[conf] In-gas-cell laser ionization spectroscopy at KISS

In-gas-cell laser ionization spectroscopy at KISS

Yoshikazu Hirayama, Momo Mukai, Yutaka Watanabe, Peter Schury, Toshitaka Niwase, Hyunsuk Choi, Takashi Hashimoto, Shun Iimura, SunChan Jeong, Hiroari Miyatake, JunYoung Moon, Hitoshi Nakada, Michihiro Oyaizu, Marco Rosenbusch, Aiko Takamine, Minori Tajima, Akihiro Taniguchi, and Michiharu Wada

doi: 10.1007/s10751-024-01886-1

abstract

We have developed the KEK Isotope Separation System (KISS) at RIKEN to study the nuclear structure of the nuclei in the vicinity of neutron magic number N=126 from the astrophysical perspective. These neutron-rich nuclei have been produced by using multinucleon transfer (MNT) reactions with combinations of the low-energy 126Xe beam and the production targets of W, Ir, and Pt. At the KISS facility, radioisotopes are ionized by applying in-gas-cell laser ionization technique. In this process, we can perform laser ionization spectroscopy of the refractory elements with the atomic number Z=70–78 such as Hf, Ta, W, Re, Os, Ir, and Pt, which cannot be performed in other facilities. Laser spectroscopy can effectively investigate nuclear structure through the measured magnetic moments, isotope shifts (IS) Δν, changes in the mean-square charge radii δ<r2>, and quadrupole deformation parameters |<β2>|1/2. We have studied the ionization schemes of these elements through offline tests and performed in-gas-cell laser ionization spectroscopy of these refractory neutron-rich nuclei produced at KISS.

Mar 24, 2024 by experiment 0

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

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 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.

Feb 17, 2024 by 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(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.

Feb 17, 2024 by 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 g factor 0

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!

May 21, 2019 by upgrade 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 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 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 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.

Jan 2, 2019 by 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 252,253,254No, 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

Jun 10, 2018 by g factor 0

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21Mg 22Mg 23Mg 24Mg 25Mg 26Mg 27Mg 28Mg 29Mg 30Mg 31Al 31Mg 32Mg 33Al 33Mg 40Ar 42Sc 43S 43Sc 44Ar 44Cl 44Sc 45Sc 46Sc 55Ni 57Cu 58Cu 59Cu 61Cu 62Cu 63Cu 64Cu 65Cu 66Cu 67Cu 68Cu 69Cu 70Cu 71Cu 72As 72Cu 72Zn 73Cu 74Cu 74Se 75Cu 76Kr 76Se 77Cu 78Cu 78Kr 78Se 80Kr 80Se 82Kr 82Se 84Kr 84Sr 86Sr 88Kr 88Sr 88Zr 96Ru 100Pd 100Sn 102Ag 104Ag 106Ag 108Ag 110Ag 110Cd 112Sn 114Sn 116Sn 122Sn 124Sn 132Sn 137Ba 140Xe 142Xe 144Nd 146Ba 146Ce 146Nd 148Ce 148Nd 150Nd 154Gd 156Gd 157Er 158Er 168Hf 171Hf 172Hf 187Tl 189Tl 191Tl 193Tl 195Tl 197Tl 229Th 239Pu 250Bk 253Es 254Es 255Fm actinides antiproton arxiv B(E2) b-NMR BCS Be charge radd charge radii chiral effective field theory chiral quark model collinear laser spectroscopy conference paper correlation attenuation Coulex covariant CPT cranker database DSAM electric quadrupole moment electromagnetic moments electron EPJA experiment Gammasphere GANIL g factor Green functions HVTF hydrogen like hyperfine field Hyperfine Interactions hyperfine splitting IBM IBM-2 IBMFM IGISOL in-gas-cell laser spectroscopy island of inversion ISOLDE isomer isotope shift JPhysG KISS laser laser-induced nuclear orientation laser spectroscopy Li LISE LISOL magnetic moment magnetic quadrupole moment mean field MEC moments Monte Carlo N3LO Nilsson-Strutinsky NMR NMR/ON nuclear moments nuclear spin nucleon octupole nuclear magnetic moment PAC PAN paper Paul trap Penning PLB PRC preprint PRL proton QCD QED quadrupole deformation quadrupole moment resonant ionization spectroscopy RIKEN Rutgers Science Science China SDPF-U shell model spin expectation value TDPAD TF theory TIPAD triaxial Λ resonance α-transfer