Alpha-decay spectroscopy of Rf and Lr isotopes

Asai, Masato  ; Haba, Hiromitsu*; Tsukada, Kazuaki  ; Sato, Nozomi; Kasamatsu, Yoshitaka*; Kaji, Daiya*; Morimoto, Koji*; Morita, Kosuke*; Sato, Tetsuya   ; Toyoshima, Atsushi; Ishii, Yasuo; Takahashi, Ryuta*; Nagame, Yuichiro ; Ishii, Tetsuro  ; Nishinaka, Ichiro; Kojima, Yasuaki*; Ichikawa, Takatoshi*

Alpha-decay spectroscopy of odd-mass Rf and Lr isotopes was performed to establish proton and neutron single-particle orbitals. rays following the decay of Rf were observed for the first time through the - coincidence measurement, and the neutron configuration of the ground state of Rf was assigned. It was found that the ground-state configuration of Rf is different from those of the lighter N = 155 isotones Fm and Cf. For the Lr isotopes, the proton configurations of the ground and isomeric states in Lr and the ground states of Lr and Lr were definitely identified through the high-resolution fine structure spectroscopy. Theoretical calculations based on the macroscopic-microscopic model revealed that the change of the ground-state configuration in the N = 155 isotones is strongly associated with the rapidly decreasing hexadecapole deformation with increasing atomic number.