin and the characteristics related with the density dependence of the nuclear symmetry energy is investigated for isotopic chains of these nuclei in the framework of the deformed self-consistent mean-field Skyrme HF+BCS method. The mass dependence of the nuclear symmetry energy and the neutron skin thickness are also studied together with the role of the neutron-proton asymmetry. The studied correlations reveal a smoother behavior in the case of spherical nuclei than for deformed ones. We also notice that the neutron skin thickness obtained for {sup 208}Pb with SLy4 force is found to be in a good agreement with the recent data. In addition to the interest that this study may have by itself, we give some numerical arguments in proof of the existence of peculiarities of the studied quantities in Ni and Sn isotopic chains that are not present in the Pb chain.

Rotating fluid models in classical and quantum mechanics

International Nuclear Information System (INIS)

Arvieu, R.; Troudet, T.

1979-01-01

To describe the behavior of high-spin nuclei it is necessary to refer back to the classical mechanics of fluids in rotation where some results are general enough to apply to the rotational nuclear fluid. It is then shown that the quantum model of rotational oscillator gives a simple classification of rotating configurations [fr

Superheavy nuclei in the relativistic mean-field theory

International Nuclear Information System (INIS)

Lalazissis, G.A.; Ring, P.; Gambhir, Y.K.

1996-01-01

We have carried out a study of superheavy nuclei in the framework of the relativistic mean-field theory. Relativistic Hartree-Bogoliubov (RHB) calculations have been performed for nuclei with large proton and neutron numbers. A finite-range pairing force of Gogny type has been used in the RHB calculations. The ground-state properties of very heavy nuclei with atomic numbers Z=100-114 and neutron numbers N=154-190 have been obtained. The results show that in addition to N=184 the neutron numbers N=160 and N=166 exhibit an extra stability as compared to their neighbors. For the case of protons the atomic number Z=106 is shown to demonstrate a closed-shell behavior in the region of well deformed nuclei about N=160. The proton number Z=114 also indicates a shell closure. Indications for a doubly magic character at Z=106 and N=160 are observed. Implications of shell closures on a possible synthesis of superheavy nuclei are discussed. (orig.)

Vibrational states in deformed nuclei. Chaos, order and individual nature of nuclei

International Nuclear Information System (INIS)

Soloviev, V.G.

1993-01-01

General properties of the vibrational states in doubly-even well-deformed are formulated. The large many-quasiparticle components of the wave functions of the neutron resonance state are responsible for enhance E1- and M1-transitions rates from the neutron resonances states to the levels lying 1-2 MeV below them. 44 refs.; 4 tabs

Rotation of small clusters in sheared metallic glasses

International Nuclear Information System (INIS)

Delogu, Francesco

2011-01-01

Graphical abstract: When a Cu 50 Ti 50 metallic glass is shear-deformed, the irreversible rearrangement of local structures allows the rigid body rotation of clusters. Highlights: → A shear-deformed Cu 50 Ti 50 metallic glass was studied by molecular dynamics. → Atomic displacements occur at irreversible rearrangements of local structures. → The dynamics of such events includes the rigid body rotation of clusters. → Relatively large clusters can undergo two or more complete rotations. - Abstract: Molecular dynamics methods were used to simulate the response of a Cu 50 Ti 50 metallic glass to shear deformation. Attention was focused on the atomic displacements taking place during the irreversible rearrangement of local atomic structures. It is shown that the apparently disordered dynamics of such events hides the rigid body rotation of small clusters. Cluster rotation was investigated by evaluating rotation angle, axis and lifetimes. This permitted to point out that relatively large clusters can undergo two or more complete rotations.

Structure of exotic nuclei and superheavy elements in meson field theory

Energy Technology Data Exchange (ETDEWEB)

Linn, Khin Nyan

2008-07-15

In this work the nuclear structure of exotic nuclei and superheavy nuclei is studied in a relativistic framework. In the relativistic mean-field (RMF) approximation, the nucleons interact with each other through the exchange of various effective mesons (scalar, vector, isovector-vector). Ground state properties of exotic nuclei and superheavy nuclei are studied in the RMF theory with the three different parameter sets (ChiM,NL3,NL-Z2). Axial deformation of nuclei within two drip lines are performed with the parameter set (ChiM). The position of drip lines are investigated with three different parameter sets (ChiM,NL3,NL-Z2) and compared with the experimental drip line nuclei. In addition, the structure of hypernuclei are studied and for a certain isotope, hyperon halo nucleus is predicted. (orig.)

Structure of exotic nuclei and superheavy elements in meson field theory

International Nuclear Information System (INIS)

Linn, Khin Nyan

2008-07-01

In this work the nuclear structure of exotic nuclei and superheavy nuclei is studied in a relativistic framework. In the relativistic mean-field (RMF) approximation, the nucleons interact with each other through the exchange of various effective mesons (scalar, vector, isovector-vector). Ground state properties of exotic nuclei and superheavy nuclei are studied in the RMF theory with the three different parameter sets (ChiM,NL3,NL-Z2). Axial deformation of nuclei within two drip lines are performed with the parameter set (ChiM). The position of drip lines are investigated with three different parameter sets (ChiM,NL3,NL-Z2) and compared with the experimental drip line nuclei. In addition, the structure of hypernuclei are studied and for a certain isotope, hyperon halo nucleus is predicted. (orig.)

An Expectation of a backbending for N> 98 of a rare earth nuclei

Energy Technology Data Exchange (ETDEWEB)

Salah, M M [Physics Dept., Faculty of Science, Minia University, (Egypt); El-Elgebaly, H [Physics Dept., Faculty of Science, Cairo University, Cairo (Egypt)

1997-12-31

The backbending of three neighboring earth nuclei [Er-Yb-Hf] with their isotopes has been studied through the cubic polynomial (CP) theoretical model in addition to [Ex vs. I (I+I)] and [0 vs.{sub 2}] plots, at high energy angular momentum in nuclear rotational bands according to the values of R 4. Also the rotational nuclei are divided into soft and hard rotors by studying the softness S. We expected that there may be a backbending for nuclei of N> 98, but with a High angular momentum, which were not expected before by studying the effect of (I+I) at the critical spin of a backbending. The work includes study of the effective moment of inertia 0eff for these nuclei, and the theoretical treatment to reduce the error in energy calculation of (CP) model. 5 figs., 1 tab.

Results and simulations on γ-spectroscopy of deformed nuclei: cases of isomers and tetrahedral nuclei

International Nuclear Information System (INIS)

Vancraeyenest, A.

