Preparation of actinide targets for the synthesis of the heaviest elements

The heaviest elements are synthesized in heavy-ion induced hot fusion reactions with various actinide targets. Because the actinide material is often available only in very limited amounts, a deposition method with high yields (similar to 90%) is needed. We report on the production of Pu-244, Am-243, Cm-248, Bk-249, and Cf-249 targets on thin Ti backings by molecular plating. Different chemical purification steps using ion chromatographic techniques were applied for the purification of Cf-249 and Pu-244. The deposition procedure applied for the production of similar to 0.4-0.8 mg/cm(2) thick targets is described. The deposition yield was determined either by alpha-particle or gamma-ray spectroscopy. Furthermore, neutron activation analysis has been applied in the case of Pu-244, Am-243, and Cm-248. Information about the spatial distribution and homogeneity of the target layer was obtained by radiographic imaging.