Measured gyromagnetic ratios of individual excited states in the ground- and gamma-bands of166Er

The gyromagnetic ratios of levels up to the 10 ₁ ⁺ in the ground-state band and of the 2 ₂ ⁺ state in theγ-band of¹⁶⁶Er were simultaneously determined experimentally by means of the thin-foil, perturbedγ-ray angular distribution technique utilizing the transient hyperfine field manifest at nuclei of Er ions rapidly traversing polarized Fe. Beams of 220- and 160-MeV⁵⁸Ni projectiles were used to Coulomb excite the levels of interest. The present results are compared with the spin-dependencies ofg-factors of levels in the ground-band predicted by recent cranked Hartree-Fock-Bogoliubov calculations and with interacting boson model expectations which includeg-boson effects.     

Gyromagnetic ratios of the 4+ and 6+ rotational states of184W

The nuclear Larmor precession has been observed for the 2⁺, 4⁺ and 6⁺ rotational states of¹⁸⁴W in the hyperfine field of WFe by application of the TDPAC and the IPAC techniques. A carrier free radioactive source of^184m Re alloyed with high purity iron was used for all three measurements. From the Larmor precession observed in the 2⁺ state by TDPACω _L = 944(15) MHz and the knowng-factor the hyperfine fieldB _{300 K} ^hf (WFe)=?69.6(27)T was derived. The deviation from the result of a spin echo experiment with¹⁸³WFe extrapolated to room temperature may be caused by the Bohr-Weisskopf effect (hyperfine anomaly). IPAC measurements with the same sample polarized in an external magnetic field of 1.6T gave for the 4⁺ and 6⁺ rotational states: ω _L τ(4⁺)=0.0609(22) andω _L τ(6⁺)=0.00735(102). By use of experimentalB(E2)-values theg _R -factors were derived asg _R (4⁺)=+0.276(26) andg _R (6⁺)=+0.281(45). The directional correlation of the 537?384 keVγ-γ cascade has been analysed in terms of anE1/M2/E3 mixture for theK-forbidden 537keV transition. We obtained the mixing ratiosδ(M2/E1)=±0.086(16),δ(E3/E1)=?0.028(5) with the sign convention of Krane and Steffen.     

Tests of interacting boson model wave functions from measured gyromagnetic ratios of states in the even Os isotopes

The gyromagnetic ratios of the 2₁⁺, 2₂⁺, and 4₁⁺ states in ^188,190,192Os were experimentally measured. It is shown that the hamiltonians of standard interacting boson models (IBM-1 and -2) fit to level spectra and B(E2) rates fail to account for either the intra-nucleus or mass-dependent g-factor variations of these states in these Os isotopes.     

Multi-quasiparticle states in 184 W via multi-nucleon transfer

A multi-nucleon transfer reaction using an 850 MeV ¹³⁶Xe beam incident on a ¹⁹⁸Pt target was used to populate high-spin states in ¹⁸⁴W, 14 nucleons from the target. A 4-quasiparticle isomer with ns has been observed for the first time and its de-excitation through collective and intrinsic structures studied. The results are compared with predictions of blocked BCS Nilsson calculations. Observation of this metastable state completes the tungsten 4-quasiparticle isomer systematics from A = 176 to 186. Mapping out the most yrast 4-quasiparticle isomers in these even-even tungsten isotopes suggests the existence of a highly favoured state in ¹⁸⁸W, within reach of current experimental set-ups.Received: 14 October 2003, Revised: 14 November 2003, Published online: 18 May 2004PACS: 21.10.Tg Lifetimes - 23.20.Lv transitions and level energies - 27.70. + q      

Gyromagnetic ratios of excited states in186W

The gyromagnetic ratios of the 4 ₁ ⁺ , 6 ₁ ⁺ , and 2 ₂ ⁺ states in¹⁸⁶W were measured relative to that of the 2 ₁ ⁺ level by means of the transient field implantation perturbedγ-ray angular distribution technique. The nuclei in the states of interest were Coulomb excited using a beam of 220-MeV⁶³Cu projectiles and recoiled swiftly through a thin, polarized Fe foil. The present measurements yielded ratiosg(4 ₁ ⁺ )/g(2 ₁ ⁺ )=1.04±0.07,g(6 ₁ ⁺ )/g(2 ₁ ⁺ )=1.03 ±0.20 andg(2 ₂ ⁺ )/g(2 ₁ ⁺ )=0.63±0.13. The sizable disparity between the measuredg-factors of the ground- and excited-band is examined within the context of the interacting boson approximation model.     

