Spin Gyromagnetic Factors Research Articles

Numerical Analysis of the Ground-State Magnetic Moments of ${}^{143,145,147}{\rm{Sm}}$ Isotopes

The explanation of the ground state magnetic properties of odd-mass nuclei is very informative in understanding of the complex structure of the deformed nuclei. The ground-state magnetic moments of most of the odd-A deformed nuclei have been measured by various experimental studies and there are numerous studies in the literature. However, many of the theoretical studies on magnetic moments and spin polarization effects affecting them are far from explaining these measured values. In this paper, the magnetic moments and effective spin g factors of 143,145,147Sm isotopes in the lanthanides region of the periodic table were investigated within the framework of the Quasiparticle-Phonon Nuclear Model (QPNM) for the first time. Spin-spin interaction parameters (χ) were determined by comparing theoretical and experimental values of magnetic moments of the related isotopes and it was determined that these interactions were found to have an isovector character (q = -1). It has been observed that the ground-state structures of the studied isotopes are weakly affected by quasiparticlephonon interactions and the contribution of these interactions ( values) to the ground-state wave functions is quite small (around 0.01%). Theoretical explanation of the renormalization of spin gyromagnetic factor is one of the most important problems of nuclear structure physics. The results obtained in this study for the effective spin gyromagnetic factor also agree with the phenological value .

Effects of the isoscalar and isovector interaction on the ground-state magnetic moments of odd-mass 137–145Ce nuclei

A systematic study of the magnetic properties of deformed odd-neutron 137–145Ce isotopes using the microscopic quasiparticle phonon nuclear model (QPNM) has been presented. The QPNM includes residual spin–spin interaction in both isoscalar and isovector channels. The analysis shows that in the isoscalar channel contributions to the magnetic moment coming from the neutron and proton systems practically cancel out each other. On the other hand, in the isovector channel, the coherent contribution coming from the quasiparticle–phonon interactions leads to a spin polarization (core polarization), which is important for determination of the quenched spin gyromagnetic factors (gs). The quenched spin gyromagnetic factors so called [Formula: see text] have been found to range from [Formula: see text] to [Formula: see text] in the odd-mass 137–145Ce isotopic chain, which is similar to its phenomenological value ([Formula: see text] between [Formula: see text] and [Formula: see text]). By taking into consideration the core polarization effects, the available experimental data are satisfactorily reproduced with an accuracy of 0.01μN–0.1μN.

A theoretical investigation of the magnetic dipole moment of the ground- and excited-states below 600keV in well-deformed 183,185W, 185,187Re and 187,189Os

Magnetic dipole moments of the ground- and excited-states below 600[Formula: see text]keV in [Formula: see text]W, [Formula: see text]Re and [Formula: see text]Os nuclei have been systematically studied in the framework of a microscopic Quasiparticle Phonon Nuclear Model (QPNM) including an axially symmetric Wood–Saxon potential as a mean field and the residual spin–spin interaction. The obtained results of the magnetic moment, intrinsic [Formula: see text] factor and the effective spin gyromagnetic factor have been compared with the available experimental data and also with the calculations based on different approaches. It has been demonstrated that the QPNM reproduces reasonably well the recent experimental value of the ground-state magnetic moment and satisfactorily describes the measured magnetic moment of low-lying states below 600[Formula: see text]keV in these nuclei.

A theoretical study on the ground and low-energy magnetic dipole characteristics of 239Pu nucleus

A microscopic model analysis of the magnetic dipole (M1) properties of 239Pu nucleus, which is a fissile material not only used in nuclear weapons but also used in some nuclear reactors as a source of energy, has been performed. The microscopic formalism used in the study is based on the Quasiparticle Phonon Nuclear Model (QPNM) and includes an axially symmetric Woods-Saxon potential as a mean field, a spin-spin residual interaction as well as the symmetry-restoring forces for the rotational invariance of the Hamiltonian. The investigations have been carried out in two steps. Firstly, the theoretical value of the ground-state magnetic moment and quenching spin gyromagnetic factor have been determined and it has been found that the predicted magnetic moment show a good agreement with the experimental data. Secondly, the calculations of M1 transitions from ground- to excited-states have been carried out in the energy range 2-4 MeV. A satisfactorily good agreement is obtained from the comparison of the theoretical results with the experimental data for 2-2.5 MeV.

