Heavy elements from the depths of the universe
Press release of the Technical University Darmstadt, 29 March 2016
The origin of the chemical elements in the universe is one of the unsolved mysteries of natural science. A collaboration of two nuclear astrophysicists of GSI Helmholtzzentrum für Schwerionenforschung and the Technical University of Darmstadt – Dirk Martin and Almudena Arcones – and two nuclear physicists of the Michigan State University – Witold Nazarewicz and Erik Olsen – discovered that the properties of nuclear interactions have influence on the synthesis of the most heavy elements in our universe.
The heavy elements in our solar system – like gold or uranium – were formed by a complex chain of nuclear reactions and decays, also known as the "rapid neutron capture" process (r-process). This mechanism requires extremely high neutron densities as well as short-lived so-called exotic isotopes which can't be produced in existing particle accelerators as of yet. Current information about these conditions stems solely of theoretical models which rely on extreme extrapolations to areas of the nuclear chart where no experimental data is available. The two favoured astrophysical scenarios for the r-process are catastrophic core-collapse supernova explosions and the merging of neutron stars. In their work the scientists predict the synthesis of the elements in the r-process with different models of nuclear interaction.
In their article published in the scientific journal Physical Review Letters they determine systematic uncertainties of the predicted abundance distributions directly linked to the modelling of masses for realistic astrophysical scenarios.
New accelerators allow important measurements
The results published in the article will be useful in the future to identify regions in the nuclear chart that are crucial for the synthesis of the heavy elements. The two accelerator facilities under construction FAIR (Facility for Antiproton and Ion Research) in Darmstadt and FRIB (Facility for Rare Isotope Beams) in Michigan will be world leaders in this area and conduct important measurements to verify these predictions.
While it is not yet possible to determine whether the gold in jewellery or the dysprosium in the engine of an electric car come from colliding neutron stars or from a supernova, still the scientists are closer to the understanding of their astrophysical origin than ever.