Scientists have reported a major experimental advance in understanding how some of the rarest elements in the universe are formed. These unusual atoms, known as p-nuclei, are proton-rich isotopes heavier than iron that have long puzzled researchers.

The new study, led by Artemis Tsantiri, who conducted the work as a graduate student at the Facility for Rare Isotope Beams (FRIB) and is now a postdoctoral fellow at the University of Regina in Canada, achieved a milestone. For the first time, researchers directly measured how arsenic-73 captures a proton to form selenium-74 using a rare isotope beam.…