A window on nucleosynthesis through detection of short-lived radionuclides

The detection of cosmic γ radioactivity of live nuclides from supernovae remnants during the last decade has had an immense impact on our understanding of stellar nucleosynthesis. It is expected that, similarly, nuclides such as 146 Sm, 244 Pu, 182 Hf, 247 Cm with halflives of the order of a few 107 years be present in the Interstellar Medium (ISM) as freshly synthesized matter; they are however not detectable by γ-ray astronomy because of their lower activity. Depending on their steady-state abundance and the ISM influx rate in the solar system, deposition on Earth of these nuclides through cosmic dust and their detection may provide a complementary approach. A search for 244 Pu in a deep-sea sediment sample, acting here as repository archive for cosmic dust, was performed by accelerator mass, spectrometry (AMS) and an upper limit for deposition of interstellar 244 Pu of 0.2 atoms/cm 2 /yr obtained. Derived constraints on 244 Pu abundance in the ISM are discussed. Further development of detection techniques for 244 Pu and other nuclides is under way.