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

The QPNM equations are derived taking account of p-h and p-p interactions. The calculated quadrupole, octupole and hexadecapole vibrational states in¹⁶⁸Er,¹⁷²Yb and¹⁷⁸Hf are found to be in reasonable agreement with experimental data. It is shown that distribution of theEλ strength in some deformed nuclei differs from the standard one. There are cases when for a givenK ^π theEλ 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.     

Calculation of excited molecular states taking account of partial relaxation of the core

Effects of electron-core relaxation in the excitation of atomic systems are considered. A new approach to the consideration of relaxation is proposed, and the corresponding equations are obtained. In the -electron approximation, the first excited states of some organic molecules are calculated by the V^(N–1)-potential method, the Morokuma-Iwata method, and a method proposed in the present work.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 55–59, October, 1985.     

Are there low-lying,intrashell-excited,highly deformed states in the 1f-2p shell nuclei?

It is shown that the improved effective interactions in the fp shell imply the existence of an excited band of states which is much more deformed than the ground state band for some fp shell nuclei. Such states are to a certain extent analogous to the fission isomers occurring in heavy nuclei. Their experimental identification would be interesting and might also help to further improve the effective interaction.     

Regular and chaotic vibrations of deformed nuclei with increasing gamma rigidity

We study classical trajectories corresponding to L=0 vibrations in the geometric collective model of nuclei with stable axially symmetric quadrupole deformations. It is shown that with increasing stability against the onset of triaxiality the dynamics passes between a fully regular and semiregular limiting regime. In the transitional region, an interplay of chaotic and regular motions results in complex oscillatory dependence of the regular phase space on the Hamiltonian parameter and energy.     

Description of the low-lying negative parity states in153Gd

To explain the properties of the recently observed negative parity states in the 89-neutron nucleus¹⁵³Gd, the Nilsson model is extended to include the Coriolis couplings between the 3^?/2 [521], 5^?/2 [523], 3^?/2 [532], 1^?/2 [530], 1^?/2 [510], 1^?/2 [521] and 5^?/2 [512] bands. The calculation reproduces rather well the experimental level energies, single neutron transfer cross sections and electromagnetic transition rates.     

Description of low-lying vibrational and two-quasiparticle states in164Dy

The calculation with the deformed Woods-Saxon potential and residual interaction allowing for a twophonon admixture of the quadrupole, octupole and hexadecapole vibrational and two-quasiparticle states in¹⁶⁴Dy have been made. The calculated excitation energies and B(E; =2, 3, 4) values are found to be in reasonable agreement with experimental data. The calculated 0⁺ states in¹⁶⁸Er do not contradict experimental data. It is shown that the wave functions of states with energies below 2.3 MeV have dominating one-phonon components.     

Properties of the lowest states in the odd-odd160Tm and160Tm nuclei

Detailed study of the lowest states in the odd-odd¹⁶⁰Tm and¹⁶²Tm deformed nuclei and of corresponding electromagnetic transitions has been performed. In the theoretical analysis, performed within the framework of the two-quasiparticle + rotor model, the nondiagonal matrix elements of the residual p-n interaction have been included. Comparison of calculated energies and reduced transition probabilitiesB(XL) with experimental ones have proved importance of these matrix elements in the model calculations. More complex interpretation of the lowest states in both Tm nuclei has been achieved although some ambiguity has not been removed.     

High spin states in the transitional odd-odd nuclei150Eu and152Tb

Zeitschrift für Physik A Hadrons and nuclei - The (7Li, 5n) and (11B, 5n) reactions have been used to study the high-spin states in the two odd-odd nuclei150Eu and152Tb. Three decoupled bands...     

Nuclear vibrations and rotations of like nucleons in the same shell in even-even nuclei

The vibrational and rotational motions in even nuclei are considered. A microscopic study of these motions leads to a relation between the vibrational motion in spherical nuclei and the rotational motion in deformed nuclei. Nuclei with like nucleons in the same shell are considered. The quadrupole two-body interactions are used in the large singlej-shell of even nuclei. The energies and transition operators of nuclei in the nuclear rotational region are calculated using this microscopic method. Quadrupole moments are also calculated. These calculations are compared with the rotational model of the aligned coupling scheme. The present calculations are in good agreement with previous calculations.     

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.     

Systematics of low-lying octupole states in the doubly-even nuclei from Ge to Sr

Low-lying octupole states of doubly-even ^78–86Kr isotopes have been studied with inelastic scattering of 51.9 MeV protons. It is shown that in the doubly-even nuclei from Ge to Sr with N = 42–50, the lowest octupole vibrational energies of nuclei with equal neutron excess are almost the same. The transition strengths of these states increase with Z.     

Inelastic electron scattering from low-lying states in the nuclei 36Ar and 40Ar

The low-lying level structure of ³⁶Ar and ⁴⁰Ar has been investigated using the technique of inelastic electron scattering. Data were collected at the National Bureau of Standards Linear Accelerator with incident electron energies between 65 and 115 MeV and scattering angles of 92.5° and 110°. The data span a range of momentum transfer squared between 0.29 and 0.92 fm^?2. Tassie model and Helm model analyses have been applied to data for levels at 1.97 and 4.18 MeV in ³⁶Ar and at 1.46, 2.52, 3.21 and 3.68 MeV in ⁴⁰Ar. A 2⁺ assignment to the 3.21 MeV state in ⁴⁰Ar is suggested. Transition strengths, transition radii, and mean lifetimes for these states are computed and compared with results of previous experiments.     

Nucleon states of strongly deformed nuclei and dinuclear systems in the nonoscillator two-center model

A new method for numerically solving the Schrö dinger equation for an arbitrary axisymmetric field with allowance for spin-orbit interaction is used to study neutron and proton states in strongly deformed nuclei and dinuclear systems produced at the first step of the fusion of nuclei. A quadrupole-octupole parametrization is proposed for the shape of a dinuclear system and for the potential energy of nucleons in this system. The experimentally observed deformations of the ^26,27,28Mg nuclei and the difference in the cross sections for the fusion of nuclei in the ¹⁸O + ⁵⁸Ni and ¹⁶O + ⁶⁰Ni systems are explained qualitatively.     

Non-linear vibrations of three-layer beams with viscoelastic cores I. Theory

Approximate equations of motion are developed for large amplitude motions of three-layer axially restrained unsymmetrical beams with viscoelastic cores. The external force consists of a constant plus an oscillatory term. The combination of this form of forcing and the large amplitude motions cause the beam to respond at multiples of the forcing frequency. This can lead to difficulties in the complex modulus approach to viscoelasticity. These are overcome here through use of hereditary integrals and their relationships with complex moduli. Theoretical results on the frequency response of clamped, symmetrical beams are compared with earlier experimental work. On the whole, reasonable agreement is found.     

Microscopical structure of the states of deformed nuclei in the neighborhood of the yrast line

A simple model is derived which allows one to study the structure of the nuclear states in the neighborhood of the “yrast” band. In the present scheme the precession motion plays a role of one of the normal modes of oscillations. (The structure of the dispersion equation for this mode corresponds to the well known classical formula.) Vibrational states associated with quadrupole oscillations of the nuclear shape are determined from a general equation. At slow rotation this equation breaks up into the known equations for β-, Δ- and γ-vibrations and non-collectivized K^π = 1⁺ excitations.