isomers in Cf and the =100 deformed shell gap

Cfの異性体と=100変形シェルギャップ

Orlandi, R.  ; 牧井 宏之   ; 西尾 勝久   ; 廣瀬 健太郎  ; 浅井 雅人  ; 塚田 和明  ; 佐藤 哲也   ; 伊藤 由太   ; 洲嵜 ふみ  

Orlandi, R.; Makii, Hiroyuki; Nishio, Katsuhisa; Hirose, Kentaro; Asai, Masato; Tsukada, Kazuaki; Sato, Tetsuya; Ito, Yuta; Suzaki, Fumi

The nuclear structure of actinide Cf was investigated at the Tokai Tandem Accelerator Laboratory. This isotopes lies two neutrons and two protons below the generally accepted =100 and =152 deformed shell gaps, but recently the location of these gaps has been heavily debated and =98 has also been suggested. Two isomeric states with half-lives in the nanosecond range were found among low-lying excited states. One of these isomers, with t11 ns, is a new state which decays via a low-energy transition to a much longer-lived state lying below 1 MeV of excitation. In the talk it will be discussed how the observation of these low-lying isomeric states favors =100 over =98 for the location of the deformed proton shell gap also in Cf.