2010-10-01

The major part of this work is about the realization and complete analysis of an experiment for studying isomeric states in 138,139,140 Nd nuclei. This was performed at Jyvaeskylae laboratory (Finland) using a fusion-evaporation reaction with 48 Ca beam on a thin 96 Zr target. Experimental setup consisted in the target position gamma ray detector Jurogam II which was coupled with the RITU recoil separator and the GREAT focal plane detector array. This particularly well adapted setup permit to manage γ spectroscopy of the interest nuclei around isomeric states. Indeed, we used prompt-delayed matrices to separate rays that come onto isomeric states and these who decay from them. Then, the correlations between the two components permit to establish feeding transitions of isomeric states. Thanks to this experiment, a new isomeric state was also highlighted in 139 Nd with spin 23/2+, which was predicted and interpreted in Cranked-Nilsson-Strutinsky calculation. Finally, very clean time spectra allow to determine precisely life-time of four states in four nuclei. This Ph.d. is also made of a part of the analysis of the first experimental search for fingerprints of tetrahedral symmetry in 156 Gd using high fold gamma ray spectroscopy. Thanks to a large number of triple coincidence events, we managed a detailed spectroscopy of this nucleus. Particularly, we found out 13 new transitions in positive parity bands. As a complement of this work, we have done GEANT4 simulations about the detection limits of low intensity transitions by Agata multidetector. Indeed, tetrahedral symmetry predicts vanishing of E2 transitions at lower spin states and simulations permit to determine observation limit of these transitions with different version of Agata. (author)

Investigation of the neutron emission spectra of some deformed nuclei for (n, xn) reactions up to 26 MeV energy

International Nuclear Information System (INIS)

Kaplan, A.; Bueyuekuslu, H.; Tel, E.; Aydin, A.; Boeluekdemir, M.H.

2011-01-01

In this study, neutron-emission spectra produced by (n, xn) reactions up to 26 MeV for some deformed target nuclei as 165 Ho, 181 Ta, 184 W, 232 Th and 238 U have been investigated. Also, the mean free path parameter's effect for 9n, xn) neutron-emission spectra has been examined. In the calculations, pre-equilibrium neutron-emission spectra have been calculated by using new evaluated hybrid model and geometry dependent hybrid model, full exciton model and cascade exciton model. The reaction equilibrium component has been calculated by Weisskopf-Ewing model. The obtained results have been discussed and compared with the available experimental data and found agreement with each other. (author)

Role of hexadecapole deformation of projectile 28Si in heavy-ion fusion reactions near the Coulomb barrier

Science.gov (United States)

Kaur, Gurpreet; Hagino, K.; Rowley, N.

2018-06-01

The vast knowledge regarding the strong influence of quadrupole deformation β2 of colliding nuclei in heavy-ion sub-barrier fusion reactions inspires a desire to quest the sensitivity of fusion dynamics to higher order deformations, such as β4 and β6 deformations. However, such studies have rarely been carried out, especially for deformation of projectile nuclei. In this article, we investigated the role of β4 of the projectile nucleus in the fusion of the 28Si+92Zr system. We demonstrated that the fusion barrier distribution is sensitive to the sign and value of the β4 parameter of the projectile, 28Si, and confirmed that the 28Si nucleus has a large positive β4. This study opens an indirect way to estimate deformation parameters of radioactive nuclei using fusion reactions, which is otherwise difficult because of experimental constraints.

Geiger-Nuttall Law for Nuclei in Strong Electromagnetic Fields

Science.gov (United States)

Delion, D. S.; Ghinescu, S. A.

2017-11-01

We investigate the influence of a strong laser electromagnetic field on the α -decay rate by using the Hennenberger frame of reference. We introduce an adimensional parameter D =S0/R0, where R0 is the geometrical nuclear radius and S0˜√{I }/ω2 is a length parameter depending on the laser intensity I and frequency ω . We show that the barrier penetrability has a strong increase for intensities corresponding to D >Dcrit=1 , due to the fact that the resulting Coulomb potential becomes strongly anisotropic even for spherical nuclei. As a consequence, the contribution of the monopole term increases the barrier penetrability by 2 orders of magnitude, while the total contribution has an effect of 6 orders of magnitude at D ˜3 Dcrit. In the case of deformed nuclei, the electromagnetic field increases the penetrability by an additional order of magnitude for a quadrupole deformation β2˜0.3 . The influence of the electromagnetic field can be expressed in terms of a shifted Geiger-Nuttal law by a term depending on S0 and deformation.

Comet nuclei and Trojan asteroids - A new link and a possible mechanism for comet splittings

International Nuclear Information System (INIS)

Hartmann, W.K.; Tholen, D.J.

1990-01-01

Relatively elongated shapes, implied by recent evidence of a greater incidence of high amplitude lightcurves for comet nuclei and Trojan asteroids than for similarly scaled main belt asteroids, are suggested to have evolved among comet nuclei and Trojans due to volatile loss. It is further suggested that such an evolutionary course may account for observed comet splitting; rotational splitting may specifically occur as a result of evolution in the direction of an elongated shape through sublimation. Supporting these hypotheses, the few m/sec separation velocities projected for rotationally splitting elongated nuclei are precisely in the observed range. 40 refs

Rotation of cometary nuclei: new light curves and an update of the ensemble properties of Jupiter-family comets

Science.gov (United States)

Kokotanekova, R.; Snodgrass, C.; Lacerda, P.; Green, S. F.; Lowry, S. C.; Fernández, Y. R.; Tubiana, C.; Fitzsimmons, A.; Hsieh, H. H.

2017-11-01

We report new light curves and phase functions for nine Jupiter-family comets (JFCs). They were observed in the period 2004-2015 with various ground telescopes as part of the Survey of Ensemble Physical Properties of Cometary Nuclei as well as during devoted observing campaigns. We add to this a review of the properties of 35 JFCs with previously published rotation properties. The photometric time series were obtained in Bessel R, Harris R and SDSS r΄ filters and were absolutely calibrated using stars from the Pan-STARRS survey. This specially developed method allowed us to combine data sets taken at different epochs and instruments with absolute-calibration uncertainty down to 0.02 mag. We used the resulting time series to improve the rotation periods for comets 14P/Wolf, 47P/Ashbrook-Jackson, 94P/Russell and 110P/Hartley 3 and to determine the rotation rates of comets 93P/Lovas and 162P/Siding Spring for the first time. In addition to this, we determined the phase functions for seven of the examined comets and derived geometric albedos for eight of them. We confirm the known cut-off in bulk densities at ˜0.6 g cm-3 if JFCs are strengthless. Using a model for prolate ellipsoids with typical density and elongations, we conclude that none of the known JFCs requires tensile strength larger than 10-25 Pa to remain stable against rotational instabilities. We find evidence for an increasing linear phase function coefficient with increasing geometric albedo. The median linear phase function coefficient for JFCs is 0.046 mag deg-1 and the median geometric albedo is 4.2 per cent.

