G.J. Lampard

Gyromagnetic ratios of excited states in 150Sm and 152Sm

Abstract The gyromagnetic ratios of the 2 1 + , 4 1 + , 6 1 + , 2 2 + , and 2 3 + states in 150 Sm and the 2 1 + , 4 1 + , 6 1 + , 8 1 + , 10 1 + , 2 2 + , and 2 3 + levels in 152 Sm have been measured using the transient field perturbed γ-ray angular correlation technique. States of interest were populated by multiple Coulomb excitation using 150- and 220-MeV 58 Ni beams. The present results display no significant deviation from constancy of the g -factors of all levels investigated in either isotope separately or of corresponding states in 150,152 Sm. These findings are compared with available prior measurements and assessed in terms of applicable theoretical model calculations.

Transient field measurements of g-factors in 194,196,198Pt; g(21+) systematics in transitional W, Os, Pt nuclei

Abstract Transient field precessions were measured simultaneously for levels in the nuclei 182,184,186 W and 1942,196,198 Pt as their ions traversed polarized Gd hosts. These results allow a critical evaluation of conflicting g -factor values reported previously for the even Pt isotopes. Mass variations of g (2 1 + ) in the even W, Os, Pt nuclei are examined using the proton-neutron interacting boson model (IBM-2). The measured g -factors depart from the simplest IBM-2 description perhaps due to Subshell effects and/or small contributions from non-collective configurations which cause the neutron boson g -factor to vary with mass.

Measured gyromagnetic ratios and the low-excitation spectroscopy of 197Au

Abstract Transient-field precessions were measured for levels in 197 Au and 182,184,186 W as their ions simultaneously traversed polarized Gd hosts. Gyromagnetic ratios were inferred for the positiveparity levels between, and including, the lowest 5 2 + and 11 2 + states in 197 Au. Lifetimes of several levels were determined using the Doppler-broadened lineshape technique, and multipole mixing ratios of a number of transitions were deduced from measured particle-γ-ray angular correlations. The measured static and dynamic electromagnetic moments are compared with the predictions of the weak-coupling core-excitation model and with those of the interacting boson-fermion model (IBFM), including its Spin(6) supersymmetry limit.

Spectroscopy of 155Gd following Coulomb excitation: Signature-independent M1 properties and evidence for octupole correlations

Abstract The spectroscopy of 155 Gd has been studied following Coulomb excitation. Gyromagnetic ratios were measured in the 3 2 − [521] ground-state band by the transient field technique and the identification of states up to spin 23 2 − in the ground-state band was confirmed by γ-γ coincidence measurements. Level lifetimes were deduced from Doppler broadened lineshapes; γ-ray branching intensities and multipolarity mixing ratios were determined from particle-γ-ray angular correlations. The population of a positive parity band (mainly 3 2 + [651] ) by E3 Coulomb excitation from the ground-state band provides evidence of octupole correlations. Particle-rotor model calculations were performed for the negative parity states. The spectroscopy is best described when the Coriolis interactions are attenuated by ≈50%.

Spectroscopy of 183W Measured magnetic moments and rotation-particle coupling

The gyromagnetic ratios of 6 excited levels in the lowest K = 12 and 23 bands of 183W were measured using the thin-foil transient-field technique. The level scheme was extended to spin 17−2 and multipole mixing ratios measured for several transitions. Detailed comparisons of the spectroscopic data on 183W with the rotation-particle coupling model show good agreement, but favour a Carlolis mixing strength much larger than predicted by previous Nilsson model calculations in which hexadecapole deformation was neglected.

Gyromagnetic ratios in the transitional nuclei 144,146,148,150Nd

Abstract The gyromagnetic rati1os of the first-excited 2 + levels in the even 144 – 150 Nd isotopes were measured using the thin-foil transient-field technique. A marked isotopic mass dependence of the g -factors obtained can be correlated with changes in the proton and neutron pairing gaps as the deformation increases. Results are compared with and discussed in terms of theoretical calculations, including the interacting boson model.

Magnetic moment measurements in 195Pt; a critical test of U(612) supersymmetry

The gyromagnetic ratios of excited states in 195Pt were measured using the thin-foil transient-field technique. The level scheme and level properties were also studied using γ-ray spectroscopy techniques following Coulomb excitation, largely confirming earlier work. The measured g-factors provide a sensitive, parameter-free test of the U(612) multi-j interacting boson-fermion supersymmetry model.

Systematics of gyromagnetic ratios of the 2+-1- states in even Ge isotopes

The relative gyromagnetic ratios of the 2t states in 70,72,74,76Ge were measured simultaneously by me ns of the thin-foil, perturbed y-r yngular distribution technique utilising the transient hyperfine field manifest t nuclei of Ge ions rapidly traversing polarised Fe. The states of interest were Coulomb excited using 75-MeV 34S projectiles incident upon natural element l Ge t rget. The present results re comp red with previously reported measurements and collective model expectations.

Gyromagnetic ratios of excited states in 103Rh

Abstract Transient-field precessions were measured simultaneously for levels in 103 Rh and the first 2 + states in even Pd isotopes as their ions traversed polarized Fe hosts, Gyromagnetic ratios were inferred for the negative-parity levels in 103 Rh up to an excitation energy of ∼1 MeV. E2/M1 multipolarity mixing ratios were determined and/or confirmed for some transitions from measured unperturbed particle-γ-ray angular correlations. The measured static and dynamic electromagnetic moments are compared with present interacting boson-fermion model (IBFM) calculations which reproduce the main features of the spectrum of both the positive- and negative-parity levels in 103 Rh below an excitation energy of ∼1 MeV.

Disparity in transient field characteristics for Au ions traversing Fe and Gd hosts through measurements ofg-factors in197Au

Transient field precessions were measured for levels in the nuclides of182,184,186W and197Au as their ions simultaneously traversed polarized Fe and Gd hosts. Consistent sets of gyromagnetic ratios were inferred for the lowest 5/2+ and 7/2+ states in197Au using these two ferromagnetic host media, provided that (i) the transient field for Au ions in Gd is calibrated using the W in Gd precessions (simultaneously measured) and, (ii) the transient field for Au in Fe is calibrated using the field strength and velocity dependence for Pt in Fe (previously measured). The presentg-factor results are: g(5/21+;197Au)=0.296±0.023, g(7/21+;197Au)=0.241±0.021, and g(5/21+;197Au)=1.2±0.2.