Aligned bands and gyromagnetic ratios in 162,164Tm

High-spin states in ¹⁶²Tm and ¹⁶⁴Tm have been studied by ^152,154Sm(¹⁴N, 4n) reactions. Measurements of γ-rays, angular distributions and γγ-coincidences were performed using Ge detectors. In each isotope, two side bands are observed besides the yrast band, which are followed up to high-spin states. An interpretation of the experimental results is proposed in the framework of the cranked shell-model. Results on gyromagnetic ratios in the yrast band of a series of odd-N Tm nuclei are presented. Magnetic properties of the side bands are also discussed.     

Effective gyromagnetic ratios in odd Thallium isotopes

Effective gyromagnetic ratios in theM1 operator have been determined in odd Thallium isotopes. The analysis has been performed within the framework of the intermediate coupling model, taking into account penetration electron matrix elements in addition to static and dynamic magnetic dipole moments.     

Self-consistent calculation of phonon gyromagnetic ratios in 208Pb

Within the Theory of Finite Fermi Systems the gyromagnetic ratios g _L ^ph of all low-lying phonons in ²⁰⁸Pb are calculated. The input data, i.e., single-particle energies, single-particle wavefunctions, and the ph interaction are derived from the Energy Density Functional by Fayans et al. For the 3 ₁ ^? phonon which is the most collective state, the g _L ^ph value is close to the prediction of the collective Bohr-Mottelson (BM) model. Gyromagnetic ratios of other phonons that are included in our calculations, two 5^? states and six positive parity phonons, differ significantly from the BM model prediction.     

Noncollinear itinerant-electron magnets: ground- and excited states simulations

The Heisenberg model cannot uncritically be applied to itinerant-electron magnets, including those that show noncollinear order. Density functional theory is, therefore, generalized to apply to noncollinear itinerant-electron magnets. The appropriate Kohn-Sham equations are discussed and the total energy of Spiral Magnetic Order (SMO) is found to describe the ground states of those magnets that possess a high-moment to low-moment transition such as, e.g., INVAR. Concerning excited-states properties, the energy spectrum of transverse and longitudinal spin fluctuations can be estimated with the total energy of SMO and allows a determination of thermal properties of itinerant-electron magnets. As an example calculated results for bcc-Fe are discussed in detail and compared with experimental results. Furthermore, results for Co, Ni and FeCo are collected. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direct neutron scattering from 182W and 184W

Differential elastic and inelastic neutron scattering cross sections for ¹⁸²W and ¹⁸⁴W have been measured at incident energies 4.87 and 6.00 MeV. Cross sections for the first (0⁺, 2⁺, 4⁺, 6⁺), second (0⁺, 2⁺), and some higher excitations are presented. Angular distributions exhibit direct reaction characteristics, suggesting that compound cross sections for these states are small. This is supported by statistical-model calculations. Coupled-channel calculations of cross sections are made using a phenomenological deformed optical potential. Quadrupole and hexadecapole deformations have been searched to optimize fits. The necessity of introducing a β₆ deformation is investigated. Electric multipole transition matrix elements, used in the coupled-channel analysis, are obtained from the rotation-vibration model and the dynamic-deformation theory.     

Half-life measurements and gamma spectroscopy in the decay184Re m →184W

The half-lives of the intrinsic states at 1,285.8 and 1,502.2 keV in¹⁸⁴W have been measured in the decay of¹⁸⁴Re ^m to be 8.33±0.18Μs and 2.35±0.10 ns, respectively. These half-lives determine absolute gamma-ray transition probabilities of eight transitions and yield upper limits for three transitions. The decay scheme of¹⁸⁴Re ^m →¹⁸⁴W is improved through measurements of delayed gamma-ray spectra with a Ge(Li) detector. Spin and Nilsson model interpretations are discussed.     

