Alpha- spectroscopy of N = 155 and 157 nuclei using a gas-jet transport technique

Asai, Masato  ; Tsukada, Kazuaki  ; Sakama, Minoru*; Ishii, Yasuo; Toyoshima, Atsushi; Ishii, Tetsuro  ; Nishinaka, Ichiro; Nagame, Yuichiro ; Kasamatsu, Yoshitaka; Haba, Hiromitsu*; Kojima, Yasuaki*; Shibata, Michihiro*; Hayashi, Hiroaki*; Sueki, Keisuke*

Alpha- spectroscopy of No and Rf nuclei with the neutron number N=155 and 157 have been performed for the first time at the JAEA tandem accelerator using a gas-jet transport technique. Spin-parities and neutron single-particle configurations of ground states of these nuclei as well as excited states in their daughter nuclei have been identified. On the basis of these experimental results, energy spacings and order of neutron single-particle orbitals between N=153 and 161 were evaluated. The result implies that the order of the neutron orbitals between N=153 and 161 should be inverted between lighter nuclei around Fm and heavier ones around Hs.