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Total-Routhian-surface calculations have been performed to investigate the shape evolutions of A~80 nuclei: 80-84Zr, 76-80Sr, and 84,86Mo. Shape coexistences of spherical, prolate, and oblate deformations have been found in these nuclei. Particularly for the nuclei 80Sr and 82Zr, the energy differences between two shape-coexisting states are less than 220 keV. At high spins, the g9/2 shell plays an important role in shape evolutions. It has been found that the alignment of the g9/2 quasiparticles drives nuclei to be triaxial. [ABSTRACT FROM AUTHOR]

Motivated by new experimental spectra in transfermium mass region, we have investigated broken-pair high-K multiparticle excited states and their rotational bands for the N = 150 isotones around Z = 100, by using the configuration-constrained pairing-deformation-frequency self-consistent total-Routhian-surface (TRS) model. In order to avoid the spurious phase transition encountered in the Bardeen-Copper-Schrieffer (BCS) pairing, the particle-number-conserving method has been employed for pairing calculations. Pairing correlations are remarkably reduced for the rotations of broken-pair multiparticle states. The present configuration-constrained TRS calculations reproduce reasonably existing experimental data. The abnormal feature in the recently observed Kπ = 8- bands of 252No and 250Fm would be associated with configuration mixing. [ABSTRACT FROM AUTHOR]

The total-Routhian-surface (TRS) calculation provides a powerful theoretical tool to describe the collective rotations of nuclei. It gives a straightforward way to determine nuclear deformation which can change with increasing rotational frequency. In most cases, however, TRS calculations with a conventional pairing approach (e.g., Bardeen-Cooper-Schrieffer pairing) encounter a nonconvergence problem when applied to sidebands which are built on broken-pair excited intrinsic configurations. To overcome this problem, we have developed the TRS calculations with a particle-number-conserving pairing method in which the pairing correlation is treated with the merit of the shell model. In this paper, we present the first results of the calculations, focusing on the sidebands of the 178W nucleus, investigating deformation changes and incurred effects on the rotational behaviors of sidebands. [ABSTRACT FROM AUTHOR]

Total Routhian surface calculations have been performed to investigate rapidly rotating transfermium nuclei, the heaviest nuclei accessible by detailed spectroscopy experiments. The observed fast alignment in 252No and slow alignment in 254No are well reproduced by the calculations incorporating high-order deformations. The different rotational behaviors of 252No and 254No can be understood for the first time in terms of β6 deformation that decreases the energies of the vj15/2 intruder orbitals below the N = 152 gap. Our investigations reveal the importance of high-order deformation in describing not only the multiquasiparticle states but also the rotational spectra, both providing probes of the single-particle structure concerning the expected doubly magic superheavy nuclei. [ABSTRACT FROM AUTHOR]

The article presents a study which investigated the different rotational behaviors of 252No and 254No., which are said to be transfermium nuclei. In the study, the total Routhian surface (TRS) calculations were used to examine the substantial moments of inertia (MOI) difference between the two nuclei. The TRS method used is a pairing-deformation-frequency self-consistent calculation based on the cranked shell model.

Configuration-constrained potential-energy-surface calculations have been performed to investigate multiquasiparticle high-if states built on superdeformed minima in 192,194,196Pb and 198Po. The calculations predict that 196Pb and 198Po would be favorable candidates for the observation of low-lying superdeformed two- and four-quasiparticle high-K states. The possible decay paths and lifetimes that could lead to isomers are evaluated in detail for 196Pb. Comparisons between the predictions and previous observations of octupole-vibrational excitations indicate also that bands built on superdeformed high-K intrinsic states may compete with the octupole-vibrational mode in this mass region. The quadrupole moments of both the collective and intrinsic excitations are analyzed. [ABSTRACT FROM AUTHOR]

The partial conservation of the seniority symmetry in j = 9/2 shells has been discussed recently. In this work we show that the occurrence of the partial conservation of the seniority is the consequence of special properties of certain one-particle coefficients of fractional parentage. Further studies have also been done to pursue the similar special relations of the coefficients of fractional parentage in other single-;' shells with j ≲15/2. [ABSTRACT FROM AUTHOR]

We investigate the influence of deformation on the possible occurrence of long-lived K isomers in Hf isotopes around N = 116, using configuration-constrained calculations of potential-energy surfaces. Despite having reduced shape elongation, the multiquasiparticle states in 186,188Hf remain moderately robust against triaxial distortion, supporting the long expected occurrence of exceptionally long-lived isomers. The calculations are compared with available experimental data. [ABSTRACT FROM AUTHOR]

