Despite a bit away from the nuclear magnetic moments, this interesting preprint article talks about the anomalous moment of quarks.
magnetic moment
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.
[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
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.
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]
[paper] Addenda to general spin precession and betatron oscillation in storage ring
Addenda to general spin precession and betatron oscillation in storage ring
T. Fukuyama
doi: 10.1142/S0217732317910011
We give the generalized expression of spin precession of extended bunch particles having both anomalous magnetic and electric dipole moments (EDMs) in storage ring in higher order than the previous work and in the presence of E field as well as B field. These addenda are essential since some experiments consider the focusing field in the second-order of the beam extent and in the presence of both B and E fields.
[paper] Sixfold improved single particle measurement of the magnetic moment of the antiproton
Sixfold improved single particle measurement of the magnetic moment of the antiproton
H. Nagahama et al.
doi: 10.1038/ncomms14084
Our current understanding of the Universe comes, among others, from particle physics and cosmology. In particle physics an almost perfect symmetry between matter and antimatter exists. On cosmological scales, however, a striking matter/antimatter imbalance is observed. This contradiction inspires comparisons of the fundamental properties of particles and antiparticles with high precision. Here we report on a measurement of the g-factor of the antiproton with a fractional precision of 0.8 parts per million at 95% confidence level. Our value g(antiproton)=2=2.7928465(23) outperforms the previous best measurement by a factor of 6. The result is consistent with our proton g-factor measurement g(proton)=2=2.792847350(9), and therefore agrees with the fundamental charge, parity, time (CPT) invariance of the Standard Model of particle physics. Additionally, our result improves coefficients of the standard model extension which discusses the sensitivity of experiments with respect to CPT violation by up to a factor of 20.
[Paper] Sensitivities and correlations of nuclear structure observables emerging from chiral interactions
Sensitivities and correlations of nuclear structure observables emerging from chiral interactions
Angelo Calci and Robert Roth
doi: 10.1103/PhysRevC.94.014322
Abstract
Starting from a set of different two- and three-nucleon interactions from chiral effective field theory, we use the importance-truncated no-core shell model for ab initio calculations of excitation energies as well as electric quadrupole (E2) and magnetic dipole (M1) moments and transition strengths for selected p-shell nuclei. We explore the sensitivity of the excitation energies to the chiral interactions as a first step towards and systematic uncertainty propagation from chiral inputs to nuclear structure observables. The uncertainty band spanned by the different chiral interactions is typically in agreement with experimental excitation energies, but we also identify observables with notable discrepancies beyond the theoretical uncertainty that reveal insufficiencies in the chiral interactions. For electromagnetic observables we identify correlations among pairs of E2 or M1 observables based on the ab initio calculations for the different interactions. We find extremely robust correlations for E2 observables and illustrate how these correlations can be used to predict one observable based on an experimental datum for the second observable. In this way we circumvent convergence issues and arrive at far more accurate results than any direct ab initio calculation. A prime example for this approach is the quadrupole moment of the first 2+ state in C12, which is predicted with an drastically improved accuracy.
[paper] Microscopic description of ground state magnetic moment and low-lying magnetic dipole excitations in heavy odd-mass 181Ta nucleus
Microscopic description of ground state magnetic moment and low-lying magnetic dipole excitations in heavy odd-mass181Ta nucleus
E. Tabar et al.
doi: http://dx.doi.org/10.1142/S0218301316500531
The ground state magnetic moments and the low-lying magnetic dipole (Ml) transitions from the ground to excited states in heavy deformed odd-mass 181Ta have been microscopically investigated on the basis of the quasiparticle-phonon nuclear model (QPNM). The problem of the spurious state mixing in M1 excitations is overcome by a restoration method allowing a self-consistent determination of the separable effective restoration forces. Due to the self-consistency of the method, these effective forces contain no arbitrary parameters. The results of calculations are compared with the available experimental data, the agreement being reasonably satisfactory.