[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 experiment quadrupole 0

[Paper] Hyperfine magnetic fields in substituted Finemet alloys

Hyperfine magnetic fields in substituted Finemet alloys

K. Brzózka et al.

doi: 10.1007/s10751-016-1245-1

Transmission Mössbauer spectroscopy was used to determine the hyperfine fields of Finemet-type alloys in form of ribbons, substituted alternatively by Mn, Ni, Co, Al, Zn, V or Ge of various concentration. The comparative analysis of magnetic hyperfine fields was carried out which enabled to understand the role of added elements in as-quenched as well as annealed samples. Moreover, the influence of the substitution on the mean direction of the local hyperfine magnetic field was examined.

Mar 18, 2016 by g factor 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 experiment quadrupole 0

[preprint] Populating Low-Spin States in Radioactive Nuclei to Measure Magnetic Moments Using the Transient Field Technique

Populating Low-Spin States in Radioactive Nuclei to Measure Magnetic Moments Using the Transient Field Technique

D.A. Torres and F. Ramírez

arXiv: 1601.03602

The experimental study of magnetic moments for nuclear states near the ground state, I≥2, provides a powerful tool to test nuclear structure models. The study of magnetic moments in nuclei far away from the stability line is the next frontier in such studies. Two techniques have been utilized to populated low-spin states in radioactive nuclei: coulomb excitation reactions using radioactive nuclei, and the transfer of α particles to stable beams to populate low spin states in radioactive nuclei. A presentations of these two techniques, along with the experimental challenges presented for future uses with nuclei far away from the stability line, will be presented.

Jan 17, 2016 by experiment g factor 0

[Paper] Recent Advances in On-Line Laser Spectroscopy

Recent Advances in On-Line Laser Spectroscopy

B. Cheal et al.

doi: 10.1080/10619127.2015.1104126

Abstract

At radioactive ion beam facilities, particle accelerators are employed to induce nuclear reactions in order to provide short-lived nuclei for immediate study using a variety of spectroscopic techniques. These exotic isotopes/isomers are formed into a beam of fast ions, which are mass analyzed in-flight during transport to a chosen experimental set-up. As an additional filter, the atomic level structure provides a selective fingerprint, which distinguishes one element from another due to the varying numbers of protons and electrons. This property is exploited in laser ion sources whereby high power, pulsed tuneable laser radiation is used to excite and ionize the atom in order to enhance the yield of a selected element. This not only provides a means of identification but also purification.

Dec 26, 2015 by experiment 0

[paper] Laser spectroscopy of atoms in superfluid helium for the measurement of nuclear spins and electromagnetic moments of radioactive atoms

Laser spectroscopy of atoms in superfluid helium for the measurement of nuclear spins and electromagnetic moments of radioactive atoms

T. Fujita et al.

doi: 10.1007/s10751-015-1206-0

A new laser spectroscopic method named “OROCHI (Optical RI-atom Observation in Condensed Helium as Ion catcher)” has been developed for deriving the nuclear spins and electromagnetic moments of low-yield exotic nuclei. In this method, we observe atomic Zeeman and hyperfine structures using laser-radio-frequency/microwave double-resonance spectroscopy. In our previous works, double-resonance spectroscopy was performed successfully with laser-sputtered stable atoms including non-alkali Au atoms as well as alkali Rb and Cs atoms. Following these works, measurements with 84−87Rb energetic ion beams were carried out in the RIKEN projectile fragment separator (RIPS). In this paper, we report the present status of OROCHI and discuss its feasibility, especially for low-yield nuclei such as unstable Au isotopes.

Nov 26, 2015 by experiment 0

[preprint] Effective field theory for nuclear vibrations with quantified uncertainties

Effective field theory for nuclear vibrations with quantified uncertainties

E.A. Coello Pérez and T. Papenbrock

arXiv: 1510.02401

We develop an effective field theory (EFT) for nuclear vibrations. The key ingredients – quadrupole degrees of freedom, rotational invariance, and a breakdown scale around the three-phonon level – are taken from data. The EFT is developed for spectra and electromagnetic moments and transitions. We employ tools from Bayesian statistics for the quantification of theoretical uncertainties. The EFT consistently describes spectra and electromagnetic transitions for 62Ni, 98,100Ru, 106,108Pd, 110,112,114Cd, and 118,120,122Te within the theoretical uncertainties. This suggests that these nuclei can be viewed as anharmonic vibrators.

