Spontaneous fission measurements using Es target

Asai, Masato  ; Tsukada, Kazuaki  ; Sato, Tetsuya   ; Ito, Yuta   ; Nishio, Katsuhisa   ; Makii, Hiroyuki   ; Hirose, Kentaro  ; Orlandi, R.  ; Suzaki, Fumi  ; Aoki, Ryota; Uchibaba, Yuta; Gong, G.; Natori, Hina*; Miyachi, Yuta*

Fission of neutron-rich heavy-actinide nuclei exhibits extremely characteristic fission-fragment mass distributions which differ significantly from those of typical actinide nuclei. In the present study, we have succeeded in producing those neutron-rich heavy-actinide nuclei with multinucleon transfer reactions using an extremely rare and short-lived Es target bombarded with heavy-ion beam from the JAEA Tandem Accelerator. The products were mass-separated with an on-line isotope separator (ISOL), and spontaneous fission of Fm, Fm, Md, Lr was observed. Fission-fragment mass distributions and total kinetic energy distributions were obtained precisely, which provides us with important information to clarify the characteristic fission mechanism observed in this nuclear region.