Using, for the first time, configuration-constrained potential-energy-surface calculations with the inclusion of β6 deformation, we find remarkable effects of the high-order deformation on the high-K isomers in 254No, 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 β6 deformation significantly improves the description of the very heavy high-K isomers. [ABSTRACT FROM AUTHOR]

We have studied nuclear odd-even mass staggering with the Skyrme-Hartree-Fock-Bogoliubov theory by employing isoscalar and isovector contact pairing interactions. By reproducing the empirical odd-even mass differences of the Sn isotopie chain, the strengths of pairing interactions are determined. The optimal strengths adjusted in this work can give better description of odd-even mass differences than that fitted by reproducing the experimental neutron pairing gap of 120Sn. [ABSTRACT FROM AUTHOR]

The rotational symmetry is broken in mean-field models. The symmetry breaking may lead to significant effects even on the ground states of nuclei. The recent observations of enhanced collectivities in neutron-rich Fe and Cr isotopes are challenging the current calculations of mean-field models. By performing angular-momentum projection on mean-field potential energy surface (PES), we can obtain an angular-momentum-conserved PES at each given spin. With the projected PES, we have investigated the collectivity of neutron-rich Fe and Cr isotopes. The calculations reproduce well the excitation energies and electric quadrupole transitions of the collective excited states of the isotopes, indicating the importance of the restoration of the rotational symmetry. [ABSTRACT FROM AUTHOR]

Configuration-constrained potential-energy-surface calculations are performed including ß6 deformation to investigate high-K" isomeric states in nuclei around 254No and 270Ds, the heaviest nuclei where there have been some observations of two-quasiparticle isomers, while data for four-quasiparticle isomers are scarce. We predict the prevalent occurrence of four-quasiparticle isomeric states in these nuclei, together with their favored configurations. The most notable examples, among others, are Kπ = 20+ states in 266-268DS and 268,270Cn having very high K value, relatively low excitation energy, and well-deformed axially symmetric shape. The predicted isomeric states, with hindered spontaneous fission and a decay, could play a significant role in the future study of superheavy nuclei. [ABSTRACT FROM AUTHOR]

We study weakly bound deformed nuclei based on the coordinate-space Skyrme Hartree-Fock-Bogoliubov (HFB) approach, in which a large box is employed for treating the continuum and large spatial extensions. When the limit of the core-halo deformation decoupling is approached, calculations found an exotic "egg"-like structure consisting of a spherical core plus a prolate halo in 38Ne, in which the near-threshold nonresonant continuum plays an essential role. Generally the halo probability and the decoupling effect in heavy nuclei can be hindered by high level densities around Fermi surfaces. However, deformed halos in medium-mass nuclei are possible as the negative-parity levels are sparse, e.g., in 110Ge. The deformation decoupling has also been demonstrated in pairing density distributions. [ABSTRACT FROM AUTHOR]

Using a new local cluster potential, cluster structures around double shell closures have been investigated. The calculations of spectra including electromagnetic transitions are in reasonable agreement with experimental data. Besides the nuclei, 20Ne, 44Ti, 60Zn, and 212Po, which have been intensively analyzed by cluster models, we have also studied two other good candidates, 52Ti and 136Te, for α-cluster structure in neutron-rich regions. In 136Te, the unexpectedly small B(E2;0+ 2+) would be due to the cluster characteristic. The new cluster potential without any readjustment of the parameter values has been also applied to the investigations of possible 6He-cluster structure in nuclei, 22Ne, 46Ti, 54Ti, 62Zn, and 138Te, which have the same doubly magic cores as the α-cluster nuclei above. Similarly good results can be obtained, compared with experimental data. It is an advantage that the new cluster potential suits the different types of cluster structures with a set of fixed parameters which do not need any readjustment for different cluster-core structures. [ABSTRACT FROM AUTHOR]

Total-Routhian-surface calculations by means of the pairing-deformation-frequency self-consistent cranked shell model have been carried out for even-even germanium and selenium isotopes to search for possible stable triaxial deformations of nuclear states. The maximum triaxiality of |γ| = 30° is found in the ground and excited rotational states of the nuclei 64,74Ge. The calculations are compared with available experimental data, giving a general agreement with observed triaxiality in the isotopes. [ABSTRACT FROM AUTHOR]

