Development of a very sensitive AMS method for the detection of supernova-produced longliving actinide nuclei in terrestrial archives C. Wallner a, * , T. Faestermann a , U. Gerstmann b , W. Hillebrandt c , K. Knie a,d , G. Korschinek a , C. Lierse b , C. Pomar e , G. Rugel a,d a Technische Universt atM unchen, Physikdepartment der Technischen Universit atM unchen E12, 85748 Garching, Germany b Institut f ur Radiochemie der TU M unchen, 85748 Garching, Germany c Max-Planck Institut f ur Astrophysik, 85748 Garching, Germany d Strahlenbiologisches Institut, Ludwig-Maximillians-Universit atM unchen, Schillerstraûe 42, 80336 M unchen, Germany e ENREN, Autoridad Regulatoria Nuclear, Ada. Del Libertador 8250, 1429 Buenos Aires, Argentina Abstract 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 analyzing magnet has been installed, able to bend even the heavy transuranic ions at the high energies achievable with our MP tandem. The ®nal detector is a time-of-¯ight and a multiple energy loss measurement which allows a nearly back- ground-free detection of individual actinides like 244 Pu. An ecient chemical preparation method has been developed for the extraction of small amounts of plutonium from samples up to nearly 1 kg. Furthermore, the preparation of sputter cathodes, containing the ®nal sample material, was optimized for high yields of negative molecules in the Cs- sputter ion source. The ®rst search for supernova-originated 244 Pu in a deep sea ferromanganese crust has already been carried out. Ó 2000 Elsevier Science B.V. All rights reserved. Keywords: Actinides; 244 Pu; Supernova; Nucleosynthesis; Deep sea manganese crusts 1. Introduction After our discovery of supernova-produced 60 Fe in three layers of a ferromanganese crust [1] covering a time span up to 13 million years, we extended this research also to actinide isotopes. The production rates of the actinides in superno- vae are some orders of magnitude smaller than that of 60 Fe [2], nevertheless the lack of stable isotopes and stable isobars oers favorable con- ditions for a measurement: 1. Actinides can be chemically highly enriched, be- cause there is no stable isotope which dilutes the isotope to be measured and might form a mac- roscopic amount of matrix material. Nuclear Instruments and Methods in Physics Research B 172 (2000) 333±337 www.elsevier.nl/locate/nimb * Corresponding author. Tel.: +49-89-289-14282; fax: +49- 89-289-14280. E-mail address: cwallner@bl.physik.tu-muenchen.de (C. Wallner). 0168-583X/00/$ - see front matter Ó 2000 Elsevier Science B.V. All rights reserved. PII: S 0 1 6 8 - 5 8 3 X ( 0 0 ) 0 0 1 3 8 - 5