Ionization potential measurement of lawrencium (Lr, Z=103) by the surface ionization method

Sato, Tetsuya   ; Sato, Nozomi; Asai, Masato  ; Tsukada, Kazuaki  ; Toyoshima, Atsushi; Oe, Kazuhiro; Miyashita, Sunao; Nagame, Yuichiro ; Schdel, M.; Osa, Akihiko  ; Ichikawa, Shinichi; Stora, T.*; Kratz, J. V.*; Kaneya, Yusuke*

In order to determine the IP of lawrencium (Lr, Z = 103) by a surface ionization technique, we have developed a thermal ion source coupled to a gas-jet transport system for an Isotope Separator On-Line (ISOL) at the JAEA tandem accelerator facility. We measured ionization efficiencies of the short-lived Lr isotope, Lr ( = 27 s), and the Lu isotope, Lu ( = 3.1 min), using the ion source. The mass-separated Lr ions were successfully observed. Ionization efficiencies on the Re surface at 2600 K of Lr and Lu were evaluated to be 42% and 20%, respectively. Those experimental results suggests that the ionization potential of Lr could be lower than that of Lu as expected from theoretical calculation.