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#### Shape staggering of mid-shell mercury isotopes from in-source laser spectroscopy compared with Density Functional Theory and Monte Carlo Shell Model calculations

##### MPS-Authors
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Atanasov,  Dinko
Division Prof. Dr. Klaus Blaum, MPI for Nuclear Physics, Max Planck Society;

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Blaum,  Klaus
Division Prof. Dr. Klaus Blaum, MPI for Nuclear Physics, Max Planck Society;

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Kreim,  Susanne Waltraud
Division Prof. Dr. Klaus Blaum, MPI for Nuclear Physics, Max Planck Society;

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Division Prof. Dr. Klaus Blaum, MPI for Nuclear Physics, Max Planck Society;

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Wolf,  Robert
Division Prof. Dr. Klaus Blaum, MPI for Nuclear Physics, Max Planck Society;

##### Fulltext (public)

1902.11211.pdf
(Publisher version), 3MB

##### Supplementary Material (public)
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##### Citation

Sels, S., Goodacre, T. D., Marsh, B. A., Pastore, A., Ryssens, W., Tsunoda, Y., et al. (2019). Shape staggering of mid-shell mercury isotopes from in-source laser spectroscopy compared with Density Functional Theory and Monte Carlo Shell Model calculations. Physical Review C, 99: 044306. doi:10.1103/PhysRevC.99.044306.

Cite as: http://hdl.handle.net/21.11116/0000-0003-7D47-2
##### Abstract
Neutron-deficient $^{177-185}$Hg isotopes were studied using in-source laser resonance-ionization spectroscopy at the CERN-ISOLDE radioactive ion-beam facility, in an experiment combining different detection methods tailored to the studied isotopes. These include either alpha-decay tagging or Multi-reflection Time-of-Flight gating to identify the isotopes of interest. The endpoint of the odd-even nuclear shape staggering in mercury was observed directly by measuring for the first time the isotope shifts and hyperfine structures of $^{177-180}$Hg. Changes in the mean-square charge radii for all mentioned isotopes, magnetic dipole and electric quadrupole moments of the odd-A isotopes and arguments in favor of $I = 7/2$ spin assignment for $^{177,179}$Hg were deduced. Experimental results are compared with Density Functional Theory (DFT) and Monte-Carlo Shell Model (MCSM) calculations. DFT calculations with several Skyrme parameterizations predict a large jump in the charge radius around the neutron $N = 104$ mid shell, with an odd-even staggering pattern related to the coexistence of nearly-degenerate oblate and prolate minima. This near-degeneracy is highly sensitive to many aspects of the effective interaction, a fact that renders perfect agreement with experiment out of reach for current functionals. Despite this inherent diffculty, the SLy5s1 and a modified UNEDF1^{SO} parameterization predict a qualitatively correct staggering that is off by two neutron numbers. MCSM calculations of states with the experimental spins and parities show good agreement for both electromagnetic moments and the observed charge radii. A clear mechanism for the origin of shape staggering within this context is identified: a substantial change in occupancy of the proton $\pi h_{9/2}$ and neutron $\nu i_{13/2}$ orbitals.