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Development of a surface ionization source for the SPIRAL 2 project.

Development of new radioactive beams, and thus of new target ion sources (TISs) for isotope-separator-on-line production systems are in progress at GANIL for the SPIRAL 2 project. The efficiency and time response measurements of each step in the production process are crucial to predict and maximize the available yields, in particular, for short lived isotopes. This paper presents a method for measuring these quantities that makes use of a stable alkali chopped beam of controlled intensity. This method was applied to surface ionization source test for high efficiency. Results of recent experiments are presented that include ionization efficiency measurements for Cs, Rb, K, Na, and Li with a graphite and rhenium ionizer and dwell time of these alkalis on graphite. The results enabled to design a first surface ionization source prototype which will be installed in the SPIRAL 2 TIS.