Magnetic properties of K = 1/2 states in deformed odd-mass nuclei

A method for calculation of the ground-state magnetic moment, effective spin gyromagnetic factors and rotational decoupling parameter of the K=1/2 states in deformed odd-mass nuclei has been described by using the concept of the Quasiparticle Phonon Nuclear Model (QPNM). The model includes a Woods-Saxon potential as a mean field with pairing correlations and the residual separable spin-spin force in both isovector and isoscalar channels. The method has been employed to investigate K=1/2 ground-state magnetic properties of 169Er, 167,169Tm, and 171Yb nuclei, as an example. It has been shown that two different quenched spin gyromagnetic factors, i.e., gsz(eff.) and gs+(eff.) have a significant effect on the magnetic properties of K=1/2 states in odd-mass nuclei. Whereas the first one is occurred due to the interaction between the valence nucleon and IπK=1+0 excitations of the core, second one is associated with the coupling of the valence nucleon to IπK=1+1 excitations of the core. The observed magnetic moments and the phenomenological value of gsz(eff.) for considered odd-mass nuclei have been reproduced very well by the calculations. The role of the isoscalar and isovector interactions on the magnetic properties of K=1/2 states in these nuclei has been also discussed.

Magnetic moments and g-factors in odd-A Ho isotopes**Supported by Scientific and Technological Research Council of Turkey (TUBITAK) (115F564)

The ground-state magnetic moment, gK factor and quenching spin gyromagnetic ratio have been calculated using the microscopic method based on the Quasiparticle Phonon Nuclear Model (QPNM) for 155−169Ho nuclei for the first time. It is shown that the residual spin-spin interactions are responsible for the core polarization, and because of the core polarization the spin gyromagnetic factors are quenched. By considering the core polarization effects, a satisfactory agreement is obtained for the computed ground state gK factor, which gives an intrinsic contribution to the magnetic moments. In order to assess the collective contribution to the magnetic moments, the rotational gyromagnetic factors gR have been also calculated within the cranking approximation using the single particle wave function of the axially symmetric Woods-Saxon potential. For the ground-state magnetic moments of odd-proton 155−165Ho nuclei, a good description of the experimental data is obtained with an accuracy of 0.01–0.1 μN. From systematic trends, the quenching spin gyromagnetic factor, gK factor and magnetic moment have also been theoretically predicted for 167,169Ho where there is no existing experimental data.

The ground-state magnetic moments of odd-mass Hf isotopes

Abstract In this paper the Quasiparticle-Phonon Nuclear Model (QPNM), based on QRPA (Quasiparticle Random Phase Approximation) phonons, has been utilized to investigate spin polarization effects on the groundstate magnetic properties such as intrinsic magnetic moment (g K) and effective spin gyromagnetic factor (g seff.) of odd-mass deformed 165–179Hf isotopes with K > 1/2. Investigations of the spin polarization effects of the even core on the magnetic moments show that the spin gyromagnetic factors (g s) of the nucleons in the nucleus differ noticeably from the corresponding values for free nucleons and that the spin-spin interactions play an important role in the re-normalization of g s factors of the odd-mass 165–179Hf isotopes. In addition, some theoretical predictions are presented for the magnetic moments of 165Hf, 167Hf, and 169Hf, whose ground state magnetic moments haven’t been experimentally determined yet.

GROUND STATE MAGNETIC PROPERTIES OF ODD NEUTRON DY ISOTOPES

Using the quasiparticle phonon nuclear model (QPNM) and taking into account the spin–spin interaction, the effects of the spin polarization on spin gyromagnetic factors (gs) as well as the intrinsic magnetic moments (gK) of the deformed odd neutron155-165Dy isotopes were studied. The calculated values of gsand gKare in fair agreement with the experiment as well as with other microscopic calculations. Our calculations indicated that because of the core polarization, the gsfactors of the nucleons in the nucleus reduce noticeably from its free nucleon value and the spin–spin interactions play an important role in the explanation of the quenching of the gsfactors. A very good reproduction of the phenomenological quenching of gsfactor from its free values [Formula: see text] is obtained for155-165Dy .

