Reexamination of nuclear magnetic dipole and electric quadrupole moments of polonium isotopes

Leonid V. Skripnikov and Anatoly E. Barzak

DOI: 10.1103/PhysRevC.109.024315


We reexamined the electronic structure parameters used to interpret the hyperfine structure of neutral polonium. We used a computational scheme that treats relativistic and high-order electronic correlation effects within the coupled cluster with single, double, triple, and perturbative quadruple excitations (CCSDT(Q) method), as well as estimated the contribution of quantum electrodynamics and finite nuclear size effects. A systematic study of the uncertainty is carried out. This allowed us to obtain significantly refined values for the nuclear magnetic dipole and electric quadrupole moments of a wide range of odd-mass polonium isotopes. For 205Po and 207Po we extracted both the magnetic moment and the nuclear magnetization distribution parameter in a nuclear model-independent way. To assess the accuracy of the calculations, we also computed the ionization potential (IP), excitation energies (EEs) of the 6p4 1D2 and 6p37s1 5S2 electronic states, and the electronic gJ factor in the same theoretical framework. A good agreement of the theory and experiment for IP, EEs, and gJ confirms the reliability of the computational scheme and uncertainty estimation for the Po electromagnetic moments. We identify the 6p4 1D2 electronic level as a potentially promising state for further studies of the nuclear moments of polonium isotopes.

g factor of chiral doublets with $π{(1{h}_{11/2})}^{1}⊗ν{(1{h}_{11/2})}^{−1}$ configuration

Q.B. Chen

DOI: 10.1103/PhysRevC.109.024308


The g factor of chiral doublet bands has been extensively studied within the framework of the particle rotor model. Specifically, these investigations have focused on systems characterized by the particle-hole configuration π(1h11/2)1⊗ν(1h11/2)−1. Comprehensive examinations have been carried out to assess the influence of deformation parameters β and γ, the moment of inertia j0, the total spin I, and the angular momentum of the collective rotor jR on the g factor. The findings reveal that the g factor exhibits insensitivity to variations in J0 and β values, while its behavior is highly sensitive to changes in the γ parameter. Moreover, it has been observed that the g factors and the g(jR) plots associated with the doublet bands demonstrate remarkable similarity in the static chirality region. However, noticeable differences arise in regions characterized by chiral vibration or lacking chirality.

Recovering from a major crash server: status and updates

Some details on the recovery of our database after a major crash we experienced a few months back. We had to restore the full database and re-install it on a new host maintaining the signature domain name. This has been somewhat elaborate and cost us time to put everything back online. We’ve been running in a stable fashion for some time now with upgraded stability and cloud-provided data. Same domain, same experience.

In the meantime, the restore has given us the opportunity to improve various aspects of the database and add new features. Some of them are quite apparent to the user, some exist in the backbone, where we have re-designed all scripts to meet the latest standards of php and ensure maximum compatibility with modern browsers.

An interesting, but still quite experimental, feature is the addition of trend plots for the values of magnetic moments for particulara isotopes. In the process, we have realized this feature can be implemented it efficiently, as various parameters, such as different spins for the ground states, the even-odd disparity and more can influence negatively the realistic representation of the trends in the plots. The only criterion applied for the plots is that we take the value for the lowest energy state, either this is a ground state or a first excited state (e.g. a 2+ in even-even nuclei). Therefore, all plots are provided as experimental and the user should exercise caution on scientific reasoning based on these.

A major upgrade is also in the work with more than 200 new measurements, as registered directly out of published works and not tables of recommended values that provide data in a subjective, non-evaluating way. We trust the data generators and their peer reviewers.

Comments are always welcome.


New looks

As we are currently working on the latest update (cut-off date 2019-03-31), the nuclear moments and charge radii database has been silently synced with the ENSDF library in regards with nuclear level lifetimes, following a recommendation of the IAEA moments evaluation panel.

We have also updated the particle data, as always adopting the evaluations published on the Particle Data Group website. Model-extracted magnetic moments for quarks are now available besides baryons, leptons (and mesons).

The major change in this update is the front looks of the database. In summary:

  • A new color scheme was adopted
  • Wherever possible, the interface became less strict in placement to facilitate mobile-friendly searches
  • A new UI is introduced in the main page when the database is first loaded
  • The periodic table UI has a lighter color scheme
  • The Help section is fully rewritten
  • Last, but not least, we have a name after all: NUclear MOments and Radii (NUMOR). The name was the most popular vote on a poll run on twitter for a day among two more candidates. We sure like it!

