Description of proton-neutron mixed-symmetry states with Skyrme interaction

Starting from an effective Skyrme interaction we study the effects of the phonon-phonon coupling on the M1 transitions between quadrupole states. The finite rank separable approach for the quasiparticle random phase approximation is used. Choosing as an example the nucleus ⁹⁴Mo, we demonstrate an ability of the method to describe the properties of the low-lying states.     

Description of the properties of the low-lying energy states in 100Mo with IBM2

The properties of the low-lying energy states for the 100Mo isotope is investigated within the framework of the proton-neutron interacting model IBM2.By considering the relative energy of the d proton boson to be diferent from that of the neutron boson and taking into account the dipole interacting among like-boson LπLπand LνLν,the low-lying energy spectrum is reproduced well.Particularly,the relative position of the energies for 2+1,0+2,2+2 and 4+1states shifted correctly fit the experimental data.The electromagnetic properties,including the key observable B(E2)reduced transition branching ratios and the E2 reduced matrix elements of the experimental data,are well described.Our calculations show possible shape coexistence in the 100Mo nucleus.     

Microscopic description of the collective states in N = 70 isotones on the IBM basis

Low-lying collective quadrupole states in four N = 70 isotones are analyzed within interacting boson model (IBM1) using parameters calculated on the basis of a microscopic quasiparticle theory that considers variation of the superconducting and collective quadrupole properties with increasing excitation energies and spins.     

Microscopic description of mixed-symmetry states in nearly spherical nuclei

We adopt the quasiparticle-phonon model to investigate the phonon content and the proton-neutron symmetry of low-lying states recently discovered in nuclei around shell closure. The results are in overall agreement with experiments and consistent with the interacting boson model.     

Description of the Structural Properties of Low-Lying States in ^102Ru with IBM2

We describe the properties of low-lying states of ^102Ru within the framework of the proton-neutron interacting model IBM2. The theoretical predictions of the ground state, quasi-γ and quasi-β bands, and the ratios of the B（E2） transition strengths are reproduced very well. The structural properties of ^102Ru are identified in the parameters space of the interacting boson model （IBM2）. The characteristic feature of the energy spectrum structure exhibits that ^102Ru is very close to the critical point of Uπv（5）-Oπv（6） transition and towards Uπv（5） symmetry. The key sensitive quantities of the B（E2） branching ratio clearly indicate that ^102Ru is a primary Oπv（6） symmetry, while with a somewhat Uπv（5） symmetry. It is possible that the shape coexistence persists in ^102Ru, whereas the evident fingerprint of the shape coexistence has not been observed.     

Identification of mixed-symmetry states in an odd-mass nearly spherical nucleus

The low-spin structure of 93Nb has been studied using the (n,n'gamma) reaction at neutron energies ranging from 1.5 to 3 MeV and the 94Zr(p,2ngamma)93Nb reaction at bombarding energies from 11.5 to 19 MeV. States at 1779.7 and 1840.6 keV, respectively, are proposed as mixed-symmetry states associated with the pi2p(1/2)-1x(2(1),MS+,94Mo) coupling. These assignments are derived from the observed M1 and E2 transition strengths to the 2p(1/2)-1x(2(1)+,94Mo) symmetric one-phonon states, energy systematics, spins and parities, and comparison with shell model calculations.     

Monopole and dyon bound states in N = 2 supersymmetric Yang-Mills theories

We study the existence of monopole bound states saturating the BPS bound in N = 2 supersymmetric Yang-Mills theories. We describe how the existence of such bound states relates to the topology of index bundles over the moduli space of BPS solutions. Using an L² index theorem, we prove the existence of certain BPS states predicted by Seiberg and Witten based on their study of the vacuum structure of N = 2 Yang-Mills theories.     

Xe偶－偶同位素低激发态性质的IBM2描述

通过考虑同类核子相干对Ｓρ、Ｄρ间的四极相互作用，在ＩＢＭＺ中对Ｘｅ偶一偶同位素１１６Ｘｅ—１３２Ｘｅ的低激发态能谱和Ｅ２跃过几率进行了理论分析．计算结果有效地改善了ＩＢＭ中这些核的准γ带能谱的Ｓｔａａｓｅｒｉｎｇ现象，较精确地描述了实验观察到的低激发态的性质．     

High-spin states in the N=50 nucleus86Kr

The unreported platinum isotope,²⁰²Pt, has been identified for the first time byγ-ray measurement of chemically separated activities. The reaction²⁰⁴Hg(n, 2pn)²⁰²Pt was used to produce²⁰²Pt activity. The half-life of²⁰²Pt has been determined to be 43.6±15.2h.     

