Krypton-88 data refine stellar strontium production models

An international research team has conducted the first experimental study of a nuclear reaction key to understanding strontium production in stars, reducing uncertainty in the krypton-88 neutron-capture rate from at least a factor of eight to about three. The findings, published June 8 in Communications Physics, improve stellar model agreement with astronomical observations. The team used indirect techniques at Argonne National Laboratory's ATLAS facility, employing the SuN detector to measure gamma-ray emissions from krypton-89 decay. Their results showed the true neutron-capture rate is consistently lower than theoretical predictions, and incorporating this into i-process models increased predicted strontium amounts, better matching observations of old stars. Strontium, used in glow-in-the-dark paint and archaeological analysis, has puzzled scientists since the 1990s because its abundance in very old stars didn't fit established element-formation processes. The i-process was proposed as a solution, but models consistently underproduced strontium, pointing to the krypton-88 reaction as the key unknown now addressed.