g factor

[paper] Structure of the Sr-Zr isotopes near and at the magic N=50 shell from g-factor and lifetime measurements in8840Zr and 84,86,8838Sr

Structure of the Sr-Zr isotopes near and at the magic N=50 shell from g-factor and lifetime measurements in8840Zr and 84,86,8838Sr

G. Kumbartzki et al.

doi: 10.1103/PhysRevC.85.044322

Background: The evolution of and interplay between single-particle and collective excitations in the 40 ⩽N⩽ 50 range for 38Sr and 40Zr isotopes have been studied.

Purpose: Measurement of the g factor of the 21+ and 41+ states in radioactive 88Zr while simultaneously remeasuring the g(21+) factors in the Sr isotopes and extention of the measurements to higher energy states in the Sr isotopes. Lifetimes of states in these nuclei are determined.

Methods: The transient field technique in inverse kinematics and line-shape analysis using the Doppler-shift attenuation method are applied. The 88Zr nuclei were produced by the transfer of an α particle from the 12C nuclei of the target to 84Sr nuclei in the beam. The excited states in the stable 84Sr isotopes were simultaneously populated via Coulomb excitation by 12C in the same target. Coulomb excitation measurements on 86,88Sr were carried out with the same apparatus.

Results: The resulting g factors and B(E2) values of these nuclei reveal similarities between the two chains of Zr and Sr isotopes. Large-scale shell-model calculations were performed within the p3/2, f5/2, p1/2, g9/2 orbital space for both protons and neutrons and yielded results in agreement with the experimental data.

Conclusions: In this paper the magnetic moments and lifetimes of several low-lying states in 88Zr and 84,86,88Sr have been measured and compared to large-scale shell-model calculations.

[paper] First g(2+) measurement on neutron-rich 72Zn, and the high-velocity transient field technique for radioactive heavy-ion beams

First g(2+) measurement on neutron-rich 72Zn, and the high-velocity transient field technique for radioactive heavy-ion beams

E. Fiori et al.

doi: 10.1103/PhysRevC.85.034334

The high-velocity transient-field (HVTF) technique was used to measure the g factor of the 2+ state of 72Zn produced as a radioactive beam. The transient-field strength was probed at high velocity in ferromagnetic iron and gadolinium hosts using 76Ge beams. The potential of the HVTF method is demonstrated and the difficulties that need to be overcome for a reliable use of the TF technique with high-Z, high-velocity radioactive beams are revealed. The polarization of K-shell vacancies at high velocity, which shows more than an order of magnitude difference between Z=20 and Z=30 is discussed. The g-factor measurement hints at the theoretically predicted transition in the structure of the Zn isotopes near N=40

[paper] g factor of the 21+ state of 168Hf

g factor of the 21+ state of 168Hf

A. Wolf et al.

doi: 10.1103/PhysRevC.85.037304

The g factor of the 21+ state of 168Hf was measured using the perturbed angular correlation technique in a static external magnetic field. The result, g(21+)=0.17(3), is discussed in relation to the systematics of the previously reported g factors in the Hf isotopes and compared to the predictions of several models. An interesting outcome of the analysis presented in this paper has to do with the relatively small result for the g factor. This indicates that in the Hf isotopes, a minimum in the g(21+) dependence on N occurs at N≤98 and not at midshell, as expected from IBA-2 or large-scale shell-model calculations. The pairing plus quadrupole model of Kumar and Baranger predicts a minimum at N=98 and gives the best description of the experimental data. The present result clearly shows the importance of g-factor measurements in “fine-tuning” among different models.

[paper] Measurement of the 96Ru g(41+) factor and its nuclear structure interpretation

Measurement of the 96Ru g(41+) factor and its nuclear structure interpretation

D.A. Torres et al.

doi: 10.1103/PhysRevC.85.017305

Background: The experimental study of g(I>2) factors of nuclear states can provide information about the evolution of collectivity in certain regions of the nuclear chart, and assist in obtaining a microscopic description of the nuclear wave functions. The measurements and explanations of g(I>2) factors are still a challenge for experiments and theory.

Purpose: Measurement of the g(21+) and g(41+) factors, the latter for the first time, in the 9644Ru nucleus. Comparison of the experimental results with calculations using the shell model and collective models.

Methods: The experiments made use of the transient field technique, using a Coulomb-excitation reaction in inverse kinematics. Large scale shell model calculations were performed; comparisons with previous theoretical predictions, using the tidal-wave model and the hydrodynamical model, were carried out.

Results: The values of g(21+)=+0.46(2) and g(41+)=+0.58(8) were experimentally obtained. While the g(21+) value agrees with the hydrodynamical model prediction of g=Z/A=+0.46, the g(41+) is in agreement with the shell model predictions. The trend of the experimental g factors, as a function of nuclear spin, is not reproduced by the theoretical models discussed.

