Abstract
The presence of 244Pu (t1/2=81 Ma) in the early solar system is long established [Nature 187 (1960) 36; Science 172 (1971) 837]. 244Pu is also one of a number of isotopes which may be detectable as live radioactivity on earth, originating from the Interstellar Medium (ISM). There has been a recent attempt to measure a ISM isotope signature of 244Pu [ApJ 558 (2001) L133]. This rises the question of the presence of an anthropogenic contribution in the environment. In order to better assess the 244Pu fall-out on earth, we have started a program at VERA to measure 244Pu in surface sediments of Lake Michigan, routinely sampled for 239,240Pu measurements. Considerable amount of information on other isotopes exist for Lake Michigan. We have reproduced the expected 241Pu/239Pu and 240Pu/239Pu ratios for the global fallout. The measured 244Pu/239Pu was considerably higher than expected and was therefore most likely the result of contamination. Measurement of samples specifically prepared for the measurement of 244Pu will be tried in the future.
Original language | English |
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Pages (from-to) | 151-154 |
Number of pages | 4 |
Journal | New Astronomy Reviews |
Volume | 48 |
Issue number | 1-4 |
DOIs | |
State | Published - Feb 2004 |
Keywords
- Pu
- Accelerator mass spectrometry
- VERA