0000000000359559

AUTHOR

W. Dexters

Early onset of deformation in the neutron-deficient polonium isotopes

In-source laser spectroscopy has been performed at CERN-ISOLDE with the RILIS laser ion source on Po-191-204,Po-206,Po-208-211,Po-216,Po-218. New information on the beta decay of Po-199 were extracted in the process, challenging previous results. Large-scale atomic calculations were performed to extract the changes in the mean-square charge radius delta from the isotope shifts. The delta for the even-A isotopes reveal a large deviation from the spherical droplet model for N < 116.

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Structure of191Pb from α- and β-decay spectroscopy

International audience; Complementary studies of 191 Pb have been made in the β decay of 191 Bi at LISOL (CRC) and in the α decay of 195 Po at ISOLDE (CERN). Fine structures in the α decay of the low-spin and high-spin isomers of 195 Po have been fully resolved. Identification of the parent state is made possible via isomer selection based on narrowband laser frequency scanning. The α-particle and γ-ray energies have been determined with greater precision. New α-particle and γ-ray energies are identified. Branching ratios in the decay of 195 Po and 191 Pb have been examined. Structure of 191 Pb from α- and β-decay spectroscopy 2 PACS numbers: 23.20.Nx Internal conversion, 23.60.+e α decay, …

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Charge radii of odd-A 191–211Po isotopes

Isotope shifts have been measured for the odd-A polonium isotopes 191–211Po and changes in the nuclear mean square charge radii δr2 have been deduced. The measurements were performed at CERN-ISOLDE using the in-source resonance-ionization spectroscopy technique. The combined analysis of these data and our recent results for even-A polonium isotopes indicates an onset of deformation already at 197,198Po, when going away from stability. This is significantly earlier than was suggested by previous theoretical and experimental studies of the polonium isotopes. Moreover and in contrast to the mercury isotopes, where a strong odd–even staggering of the charge radii of the ground states was observ…

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