Masses and β-Decay Spectroscopy of Neutron-Rich Odd-Odd ^{160,162}Eu Nuclei: Evidence for a Subshell Gap with Large Deformation at N=98

• Published in: Physical review letters Vol. 120; no. 18; p. 182502
• Main Authors: Hartley, D J, Kondev, F G, Orford, R, Clark, J A, Savard, G, Ayangeakaa, A D, Bottoni, S, Buchinger, F, Burkey, M T, Carpenter, M P, Copp, P, Gorelov, D A, Hicks, K, Hoffman, C R, Hu, C, Janssens, R V F, Klimes, J W, Lauritsen, T, Sethi, J, Seweryniak, D, Sharma, K S, Zhang, H, Zhu, S, Zhu, Y
• Format: Journal Article
• Language: English
• Published: United States 04.05.2018
• ISSN: 1079-7114
• DOI: 10.1103/PhysRevLett.120.182502

The structure of deformed neutron-rich nuclei in the rare-earth region is of significant interest for both the astrophysics and nuclear structure fields. At present, a complete explanation for the observed peak in the elemental abundances at A∼160 eludes astrophysicists, and models depend on accurate quantities, such as masses, lifetimes, and branching ratios of deformed neutron-rich nuclei in this region. Unusual nuclear structure effects are also observed, such as the unexpectedly low energies of the first 2^{+} levels in some even-even nuclei at N=98. In order to address these issues, mass and β-decay spectroscopy measurements of the ^{160}Eu_{97} and ^{162}Eu_{99} nuclei were performed at the Californium Rare Isotope Breeder Upgrade radioactive beam facility at Argonne National Laboratory. Evidence for a gap in the single-particle neutron energies at N=98 and for large deformation (β_{2}∼0.3) is discussed in relation to the unusual phenomena observed at this neutron number.