electric quadrupole moment

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

[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.

Jul 31, 2016 by Theo theory 0

[Paper] Table of nuclear electric quadrupole moments

Table of nuclear electric quadrupole moments

N.J. Stone

doi: 10.1016/j.adt.2015.12.002

This Table is a compilation of experimental measurements of static electric quadrupole moments of ground states and excited states of atomic nuclei throughout the periodic table. To aid identification of the states, their excitation energy, half-life, spin and parity are given, along with a brief indication of the method and any reference standard used in the particular measurement. Experimental data from all quadrupole moment measurements actually provide a value of the product of the moment and the electric field gradient [EFG] acting at the nucleus. Knowledge of the EFG is thus necessary to extract the quadrupole moment. A single recommended moment value is given for each state, based, for each element, wherever possible, upon a standard reference moment for a nuclear state of that element studied in a situation in which the electric field gradient has been well calculated. For several elements one or more subsidiary EFG/moment reference is required and their use is specified.

The literature search covers the period to mid-2015.

Apr 12, 2016 by Theo experiment quadrupole 0

[Paper] Spectroscopic Quadrupole Moments in ^96,98Sr: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60

Spectroscopic Quadrupole Moments in Sr96,98: Evidence for Shape Coexistence in Neutron-Rich Strontium Isotopes at N=60

E. Clément et al.

doi: 10.1103/PhysRevLett.116.022701

Neutron-rich ^96,98Sr isotopes have been investigated by safe Coulomb excitation of radioactive beams at the REX-ISOLDE facility. Reduced transition probabilities and spectroscopic quadrupole moments have been extracted from the differential Coulomb excitation cross sections. These results allow, for the first time, the drawing of definite conclusions about the shape coexistence of highly deformed prolate and spherical configurations. In particular, a very small mixing between the coexisting states is observed, contrary to other mass regions where strong mixing is present. Experimental results have been compared to beyond-mean-field calculations using the Gogny D1S interaction in a five-dimensional collective Hamiltonian formalism, which reproduce the shape change at N=60.

Jan 20, 2016 by Theo experiment quadrupole 0

[paper] Quadrupole moments of neutron-deficient ^20,21Na

Quadrupole moments of neutron-deficient ^20,21Na

K. Minamisono et al.

doi: 10.1016/j.physletb.2009.01.006

The electric-quadrupole coupling constant of the ground states of the proton drip line nucleus ²⁰Na (I^π=2⁺, T_1/2=447.9 ms) and the neutron-deficient nucleus ²¹Na (I^π=3/2⁺, T_1/2=22.49 s) in a hexagonal ZnO single crystal were precisely measured to be |eqQ/h|=690±12 kHz and 939±14 kHz, respectively, using the multi-frequency β-ray detecting nuclear magnetic resonance technique under presence of an electric-quadrupole interaction. An electric-quadrupole coupling constant of ²⁷Na in the ZnO crystal was also measured to be |eqQ/h|=48.4±3.8 kHz. The electric-quadrupole moments were extracted as |Q(²⁰Na)|=10.3±0.8 efm² and |Q(²¹Na)|=14.0±1.1 efm², using the electric-coupling constant of ²⁷Na and the known quadrupole moment of this nucleus as references. The present results are well explained by shell-model calculations in the full sd-shell model space.

Feb 16, 2009 by Theo experiment 0

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