A single-folding (SF) model analysis has been performed for α and deuteron elastic scattering from 58Ni, 90Zr, 116Sn, and 208Pb at incident energies between 10 and 100 MeV/nucleon with the Lane-consistent Bruyères Jeukenne-Lejeune-Mahaux model nucleon-nucleus potential. The energy dependence of a set of only three potential parameters was derived, and the resulting global optical model potentials were found to account well for α and deuteron elastic scattering within their studied energy ranges. The energy dependence of a real potential form factor is found to be important for describing α-nucleus scattering within large energy ranges. Corrections due to the compositeness of projectiles to the SF potentials were studied and were compared with theoretical estimations through the renormalization factor. Systematic differences in renormalization factors between α particles and deuterons were observed. [ABSTRACT FROM AUTHOR]

The neutron-rich zirconium isotopes are a key testing ground for nuclear models due to their sensitivity to shape changes, and because they cross the r-process path of explosive nucleosynthesis. Furthermore, recent experimental data have revealed a high-spin isomer in l08Zr. Here we report the results of configuration-constrained potential-energy-surface calculations of ground states and high-K states in 104-110Zr, restricted to quadrupole and hexadecapole shapes. These calculations enable the existing isomer data to be understood, and predictions are made for 110Zr. [ABSTRACT FROM AUTHOR]

Background: Nuclear collective rotations have been successfully described by the cranking Hartree-Fock- Bogoliubov (HFB) model. However, for rotational sidebands which are built on intrinsic excited configurations, it may not be easy to find converged cranking HFB solutions. The nonconservation of the particle number in the BCS pairing is another shortcoming. To improve the pairing treatment, a particle-number-conserving (PNC) pairing method was suggested. But the existing PNC calculations were performed within a phenomenological one-body potential (e.g., Nilsson or Woods-Saxon) in which one has to deal the double-counting problem. Purpose: The present work aims at an improved description of nuclear rotations, particularly for the rotations of excited configurations, i.e., sidebands. Methods: We developed a configuration-constrained cranking Skyrme Hartree-Fock (SHF) calculation with the pairing correlation treated by the PNC method. The PNC pairing takes the philosophy of the shell model which diagonalizes the Hamiltonian in a truncated model space. The cranked deformed SHF basis provides a small but efficient model space for the PNC diagonalization. Results: We have applied the present method to the calculations of collective rotations of hafnium isotopes for both ground-state bands and sidebands, reproducing well experimental observations. The first up-bendings observed in the yrast bands of the hafnium isotopes are reproduced, and the second up-bendings are predicted. Calculations for rotational bands built on broken-pair excited configurations agree well with experimental data. The band-mixing between two Kπ = 6+ bands observed in l76Hf and the K purity of the l78Hf rotational state built on the famous 31 yr Kπ = 16+ isomer are discussed. Conclusions: The developed configuration-constrained cranking calculation has been proved to be a powerful tool to describe both the yrast bands and sidebands of deformed nuclei. The analyses of rotational moments of inertia help to understand the structures of nuclei, including rotational alignments, configurations, and competitions between collective and single-particle excitations. [ABSTRACT FROM AUTHOR]

The spectroscopy of 73Ge has been investigated via the 70Zn(7Li,3np) 73Ge fusion-evaporation reaction. A previously known band built on the v(f5/2) orbital is extended up to higher-spin states and a new rotational band built on the v(g9/2) orbital is established. The observed band crossing and shape evolution induced by the alignment in 73Ge are studied in comparison with the similar structures in the neighboring N = 41 isotones and the cranked Woods-Saxon-Strutinsky calculations by means of total-Routhian-surface (TRS) methods. The inversion of the order of the g9/2 neutron and the g9/2 proton crossing frequency observed in the negative-parity v(f5/2) bands between 73Ge and 75Se, 77Kr can be ascribed to their different triaxial deformations. At higher spins, both the v(f5/2) and v(g9/2) bands in 73Ge undergo a shape evolution with sizable alignments occurring. The characters of large signature splitting in v(g9/2) band of 73Ge are discussed. [ABSTRACT FROM AUTHOR]

