Nav: Home

How heavy elements come about in the universe

March 18, 2019

FRANKFURT. Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international research team headed by Goethe University has now succeeded in investigating the capture of protons at the storage ring of the GSI Helmholtzzentrum für Schwerionenforschung.

As the scientists report in the current issue of Physical Review Letters, their goal was to determine more precisely the probability for a proton capture in astrophysical scenarios. As Dr. Jan Glorius from the GSI atomic physics research department explains, they were faced with two challenges in this endeavour: "The reactions are most probable under astrophysical circumstances in an energy range called the Gamow window. In this range, nuclei tend to be somewhat slow, making them difficult to obtain in the required intensity. In addition, the cross section - the probability of proton capture - decreases rapidly with energy. Until now, it has been almost impossible to create the right conditions in a laboratory for these kinds of reactions."

René Reifarth, Professor for experimental astrophysics at Goethe University suggested a solution as early as ten years ago: The low energies within the Gamow window range can be reached more precisely when the heavy reaction partner circulates in an accelerator in which it interact with an stationary proton gas. He achieved first successes in September 2015 with a group of Heimholtz early career researchers. Since then, his team has gained excellent support from Professor Yuri Litvinov, who leads the EU-funded research project ASTRUm at GSI.

In the experiment, the international team first produced xenon ions. They were decelerated in the experimental storage ring ESR and caused to interact with protons. This resulted in reactions in which the xenon nuclei captured a proton and were transformed into heavier caesium - a process like that which occurs in astrophysical scenarios.

"The experiment makes a decisive contribution to advancing our understanding of nucleosynthesis in the cosmos," says René Reifarth. "Thanks to the high-performance accelerator facility at GSI, we were able to improve the experimental technique for decelerating the heavy reaction partner. We now have more exact knowledge of the area in which the reaction rates occur, which until now had only been theoretically predicted. This allows us to more precisely model the production of elements in the universe."
The experiment took place as part of the research collaboration SPARC (Stored Particles Atomic Physics Research Collaboration), which is part of the FAIR research programme. Equipment funded by the Verbundforschung (collaborative research) of the Federal Ministry for Education and Research was used in this experiment.

A picture can be downloaded here:

Caption: For the first time, the fusion of hydrogen and xenon was able to be investigated at the same temperatures as occur in stellar explosions using an ion storage ring.
Credit: Mario Weigand, Goethe-Universität


J. Glorius et al: Approaching the Gamow window with stored ions: Direct measurement of 124Xe(p,γ) in the ESR storage ring, in PRL, DOI:10.1103/PhysRevLett.122.092701

Further information: Professor René Reifarth, Institute for Applied Physics at Goethe University, Riedberg Campus, Tel.: +49 69 798-47442,

Current news about science, teaching, and society can be found on GOETHE-UNI online

Goethe University is a research-oriented university in the European financial centre Frankfurt am Main. The university was founded in 1914 through private funding, primarily from Jewish sponsors, and has since produced pioneering achievements in the areas of social sciences, sociology and economics, medicine, quantum physics, brain research, and labour law. It gained a unique level of autonomy on 1 January 2008 by returning to its historic roots as a "foundation university". Today, it is one of the three largest universities in Germany. Together with the Technical University of Darmstadt and the University of Mainz, it is a partner in the inter-state strategic Rhine-Main University Alliance. Internet:

Publisher: The President of Goethe University Editor: Dr. Anne Hardy, Science Editor, PR & Communication Department, Theodor-W.-Adorno-Platz 1, 60323 Frankfurt am Main, Tel: +49 69 798-13035, Fax: +49 69 798-763 12531, ,

Goethe University Frankfurt

Related Neutron Stars Articles:

Neutron-rich nucleus shapeshifts between a rugby ball and a discus
Researchers have shown that there are two coexisting, competing quantum shapes at low energy in 98Kr, never before seen for neutron-rich Kr isotopes.
Neutron lifetime measurements take new shape for in situ detection
Neutrons are inherently unstable and don't last long outside an atomic nucleus, and because they decay on a time scale similar to the period for Big Bang Nucleosynthesis, accurate simulations of the BBN era require thorough knowledge of the neutron lifetime, but this value is still not precisely known.
Brightest neutron star yet has a multipolar magnetic field
Scientists have identified a neutron star that is consuming material so fast it emits more x-rays than any other.
A population of neutron stars can generate gravitational waves continuously
Scientists at TIFR show that a population of neutron stars have a spin rate that is much higher than that calculated by the conventional method.
Neutron crystallography aids in drug design
Knowledge of H-bonding networks, water molecule orientations and protonation states, along with details of hydrophobic and electrostatic interactions, can prove vital towards a better understanding of many biological processes, such as enzyme mechanisms and can help guide structure-based drug design.
Mapping the exotic matter inside neutron stars
Scientists performed the first accurate determination of the thermodynamic properties of dense quark matter under violent conditions that occur during neutron star mergers, and suggest a step towards distinguishing between neutron and quark matter cores in neutron stars.
Improving safety of neutron sources
There is a growing interest in the scientific community in a type of high-power neutron source that is created via a process referred to as spallation.
When will a neutron star collapse to a black hole?
Astrophysicists from Goethe-University Frankfurt have found a simple formula for the maximum mass of a rotating neutron star and hence answered a question that had been open for decades.
ORNL neutron 'splashes' reveal signature of exotic particles
Researchers used neutrons to uncover novel behavior in materials that holds promise for quantum computing.
Cellular 'light switch' analyzed using neutron scattering
The internal movements of proteins can be important for their functionality; researchers are discovering more and more examples of this.

Related Neutron Stars Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#530 Why Aren't We Dead Yet?
We only notice our immune systems when they aren't working properly, or when they're under attack. How does our immune system understand what bits of us are us, and what bits are invading germs and viruses? How different are human immune systems from the immune systems of other creatures? And is the immune system so often the target of sketchy medical advice? Those questions and more, this week in our conversation with author Idan Ben-Barak about his book "Why Aren't We Dead Yet?: The Survivor’s Guide to the Immune System".