Production of Lr in the Cm + N reaction

Sato, Nozomi; Sato, Tetsuya   ; Asai, Masato  ; Toyoshima, Atsushi; Tsukada, Kazuaki  ; Li, Z.*; Nishio, Katsuhisa   ; Nagame, Yuichiro ; Schdel, M.; Haba, Hiromitsu*; Ichikawa, Shinichi; Kikunaga, Hidetoshi*

Due to the strong relativistic effects, the weakly-bound outermost electron results in a significantly low first ionization potential (IP) of Lr as compared with its neighboring heavy actinides. The isotope Lr, with a relatively long half-life of 27 s, is the suitable candidates for the IP measurement of Lr through the surface ionization method. In the present study, we measured the cross section of the Cm(N, 6)Lr reaction to evaluate the production rate of Lr. A Cm target with 960 60 g/cm thickness was bombarded with a N beam from the RIKEN AVF Cyclotron. The beam energy was 91 MeV in the middle of the target. The average beam intensity was 1.2 particle-A. Reaction products were transported to the rotating wheel -particle detection system with a He/KCl gas-jet system. The Lr cross section of 271 nb was calculated based on the -particle events between 8.3 and 8.7 MeV.