Background: The previously reported levels assigned to 151,152,153pr have recently been called into question regarding their mass assignment. Purpose: We clarify the above questioned level assignments by measuring γ transitions tagged with A and Z in an in-beam experiment in addition to the measurements from 252Cf spontaneous fission (SF) and establish new spectroscopic information from N = 84 to N = 94 in the Pr isotopic chain. Methods: The isotopic chain 143-153pr has been studied from the spontaneous fission of 252Cf by using Gammasphere and also from the measurement of the prompt y rays in coincidence with isotopically identified fission fragments using VAMOS++ and EXOGAM at Grand Accelerateur National d'Ions Lourds (GANIL). The latter were produced using 238U beams on a 9Be target at energies around the Coulomb barrier. The γ-γ-γ-γ data from 252Cf (SF) and those from the GANIL in-beam A- and Z-gated spectra were combined to unambiguously assign the various transitions and levels in 151,152,153Pr and other isotopes. Results: A band of 3 new transitions added to the known level in 145Pr, 9 new transitions in two new bands in 147Pr, 6 new transitions in a new level scheme for 148Pr, two new bands with 17 new transitions in 149Pr, and two new bands with 11 new transitions in 150Pr were identified by using γ-γ-γ and γ-γ-γ-γ coincidences and A and Z-gated γ-γ spectra. The transitions and levels previously assigned to 151,153Pr have been confirmed by the (A,Z)-gated spectra. Small changes have been made to their original level schemes. The transitions previously assigned to 152Pr are now assigned to 151Pr on the basis of the (A,Z)-gated spectra. Two new bands with 20 new transitions in 152Pr and one new band with 7 new transitions in 153Pr are identified from the γ-γ-γ-γ coincidence spectra and the (A,Z)-gated spectrum. In addition, new γ rays are also reported in 143,146Pr. Conclusions: New levels of 145,147-153pr have been established, reliable mass assignments of the levels in 151,152,153pr have been given in the present work, and new transitions have been identified in 143-146Pr showing the new avenues that are opened by combining the two experimental approaches. [ABSTRACT FROM AUTHOR]

For a shape-soft nucleus, the deformation change with increasing angular momentum of rotation can be significant. Total-Routhian-surface (TRS) calculations include the shape changes, but angular momentum is not conserved (neither is it a good quantum number, nor is it kept unchanged in the whole TRS mesh). In the projected shell model (PSM), the angular momentum appears as a good quantum number, but calculations have usually been performed with fixed deformation. In the present work, by performing angular-momentum projection on the mean-field potential-energy surface (PES), we can obtain an angular-momentum-conserved PES which gives deformation for a rotational state at a given spin. In order to investigate the shape-changing effect, we have chosen neutron-deficient Hg and Pb isotopes in which shape coexistence occurs. We interpret the irregular rotational behavior of the oblate bands at low spin as arising from deformation changes which are induced by collective rotation. At higher spin, the oblate rotational spectrum can also be influenced by the crossing between the K = 0 ground-state band and a low-AT two-quasineutron band. Calculated g factors for the states of oblate bands are given for future experimental testing, and the intrinsic structures of high-A" oblate states are investigated. [ABSTRACT FROM AUTHOR]

An inelastic excitation experiment was performed with a 12Be beam at 29 MeV/u on a carbon target. New resonances close to the respective cluster separation thresholds were observed in 12Be for the 4He + 8He and 6He + 6He decay channels, confirming the previously proposed molecular rotational bands. Using the model-independent angular correlation analysis, a 0+ spin parity is assigned to the remarkably large peak at 10.3 MeV in the 4He + 8He channel. A distorted wave Born approximation (DWBA) calculation was compared to the experimental differential cross section of this state, resulting in a largely enhanced monopole transition matrix element of 7.0 ± 1.0fm², in good agreement with the generalized two-center cluster model (GTCM) prediction assuming a preformed α-4n-α configuration. Together with the previously reported large cluster spectroscopic factor, the strong clustering in 12Be is well demonstrated. The detection focused on the most forward angles, by using a zero-deg telescope, is essential in the present measurement. [ABSTRACT FROM AUTHOR]