Universal correlations of nuclear observables and the structure of exotic nuclei

International Nuclear Information System (INIS)

Casten, R.F.; Zamfir, N.V.

1996-01-01

Despite the apparent complexity of nuclear structural evolution, recent work has shown a remarkable underlying simplicity that is unexpected, global, and which leads to new signatures for structure based on the easiest-to-obtain data. As such they will be extremely valuable for use in the experiments with low intensity radioactive beams. Beautiful correlations based either on extrinsic variables such as N p N n or the P-factor or correlations between collective observables themselves have been discovered. Examples to be discussed include a tri-partite classification of structural evolution, leading to a new paradigm that discloses certain specific classes of nuclei, universal trajectories for B(E2: w 1 + → 0 1 + ) values and their use in extracting hexadecapole deformations from this observable alone, the use of these B(E2) values to identify shell gaps and magic numbers in exotic nuclei, the relationship of β and γ deformations, and single nucleon separation energies. Predictions for nuclei far off stability by interpolation will also be discussed

Collective description of magnetic properties of even-even nuclei

International Nuclear Information System (INIS)

Maruhn, V.

1975-01-01

The generalized collective model is modified by introducing a number of quadrupole deformations for protons and neutrons. The coupling potential is described by physical approaches, and the overall model is applied to even-even nuclei. (WL) [de

In-flight measurements of aircraft propeller deformation by means of an autarkic fast rotating imaging system

Science.gov (United States)

Stasicki, Boleslaw; Boden, Fritz

2015-03-01

The non-intrusive in-flight measurement of the deformation and pitch of the aircraft propeller is a demanding task. The idea of an imaging system integrated and rotating with the aircraft propeller has been presented on the 30th International Congress on High-Speed Imaging and Photonics (ICHSIP30) in 2012. Since then this system has been constructed and tested in the laboratory as well as on the real aircraft. In this paper we outline the principle of Image Pattern Correlation Technique (IPCT) based on Digital Image Correlation (DIC) and describe the construction of a dedicated autarkic 3D camera system placed on the investigated propeller and rotating at its full speed. Furthermore, the results of the first ground and in-flight tests are shown and discussed. This development has been found by the European Commission within the 7th frame project AIM2 (contract no. 266107).

Otolith-Canal Convergence In Vestibular Nuclei Neurons

Science.gov (United States)

Dickman, J. David; Si, Xiao-Hong

2002-01-01

The current final report covers the period from June 1, 1999 to May 31, 2002. The primary objective of the investigation was to determine how information regarding head movements and head position relative to gravity is received and processed by central vestibular nuclei neurons in the brainstem. Specialized receptors in the vestibular labyrinths of the inner ear function to detect angular and linear accelerations of the head, with receptors located in the semicircular canals transducing rotational head movements and receptors located in the otolith organs transducing changes in head position relative to gravity or linear accelerations of the head. The information from these different receptors is then transmitted to central vestibular nuclei neurons which process the input signals, then project the appropriate output information to the eye, head, and body musculature motor neurons to control compensatory reflexes. Although a number of studies have reported on the responsiveness of vestibular nuclei neurons, it has not yet been possible to determine precisely how these cells combine the information from the different angular and linear acceleration receptors into a correct neural output signal. In the present project, rotational and linear motion stimuli were separately delivered while recording responses from vestibular nuclei neurons that were characterized according to direct input from the labyrinth and eye movement sensitivity. Responses from neurons receiving convergent input from the semicircular canals and otolith organs were quantified and compared to non-convergent neurons.

Electromagnetic properties in {sup 160-170}Dy nuclei. A microscopic description by the pseudo-SU(3) shell model

Energy Technology Data Exchange (ETDEWEB)

Vargas, Carlos E.; Bagatella-Flores, Norma [Universidad Veracruzana, Facultad de Fisica, Veracruz (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Mexico D.F. (Mexico); Lerma-Hernandez, Sergio [Universidad Veracruzana, Facultad de Fisica, Veracruz (Mexico); Universidad Nacional Autonoma de Mexico, Instituto de Ciencias Nucleares, Mexico D.F. (Mexico)

2017-04-15

The large collectivity observed in the rare-earth region of the nuclear landscape is well known. The microscopic studies are difficult to perform in this region due to the enormous size of the valence spaces, a problem that can be avoided by means of the use of symmetry-based models. Here we present calculations for electromagnetic properties of {sup 160-170}Dy nuclei within the pseudo-SU(3) scheme. The model Hamiltonian includes the preserving symmetry Q.Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized for all members of the chain. The model is used to calculate B(E2) and B(M1) inter-band transition strengths between the ground state, γ and β-bands. In addition, we present results for quadrupole moments and g factors in these rotational bands. The results show that the pseudo-SU(3) shell model is a powerful microscopic theory for a description of electromagnetic properties of states in the normal parity sector in heavy deformed nuclei. (orig.)

Structural and decay properties of Z = 132, 138 superheavy nuclei

Energy Technology Data Exchange (ETDEWEB)

Rather, Asloob A.; Ikram, M.; Usmani, A.A. [Aligarh Muslim University, Department of Physics, Aligarh (India); Kumar, Bharat; Patra, S.K. [Institute of Physics, Bhubaneswar (India); Homi Bhabha National Institute, Mumbai, Anushakti Nagar (India)

2016-12-15

In this paper, we analyze the structural properties of Z = 132 and Z = 138 superheavy nuclei within the ambit of axially deformed relativistic mean-field framework with NL3* parametrization and calculate the total binding energies, radii, quadrupole deformation parameter, separation energies, density distributions. We also investigate the phenomenon of shape coexistence by performing the calculations for prolate, oblate and spherical configurations. For clear presentation of nucleon distributions, the two-dimensional contour representation of individual nucleon density and total matter density has been made. Further, a competition between possible decay modes such as α-decay, β-decay and spontaneous fission of the isotopic chain of superheavy nuclei with Z = 132 within the range 312 ≤ A ≤ 392 and 318 ≤ A ≤ 398 for Z = 138 is systematically analyzed within self-consistent relativistic mean-field model. From our analysis, we inferred that the α-decay and spontaneous fission are the principal modes of decay in majority of the isotopes of superheavy nuclei under investigation apart from β-decay as dominant mode of decay in {sup 318-322}138 isotopes. (orig.)

