Development of a very sensitive AMS method for the detection of supernova-produced longliving actinide nuclei in terrestrial archives

For a search of supernova-produced actinide atoms in terrestrial archives, techniques for measuring minute amounts of atoms of actinides with AMS have been developed at the Munich tandem accelerator laboratory. A large analyz ing magnet has been installed, able to bend even the heavy transuranic ions at the high energies achievable with our MP tandem. The final detector is a time-of-flight and a multiple energy loss measurement which allows a near ly background-free detection of individual actinides like Pu-244. A, effici ent chemical preparation method has been developed for the extraction of sm all amounts of plutonium from samples up to nearly 1 kg. Furthermore, the p reparation of sputter cathodes, containing the final sample material, was o ptimized for high yields of negative molecules in the Cs-sputter ion source . The first search for supernova-originated Pu-244 in a deep sea ferromanga nese crust has already been carried out. (C) 2000 Elsevier Science B.V. All rights reserved.