Effective gyromagnetic ratios in a mixture of noble gases with artificial nuclear magnetization

The precession of nuclear magnetic moments for a noble gas in an external magnetic field upon the laser pumping of nuclear magnetization is considered. A shift of the nuclear magnetic resonance for a mixture of noble gases with different gyromagnetic ratios of nuclei is observed.     

Low-spin states of doubly odd 184Au

Low-spin states of ¹⁸⁴Au have been studied using the β⁺/EC decay of ¹⁸⁴Hg. γ-ray and conversion-electron singles spectra were recorded with ¹⁸⁴Hg mass-separated sources. For γ-γ-t and X-γ-t coincidence measurements, mercury nuclei were produced in the ¹⁴⁸Sm + ⁴⁰Ar reaction and transported by a He-jet system. The electron spectra were recorded from ¹⁸⁴Hg sources produced at ISOLDE. A level scheme of ¹⁸⁴Au including 48 transitions is proposed. The experimental results are interpreted in the frame of a semi-microscopic axial-rotor-plus-two-quasiparticle model developed in the context of the HF+BCS approximation.     

Topological photonic states in gyromagnetic photonic crystals: Physics,properties, and applications

Topological photonic states (TPSs) as a new type of waveguide state with one-way transport property can resist backscattering and are impervious to defects, disorders and metallic obstacles. Gyromagnetic photonic crystal (GPC) is the first artificial microstructure to implement TPSs, and it is also one of the most important platforms for generating truly one-way TPSs and exploring their novel physical properties, transport phenomena, and advanced applications. Herein, we present a brief review of the fundamental physics, novel properties, and practical applications of TPSs based on GPCs. We first examine chiral one-way edge states existing in uniformly magnetized GPCs of ordered and disordered lattices, antichiral one-way edge states in cross magnetized GPCs, and robust one-way bulk states in heterogeneously magnetized GPCs. Then, we discuss the strongly coupling effect between two co-propagating (or counter-propagating) TPSs and the resulting physical phenomena and device applications. Finally, we analyze the key issues and prospect the future development trends for TPSs in GPCs. The purpose of this brief review is to provide an overview of the main features of TPSs in GPC systems and offer a useful guidance and motivation for interested scientists and engineers working in related scientific and technological areas.     

Low-lying states of 184W and 184Os nuclei

The energy levels, transition energy, B （E2） values,intrinsic quadrupole moment Q₀ and potential energy surface for even-even ¹⁸⁴W and ¹⁸⁴Os nuclei were calculated using IBM-1. The predicted energy levels, transition energy, B（E2） values and intrinsic quadrupole moment Q₀ 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.     

The ground- and first-excited states of magnetopolarons in two-dimensional quantum dots for all coupling strengths

The ground- and first-excited state energies of a magnetopolaron in a two dimensional parabolic quantum dot are studied within a variational calculation for all coupling strength. The Lee-Low-Pines-Huybrecht variational technique that is developed previously for all coupling strength has been extented for polarons in a magnetic field. The dependence of the polaronic correction on the magnetic field and the confinement length is investigated. The polarization potential and the renormalized cyclotron masses as a function of electron-phonon coupling strength and the strength of both confinement potential and magnetic field are also studied within the same approach. Received 16 December 2002 / Received in final form 14 April 2003 Published online 4 June 2003 RID="a" ID="a"e-mail: kandemir@science.ankara.edu.tr     

The scattering of fast neutrons from W184

Neutrons with energies of 0.3 to 1.5 MeV are scattered from W¹⁸⁴. Pulsed-beam fast time-of-flight techniques including a magnetic bunching system are utilized to resolve the elastically scattered neutrons from those inelastically scattered. The differential elastic cross section is measured at 50 keV intervals with an ≈20 keV incident neutron energy spread. The differential cross sections for inelastic scattering resulting in the excitation of residual nuclear levels at 111±5, 365±10, 690±40, 900±25, 1000±30, and 1120±30 keV are determined. In all instances the inelastically scattered neutrons are emitted, within experimental error, isotropically. The experimental results are compared with those obtained in previous work and with the predictions of theory.