title: Isomer decay spectroscopy of 164Sm and 166Gd: midshell collectivity around N=100.
abstract: Excited states in the N=102 isotones 166Gd and 164Sm have been observed following isomeric decay for the first time at RIBF, RIKEN. The half-lives of the isomeric states have been measured to be 950(60) and 600(140) ns for 166Gd and 164Sm, respectively. Based on the decay patterns and potential energy surface calculations, including β6 deformation, a spin and parity of 6- has been assigned to the isomeric states in both nuclei. Collective observables are discussed in light of the systematics of the region, giving insight into nuclear shape evolution. The decrease in the ground-band energies of 166Gd and 164Sm (N=102) compared to 164Gd and 162Sm (N=100), respectively, presents evidence for the predicted deformed shell closure at N=100.
authors.affiliation: Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom and RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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authors.lastname: Söderström
authors.affiliation: Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom.
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authors.affiliation: Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom and National Physical Laboratory, Teddington, Middlesex TW11 0LW, United Kingdom.
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authors.affiliation: Department of Physics, University of Surrey, Guildford GU2 7XH, United Kingdom.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan and International Research Center for Nuclei and Particles in the Cosmos, Beihang University, Beijing 100191, China and School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China.
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authors.affiliation: Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047, Japan and Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka, Japan.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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authors.affiliation: School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China.
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authors.affiliation: School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan and School of Computing, Engineering and Mathematics, University of Brighton, Brighton, BN2 4JG, United Kingdom.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan and School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China.
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authors.affiliation: Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047, Japan and Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka, Japan.
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authors.affiliation: Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka, Japan.
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authors.affiliation: Department of Physics, Osaka University, Machikaneyama-machi 1-1, Osaka 560-0043 Toyonaka, Japan.
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authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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