The Gamow-Teller (GT) strength distributions and isobaric analog resonance (IAR) states of several N = Z + 2 nuclei with mass number A = 42 - 58 are studied by using a self-consistent Skyrme Hartree-Fock-Bogoliubov method plus quasiparticle random phase approximation (HFB+QRPA) formalism. The isoscalar spin-triplet pairing interaction is included in QRPA on top of the isovector spin-singlet one in the HFB method. It is found that the isoscalar pairing correlations mix largely the (νj> → πj<) configurations into the low-energy states, and this mixing plays an important role in the formation and in the collectivity of these low-energy states. Furthermore, the observed excitation energy of the low-energy GT state with respect to the IAR can be well reproduced when the strength of isoscalar pairing is about 1.0-1.05 times that of the isovector pairing, irrespective of the adopted Skyrme interactions. In N = Z + 2 nuclei in the middle of the pf-shell, a mutual cooperative effect of isoscalar pairing and tensor interaction is found; namely, the tensor force reduces the spin-orbit splittings and enhances the effect of the isoscalar pairing. [ABSTRACT FROM AUTHOR]

Based on the Hartree-Fock-Bogoliubov solutions in large deformed coordinate spaces, the finite amplitude method for the quasiparticle random-phase approximation (FAM-QRPA) has been implemented, providing a suitable approach to probing collective excitations of weakly bound nuclei embedded in the continuum. The monopole excitation modes in magnesium isotopes up to the neutron drip line have been studied with the FAM-QRPA framework on both the coordinate-space and harmonic oscillator basis methods. Enhanced soft monopole strengths and collectivity as a result of weak-binding effects have been unambiguously demonstrated. [ABSTRACT FROM AUTHOR]

We present a basis selection method for truncated shell-model calculations. In this method, the correlated basis is constructed with the eigenvectors of the Hamiltonian that is diagonalized in each partition of the shell model. A truncation scheme is established by naturally taking the low-lying correlated-basis vectors in different partitions, which is equivalent to the j j -coupling scheme of the shell model when all the correlated-basis vectors are considered. The results are compared with standard shell-model calculations. The convergence properties of the correlated-basis method are discussed. [ABSTRACT FROM AUTHOR]

The author discusses a basis selection method for the truncated shell-model calculations. Topics discussed include construction of correlated basis with eigenvectors of the Hamiltonian, establishment of truncation scheme by taking the low-lying correlated-basis vectors, and analysis of the convergence of wave functions. It adds that the correlated-basis scheme is equivalent to J J-coupling scheme.

The article discusses a study to determine a basis selection method for truncated nuclear shell-model calculations which is constructed using the eigenvectors of the Hamiltonian system. Topics discussed include application of interacting shell model in other quantum many-body systems such as quantum chemistry and atomic and molecular physics, calculation of wave function amplitudes, and determination of excitation energies for the study.

The article offers information on a study related to the use of correlated-basis selection method (CBSM) for calculation of truncated shell-model. Topics discussed include diagonal matrix elements of Hamiltonian matrix, convergence properties of CBSM and challenges of developing practical computational approaches. The study highlights the role of SBSM approach for description of other quantum body systems including quantum chemistry and molecular physics.

The article discusses the Correlated method for shell-model calculations. Topics discussed include constructing the wave function as a linear superposition of all possible antisymmetric Slater determinants , presenting a basis selection method for the nuclear shell model, and diagonalizing the Hamiltonian in each partition.

The article presents brief information on correlated-basis method for shell-model calculations. It discussed that the correlated basis is constructed with the eigenvectors of the Hamiltonian that is diagonalized in each part of the nuclear shell model. Information on amplitude distributions of the ground-state wave function of Silicon isotopes is also offered.

The high-spin spectroscopy of 144Tb has been studied via 116Sn(32S, 3n1p)144Tb fusion-evaporation reaction at a beam energy of 156 MeV. A dipole band built on the πh311/2³ ⊗ νh11/2-1 configuration is newly observed in 144Tb. Together with similar observation in neighboring nuclei, the properties of dipole bands in N = 79 isotones are investigated in terms of the self-consistent tilted-axis-cranking covariant density functional theory. Based on systematic comparison and examination of the shears mechanism, the dipole band in 144Tb can be interpreted as a magnetic rotational band. [ABSTRACT FROM AUTHOR]

