Measurement of the first ionization potential of lawrencium, element 103

Sato, Tetsuya   ; Asai, Masato  ; Borschevsky, A.*; Stora, T.*; Sato, Nozomi; Kaneya, Yusuke; Tsukada, Kazuaki  ; Dllmann, Ch. E.*; Eberhardt, K.*; Eliav, E.*; Ichikawa, Shinichi; Kaldor, U.*; Kratz, J. V.; Miyashita, Sunao*; Nagame, Yuichiro ; Oe, Kazuhiro*; Osa, Akihiko  ; Renisch, D.*; Runke, J.*; Schdel, M.; Thrle-Pospiech, P.*; Toyoshima, Atsushi; Trautmann, N.*

Ionization efficiency in a surface ionization process depends on the first ionization potential of the atom. Based on the dependence, the ionization potential of the atom can be determined. We successfully measured ionization efficiencies of lawrencium (Lr, =103) using a gas-jet coupled surface ion-source. The ionization potential of Lr has not been determined owing to its low production rate and its short half-life. Based on a relationship between the ionization efficiency and the ionization potential obtained via measurements of short-lived lanthanide isotopes, the ionization potential of Lr was determined.