Magnetic Moments

[paper] Quadrupole moment measurements for strongly deformed bands in ^171,172Hf

Quadrupole moment measurements for strongly deformed bands in ^171,172Hf

S. Mukhopadhyay et al.

A lifetime experiment, using the Doppler-shift attenuation method, has been performed at Gammasphere to measure the transition quadrupole moments Qt of strongly deformed bands in ¹⁷¹Hf and ¹⁷²Hf. The measured value of Q_t ~ 9.5 e b for the band labeled ED in ¹⁷¹Hf strongly supports the recent suggestion that this sequence and several structures with similar properties in neighboring Hf isotopes are associated with a near-prolate shape with a deformation enhanced relative to that of normal deformed structures. The measured values of Q_t ~ 14 e b for the bands labeled SD1 and SD3 in ¹⁷²Hf confirm that these sequences are associated with a prolate superdeformed shape, a property inferred in earlier work from other measured characteristics of the bands. Similar bands in ^173-175Hf are also likely to be associated with superdeformed shapes. The observations are in contrast to predictions of cranking calculations performed with the ultimate cranker code.

Apr 13, 2011 by Theo experiment 1

[paper] Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers

Nuclear charge radii and electromagnetic moments of radioactive scandium isotopes and isomers

M. Avgoulea et al.

doi: 10.1088/0954-3899/38/2/025104

Collinear laser spectroscopy experiments with the Sc⁺ transition 3d4s ³D₂ → 3d4p ³F3 at λ = 363.1 nm were performed on the ^42–46Sc isotopic chain using an ion guide isotope separator with a cooler-buncher. Nuclear magnetic dipole and electric quadrupole moments as well as isotope shifts were determined from the hyperfine structure for five ground states and two isomers. Extensive multi-configurational Dirac–Fock calculations were performed in order to evaluate the specific mass-shift, MSMS, and field-shift, F, parameters which allowed evaluation of the charge radii trend of the Sc isotopic sequence. The charge radii obtained show systematics more like the Ti radii, which increase towards the neutron shell closure N = 20, than the symmetric parabolic curve for Ca. The changes in mean-square charge radii of the isomeric states relative to the ground states for ⁴⁴Sc and ⁴⁵Sc were also extracted. The charge radii difference between the ground and isomeric states of ⁴⁵Sc is in agreement with the deformation effect estimated from the B(E2) measurements but is smaller than the deformation extracted from the spectroscopic quadrupole moments.

Jan 5, 2011 by Theo experiment g factor 0

Up and running again

Hi all,

in case you’ve noticed, the blog has suffered a major breakdown due to db problems that forced me to take it offline for a few days. Unfortunately, there is no happy end to my effort to restore the information that was previously included in here.

Therefore, I am starting again with data from 2010 and on and hopefully this will be the last time to have such issues. A great many thanks to my hosting provider reload.gr for their prompt assistance.

Have a Happy New Year!

Dec 28, 2010 by Theo g factor 0

[paper] Nuclear spins, magnetic moments, and quadrupole moments of Cu isotopes from N=28 to N=46: Probes for core polarization effects

Nuclear spins, magnetic moments, and quadrupole moments of Cu isotopes from N=28 to N=46: Probes for core polarization effects

P. Vingerhoets et al.

doi: 10.1103/PhysRevC.82.064311

Measurements of the ground-state nuclear spins and magnetic and quadrupole moments of the copper isotopes from ⁶¹Cu up to ⁷⁵Cu are reported. The experiments were performed at the CERN online isotope mass separator (ISOLDE) facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a ⁵⁶Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is, however, strongly reduced at N=40 due to the parity change between the pf and g orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the ⁵⁶Ni core and weakening of the Z=28 and N=28 shell gaps.

Dec 17, 2010 by Theo experiment g factor 0

[paper] g factors of nuclear low-lying states: A covariant description

g factors of nuclear low-lying states: A covariant description

JiangMing Yao et al.

doi: 10.1007/s11433-010-4214-8

The g factors and spectroscopic quadrupole moments of low-lying excited states 2₁⁺, …, 8₁⁺ in ₂₄Mg are studied in a covariant density functional theory. The wave functions are constructed by configuration mixing of axially deformed mean-field states projected on good angular momentum. The mean-field states are obtained from the constraint relativistic point-coupling model plus BCS calculations using the PC-F1 parametrization for the particle-hole channel and a density-independent delta-force for the particle-particle channel. The available experimental g factor and spectroscopic quadrupole moment of 2₁/⁺ state are reproduced quite well. The angular momentum dependence of g factors and spectroscopic quadrupole moments, as well as the effects of pairing correlations are investigated

Dec 6, 2010 by Theo theory 0

[paper] Shape coexistence near the N=38 shell gap: Magnetic moment of the 981.6 keV J^π=8⁺ level in ⁷²As

Shape coexistence near the N=38 shell gap: Magnetic moment of the 981.6 keV J^π=8⁺ level in ⁷²As

D. Pantelică et al.

doi: 10.1103/PhysRevC.82.044313

We report on the first determination of the magnetic moment of the 981.1 keV, J^π=8⁺ level in ⁷²As, a nucleus that belongs to the A≈70 mass region dominated by rapidly changing deformations and shapes. The 8⁺ level is the bandhead of a collective sequence of positive parity levels coexisting with low-spin and medium-spin spherical shell-model states. The magnetic moment was measured by the time-integral perturbed angular distributions method to be μ=-(4.272±0.280)μ_N. This value is in disagreement with the presumed [π(1g_9/2),ν(1g_9/2)] configuration and points to a more complex configuration involving two neutrons in the 1g_9/2 orbital.

