|Francium isotopes are obtained after thorium or uranium targets bombarding by high-energy protons. 212Fr with half-life 19.3 min is the most long-lived of them. 5x10-13 g of Francium-212 with activity of 2.5x107 decays per minute appear after 15 min uranium target bombardment by proton beam with energy 660 MeV on synchrocyclotron accelerator of the Laboratory of Nuclear Problems at United Institute of Nuclear Research (Dubna, Russia). |
Francium extraction from irradiated targets is a very complex process, which must take a very short time in which it has to be separated from the material containing all known elements. Some methods of retrieving francium from irradiated uranium were worked out by Russian radiochemists A.K. Lavrukhina, A.A. Pozdnyakov and S.S. Rodin. Radiochemical methods for the isolation of francium were worked out by an American scientist E.K. Hyde. Francium separation is based on its coprecipitation with insoluble salts (caesium perchlorate or silicotungstate) or with tungstosilicic acid. The separation of these fractions takes 25 - 30 minutes.