g factor

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

Leonid V. Skripnikov and Anatoly E. Barzak

Abstract

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 g_J factor in the same theoretical framework. A good agreement of the theory and experiment for IP, EEs, and g_J 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.

Feb 17, 2024 by Theo g factor 0

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

Abstract

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(1h_11/2)¹⊗ν(1h_11/2)⁻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 j_R 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(j_R) 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.

Feb 17, 2024 by Theo g factor theory 0

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.

-Theo

Feb 22, 2022 by Theo g factor 0

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 (ekt.gr).

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

https://is.gd/hnps_praktika

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

Apr 2, 2019 by Theo g factor 0

[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.

Jan 22, 2019 by Theo g factor 0

[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 g_s^IS 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 g_L^IS 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.

Jan 2, 2019 by Theo g factor 0

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 $252, 253, 254 No$ , 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 $252, 254 No$ isotopes. Finally, the hyperfine splitting of $253 No$ 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.

Read the full article on Phys. Rev. Lett

Jun 10, 2018 by Theo g factor 0

[paper] Perturbed angular distributions with LaBr₃ detectors: The $g$ factor of the first 10$^+$ state in $^{110}$Cd reexamined

Perturbed angular distributions with LaBr₃ detectors: The g factor of the first 10⁺ state in ¹¹⁰Cd reexamined

T.J. Gray et al.

doi: 10.1103/PhysRevC.96.054332

The time differential perturbed angular distribution technique with LaBr₃ detectors has been applied to the I^π=11/2⁻ isomeric state (E_x = 846 keV, τ=107 ns) in ¹⁰⁷Cd, which was populated and recoil-implanted into a gadolinium host following the ⁹⁸Mo(¹²C, 3n)¹⁰⁷Cd reaction. The static hyperfine field strength of Cd recoil implanted into gadolinium was thus measured, together with the fraction of nuclei implanted into field-free sites, under similar conditions as pertained for a previous implantation perturbed angular distribution
g-factor measurement on the I^π=10⁺ state in ¹¹⁰Cd. The ¹¹⁰Cd g(10⁺) value was thereby reevaluated, bringing it into agreement with the value expected for a seniority-two νh_11/2 configuration.

Nov 29, 2017 by Theo g factor 0

[paper] In-gas-cell laser spectroscopy of the magnetic dipole moment of the N≈126 isotope ¹⁹⁹Pt

In-gas-cell laser spectroscopy of the magnetic dipole moment of the N≈126 isotope ¹⁹⁹Pt

Y. Hirayama et al.
doi: 10.1103/PhysRevC.96.014307

The magnetic dipole moment and mean-square charge radius of $199 g Pt$ $(I^{π} =$ $5 / 2^{-}, t_{1 / 2} = 30.8$ min) ground state and $199 m Pt$ $(E_{ex} = 424$ keV, $I^{π} =$ (13/2) $^{+}, t_{1 / 2} = 13.6$ s) isomeric state are evaluated for the first time from investigations of the hyperfine splitting of the $λ_{1} = 248.792$ nm transition by in-gas-cell laser ionization spectroscopy. Ground and isomeric states of neutron-rich $199 Pt$ nucleus were produced by a multinucleon transfer reaction at the KEK Isotope Separation System (KISS), designed for the study of nuclear spectroscopy in the vicinity of $N = 126$ . The measured magnetic dipole moments $+ 0.75$ (8) $μ_{N}$ and $- 0.57$ (5) $μ_{N}$ are consistent with the systematics of those of nuclei with $I^{π} =$ $5 / 2^{-}$ and $I^{π} =$ $13 / 2^{+}$ , respectively.

Jul 11, 2017 by Theo experiment g factor radii 0

Getting ready for HNPS2017

It’s been a while since my last blog post. I have been really busy with end of the semester and preparing for a couple of Conferences where our group are participating.

The first one is coming up this weekend, Friday and Saturday 9-10.06.2017. It is the 26th Annual Symposium of our Hellenic Nuclear Physics Society, our little body of nuke people who gather together, present their recent works and give lots of space to young researchers to immense in what is going on in our field.

This year we have prepared an impressive number of 7 posters and 1 oral talk spanning all aspects of our scientific activities. The NuSTRAP group are active in three main directions, namely nuclear structure, nuclear reactions and applications of radiation including instrumentation and environmental studies. Despite being mostly preliminary, our results are publicly available online. You can visit this page to view our recent posters and if you fancy, give us some feedback or publicize our work to the social media. I stress out the fact that the majority of the work has been carried out by undergrads who spend a lot of time and showed exceptional eagerness to advance science while getting educated.

We will be standing next to our posters this coming Friday and Saturday, here is a link to the official program of HNPS2017. This is the list of posters:

doi: 10.6084/m9.figshare.5084128 (S. Kolovi et al.)
doi: 10.6084/m9.figshare.5080099 (C. Andrikopoulos et al.)
doi: 10.6084/m9.figshare.5072245 (E.-M. Lykiardopoulou et al.)
doi: 10.6084/m9.figshare.5086039 (I. Sideris et al.)
doi: 10.6084/m9.figshare.5057854 (V. Lagaki et al.)
doi: 10.6084/m9.figshare.5071840 (G. Zagoraios et al.)
doi: 10.6084/m9.figshare.5089747 (N. Togia et al.)

I will be tweeting using the hashtag #hnps2017, so if you are a fellow tweep, please stand by.

Jun 7, 2017 by Theo g factor 0

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