Mechanisms of strain accommodation in plastically-deformed zircon under simple shear deformation conditions during amphibolite-facies metamorphism

Science.gov (United States)

Kovaleva, Elizaveta; Klötzli, Urs; Wheeler, John; Habler, Gerlinde

2018-02-01

This study documents the strain accommodation mechanisms in zircon under amphibolite-facies metamorphic conditions in simple shear. Microstructural data from undeformed, fractured and crystal-plastically deformed zircon crystals are described in the context of the host shear zone, and evaluated in the light of zircon elastic anisotropy. Our work challenges the existing model of zircon evolution and shows previously undescribed rheological characteristics for this important accessory mineral. Crystal-plastically deformed zircon grains have axis oriented parallel to the foliation plane, with the majority of deformed grains having axis parallel to the lineation. Zircon accommodates strain by a network of stepped low-angle boundaries, formed by switching between tilt dislocations with the slip systems {010} and {110} and rotation axis [001], twist dislocations with the rotation axis [001], and tilt dislocations with the slip system {001} and rotation axis [010]. The slip system {110} is newly described for zircon. Most misorientation axes in plastically-deformed zircon grains are parallel to the XY plane of the sample and have [001] crystallographic direction. Such behaviour of strained zircon lattice is caused by elastic anisotropy that has a direct geometric control on the rheology, deformation mechanisms and dominant slip systems in zircon. Young's modulus and P wave velocity have highest values parallel to zircon [001] axis, indicating that zircon is elastically strong along this direction. Poisson ratio and Shear modulus demonstrate that zircon is also most resistant to shearing along [001]. Thus, [001] axis is the most common rotation axis in zircon. The described zircon behaviour is important to take into account during structural and geochronological investigations of (poly)metamorphic terrains. Geometry of dislocations in zircon may help reconstructing the geometry of the host shear zone(s), large-scale stresses in the crust, and, possibly, the timing of

Three-dimensional deformation of orthodontic brackets

OpenAIRE

Melenka, Garrett W; Nobes, David S; Major, Paul W; Carey, Jason P

2013-01-01

Braces are used by orthodontists to correct the misalignment of teeth in the mouth. Archwire rotation is a particular procedure used to correct tooth inclination. Wire rotation can result in deformation to the orthodontic brackets, and an orthodontic torque simulator has been designed to examine this wire?bracket interaction. An optical technique has been employed to measure the deformation due to size and geometric constraints of the orthodontic brackets. Images of orthodontic brackets are c...

Chaos in nuclei: Theory and experiment

Science.gov (United States)

Muñoz, L.; Molina, R. A.; Gómez, J. M. G.

2018-05-01

During the last three decades the quest for chaos in nuclei has been quite intensive, both with theoretical calculations using nuclear models and with detailed analyses of experimental data. In this paper we outline the concept and characteristics of quantum chaos in two different approaches, the random matrix theory fluctuations and the time series fluctuations. Then we discuss the theoretical and experimental evidence of chaos in nuclei. Theoretical calculations, especially shell-model calculations, have shown a strongly chaotic behavior of bound states in regions of high level density. The analysis of experimental data has shown a strongly chaotic behavior of nuclear resonances just above the one-nucleon emission threshold. For bound states, combining experimental data of a large number of nuclei, a tendency towards chaotic motion is observed in spherical nuclei, while deformed nuclei exhibit a more regular behavior associated to the collective motion. On the other hand, it had never been possible to observe chaos in the experimental bound energy levels of any single nucleus. However, the complete experimental spectrum of the first 151 states up to excitation energies of 6.20 MeV in the 208Pb nucleus have been recently identified and the analysis of its spectral fluctuations clearly shows the existence of chaotic motion.

Intraplate Crustal Deformation Within the Northern Sinai Microplate: Evidence from Paleomagnetic Directions and Mechanical Modeling

Science.gov (United States)

Dembo, N.; Granot, R.; Hamiel, Y.

2017-12-01

The intraplate crustal deformation found in the northern part of the Sinai Microplate, located near the northern Dead Sea Fault plate boundary, is examined. Previous studies have suggested that distributed deformation in Lebanon is accommodated by regional uniform counterclockwise rigid block rotations. However, remanent magnetization directions observed near the Lebanese restraining bend are not entirely homogeneous suggesting that an unexplained and complex internal deformation pattern exists. In order to explain the variations in the amount of vertical-axis rotations we construct a mechanical model of the major active faults in the region that simulates the rotational deformation induced by motion along these faults. The rotational pattern calculated by the mechanical modeling predicts heterogeneous distribution of rotations around the faults. The combined rotation field that considers both the fault induced rotations and the already suggested regional block rotations stands in general agreement with the observed magnetization directions. Overall, the modeling results provide a more detailed and complete picture of the deformation pattern in this region and show that rotations induced by motion along the Dead Sea Fault act in parallel to rigid block rotations. Finally, the new modeling results unravel important insights as to the fashion in which crustal deformation is distributed within the northern part of the Sinai Microplate and propose an improved deformational mechanism that might be appropriate for other plate margins as well.

Nuclei at extreme conditions. A relativistic study

Energy Technology Data Exchange (ETDEWEB)

Afanasjev, Anatoli [Mississippi State Univ., Mississippi State, MS (United States)

2014-11-14

The major goals of the current project were further development of covariant density functional theory (CDFT), better understanding of its features, its application to different nuclear structure and nuclear astrophysics phenomena and training of graduate and undergraduate students. The investigations have proceeded in a number of directions which are discussed in detail in the part “Accomplishments” of this report. We have studied the role of isovector and isoscalar proton-neutron pairings in rotating nuclei; based on available experimental data it was concluded that there are no evidences for the existence of isoscalar proton-neutron pairing. Generalized theoretical approach has been developed for pycnonuclear reaction rates in the crust of neutron stars and interior of white dwarfs. Using this approach, extensive database for considerable number of pycnonuclear reactions involving stable and neutron-rich light nuclei has been created; it can be used in future for the study of various nuclear burning phenomena in different environments. Time-odd mean fields and their manifestations in terminating states, non-rotating and rotating nuclei have been studied in the framework of covariant density functional theory. Contrary to non-relativistic density functional theories these fields, which are important for a proper description of nuclear systems with broken time-reversal symmetry, are uniquely defined in the CDFT framework. Hyperdeformed nuclear shapes (with semi-axis ratio 2.5:1 and larger) have been studied in the Z = 40-58 part of nuclear chart. We strongly believe that such shapes could be studied experimentally in the future with full scale GRETA detector.

Single-particle motion in rapidly rotating nuclei

International Nuclear Information System (INIS)

Bengtsson, R.; Frisk, H.

1985-01-01

The motion of particles belonging to a single-j shell is described in terms of classical orbitals. The effects of rapid rotation and pairing correlations are discussed and the results are compared with the quantum mechanical orbitals. (orig.)