We should stress the newly introduced feature for fellow researchers who want to send us data. A new online form has been created to facilitate data or citation submission directly, so that it would be processed in the next update.

It is good if you run business with company: Stefanos Pelonis is a new member to the very small team who has helped significantly in this update.

And please, do not forget: send us feedback and if you use NUMOR, please cite it!

Advances in Nuclear Physics

My dream to upgrade the status of the Proceedings of the Annual Symposium of the Hellenic Nuclear Physics Society has finally passed the first critical phase: Five recent volumes, those from years 2014 to 2018 are now fully available online, under the Creative Commons license, on the National Accreditation Center (

People interested to see our “Advances in Nuclear Physics” and link to our community, please visit the archive here:

Articles will soon be assigned their unique DOI number as has been stated in the MoU we have signed with EKT, thus facilitating the dissemination of the published results. More volumes will be added soon, after the hard copies have been converted to electronic documents. Some people will have to rip off the hard cover volumes existing from 1991 when the first symposium took place, and digitize their pages before uploading the content to the website.

If you are a fellow researcher, consider participating to our Annual Symposia, this year it will take place in Thessaloniki. It’s fun and you might end up strengthening your international collaborations with Greek nuclear scientists working on a variety of projects.

You have comments on the Proceedings? Feel free to contact me

[paper] Interplay between nuclear shell evolution and shape deformation revealed by the magnetic moment of 75Cu

Interplay between nuclear shell evolution and shape deformation revealed by the magnetic moment of 75Cu

Y. Ishikawa et al.
Nature Physics (2019)
DOI: 10.1038/s41567-018-0410-7

Exotic nuclei are characterized by having a number of neutrons (or protons) in excess relative to stable nuclei. Their shell structure, which represents single-particle motion in a nucleus, may vary due to nuclear force and excess neutrons, in a phenomenon called shell evolution. This effect could be counterbalanced by collective modes causing deformations of the nuclear surface. Here, we study the interplay between shell evolution and shape deformation by focusing on the magnetic moment of an isomeric state of the neutron-rich nucleus 75Cu. We measure the magnetic moment using highly spin-controlled rare-isotope beams and achieve large spin alignment via a two-step reaction scheme that incorporates an angular-momentum-selecting nucleon removal. By combining our experiments with numerical simulations of many-fermion correlations, we find that the low-lying states in 75Cu are, to a large extent, of single-particle nature on top of a correlated 74Ni core. We elucidate the crucial role of shell evolution even in the presence of the collective mode, and within the same framework we consider whether and how the double magicity of the 78Ni nucleus is restored, which is also of keen interest from the perspective of nucleosynthesis in explosive stellar processes.

[paper] Isoscalar Spin Matrix Elements in s–d Shell Nuclei

Isoscalar Spin Matrix Elements in s–d Shell Nuclei

by Akito Arima and Wolfgang Bentz

doi: 10.7566/JPSCP.23.012011

The quenching of isovector spin matrix elements in s–d shell nuclei is well established experimentally as well as theoretically [1,2,3]. The isoscalar spin gyromagnetic ratios gsIS of nuclei with one nucleon or hole outside of LS closed shells are also quenched by the same mechanism. On the other hand, their isoscalar orbital gyromagnetic ratios gLIS are slightly enhanced by meson exchange currents [1,2]. Then we are interested very much in the following question: Are the isoscalar spin matrix elements generally quenched in s–d shell nuclei? We will try to answer this question in this paper.

Probing Sizes and Shapes of Nobelium Isotopes by Laser Spectroscopy

Until recently, ground-state nuclear moments of the heaviest nuclei could only be inferred from nuclear spectroscopy, where model assumptions are required. Laser spectroscopy in combination with modern atomic structure calculations is now able to probe these moments directly, in a comprehensive and nuclear-model-independent way. Here we report on unique access to the differential mean-square charge radii of 252,253,254No, and therefore to changes in nuclear size and shape. State-of-the-art nuclear density functional calculations describe well the changes in nuclear charge radii in the region of the heavy actinides, indicating an appreciable central depression in the deformed proton density distribution in 252,254No isotopes. Finally, the hyperfine splitting of 253No was evaluated, enabling a complementary measure of its (quadrupole) deformation, as well as an insight into the neutron single-particle wave function via the nuclear spin and magnetic moment.


Figure 3

Read the full article on Phys. Rev. Lett

A little bit of history

I am in the process of upgrading the database and I ran onto this article by de Shalit from 1951. A little piece of history, with ideas still holding.

Thanks to ETH for digitizing the entire collection of Helvetica Acta.

Here is the (open-access) article: [-link]

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