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Physical Chemistry

Nucleosynthesis Has A Ring To It

Astrophysics: Stellar reaction details revealed by circulating ions in an accelerator ring

by Jyllian Kemsley
September 14, 2015 | A version of this story appeared in Volume 93, Issue 36

Credit: A. Zschau/GSI
These magnets steer ions circulating in a storage ring at GSI.
Magnets inside the GSI storage ring.
Credit: A. Zschau/GSI
These magnets steer ions circulating in a storage ring at GSI.

In the heart of a star, one process to create new elements is the so-called p process, in which an atom captures a proton. Such reactions are poorly understood because the nuclei involved often decay rapidly. A standard experiment involves aiming a proton beam from an accelerator onto a target made of a heavy element of interest. In a new approach, researchers working at Germany’s GSI Helmholtz Centre for Heavy Ion Research instead routed a stream of the heavy ions into a so-called storage ring, where they could hit a hydrogen target. The storage ring enabled the ions to circulate and repeatedly hit the target. It also allowed researchers to tune the energy of the ions to a range appropriate for p process reactions. In particular, the team led by René Reifarth of Goethe University Frankfurt used a stream of 96Ru ions to generate 97Rh ions and measured the reaction rate (Phys. Rev. C 2015, DOI: 10.1103/physrevc.92.035803). The technique could be applied to additional p process reactions as well as other astrophysical processes at similar energies, says Brad Sherrill of Michigan State University and the U.S. National Superconducting Cyclotron Laboratory.


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