Nuclear structure investigations on spherical nuclei

International Nuclear Information System (INIS)

Heisenberg, J.; Calarco, J.; Dawson, J.; Hersman, F.W.

1989-09-01

This report discusses the following topics: electron scattering studies on spherical nuclei; electron scattering from collective states in deformed nuclei; proton and pion scattering studies; 12 C(e,e'p) and 16 O(e,e'p); 12 C(e,e'α) and 16 O(e,e'α); studies at high q at Bates; measurements with rvec e at Bates; 12 C(γ,p); future directions in giant resonance studies; proton knockout from 16 O; quasielastic studies at Bates; triple coincidence studies of nuclear correlations; contributions to (e,e'2p) at KIKHEF; contributions to instrumentation at CEBAF; instrumentation development at UNH; the Bates large acceptance spectrometer toroid; shell model and core polarization calculations; and the relativistic nuclear model

Interplay between symmetries and residual interactions in rotating nuclei

International Nuclear Information System (INIS)

Cwiok, S.; Kvasil, J.; Nazmitdinov, R.G.

1990-01-01

Using the space rotation and translation invariance of the nuclear Hamiltonian, the residual interactions for a rotating nucleus are constructed. The connection is found between the Goldstone modes of motion (spurious states) and the symmetries of equations of motion in Random Phase Approximation for states near the yrast line. (author). 18 figs

The core-quasiparticle model for odd-odd nuclei and applications to candidates for gamma-ray lasers

International Nuclear Information System (INIS)

Strottman, D.D.

1988-01-01

A reliable estimate of the properties of isomers that may be viable candidates for a gamma-ray laser requires the use of the most accurate save functions possible. The majority of models that have been used to estimate the properties of isomers are applicable to only selected regions of the nuclear mass table. In particular, the Bohr-Mottelson model of odd-A and odd-odd nuclei will fail if the even-even core is not strongly deformed or if the deformations are changing strongly as a function of mass. This paper reports how the problem is overcome in a new core- quasiparticle model for odd-odd nuclei. The model introduces the pairing interaction ab initio; the odd-A states are mixtures of particle and hole states. The core may be soft towards deformation or axial asymmetry and may change rapidly as a function of mass. Thus, the model is ideally suited for application to the region of transitional nuclei such as the Te, La, and Os regions

Interplay of single particle and collective excitations in antimony nuclei

International Nuclear Information System (INIS)

Stan-Sion, C.

1987-01-01

The antimony nuclei are considered classical examples for coexisting spherical and well-deformed structures. The electromagnetic moment measurements presented in this paper provide direct evidence for shape coexistence. 8 refs., 3 figs. (M.F.W.)

Is nucleon deformed?

International Nuclear Information System (INIS)

Abbas, Afsar

1992-01-01

The surprising answer to this question Is nucleon deformed? is : Yes. The evidence comes from a study of the quark model of the single nucleon and when it is found in a nucleus. It turns out that many of the long standing problems of the Naive Quark Model are taken care of if the nucleon is assumed to be deformed. Only one value of the parameter P D ∼1/4 (which specifies deformation) fits g A (the axial vector coupling constant) for all the semileptonic decay of baryons, the F/D ratio, the pion-nucleon-delta coupling constant fsub(πNΔ), the double delta coupling constant 1 fsub(πΔΔ), the Ml transition moment μΔN and g 1 p the spin structure function of proton 2 . All this gives strong hint that both neutron and proton are deformed. It is important to look for further signatures of this deformation. When this deformed nucleon finds itself in a nuclear medium its deformation decreases. So much that in a heavy nucleus the nucleons are actually spherical. We look into the Gamow-Teller strengths, magnetic moments and magnetic transition strengths in nuclei to study this property. (author). 15 refs

Exotic Nuclei and Yukawa's Forces

International Nuclear Information System (INIS)

Otsuka, Takaharu; Suzuki, Toshio; Utsuno, Yutaka

2008-01-01

In this plenary talk, we will overview the evolution of the shell structure in stable and exotic nuclei as a new paradigm of nuclear structure physics. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, ... This turned out to be changed, once we entered the regime of exotic nuclei. This shell evolution develops at many places on the nuclear chart in various forms. For example, superheavy magic numbers may be altered. Thus, we are led to a new paradigm as to how and where the nuclear shell evolves, and what consequences arise. The evolution of the shell affects weak process transitions, and plays a crucial role in deformation. The π and ρ mesons generate tensor forces, and are the fundamental elements of such intriguing phenomena. Thus, physics of exotic nuclei arises as a manifestation of Yukawa's forces

Collective rotation from ab initio theory

International Nuclear Information System (INIS)

Caprio, M.A.; Maris, P.; Vary, J.P.; Smith, R.

2015-01-01

Through ab initio approaches in nuclear theory, we may now seek to quantitatively understand the wealth of nuclear collective phenomena starting from the underlying internucleon interactions. No-core configuration interaction (NCCI) calculations for p-shell nuclei give rise to rotational bands, as evidenced by rotational patterns for excitation energies, electromagnetic moments and electromagnetic transitions. In this review, NCCI calculations of 7–9 Be are used to illustrate and explore ab initio rotational structure, and the resulting predictions for rotational band properties are compared with experiment. We highlight the robustness of ab initio rotational predictions across different choices for the internucleon interaction. (author)

On peculiarities of the cascade γ decay of heavy nuclei

International Nuclear Information System (INIS)

Boneva, S.T.; Khitrov, V.A.; Popov, Yu.P.; Sukhovoj, A.M.; Vasil'eva, E.V.; Yazvitskij, Yu.S.

1987-01-01

Comparison of measured and calculated by statistical theory sums of two-quanta cascade intensities in compound-nuclei 163 ≤ A ≤ 183 points to the dependence of cascade intensity on the structure of initial and intermediate levels. The dependence of two-quanta cascade intensity sum on reduced neutron widths of compound states of even-even nuclei-targets of rare earth regions is detected. In 175 Yb and 179 Hf nuclei a considerable increase in the intensity of two-quanta cascades at the energy of their intermediate level in the range of the calculated position of one-quasiparticle states of the Saxon-Woods deformed potential is observed

Giant resonances in the deformed continuum

International Nuclear Information System (INIS)

Nakatsukasa, T.; Yabana, K.

2004-01-01

Giant resonances in the continuum for deformed nuclei are studied with the time-dependent Hartree-Fock (TDHF) theory in real time and real space. The continuum effect is effectively taken into account by introducing a complex Absorbing Boundary Condition (ABC). (orig.)