Nov 12, 2015 by theory 0

[Paper] The ASACUSA CUSP: an antihydrogen experiment

The ASACUSA CUSP: an anti hydrogen experiment

N. Kuroda et al.

doi: 10.1007/s10751-015-1205-1

In order to test CPT symmetry between antihydrogen and its counterpart hydrogen, the ASACUSA collaboration plans to perform high precision microwave spectroscopy of ground-state hyperfine splitting of antihydrogen atom in-flight. We have developed an apparatus (“cusp trap”) which consists of a superconducting anti-Helmholtz coil and multiple ring electrodes. For the preparation of slow antiprotons and positrons, Penning-Malmberg type traps were utilized. The spectrometer line was positioned downstream of the cusp trap. At the end of the beamline, an antihydrogen beam detector was located, which comprises an inorganic Bismuth Germanium Oxide (BGO) single-crystal scintillator housed in a vacuum duct and surrounding plastic scintillators. A significant fraction of antihydrogen atoms flowing out the cusp trap were detected.

Nov 10, 2015 by experiment 0

[Paper] Magnetic moments in odd-A Cd isotopes and coupling of particles with zero-point vibrations

Magnetic moments in odd-A Cd isotopes and coupling of particles with zero-point vibrations

S. Mishev and V. V. Voronov

DOI: 10.1103/PhysRevC.92.044329

Background: The coupling of the last nucleon with configurations in the ground state of the even-even core is known to augment the single quasiparticle fragmentation pattern. In a recent experimental study by Yordanov et al. the values of the magnetic dipole and electric quadrupole moments of the 11/2− state in a long chain of Cd isotopes were found to follow a simple trend which we try to explain by means of incorporating long-range correlations in the ground state.

Purpose: Our purpose is to study the influence of ground-state correlations (GSCs) on the magnetic moments and compare our results with the data for the odd-A Cd isotopes.

Method: In order to evaluate if the additional correlations have bearing on the magnetic moments we employ an extension to the quasiparticle-phonon model (QPM) which takes into account quasiparticle⊗phonon configurations in the ground state of the even-even core affecting the structure of the odd-A nucleus wave function.

Results: It is shown that the values for the magnetic moments which the applied QPM extension yields deviate further from the Schmidt values. The latter is in agreement with the measured values for the Cd isotopes.

Conclusions: The GSCs exert significant influence on the magnetic dipole moments and reveal a potential for reproducing the experimental values for the studied cadmium isotopes.

Oct 28, 2015 by g factor theory 0

[Paper] Investigation into the semimagic nature of the tin isotopes through electromagnetic moments

Investigation into the semimagic nature of the tin isotopes through electromagnetic moments

J.M. Allmond et al.

DOI: 10.1103/PhysRevC.92.041303

A complete set of electromagnetic moments, B(E2;0+1→2+1),Q(2+1), and g(2+1), have been measured from Coulomb excitation of semi magic 112,114,116,118,120,122,124Sn (Z=50) on natural carbon and titanium targets. The magnitude of the B(E2) values, measured to a precision of ∼4%, disagree with a recent lifetime study [Phys. Lett. B 695, 110 (2011)] that employed the Doppler-shift attenuation method. The B(E2) values show an overall enhancement compared with recent theoretical calculations and a clear asymmetry about midshell, contrary to naive expectations. A new static electric quadrupole moment, Q(2+1), has been measured for 114Sn. The static quadrupole moments are generally consistent with zero but reveal an enhancement near midshell; this had not been previously observed. The magnetic dipole moments are consistent with previous measurements and show a near monotonic decrease in value with neutron number. The g-factor measurements in 112,114Sn establish the recoil-in-vacuum method for states with τ∼0.5 ps and hence demonstrate that this method can be used for future g-factor measurements on proton-rich isotopes toward 100Sn. Current theory calculations fail to reproduce the electromagnetic moments of the tin isotopes. The role of 2p-2h and 4p-4h intruders, which are lowest in energy at midshell and outside of current model spaces, needs to be investigated in the future.

Oct 19, 2015 by g factor quadrupole 0

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