High-energy-resolution inelastic electron and proton scattering and the multiphonon nature of mixed-symmetry 2+ states in 94Mo

High-energy-resolution inelastic electron scattering (at the S-DALINAC) and proton scattering (at iThemba LABS) experiments permit a thorough test of the nature of proposed one- and two-phonon symmetric and mixed-symmetric 2+ states of the nucleus 94Mo. The combined analysis reveals the one-phonon content of the mixed-symmetry state and its isovector character suggested by microscopic nuclear model calculations. The purity of two-phonon 2+ states is extracted.     

Evolution of the N=50 shell gap energy towards 78Ni

Atomic masses of the neutron-rich isotopes (76-80)Zn, (78-83)Ga, (80-85)Ge, (81-87)As, and (84-89)Se have been measured with high precision using the Penning trap mass spectrometer JYFLTRAP at the IGISOL facility. The masses of (82,83)Ga, (83-85)Ge, (84-87)As, and 89Se were measured for the first time. These new data represent a major improvement in the knowledge of the masses in this neutron-rich region. Two-neutron separation energies provide evidence for the reduction of the N=50 shell gap energy towards germanium (Z=32) and a subsequent increase at gallium (Z=31). The data are compared with a number of theoretical models. An indication of the persistent rigidity of the shell gap towards nickel (Z=28) is obtained.     

Neutron halos in the excited states for N=127 isotones

Properties of the ground states and the excited states of N=127 isotones are investigated by using the nonlinear relativistic mean field theory with the interactions PK1. By analyzing the rms of proton and neutron, the single particle energies of valence nucleon and the density distributions of neutron, proton and the last neutron, it can be found that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in 209Pb. It is also predicted that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in 207Hg, 208Tl, 210Bi and 211Po.     

A microscopic explanation of the isotonic multiplet at N = 90 and of the F-spin multiplet in Dy-Hf

The N = 90 isotones of Nd, Sm, Gd and Dy, with almost similar deformed level structure and associated with X (5) symmetry, form the isotonic multiplet in Z = 50?C66, N = 82?C104 quadrant. This is explained microscopically in terms of the Nilsson level diagram. Using the Dynamic Pairing-Plus-Quadrupole model of Kumar-Baranger, the quadrupole deformation and the occupancies of the neutrons and protons in these nuclei in the Nilsson orbits have been calculated, which support the formation of N = 88, 90 isotonic multiplets. The existence of the F-spin multiplets, with almost identical spectra, recognized in earlier works, in Z = 66?C82, N = 82?C104 quadrant, is also explained microscopically in our study.     

Neutron halos in the excited states for N=127 isotones

Properties of the ground states and the excited states of N=127 isotones are investigated by using the nonlinear relativistic mean field theory with the interactions PK1. By analyzing the rms of proton and neutron, the single particle energies of valence nucleon and the density distributions of neutron, proton and the last neutron, it can be found that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in ²⁰⁹Pb. It is also predicted that there exists a neutron halo in the excited states of 3d5/2, 4s1/2 and 3d3/2 in ²⁰⁷Hg, ²⁰⁸Tl, ²¹⁰Bi and ²¹¹Po.     

Dynamics of localized states in N = 4 SUSY QM

A consistent approach is offered for investigating the temporal dynamics of localized states. It is based on exactly solvable quantum mechanical models with multi-well potentials and the associate propagators. The Hamiltonian states with multi-well potentials form an adequate basis for expanding wave packets (WP) of various types and degrees of localization. Special features of WP tunneling have been studied with due regard for all Hamiltonian states with symmetric and asymmetric potentials.     

Description of the shape evolution in the yrast states of 186Pt

¹⁸⁶Pt was tested in the framework of IBM-1 and the X(3) model. The results show that ¹⁸⁶Pt is located close to the shape phase transition point, but the B(E2) values little agree with the X(3) model. The shape evolution in the yrast states of ¹⁸⁶Pt is also discussed in detail. TRS calculation exhibits a flat bottomed potential at low spin states, but a relatively deep minimum at high spin states. It suggests that a shape evolution from vibrational mode to rotational mode happens in ¹⁸⁶Pt. The result is in agreement with the E-GOS calculation.