A systematic study of even-even nuclei in the nuclear chart by the relativistic mean field theory

Energy Technology Data Exchange (ETDEWEB)

Sumiyoshi, K.; Hirata, D.; Tanihata, I.; Sugahara, Y.; Toki, H. [Institute of Physical and Chemical Research, Wako, Saitama (Japan)

1997-03-01

We study systematically the properties of nuclei in the whole mass range up to the drip lines by the relativistic mean field (RMF) theory with deformations as a microscopic framework to provide the data of nuclear structure in the nuclear chart. The RMF theory is a phenomenological many-body framework, in which the self-consistent equations for nucleons and mesons are solved with arbitrary deformation, and has a potential ability to provide all the essential information of nuclear structure such as masses, radii and deformations together with single particle states and wave functions from the effective lagrangian containing nuclear interaction. As a first step toward the whole project, we study the ground state properties of even-even nuclei ranging from Z=8 to Z=120 up to the proton and neutron drip lines in the RMF theory. We adopt the parameter set TMA, which has been determined by the experimental masses and charge radii in a wide mass range, for the effective lagrangian of the RMF theory. We take into account the axially symmetric deformation using the constrained method on the quadrupole moment. We provide the properties of all even-even nuclei with all the possible ground state deformations extracted from the deformation energy curves by the constrained calculations. By studying the calculated ground state properties systematically, we aim to explore the general trend of masses, radii and deformations in the whole region of the nuclear chart. We discuss the agreement with experimental data and the predictions such as magicness and triaxial deformations beyond the experimental frontier. (author)

Superheavy nuclei – cold synthesis and structure

Indian Academy of Sciences (India)

120 and Ж = 172 or 184, for superheavy nuclei. This result is discussed in ... 1980 [7] on the basis of the QMFT, once again prior to its observation in 1984. Thus, cold ... On the other hand, based on a rather complete deformed relativistic mean field (DRMF) calculation, using the NL1 parameter set, we [16] predicted. = 120.

Single Particle energy levels in ODD-A Nuclei

International Nuclear Information System (INIS)

Lasijo, R.S.

1997-01-01

Singe particle energies for atomic nuclei with odd-A number of nucleons, i.e. nuclei possessing odd number of protons or odd number of neutrons, were calculated based on Nilsson's theory, and then the diagrams were made. the energy diagram is in the from of plot of energies as function of deformations, entities identifying the deviations from the spherical shape. The energy calculations were done using FORTRAN 77 language of PC (Personal Computer) version with Microsoft Fortran Power Station compiler, which was then combined with WORD version 6.0 and EXCEL version 5.0 of WINDOWS WORKGROUP to make the plot

Epithelial rotation is preceded by planar symmetry breaking of actomyosin and protects epithelial tissue from cell deformations.

Science.gov (United States)

Viktorinová, Ivana; Henry, Ian; Tomancak, Pavel

2017-11-01

Symmetry breaking is involved in many developmental processes that form bodies and organs. One of them is the epithelial rotation of developing tubular and acinar organs. However, how epithelial cells move, how they break symmetry to define their common direction, and what function rotational epithelial motions have remains elusive. Here, we identify a dynamic actomyosin network that breaks symmetry at the basal surface of the Drosophila follicle epithelium of acinar-like primitive organs, called egg chambers, and may represent a candidate force-generation mechanism that underlies the unidirectional motion of this epithelial tissue. We provide evidence that the atypical cadherin Fat2, a key planar cell polarity regulator in Drosophila oogenesis, directs and orchestrates transmission of the intracellular actomyosin asymmetry cue onto a tissue plane in order to break planar actomyosin symmetry, facilitate epithelial rotation in the opposite direction, and direct the elongation of follicle cells. In contrast, loss of this rotational motion results in anisotropic non-muscle Myosin II pulses that are disorganized in plane and causes cell deformations in the epithelial tissue of Drosophila eggs. Our work demonstrates that atypical cadherins play an important role in the control of symmetry breaking of cellular mechanics in order to facilitate tissue motion and model epithelial tissue. We propose that their functions may be evolutionarily conserved in tubular/acinar vertebrate organs.

The neutron-proton pairing and the moments of inertia of the rare earth even-even nuclei

International Nuclear Information System (INIS)

Calik, A. E.; Deniz, C.; Gerceklioglu, M.

2009-01-01

In this study, the possible effect of the neutron-proton pairing interaction in the heavy nuclei has been investigated in the framework of the BCS model by making a simple approximation. This effect has been searched realistically by calculating the moments of inertia of deformed even-even nuclei. Calculations show that the moments of inertia of rare earth nuclei changed dramatically and approached the experimental values.

Status and perspectives of the M1 scissors mode in nuclei

International Nuclear Information System (INIS)

Richter, A.

1988-07-01

The present status of the M1 scissors mode which is now known in deformed nuclei ranging from 46 Ti to 238 U is summarized. Particular emphasis is placed on a discussion of the structure, the excitation energy, the transition strength, the form factor and the spin to orbit ratio in the strength of the mode. Finally it is demonstrated how strongly this mode contributes to the magnetic dipole polarizability of nuclei. (orig.)

Signature effects in 2-qp rotational bands

International Nuclear Information System (INIS)

Jain, A.K.; Goel, A.

1992-01-01

The authors briefly review the progress in understanding the 2-qp rotational bands in odd-odd nuclei. Signature effects and the phenomenon of signature inversion are discussed. The Coriolis coupling appears to have all the ingredients to explain the inversion. Some recent work on signature dependence in 2-qp bands of even-even nuclei is also discussed; interesting features are pointed out

Experimental and theoretical study of several nuclei from the 1f(7/2) region for mass number 47, 48, 49

International Nuclear Information System (INIS)

Haas, Bernard.

1974-01-01

The experimental study of the following nuclei 48 V, 49 V and 48 Cr has been undertaken by in-beam γ-ray spectroscopy. The nuclear structure has been deduced from angular distribution and particle-γ angular correlation measurements as well as lifetime measurements with the Doppler shift technique. Most of the energy levels could be classified in rotational bands followings quite well the low I(I+1):K(π)=1 - ( 48 V), K(π)=3/2 + and 1/2 + ( 49 V) and K(π)=0 + ( 48 Cr). The properties of these bands, as for example the B(E2) reduced matrix elements and the intrinsic quadrupole moments Q 0 have been described in the framework of the Nilsson model using a deformation parameter β approximately 0.3. The negative parity levels of the cross-conjugate nuclei 47 V- 49 Cr and 49 V- 47 Ti have also been explained by a collective model, however a strong configuration mixing in their wave function, due to the Coriolis interaction, destroys the energy dependence in I(I+1) [fr

Collectivity in heavy nuclei in the shell model Monte Carlo approach

International Nuclear Information System (INIS)

Özen, C.; Alhassid, Y.; Nakada, H.

