Characterization of the Surface Ionization Source dedicated to radioactive alkali ion production in the frame of the SPIRAL 2 project

International audienceDevelopments of new radioactive beams and thus of new target-ion-sources (TIS) for isotopeseparator- on-line (ISOL) production systems are in progress at GANIL for the SPIRAL 2 project. Measurements of the time response and of the efficiency of each step of the production process are crucial to predict the available yields, in particular for short lived isotopes. This paper presents a method that uses a chopped beam of stable alkali of controlled intensity. This method was applied on SISTHE (Source à Ionisation de Surface de Test à Haute Efficacité). During the tests, the ionization efficiency is extracted from the ratio between the flux emerging from the TIS and the flux implanted in the TIS. Time responses are obtained using the ion gun in pulsed mode. Results of recent experiments are presented that include: ionization efficiency measurements for Cs, Rb, K, Na and Li in a graphite and rhenium ionizer, sticking time of these alkalis on graphite and the time response of the ionizer tube. The results enabled to design a first SIS prototype which will be installed in the SPIRAL 2 TIS. It is expected to be ready for testing by the end of October 09