A rotational band was observed for the first time in 106Nb by means of y-y-y and y-y-y-y measurements of prompt fission y rays from 252Cf by using the Gammasphere multidetector array. Projected shell model and potential-energy surface calculations were performed and were compared to the experimental data of l06Nb and the previously reported 104Nb. Configurations and spin-parity were assigned to the ground level, low-lying levels, and rotational bandheads of the two Nb isotopes. The new rotational band in l06Nb was interpreted as a Kπ = 2- band with a configuration π 1 /2+ [431 ] x i>5/2-[532]. The same spin-parity and configuration were assigned to the analogous band in 104Nb. πl/2+[431] × V5/2+[413], Kπ = 3+ were assigned to the 0.66-μS isomer and explained the M² isomeric decay to the ground in 106Nb. The proton intruder orbital &#960r;l/2+[431] plays an important role in shape evolution with regard to triaxial deformation in these neutron-rich Nb isotopes. [ABSTRACT FROM AUTHOR]

The neutron-rich nucleus n2Rh has been reinvestigated by examining the prompt γ rays emitted in the spontaneous fission of 252Cf with the Gammasphere detector array. A new side band was built in 112Rh. Total Routhian surface calculations have been performed and confirm the role of triaxiality in the negative-parity structure of 112Rh. [ABSTRACT FROM AUTHOR]

The spectroscopy of 157Yb has been studied via 144Sm(16O,3n)157Yb fusion-evaporation reaction. The properties of bands associated with the νi13/2 orbital and νh9/2 orbital in 157Yb are analyzed in comparison with the triaxial particle-rotor-model calculations. The characters of signature splitting for both positive-parity νi13/2 and negative-parity νh9/2 bands in 157Yb and heavier odd-A Yb isotopes are discussed. The newly observed bands 1 and 2 in 157Yb are suggested to be the signature partners of the νh9/2 band. A systematic study of the band crossing frequencies associated with the i13/2 neutron-pair and h11/2 proton-pair alignments for the Yb isotopes, as well as the Er and Hf isotopes, are made. [ABSTRACT FROM AUTHOR]

Deep-inelastic reactions and γ-ray spectroscopy have been used to study excited states in 195Au. A three-quasiparticle isomer with a mean-life of 18.6(3) µs has been assigned at 2461 + Δ keV, with decays into newly identified structures. Possible configurations for the isomer are discussed including a Jπ = 31/2- intrinsic state produced by coupling the 11/2- [505] proton hole to the 10+ state obtained from the 9/2+ [624], 11/2+ [615] two-neutron holes, expected from configuration-constrained potential-energy-surface calculations. Residual interactions are evaluated within a semi-empirical shell model basis. New lifetime information is also obtained for the 21/2+ and 25/2+ states at 1813 and 1980 keV. The relationship between these and other newly identified states and the negative-parity states in the even-even neighbors is discussed. [ABSTRACT FROM AUTHOR]

The high spin states .of 106Pd have been investigated with in-beam γ-ray spectroscopic methods using the l00Mo(11B, lp4n)106Pd reaction at a beam energy of 60 MeV. All earlier known bands were extended considerably and additional bands were identified. The configurations of these bands are discussed on the basis of the experimental aligned angular momenta and total Routhian surface calculations. Both two-quasineutron and two-quasiproton structures have been found in 106Pd. The nonyrast low-lying positive-parity band was interpreted as a γ-vibrational band. [ABSTRACT FROM AUTHOR]

The neutron-rich nuclei 109Pd and 111Pd were produced as fission fragments following the 30Si + l68Er reaction at 142 MeV. Using the identification based on the coincidences with the complementary fission fragments, the only positive-parity bands observed so far in l09Pd and 111Pd emerged from this work. A band, built on top of the 5/2+ ground state exhibiting Δ = 1 energy-level staggering, was observed in each of these nuclei. Both nuclei of interest, 109Pd and 111Pd, are suggested to lie in the transitional region of Pd isotopes of maximum y softness. The ground states of both nuclei are predicted by total Routhian surface calculations to be extremely y soft with shallow triaxial minima. The first crossing in the new bands is proposed to be attributable to an alignment of h²11/2 neutrons. [ABSTRACT FROM AUTHOR]

In-beam γ spectroscopy of the stable nucleus 127I has been studied experimentally using the 124Sn(7Li, 4nγ)127I reaction at a beam energy of 32 MeV. The high-spin level scheme of 127I is extended significantly. Negative-parity levels built on the 11/2-, πh11/2 particle state are observed up to (35/2-) and described as a decoupled band, extending our knowledge of decoupled structures to the most neutron-rich stable iodine isotope. Two ΔI = 2 yrast positive-parity sequences are proposed to be associated with the πg7/2 configuration due to observations of several strong interband transitions, and two weakly populated ΔI =2 positive-parity bands are newly identified and interpreted as arising mainly from the πd5/2 configuration. Three-quasiparticle configurations are assigned to the Iπ = 15/2+ and 23/2+ states according to the existing knowledge in neighboring nuclei; irregular noncollective and regular collective excitations built on these two (15/2+ and 23/2+) states are observed to coexist at similar energies. The observed three-quasiparticle band structures are further interpreted with the aid of configuration-constrained potential energy surface calculations. [ABSTRACT FROM AUTHOR]