2014-01-01

The microscopic description of collectivity in heavy nuclei in the framework of the configuration-interaction shell model has been a major challenge. The size of the model space required for the description of heavy nuclei prohibits the use of conventional diagonalization methods. We have overcome this difficulty by using the shell model Monte Carlo (SMMC) method, which can treat model spaces that are many orders of magnitude larger than those that can be treated by conventional methods. We identify a thermal observable that can distinguish between vibrational and rotational collectivity and use it to describe the crossover from vibrational to rotational collectivity in families of even-even rare-earth isotopes. We calculate the state densities in these nuclei and find them to be in close agreement with experimental data. We also calculate the collective enhancement factors of the corresponding level densities and find that their decay with excitation energy is correlated with the pairing and shape phase transitions. (author)

Possible Deformed States in {sup 115}In and {sup 117}ln

Energy Technology Data Exchange (ETDEWEB)

Baecklin, A; Fogelberg, B [Inst. of Physics, Univ. of Uppsala (Sweden); Swedish Research Councils' Laboratory, Studsvik, Nykoeping (Sweden); Malmskog, S G [AB Atomenergi, Nykoeping (Sweden)

1967-01-15

Levels and transitions in {sup 115}In and {sup 117}In have been studied from the beta decay of 2.3-day {sup 115g}Cd and 2.5-h {sup 117g}Cd. Using a Ge(Li) detector and a double focussing beta spectrometer energies, intensities, conversion coefficients and multipolarities were obtained for the following transitions (energies in keV and multipolarities are given): {sup 115}In: 35.63 (97.0 % M1 + 3.0 % E2), 231.47 (E1), 260.80 (M1), 267, 336. 23 (M4 + < 5 % E5), 492. 4 (96 % El +4 % M2), 527.70 (E1). {sup 117}In: 71.0, 89.80 (E2 + < 20 % M1), 273.32 (M1, E2), 315.27 (M4 + < 7 % E2), 344.29 (E1), 434.12 (E1). Using the delayed coincidence technique, half lives were measured for 2 levels in {sup 115}In and for 3 levels in {sup 117}In. Energies, spins, parities and half lives are given for the following levels: In: 597.03, 3/2{sup -}; 828.39, 3/2{sup +}, 5.4 ns; 863.95, l/2{sup +} or 3/2{sup +}, 1.1 ns. {sup 117}In: 588.59, 3/2{sup -}; 0.20 ns; 659.56, 3/2{sup +}, 58.7 ns; 749.37, 1/2{sup +} or 3/2{sup +}, 4.3 ns. Reduced transition probabilities are given for several transitions in both nuclei. The E2 transition rates between the two excited positive parity states in both nuclei were found to be about 100 s. p. u. indicating a possible deformation of these states. The energy spacing and transition rates between these states can be well accounted for within the Nilsson model assuming the states to form a K = 1/2{sup +} rotational band. A deformation {delta} of about 0.20 is obtained for both nuclei.

High and highest spin states in nuclei

International Nuclear Information System (INIS)

Ploszajczak, M.

1977-06-01

A study of the following phenomena in rotating nuclei is presented, namely: 1) the destruction of the pair-correlation between the protons and the neutrons as well as decoupling and orientation of the particles along the rotation axis; 2) the formation of a nucleus with axial symmetry rotating around the symmetry axis, caused by the strong centrifugal and Coriolis forces; 3) the shell effects at low angular momentum, which led in some Pb, Hg and Pt isotopes to the formation of a prolate nucleus, rotating around the symmetry axis; 4) the formation of longliving states at very high angular momenta ('Yrast-traps'). At low angular momenta the nucleus is described by the Cranking-Hartree-Fock-Bogolyubov theory (CHFB) with the pair-(P), quadrupole-(QQ) and hexade coupole force (HH) as residual interaction. (orig.) [de

Inelastic neutron excitation of the ground state rotational band of 238U

International Nuclear Information System (INIS)

Guenther, P.; Smith, A.

1975-01-01

Cross sections for the neutron excitation of the 2+(45 keV), 4+(148 keV) and 6+(308 keV) states in 238 U were measured to incident energies of approximately 3.0 MeV. The experimental resolution was sufficient to resolve these components throughout the measured energy range. Particular attention was given to energies near threshold and in the few MeV range where direct reaction contributions were appreciable. The experimental results were compared with theoretical estimates based upon statistical and coupled-channel models deduced from comprehensive studies of neutron scattering from heavy-rotational-deformed nuclei. An evaluated inelastic scattering data set was derived from the present experimental and calculational results and previously reported experimental values and compared with respective values from the ENDF-IV file. 4 figures

A special type of neutron-proton pairing interaction and the moments of inertia of some deformed even-even nuclei in the rare earth region

International Nuclear Information System (INIS)

Meftunoglu, E.; Gerceklioglu, M.; Erbil, H.H.; Kuliev, A.A.

1998-01-01

In this work, the effect of a special type of neutron-proton pairing interaction on the moments of inertia of some deformed nuclei in the rare earth region is investigated. First, making a perturbative approximation, we assume that the form of the equations of the BCS theory and usual Bogolyubov transformations are unchanged. Second, we use a phenomenological method for the strength of this neutron-proton pairing interaction introducing a parameter. Calculations show that this interaction is important for the ground-state moments of inertia and that it could be effectual in other nuclear phenomena. (author)

Studies of the shapes of heavy pear-shaped nuclei at ISOLDE

Energy Technology Data Exchange (ETDEWEB)

Butler, P. A., E-mail: peter.butler@liverpool.ac.uk [Oliver Lodge Laboratory, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

2016-07-07

For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a ”pear-shape” in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.

Potential energy surfaces for N = Z, 20Ne-112Ba nuclei

International Nuclear Information System (INIS)

Mehta, M.S.; Gupta, Raj K.; Jha, T.K.; Patra, S.K.

