An international research team including scientists at Michigan State University’s Facility for Rare Isotope Beams has reported the first experimental investigation of a nuclear physics reaction essential for understanding how the element strontium is produced in stars, specifically in stellar environments where traditional explanations for its formation fall short. The study, “Influence of neutron-capture reactions on the nucleosynthesis of strontium,” published June 8 in Communications Physics, reports that the team used indirect experimental techniques to extract previously inaccessible information about how an isotope of a separate element, krypton, absorbs, or captures, neutrons.
Their measurements reduced the uncertainty of the neutron-capture rate of this isotope, krypton-88, from at least a factor of eight to about a factor of three. The team found that the measured rate of neutron capture by krypton-88 is consistently lower than theoretical predictions. When they incorporated these observations into models of how stars forge heavy elements through the intermediate neutron-capture process, or i-process, they discovered that the new rate increased the predicted amount of strontium, bringing simulations into better agreement with astronomical observations.