We report the application of the new elimination of Rutherford elastic scattering
technique for the measurement of proton-induced reaction cross sections utilizing
stored ions decelerated to astrophysical energies. This approach results in a background
reduction factor of about 1 order of magnitude, enabling the first measurement of
a ( p , n ) cross section in a storage ring. Here, the reaction channels Xe 124 (
p , n ) and Xe 124 ( p , γ ) have been studied just above the neutron threshold energy.
The new data provide valuable constraints for Hauser-Feshbach theory and extrapolation
of the ( p , γ ) cross section to lower energies. Most importantly, for nuclei of
limited availability, the method represents a powerful improvement to efficiently
study proton-induced reactions at energies within or close to the astrophysical Gamow
window, bringing many reaction measurements within reach that were previously inaccessible
in the laboratory.
