Sweden team tests 100 rare nuclei to unlock nuclear fission secrets

Researchers at Chalmers University of Technology in Sweden conducted an experimental study using a large superconducting magnet to investigate nuclear fission in 100 exotic nuclei, including elements like platinum, mercury, and lead. Their goal was to better understand the fission process, which is fundamental both for improving cleaner nuclear energy generation and for insights into element formation in the universe. Nuclear fission typically produces asymmetric fragments—unequal in size and mass—due to the nuclear shell structure, where certain numbers of protons and neutrons confer greater stability. However, prior research focused mainly on a limited set of long-lived isotopes, leaving the fission behavior of many exotic, short-lived nuclei poorly understood. The team specifically studied nuclei with more protons than neutrons to identify which shell effects cause the nucleus to split asymmetrically into a lighter and a heavier fragment. Their surprising finding was that the enhanced stability of the smaller fission fragment is linked to a specific proton number—36—indicating a previously un