A search for supernova produced 244Pu in a marine sediment

We describe here the chemical and AMS procedures that we have developed to look for (PU)-P-244 in marine sediments. This study was motivated by the report of Knie et al. [K. Knie, G. Korschinek, T. Faestermann, E.A. Dorfi, G. Rugel, A.Wallner, Phys. Rev. Lett. 93 (2004) 171103] for observation of Fe-60 in a ferromanganese crust, which they have interpreted as resulting from the explosion of a supernova near the solar system similar to 2.8 My ago. A novel aspect of the AMS procedure is the use of various Mo isotopes as pilot beams, which allow us to tune the machine for the various Pit isotopes, without the necessity of using enriched Pu standards, thus minimizing the risk of Pu-244 contamination. These techniques have been tested on an IAEA marine sediment containing nuclear weapons contaminated Pu-239 and then applied to an Indian Ocean sediment over the period 2.4-4.0 My. (c) 2007 Elsevier B.V. All rights reserved.