g factor

[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.

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

The importance of magnetic moments to nuclear structure – a comment by N.D. Cook

I have received the following as a comment to the website. I strongly believe this is an important advocate of our website and motivation behind organizing it, as well as a good read for all people in the field of nuclear physics. Here it is:

Dear Theo,

I have previously relied on Nick Stone’s compilation, but I am happy to have found your website with active updating of nuclear magnetic moments. This is why the internet is so wonderful, so I wish you luck in drawing attention to this valuable resource!
Maybe anyone interested in magnetic moments already understands this, but what I think is still missing from your website is indication of the importance of specifically the magnetic moments for a proper understanding of nuclear structure.

On the one hand, the textbooks typically show the Schmidt Lines, together with data points indicating that most experimental values lie between the upper and lower values. Already by the early 1950s, the Schmidt lines clearly indicated that the independent-particle model was more-or-less valid, but there has been surprisingly little progress since then. Because the modern experimental data are precise up to 7 or 8 digits and classical electromagnetic theory is well understood, explanation of nuclear magnetic moments SHOULD be (but is not yet) an area where discrepancies between experiment and theory might be discussed with some clarity!

On the other hand, theorists who calculate nuclear magnetic moments typically use model parameters that are adjusted to reproduce the experimental data. Adjusting the parameters of the nuclear models is entirely normal practice, but such modeling gives the impression that the magnetic moments are understood quantitatively, whereas the truth is considerably less optimistic. That “hard reality” is not often acknowledged, I would say, but last year a Chinese physics journal, SCIENCE CHINA, was rather straight-forward in stating the continuing problems in explaining nuclear magnetic moments.

http://esciencenews.com/articles/2010/12/23/nuclear.magnetic.moments

In explaining why they were to publish a Special Issue devoted to nuclear moments, the Editors noted that:
“the extension of these [nuclear] models to the study of nuclear magnetic moments is quite limited and unsatisfactory. The magnetic dipole moments of most atomic nuclei throughout the periodic table still remain unexplained and the under-lying physics mechanism is not fully understood….”

And, among the invited reviews of theoretical work that were eventually published, Akito Arima went through the usual explanation of the Schmidt lines, and even cited the good agreement between experiment and theory for a few selected nuclei from his own work published in…. 1954!

I would guess that you are not interested in getting into abstruse theoretical discussions on your web-site, but I think some indication of the current lack of theoretical understanding of nuclear magnetic moments would indicate why nuclear moments are indeed an important topic!

Cheers
Norman

N.D.Cook

Jan 24, 2012 by Theo g factor 0

The database is now complete!

Folks,

This is exciting times for the database we’ve been trying to put online during the past 2 years. In the process, we’ve had severe failures, major redesigns and several updates. Nevertheless, our efforts are proven fruitful and we are now pleased to announce the complete set of nuclear magnetic dipole and electric quadrupole moments to the community. As a bonus, magnetic moments of elementary particles are now featured in the database. Also, we have tried to modernize the frontend by adding an alternative view, using a helix-like ladder that symbolizes both the expansion of our site and the future of nuclear data collection and archiving.

Our database can be directly found in this link: http://magneticmoments.info/data

The data have been collected from fully electronic and printed sources. Prof. N.J. Stone’s milestone paper was used as the major source, but our database is extended gradually to include more information, such as DOI keys and non-evaluated data as they appear in this blog, and elsewhere, for the convenience of the fellow researchers.

We welcome comments, corrections, suggestions and of course DONATIONS 🙂 This server is a fully private project without any financial support other than our pocket. So, if you think it’s interesting, send us an email and we can tell you how you can help our site grow. In any case, thanks for visiting!

Jan 8, 2012 by Theo g factor 2

News from the database battle

Dear All,

We are a couple of steps away from completing the database we’ve been putting together online. This is one of the reasons the blog has been left without recent updates. However, we are coming back in track and promise you more content in 2012.

Stay tuned!

Dec 15, 2011 by Theo g factor 0

Maintenance and update issues

Hi all,

I have been busy the last couple of months and had no real time to add more data to the site. The blog will continue being updated, so keep visiting back. We are also just a few steps away from Z=50 in magneticomoments.info

Unfortunately, I have no good way to speed up the process as I am trying to be careful with the data published and have no help by other people. Once this compilation is uploaded, I will start adding data as they appear on journal publications (NO evaluation). Till then, you may visit the blog.

Thanks,

tjm++

Nov 27, 2011 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

[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.

Sep 22, 2011 by Theo g factor 0

[paper] Hyperfine field and hyperfine anomalies of copper impurities in iron

Hyperfine field and hyperfine anomalies of copper impurities in iron

V. V. Golovko et al.

doi: 10.1103/PhysRevC.84.014323

A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving β-NMR on oriented nuclei on ⁵⁹Cu, ⁶⁹Cu, and ⁷¹Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., B_hf(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be ⁵⁹Δ⁶⁹=0.15(9)% and ⁷¹Δ⁶⁹=0.07(11)%.

Jul 22, 2011 by Theo g factor 0

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