2004-01-01

We have calculated the potential energy surfaces for N = Z, 20 Ne- 112 Ba nuclei in an axially deformed relativistic mean field approach. A quadratic constraint scheme is applied to determine the complete energy surface for a wide range of the quadrupole deformation. The NL3, NL-RAl and TM1 parameter sets are used. The phenomenon of (multiple) shape coexistence is studied and the calculated ground and excited state binding energies, quadrupole deformation parameters and root mean square (rms) charge radii are compared with the available experimental data and other theoretical predictions. (author)

Relativistic mean field theory for unstable nuclei

International Nuclear Information System (INIS)

Toki, Hiroshi

2000-01-01

We discuss the properties of unstable nuclei in the framework of the relativistic mean field (RMF) theory. We take the RMF theory as a phenomenological theory with several parameters, whose form is constrained by the successful microscopic theory (RBHF), and whose values are extracted from the experimental values of unstable nuclei. We find the outcome with the newly obtained parameter sets (TM1 and TMA) is promising in comparison with various experimental data. We calculate systematically the ground state properties of even-even nuclei up to the drip lines; about 2000 nuclei. We find that the neutron magic shells (N=82, 128) at the standard magic numbers stay at the same numbers even far from the stability line and hence provide the feature of the r-process nuclei. However, many proton magic numbers disappear at the neutron numbers far away from the magic numbers due to the deformations. We discuss how to describe giant resonances for the case of the non-linear coupling terms for the sigma and omega mesons in the relativistic RPA. We mention also the importance of the relativistic effect on the spin observables as the Gamow-Teller strength and the longitudinal and transverse spin responses. (author)

Spectroscopic study of 228-234Th nuclei using multi-nucleon transfer reactions

International Nuclear Information System (INIS)

Amzal, N.; Butler, P.A.; Cann, K.J.; Greenlees, P.T.; Jones, G.D.; Cocks, J.F.C.; Asztalos, S.; Clark, R.M.; Deleplanque, M.A.; Diamond, R.M.; Fallon, P.; Lees, I.Y.; Machiavelli, A.O.; MacLeod, R.W.; Stephens, F.S.; Jones, P.M.; Julin, R.; Broda, R.; Fornal, B.; Smith, J.F.; Lauritsen, T.; Bhattacharyya, P.; Zhang, C.T.

1999-01-01

Light-actinide nuclei in the octupole deformed region have been populated using multi-nucleon transfer from 232 Th. The energy level schemes of several thorium isotopes with A=228-234 have been extended up to I∼24ℎ and negative parity states have been observed for the first time in 234 Th. A systematic study of the difference in alignment between the positive- and negative-parity bands in thorium nuclei in this mass region shows that 228,230,234 Th behave like octupole vibrators, in contrast with 224,226 Th, which are octupole-deformed in character. An intrinsic electric dipole moment has been measured for the first time in 234 Th. The small value obtained is consistent with the vibrational description of this nucleus. (author)

Margin Evaluation in the Presence of Deformation, Rotation, and Translation in Prostate and Entire Seminal Vesicle Irradiation With Daily Marker-Based Setup Corrections

International Nuclear Information System (INIS)

Mutanga, Theodore F.; Boer, Hans C.J. de; Wielen, Gerard J. van der; Hoogeman, Mischa S.; Incrocci, Luca; Heijmen, Ben J.M.

2011-01-01

Purpose: To develop a method for margin evaluation accounting for all measured displacements during treatment of prostate cancer. Methods and Materials: For 21 patients treated with stereographic targeting marker-based online translation corrections, dose distributions with varying margins and gradients were created. Sets of possible cumulative delivered dose distributions were simulated by moving voxels and accumulating dose per voxel. Voxel motion was simulated consistent with measured distributions of systematic and random displacements due to stereographic targeting inaccuracies, deformation, rotation, and intrafraction motion. The method of simulation maintained measured correlation of voxel motions due to organ deformation. Results: For the clinical target volume including prostate and seminal vesicles (SV), the probability that some part receives <95% of the prescribed dose, the changes in minimum dose, and volume receiving 95% of prescription dose compared with planning were 80.5% ± 19.2%, 9.0 ± 6.8 Gy, and 3.0% ± 3.7%, respectively, for the smallest studied margins (3 mm prostate, 5 mm SV) and steepest dose gradients. Corresponding values for largest margins (5 mm prostate, 8 mm SV) with a clinical intensity-modulated radiotherapy dose distribution were 46.5% ± 34.7%, 6.7 ± 5.8 Gy, and 1.6% ± 2.3%. For prostate-only clinical target volume, the values were 51.8% ± 17.7%, 3.3 ± 1.6 Gy, and 0.6% ± 0.5% with the smallest margins and 5.2% ± 7.4%, 1.8 ± 0.9 Gy, and 0.1% ± 0.1% for the largest margins. Addition of three-dimensional rotation corrections only improved these values slightly. All rectal planning constraints were met in the actual reconstructed doses for all studied margins. Conclusion: We developed a system for margin validation in the presence of deformations. In our population, a 5-mm margin provided sufficient dosimetric coverage for the prostate. In contrast, an 8-mm SV margin was still insufficient owing to deformations. Addition of

Q-deformed algebras and many-body physics

Energy Technology Data Exchange (ETDEWEB)

Galetti, D; Lunardi, J T; Pimentel, B M [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil); Lima, C L [Sao Paulo Univ., SP (Brazil). Inst. de Fisica

1995-11-01

A review is presented of some applications of q-deformed algebras to many-body systems. The rotational and pairing nuclear problems will be discussed in the context of q-deformed algebras, before presenting a more microscopically based application of q-deformed concepts to many-fermion systems. (author). 30 refs., 5 figs.

Shadow casted by a Konoplya-Zhidenko rotating non-Kerr black hole

Energy Technology Data Exchange (ETDEWEB)

Wang, Mingzhi; Chen, Songbai; Jing, Jiliang, E-mail: wmz9085@126.com, E-mail: csb3752@hunnu.edu.cn, E-mail: jljing@hunnu.edu.cn [Institute of Physics and Department of Physics, Hunan Normal University, Changsha, Hunan 410081 (China)

2017-10-01

We have investigated the shadow of a Konoplya-Zhidenko rotating non-Kerr black hole with an extra deformation parameter. The spacetime structure arising from the deformed parameter affects sharply the black hole shadow. With the increase of the deformation parameter, the size of the shadow of black hole increase and its shape becomes more rounded for arbitrary rotation parameter. The D-shape shadow of black hole emerges only in the case a <2√3/3\\, M with the proper deformation parameter. Especially, the black hole shadow possesses a cusp shape with small eye lashes in the cases with a >M, and the shadow becomes less cuspidal with the increase of the deformation parameter. Our result show that the presence of the deformation parameter yields a series of significant patterns for the shadow casted by a Konoplya-Zhidenko rotating non-Kerr black hole.

Prospects for asteroseismology of rapidly rotating B-type stars

OpenAIRE

Saio, Hideyuki

2013-01-01

In rapidly rotating stars Coriolis forces and centrifugal deformations modify the properties of oscillations; the Coriolis force is important for low-frequency modes, while the centrifugal deformation affects mainly p-modes. Here, we discuss properties of g- and r-mode oscillations in rotating stars. Predicted frequency spectra of high-order g-modes (and r-modes) excited in rapidly rotating stars show frequency groupings associated with azimuthal order $m$. We compare such properties with obs...

Transitional nuclei in the A∼100 region

International Nuclear Information System (INIS)