Measurement of the first ionization potential of nobelium (No, = 102)

Sato, Tetsuya   ; Asai, Masato  ; Kaneya, Yusuke; Tsukada, Kazuaki  ; Toyoshima, Atsushi; Vascon, A.; Takeda, Shinsaku; Mitsukai, Akina*; Nagame, Yuichiro ; Ichikawa, Shinichi; Makii, Hiroyuki   ; Osa, Akihiko  ; Sakama, Minoru*; Oe, Kazuhiro*; Sato, Daisuke*; Schdel, M.; Kratz, J. V.; Stora, T.*

In order to determine the IP of the heavy elements, we have developed a novel measurement method based on a surface ionization technique by using a surface ionization ion source coupled to a He/CdI gas-jet transport system for an Isotope Separator On-Line (ISOL) at the JAEA tandem accelerator facility. In this work, we have determined IP value of No by using the method. In a surface ionization process, an ionization efficiency of an atom depends on its IP. To obtain a relationship between IP and ionization efficiency in present system, we measured ionization efficiencies of various short-lived isotopes. Ionization efficiency of No produced in the Cm(C, 4n) reaction was also measured. Measured ionization efficiency of No was 0.8%, which yields IP value of No to be 6.6 eV. This value is in a good agreement with the value which has been evaluated by extrapolation from those of the lighter actinide elements, 6.65 eV.