Conclusions: Measurements of g(21+) and g(41+) in 96Ru were performed. Further theoretical efforts are necessary to explain the trend of the g factors as a function of nuclear spin for the 96Ru nucleus. Future measurements of g(41+) should reduce the uncertainty of the result.

[paper] First g-factor measurements of the 21+ and the 41+ states of radioactive 100Pd

First g-factor measurements of the 21+ and the 41+ states of radioactive 100Pd

D.A. Torres et al.

doi: 10.1103/PhysRevC.84.044327

The g factors of the first 2+ and 4+ states of the radioactive 100Pd nucleus have been investigated for the first time, using an α-particle transfer reaction from 12C to 96Ru. The transient magnetic field technique in inverse kinematics was used. The 10046Pd54 nucleus is a suitable candidate for studying single-particle proton and neutron effects in the nuclear wave functions near the N=Z=50 shell closures. The results are discussed within the frameworks of both large-scale shell-model calculations and collective-model predictions.

[paper] Gyromagnetic factors in 144-150Nd

Gyromagnetic factors in 144-150Nd

A. Giannatiempo

doi: 10.1103/PhysRevC.84.034319

The U(5) to SU(3) evolution of the nuclear structure in the even 144-156Nd isotopes has been investigated in the framework of the interacting boson approximation (IBA-2) model, taking into account the effect of the partial Z=64 subshell closure on the structure of the states of a collective nature. The analysis, which led to a satisfactory description of excitation energy patterns, quadrupole moments, and decay properties of the states (even when important M1 components were present in the transitions), is extended to the available data on g factors, in 144-150Nd. Their values are reasonably reproduced by the calculations.

[paper] Magnetic moments of the first excited 2+ states in the semi-magic 112,114,116,122,124Sn isotopes

Magnetic moments of the first excited 2+ states in the semi-magic 112,114,116,122,124Sn isotopes

J. Walker et al.

doi: 10.1103/PhysRevC.84.014319

The g factors of the first excited 2+ states in the 112,114,116,122,124Sn isotopes have been measured with high accuracy using the transient field technique in combination with Coulomb excitation in inverse kinematics. The experimental results are discussed in a qualitative way on the basis of empirical single-particle g factors of the relevant proton and neutron orbitals and are compared to a number of different theoretical calculations. The results are found to be best described by shell-model calculations in an extended configuration space. Clear evidence for the contribution of neutron pair excitations from the 1d3/2 to the 0h11/2 orbital to the wave function of the 21+ state in 122,124Sn has been obtained.

[paper] g Factor of Hydrogenlike 28Si13+

g Factor of Hydrogenlike 28Si13+

S. Sturm et al.

doi: 10.1103/PhysRevLett.107.023002

We determined the experimental value of the g factor of the electron bound in hydrogenlike 28Si13+ by using a single ion confined in a cylindrical Penning trap. From the ratio of the ion’s cyclotron frequency and the induced spin flip frequency, we obtain g=1.995 348 958 7(5)(3)(8). It is in excellent agreement with the state-of-the-art theoretical value of 1.995 348 958 0(17), which includes QED contributions up to the two-loop level of the order of (Zα)2 and (Zα)4 and represents a stringent test of bound-state quantum electrodynamics calculations.

[paper] g factors of nuclear low-lying states: A covariant description

g factors of nuclear low-lying states: A covariant description

JiangMing Yao et al.

doi: 10.1007/s11433-010-4214-8

The g factors and spectroscopic quadrupole moments of low-lying excited states 21+, …, 81+ in 24Mg are studied in a covariant density functional theory. The wave functions are constructed by configuration mixing of axially deformed mean-field states projected on good angular momentum. The mean-field states are obtained from the constraint relativistic point-coupling model plus BCS calculations using the PC-F1 parametrization for the particle-hole channel and a density-independent delta-force for the particle-particle channel. The available experimental g factor and spectroscopic quadrupole moment of 21/+ state are reproduced quite well. The angular momentum dependence of g factors and spectroscopic quadrupole moments, as well as the effects of pairing correlations are investigated

[paper] Shape coexistence near the N=38 shell gap: Magnetic moment of the 981.6 keV Jπ=8+ level in 72As

Shape coexistence near the N=38 shell gap: Magnetic moment of the 981.6 keV Jπ=8+ level in 72As

D. Pantelică et al.

doi: 10.1103/PhysRevC.82.044313

We report on the first determination of the magnetic moment of the 981.1 keV, Jπ=8+ level in 72As, a nucleus that belongs to the A≈70 mass region dominated by rapidly changing deformations and shapes. The 8+ level is the bandhead of a collective sequence of positive parity levels coexisting with low-spin and medium-spin spherical shell-model states. The magnetic moment was measured by the time-integral perturbed angular distributions method to be μ=-(4.272±0.280)μN. This value is in disagreement with the presumed [π(1g9/2),ν(1g9/2)] configuration and points to a more complex configuration involving two neutrons in the 1g9/2 orbital.