Oct 20, 2010 by Theo experiment g factor theory 0

[paper] Magnetic moment of ¹⁰⁴Ag^m and the hyperfine magnetic field of Ag in Fe using nuclear magnetic resonance on oriented nuclei

Magnetic moment of ¹⁰⁴Ag^m and the hyperfine magnetic field of Ag in Fe using nuclear magnetic resonance on oriented nuclei

V.V. Golovko et al.

doi: 10.1103/PhysRevC.81.054323

Nuclear magnetic resonance (NMR/ON) measurements with β- and γ-ray detection have been performed on oriented ¹⁰⁴Ag^g,m nuclei with the NICOLE ³He-⁴He dilution refrigerator setup at ISOLDE/CERN. For ¹⁰⁴Ag^g (I^π=5⁺) the γ-NMR/ON resonance signal was found at ν=266.70(5) MHz. Combining this result with the known magnetic moment for this isotope, the magnetic hyperfine field of Ag impurities in an Fe host at low temperature (<1 K) is found to be |B_hf(AgFe)|=44.709(35) T. A detailed analysis of other relevant data available in the literature yields three more values for this hyperfine field. Averaging all four values yields a new and precise value for the hyperfine field of Ag in Fe; that is, |B_hf(AgFe)|=44.692(30) T. For ¹⁰⁴Ag^m (I^π=2⁺), the anisotropy of the β particles provided the NMR/ON resonance signal at ν=627.7(4) MHz. Using the new value for the hyperfine field of Ag in Fe, this frequency corresponds to the magnetic moment μ(^104mAg)=+3.691(3) μ_N, which is significantly more precise than previous results. The magnetic moments of the even-A ^102-110Ag isotopes are discussed in view of the competition between the (πg_9/2)^7/2+-3(νd_5/2νg_7/2)^5/2+ and the (πg_9/2)^9/2+-3(νd_5/2νg_7/2)^5/2+ configurations. The magnetic moments of the ground and isomeric states of ¹⁰⁴Ag can be explained by an almost complete mixing of these two configurations.

May 28, 2010 by Theo experiment g factor theory 0

[paper] g factor of the ⁴⁴Cl ground state: Probing the reduced Z=16 and N=28 gaps

g factor of the ⁴⁴Cl ground state: Probing the reduced Z=16 and N=28 gaps

M. De Rydt et al.

doi: 10.1103/PhysRevC.81.034308

The g factor of the ⁴⁴Cl ground state is measured at the LISE fragment separator at the Grand Acclérateur National d’Ions Lourds (GANIL) using the β nuclear magnetic resonance technique, resulting in g(⁴⁴Cl)=(-)0.2749(2). An analysis of the g factor value and of the theoretical level scheme in the shell-model framework reveals the presence of odd-proton s_1/2 configurations and neutron excitation across the N=28 shell gap in the ground state of ⁴⁴Cl. In addition, the measured g factor strongly supports a 2^– spin assignment for the ⁴⁴Cl ground state.

Mar 19, 2010 by Theo experiment g factor theory 0

[paper] Magnetic dipole moments of ^57,58,59Cu

Magnetic dipole moments of ^57,58,59Cu

T.E. Cocolios et al.

doi: 10.1103/PhysRevC.81.014314

In-gas-cell laser spectroscopy of the isotopes ^{57,58,59,63,65}Cu has been performed at the LISOL facility using the 244.164-nm optical transition from the atomic ground state of copper. A detailed discussion on the hyperfine structure of ⁶³Cu is presented. The magnetic dipole moments of the isotopes ^57,58,59,65Cu are extracted based on that of ⁶³Cu. The new value μ=+0.479(13)μ_N is proposed for ⁵⁸Cu, consistent with that of a πp_3/2⊗νp_3/2 ground-state configuration. Spin assignments for the radioactive isotopes ^57,58,59Cu are confirmed. The isotope shifts between the different isotopes are also given and discussed.

Jan 28, 2010 by Theo g factor 0

[paper] Magnetic moments of ³³Mg in the time-odd relativistic mean field approach

Magnetic moments of ³³Mg in the time-odd relativistic mean field approach

Jian Li et al.

doi: 10.1007/s11433-009-0194-y

The configuration-fixed deformation constrained relativistic mean field approach with time-odd component has been applied to investigate the ground state properties of ³³Mg with effective interaction PK1. The ground state of ³³Mg has been found to be prolate deformed, β₂=0.23, with the odd neutron in 1/2[330] orbital and the energy −251.85 MeV which is close to the data −252.06 MeV. The magnetic moment −0.9134 µ_N is obtained with the effective electromagnetic current which well reproduces the data −0.7456 µ_N self-consistently without introducing any parameter. The energy splittings of time reversal conjugate states, the neutron current, the energy contribution from the nuclear magnetic potential, and the effect of core polarization are discussed in detail.

Oct 10, 2009 by Theo theory 0

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