title: Experimental identification of spin-parities and single-particle configurations in 257No and its alpha-decay daughter 253Fm.
abstract: alpha-gamma and alpha-electron coincidence spectroscopy for a short-lived heavy actinide nucleus (257)No (T(1/2) = 24.5 s) has been performed using a gas-jet transport system and an on-line isotope separator. Spin-parities of excited states in (253)Fm fed by the alpha decay of (257)No have been identified on the basis of the measured internal conversion coefficients. The nu3/2(+)[622] configuration has been assigned to the ground state of (257)No as well as to the 124.1 keV level in (253)Fm. It was found that the ground-state configuration of (257)No is different from that of lighter N = 155 isotones.
authors.affiliation: Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki.
authors.forename: M
authors.initials: M
authors.lastname: Asai
authors.forename: K
authors.initials: K
authors.lastname: Tsukada
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authors.initials: M
authors.lastname: Sakama
authors.forename: S
authors.initials: S
authors.lastname: Ichikawa
authors.forename: T
authors.initials: T
authors.lastname: Ishii
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authors.initials: Y
authors.lastname: Nagame
authors.forename: I
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authors.lastname: Nishinaka
authors.forename: K
authors.initials: K
authors.lastname: Akiyama
authors.forename: A
authors.initials: A
authors.lastname: Osa
authors.forename: Y
authors.initials: Y
authors.lastname: Oura
authors.forename: K
authors.initials: K
authors.lastname: Sueki
authors.forename: M
authors.initials: M
authors.lastname: Shibata