Chronology in the first few hundred million years of the Solar System revisited
Professor Michael Paul
Racah Institute of Physics
Hebrew University, Jerusalem, Israel
The stable elements known to us in nature were made in stars over the whole history of the Galaxy. Radioactive nuclides on the other hand, produced either by astrophysical or cosmogenic processes, provide additional time information and so-called “short-lived” radioactivities, with lifetimes short compared to Galactic evolution, play an important role in astrophysics. The half-life of 146Sm, a p-process nuclide now extinct in the Solar System, was remeasured via accelerator mass spectrometry and its value found significantly smaller (68 million years) than previously adopted. The chronology of the Early Solar System established by 146Sm is shortened. 146Sm serves also as a geochemical clock for differentiation events of planets such as Earth, Moon and Mars and the shorter half-life reduces our estimate of the time span of these events.
Professor Michael Paul received a French Baccalaureat in 1962 and pursued higher education at Hebrew University of Jerusalem (Israel) with a BSc in Mathematics and Physics and a MSc in Physics, graduating with a PhD in Physics in 1972. His research interests, emerging from low-energy nuclear and heavy-ion physics, have centered on development and uses of accelerator mass spectrometry (AMS). Based jointly at Hebrew University, where he was appointed Professor of Physics in 1990, and at Argonne National Laboratory (USA) as Special Term Appointee, Prof. Paul pioneered techniques in AMS such as the gas-filled magnet and applications of AMS in hydrology with meteoric 36Cl, cosmochemistry with first measurements of cosmogenic 41Ca and 59Ni and use of AMS in nuclear physics and astrophysics and geochemistry. Prof. Paul is member of the Israel Physical Society and served in various administrative positions at Hebrew University, most recently as Dean of Studies of the Faculty of Science.
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