The odd-odd neutron-rich nucleus 152Pr has been studied from the spontaneous fission of 252Cf with Gammasphere. A high-spin level scheme of 152Pr has been established for the first time. Angular correlation and internal conversion coefficient measurements are used to determine the transition multipolarities. The possible configurations of the bandhead have been discussed based on systematics and total Routhian surface calculations. [ABSTRACT FROM AUTHOR]

Excited states in 55V and 55Cr have been populated via pn and 2n evaporation channels, respectively, following the fusion of a 48Ca beam at 172 MeV with a 9Be target. Level schemes have been deduced for the two nuclides to excitation energies of 7467 (55V) and 12226 keV (55Cr), with spins of 27/2+ and 33/2+, respectively. Negative-parity states are compared with shell-model calculations using three different effective interactions in the full fp model space. Negative-parity levels of 55Cr are explained in terms of single-particle fp-shell configurations outside N = 28 and N = 32 cores. Positive-parity states in both isotopes show evidence for the involvement of neutron g9/2 configurations. In the case of 55Cr, a quasirotational structure based on the 1/2+[440] Nilsson orbital is observed up to the terminating state. In 55V, positive-parity states do not exhibit well-developed collective features, and the observation of octupole decays is an indication of their importance in transitions from neutron g9/2 configurations to the fp shell. Experimental results are compared with the predictions of a traditional shell model, the projected shell model, and total-Routhian-surface calculations. [ABSTRACT FROM AUTHOR]

Excited states in the stable nucleus 193Ir have been investigated through an in-beam γ-ray spectroscopic technique following the 192Os(7Li, α2n) reaction at a beam energy of 44 MeV. A level scheme built on the πh11/2 isomer has been extended to high-spin states using eleven newly observed γ transitions. The πh11/2 band is proposed to be formed by coupling an h11/2 proton to a core with large triaxial deformation. Three-quasiparticle states are suggested in 193Ir on referring to the similar states in 187Ir. The features of signature splitting in the πh11/2 bands of 187-193Ir are discussed with the help of total Routhian surface calculations. [ABSTRACT FROM AUTHOR]

Gamow-Teller (GT) and charge-exchange spin-dipole (SD) excitation energies in 90Zr and 208Pb are systematically studied to determine the appropriate magnitude of the tensor terms of the Skyrme interactions. We have found that the centroid energies of GT and SD excitations are sensitive to the adopted strengths of the triplet-even and triplet-odd tensor interactions. Especially, the 1- SD state plays a crucial role in constraining the triplet-even part while the triplet-odd part is related rather to the GT peaks. Among the 36 TIJ parameter sets that include nonperturbatively the tensor terms, the four sets, T21, T32, T43, and T54, give reasonable results for the centroid energies in comparison with the experimental data. The sign and magnitude of the tensor terms are also discussed when these terms are added to the existing Skyrme interactions SGII and SLy5. The triplet-even strength can be constrained in a narrow range by using the available experimental data while further empirical data are needed to set a constraint on the triplet-odd term. [ABSTRACT FROM AUTHOR]

High-spin states in 157Yb have been populated in the 144Sm(16O,3n)157Yb fusion-evaporation reaction at a beam energy of 85 MeV. Two rotational bands built on the vf7/2 and vh9/2 intrinsic states, respectively, have been established for the first time. The newly observed vf7/2 band and previously known vf3/2 band in 157Yb are discussed in terms of total Routhian surface methods and compared with the structures in the neighboring N = 87 isotones. The structural characters observed in 157Yb provide evidence for shape coexistence of three distinct shapes: prolate, triaxial, and oblate. At higher spins, both the vf7/2 band and ?i13/2 band in 157Yb undergo a shape evolution with sizable alignments occurring. [ABSTRACT FROM AUTHOR]

Corrections to article "High-spin states in 188Au: Further evidence for nonaxial shape," by Y. D. Fang and colleagues that was published in the 2010 issue are presented.