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[paper] Quadrupole moments of spherical semi-magic nuclei within the self-consistent Theory of Finite Fermi Systems

Quadrupole moments of spherical semi-magic nuclei within the self-consistent Theory of Finite Fermi Systems

S.V. Tolokonnikov et al.

doi: 10.1140/epja/i2012-12070-1

The quadrupole moments of odd neighbors of semi-magic lead and tin isotopes and N=50, N=82 isotones are calculated within the self-consistent Theory of Finite Fermi Systems based on the Energy Density Functional by Fayans et al. Two sets of published functionals are used to estimate systematic errors of the present self-consistent approach. They differ by the spin-orbit and effective tensor force parameters. The functional DF3-a leads to quadrupole moments in reasonable agreement with the experimental ones for most, but not all, nuclei considered.

May 27, 2012 by Theo g factor 0

[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 p_3/2, f_5/2, p_1/2, g_9/2 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.

Apr 30, 2012 by Theo experiment g factor 0

[paper] Is the 7/2₁^– Isomer State of ⁴³S Spherical?

Is the 7/2₁^– Isomer State of ⁴³S Spherical?

R. Chevrier et al.

doi: 10.1103/PhysRevLett.108.162501

We report on the spectroscopic quadrupole moment measurement of the 7/2₁^– isomeric state in ⁴³₁₆S₂₇ [E^*=320.5(5) keV, T_1/2=415(3) ns], using the time dependent perturbed angular distribution technique at the RIKEN RIBF facility. Our value, ∣Q_s∣=23(3) efm², is larger than that expected for a single-particle state. Shell model calculations using the modern SDPF-U interaction for this mass region reproduce remarkably well the measured ∣Q_s∣, and show that non-negligible correlations drive the isomeric state away from a purely spherical shape.

Apr 16, 2012 by Theo g factor 0

[paper] Direct Measurement of the Proton Magnetic Moment

Direct Measurement of the Proton Magnetic Moment

J. DiSciacca and G. Gabrielse

doi: 10.1103/PhysRevLett.108.153001

The proton magnetic moment in nuclear magnetons is measured to be μ_p/μ_N≡g/2=2.792 846±0.000 007, a 2.5 parts per million uncertainty. The direct determination, using a single proton in a Penning trap, demonstrates the first method that should work as well with an antiproton (p̅ ) as with a proton (p). This opens the way to measuring the p̅ magnetic moment (whose uncertainty has essentially not been reduced for 20 years) at least 103 times more precisely.

Apr 10, 2012 by Theo g factor 0

[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

Mar 29, 2012 by Theo g factor 0

[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.

Mar 19, 2012 by Theo g factor 0

[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.

Jan 30, 2012 by Theo g factor 0

[paper] Nuclear Charge Radii of ^21-32Mg

Nuclear Charge Radii of ^21-32Mg

D.T. Yordanov et al.

doi: 10.1103/PhysRevLett.108.042504

Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on ²⁴Mg and ³²Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.

Jan 26, 2012 by Theo g factor 0

[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.

Oct 25, 2011 by Theo g factor 0

[paper] In-source laser spectroscopy of ^75,77,78Cu: Direct evidence for a change in the quasiparticle energy sequence in ^75,77Cu and an absence of longer-lived isomers in ⁷⁸Cu

In-source laser spectroscopy of ^75,77,78Cu: Direct evidence for a change in the quasiparticle energy sequence in ^75,77Cu and an absence of longer-lived isomers in ⁷⁸Cu

U. Köster et al.

doi: 10.1103/PhysRevC.84.034320

This paper describes measurements on the isotopes ^75,77,78Cu by the technique of in-source laser spectroscopy, at the ISOLDE facility, CERN. The role of this technique is briefly discussed in the context of this and other, higher resolution, methods applied to copper isotopes in the range ⁵⁷⁻⁷⁸Cu. The data, analyzed in comparison with previous results on the lighter isotopes ^59,63Cu, establish the ground-state nuclear spin of ^75,77Cu as 5/2 and yield their magnetic dipole moments as +1.01(5)μ_N and +1.61(5)μ_N, respectively. The results on ⁷⁸Cu show no evidence for long-lived isomerism at this mass number and are consistent with a spin in the range 3–6 and moment of 0.0(4) μ_N.

Sep 29, 2011 by Theo g factor 0

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