ODD NUCLEI, TIME-REVERSAL SYMMETRY BREAKING, AND MAGNETIC POLARIZATION OF THE EVEN-EVEN CORE

The addition of an extra nucleon to an even-even core generates, in most cases, a polarization of this core which is essentially due to a spin paramagnetic type of coupling. It is shown here that these results (which have been obtained so far only with the SIII Skyrme force) seems to be robust against the change of the Skyrme force parameters for the charge state corresponding to the added nucleon and somewhat less for the other charge state. The consequences drawn from calculations with the SIII force about the effect of the core polarization on the effective spin gyromagnetic factors, hold also for the two other Skyrme force parametrizations (SkM* and SLy4) considered here. A very good reproduction of the average phenomenological quenching of these factors from their free values, is also obtained. Finally, the rare cases where these rules do not hold are discussed.

Intrinsic g K factors of odd-mass 167–179Lu isotopes

In this paper, g K -factors of the intrinsic magnetic moments and effective spin gyromagnetic factors (g s eff ) of the 167–179Lu isotopes have been studied within the Tamm-Dancoff approximation (TDA) (Kuliev et al, Sov. J. Nucl. Phys. 9, 185 (1969)) by using a realistic potential such as Woods-Saxon potential for the first time. The effects of the spin-spin and spin-isospin interactions on magnetic moments were investigated. The results of the theoretical calculations are compared with the experimental data for related nuclei. The experimental values of g K and g s eff were computed from the observed magnetic moments (Georg et al, Eur. Phys. J. A3, 225 (1998)) using the spin matrix elements. The theoretical predictions for the g K factors exhibit good agreement with the experimental g K factors with increasing mass number A of the lutetium isotopes. The strongest influence of the neutron-proton spin interaction occurs at q = −1. Sufficient agreement between the calculated and the experimental values of g K is obtained for κ = (45/A) MeV and q = −1.

Magnetic properties of the υj15/2 intruder orbital in the superdeformed minimum of 197Pb

This work has established eight cross-talk transitions between the two signature partner superdeformed (SD) bands in 197Pb with the EUROBALL IV spectrometer. Directional correlations from oriented states measurements confirm the ΔI = 1 character of these transitions. The flat behaviour of the dynamical moment of inertia and the agreement between the experimental and microscopic HF+BCS values of (g K - g R)K/Q 0 suggest that the configuration of the SD bands is based upon the υ[752]5/2- neutron intruder orbital. The derived effective spin gyromagnetic factor g s eff is found to be not quenched, and is close to the theoretical g s free value.

Deuteron bremsstrahlung-weighted photonuclear sum rule.

The various contributions to the deuteron bremsstrahlung-weighted photonuclear sum rule ${\ensuremath{\sigma}}_{\mathrm{\ensuremath{-}}1}$ are analyzed. It is shown that the unretarded normal L=1 sum rule is model independent and that retardation, higher multipoles, and interaction effects are negligible. An accurate estimation of ${\ensuremath{\sigma}}_{\mathrm{\ensuremath{-}}1}$ is provided by the knowledge of the charge deuteron radius and of the spin gyromagnetic factors of the proton and of the neutron.

Intermediate coupling approach in the unified nuclear model: (II). Odd-mass molybdenum nuclei

The low-energy nuclear properties of the odd-mass molybdenum isotopes are investigated within the framework of the intermediate coupling approach in the unified nuclear model. The calculations are performed by assuming that either a last odd nucleon (particle or hole, having available to it several single-particle states or a system of nucleons (particles or holes), which can undergo excitations is coupled to the quadrupole vibrations of the doubly even core. Diagonalization of the resulting Hamiltonian yields the low-lying spectra as well as the eigenfunctions of the respective excited states. Excellent agreement is obtained with the recent experimental level structure when realistic values are chosen for the coupling strength and for the relative particle configuration state excitation energies. The eigenfunctions obtained are used to calculate the electromagnetic transition rates, which are also in good agreement with available experimental data when the free nucleonic values for the charge and spin gyromagnetic factor are used. However, when the static nuclear moments are calculated, it becomes necessary to introduce the concept of “effective” nucleonic values to fit the experimental data, Finally, the validity of the approximations used in the present analysis and the circumstances in which more extensive experimental investigations are needed are discussed.