The initial 244Pu abundance of the Solar System

ended

The proposed project is a crossroad of noble gas cosmochemistry, geochemical modelling and astrophysics. We will obtain a best estimate of the initial 244 Plutonium content of the Solar System at the time when the first condensed mineral assemblages formed in the hot solar nebula. We will apply this value to model the volatile depletion history of the silicate Earth and to produce the first self-consistent estimate on the timing of the last addition of matter produced in rapid neutron capture processes (r process) to the Solar System. 244 Pu is an r-process- only short lived radionuclide that goes through spontaneous fission to produce Xenon isotopes and in principle the 244 Pu-Xe system can be used as chronometer to date early volatile loss events in Solar System solids. We propose a comprehensive experimental approach to study noble gases in combination with Nd (similarly volatile to Pu) and U (more volatile than Pu) abundances on a complementary set of samples that is adequate to explain the possible variation in the initial Pu/U ratio in different meteorites and early condensed mineral assemblages and to evaluate the applicability of the chronometer. While the Experienced Researcher is an expert in noble gas geochemistry and has experience in geochemical modelling, she will gain the knowledge on cosmochemistry and stellar nucleosynthesis required to interpret and discuss the new results produced in this project. The individual fellowship will help her start her early career as a postdoc and provide a crucial mobility to build a network in Europe and do research with high impact.