laser spectroscopy

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.

 

Figure 3

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Jun 10, 2018 by g factor 0

[paper] Onset of deformation in neutron-deficient Bi isotopes studied by laser spectroscopy

Onset of deformation in neutron-deficient Bi isotopes studied by laser spectroscopy

A.E. Barzakh et al.

doi: 10.1103/PhysRevC.95.044324

In-source laser spectroscopy experiments for bismuth isotopes at the 306.77-nm atomic transition has been carried out at the Investigation of Radioactive Isotopes on Synchrocyclotron facility of Petersburg Nuclear Physics Institute. New data on isotope shifts and hyperfine structure for Bi ground states and isomers (189,190m1,190m2,191,192,192m,194,194m,198mBi) have been obtained. The changes in the mean-square charge radii δ⟨r2⟩ and magnetic-moment values have been deduced. For Bi nuclei a marked deviation from the isotopic trend of δ⟨r2⟩ in lead and thallium isotopic chains has been demonstrated at N<111. This has been interpreted as an indication of the onset of quadrupole deformation. Analysis of the magnetic moments for odd-odd Bi isotopes also points to the possible increase in deformation at N<111.

Apr 30, 2017 by experiment g factor radii 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

[paper] Nuclear moments and charge radii of neutron-deficient francium isotopes and isomers

Nuclear moments and charge radii of neutron-deficient francium isotopes and isomers

A. Voss et al.

doi: http://dx.doi.org/10.1103/PhysRevC.91.044307

Collinear laser fluorescence spectroscopy has been performed on the ground and isomeric states of 204,206Fr in order to determine their spins, nuclear moments, and changes in mean-squared charge radii. A new experimental technique has been developed as part of this work which much enhances the data collection rate while maintaining the high resolution. This has permitted the extension of this study to the two isomeric states in each nucleus. The investigation of nuclear g factors and mean-squared charge radii indicates that the neutron-deficient Fr isotopes lie in a transitional region from spherical towards more collective structures.

Apr 12, 2015 by g factor 0

[Conference paper] Physics highlights from laser spectroscopy at the IGISOL

Physics highlights from laser spectroscopy at the IGISOL

D.H. Forest and B. Cheal

doi: 10.1007/s10751-012-0620-9

Laser spectroscopy provides model-independent access to a variety of radioactive nuclear ground state and isomeric state properties. These include the nuclear moments, changes in mean-square charge radii, and direct measurements of the nuclear spin. At the IGISOL laboratory, the collinear laser spectroscopy programme is able to access cases, such as refractory elements and short-lived states, not available at conventional facilities. A summary of physics highlights is presented here.

Mar 30, 2012 by 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)μN and +1.61(5)μN, 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) μN.

Sep 29, 2011 by g factor 0

[paper] Hyperfine field and hyperfine anomalies of copper impurities in iron

Hyperfine field and hyperfine anomalies of copper impurities in iron

V. V. Golovko et al.

doi: 10.1103/PhysRevC.84.014323

A new value for the hyperfine magnetic field of copper impurities in iron is obtained by combining resonance frequencies from experiments involving β-NMR on oriented nuclei on 59Cu, 69Cu, and 71Cu with magnetic moment values from collinear laser spectroscopy measurements on these isotopes. The resulting value, i.e., Bhf(CuFe) = -21.794(10) T, is in agreement with the value adopted until now but is an order of magnitude more precise. It is consistent with predictions from ab initio calculations. Comparing the hyperfine field values obtained for the individual isotopes, the hyperfine anomalies in Fe were determined to be 59Δ69=0.15(9)% and 71Δ69=0.07(11)%.

Jul 22, 2011 by 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 experiment g factor 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 57,58,59,63,65Cu 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)μN is proposed for 58Cu, consistent with that of a πp3/2⊗νp3/2 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 g factor 0

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