ISOLDE

[paper] Isomer Shift and Magnetic Moment of the Long-Lived ½⁺ Isomer in ⁷⁹Zn: Signature of Shape Coexistence near ⁷⁸Ni

Isomer Shift and Magnetic Moment of the Long-Lived ½⁺ Isomer in ⁷⁹Zn: Signature of Shape Coexistence near ⁷⁸Ni

X.F. Yang et al.

Collinear laser spectroscopy is performed on the ⁷⁹Zn isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life is confirmed, and the nuclear spins and moments of the ground and isomeric states in ⁷⁹Zn, as well as the isomer shift are measured. From the observed hyperfine structures, spins I=9/2 and I=½ are firmly assigned to the ground and isomeric states. The magnetic moment μ(⁷⁹Zn)=-1.1866(10)μ_N, confirms the spin-parity I=9/2⁺ with a νg_9/2^-1 shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment μ(^79mZn)=-1.0180(12)μ_N supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the N=50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state, δ2>^79,79m=+0.204(6) fm², providing first evidence of shape coexistence.

May 16, 2016 by Theo 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 Theo experiment quadrupole 0

[paper] Nuclear Charge Radii of ^21-32Mg

Nuclear Charge Radii of ^21-32Mg

D.T. Yordanov et al.

doi: 10.1103/PhysRevLett.108.042504

Charge radii of all magnesium isotopes in the sd shell have been measured, revealing evolution of the nuclear shape throughout two prominent regions of assumed deformation centered on ²⁴Mg and ³²Mg. A striking correspondence is found between the nuclear charge radius and the neutron shell structure. The importance of cluster configurations towards N=8 and collectivity near N=20 is discussed in the framework of the fermionic molecular dynamics model. These essential results have been made possible by the first application of laser-induced nuclear orientation for isotope shift measurements.

Jan 26, 2012 by Theo g factor 0

[paper] In-source laser spectroscopy of ^75,77,78Cu: Direct evidence for a change in the quasiparticle energy sequence in ^75,77Cu and an absence of longer-lived isomers in ⁷⁸Cu

In-source laser spectroscopy of ^75,77,78Cu: Direct evidence for a change in the quasiparticle energy sequence in ^75,77Cu and an absence of longer-lived isomers in ⁷⁸Cu

U. Köster et al.

doi: 10.1103/PhysRevC.84.034320

This paper describes measurements on the isotopes ^75,77,78Cu by the technique of in-source laser spectroscopy, at the ISOLDE facility, CERN. The role of this technique is briefly discussed in the context of this and other, higher resolution, methods applied to copper isotopes in the range ⁵⁷⁻⁷⁸Cu. The data, analyzed in comparison with previous results on the lighter isotopes ^59,63Cu, establish the ground-state nuclear spin of ^75,77Cu as 5/2 and yield their magnetic dipole moments as +1.01(5)μ_N and +1.61(5)μ_N, respectively. The results on ⁷⁸Cu show no evidence for long-lived isomerism at this mass number and are consistent with a spin in the range 3–6 and moment of 0.0(4) μ_N.

Sep 29, 2011 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] 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

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