Scientists Recreate Rare Cosmic Reaction Never Seen Before in Laboratory

Scientists have achieved a major breakthrough in understanding how some of the universe's rarest elements are formed, successfully recreating for the first time a crucial nuclear reaction that occurs in stellar explosions. The groundbreaking experiment, conducted at the Facility for Rare Isotope Beams (FRIB), has provided direct measurements of how arsenic-73 captures protons to form selenium-74, offering unprecedented insight into the cosmic processes that create elements heavier than iron.

The research, led by Artemis Tsantiri who conducted the work as a graduate student at FRIB and is now a postdoctoral fellow at the University of Regina, represents a significant advance in nuclear astrophysics. The team successfully measured the proton capture reaction using rare isotope beams, a technological feat that has only become possible with the most advanced nuclear physics facilities. The experiment involved more than 45 scientists from 20 institutions across the United States, Canada, and Europe, highlighting the international scope of this scientific achievement.

The findings, published in Physical Review Letters, address one of astrophysics' most persistent mysteries: the origin of proton-rich elements known as p-nuclei. These unusual isotopes cannot be produced through the neutron-capture processes that create most heavy elements, instead requiring extreme conditions found in supernova explosions. The gamma process, which occurs during these stellar cataclysms, strips neutrons from existing nuclei through intense gamma radiation, leaving behind proton-rich isotopes that eventually decay into stable p-nuclei.

The experimental results have cut uncertainty in stellar nucleosynthesis models by half, providing crucial data that will help astronomers better understand how elements are distributed throughout the universe. However, the findings also revealed unexpected gaps in current theoretical frameworks, suggesting that the complete story of how these rare elements form remains incomplete. The research demonstrates that even selenium-74, the lightest known p-nucleus, follows more complex formation pathways than previously understood.

This breakthrough opens new possibilities for studying other rare isotopes involved in cosmic element formation. As Tsantiri noted, experiments of this kind were previously impossible but are now achievable with facilities like FRIB. The work represents a crucial step toward solving the 60-year-old puzzle of p-nuclei origins and could reshape scientists' understanding of how the periodic table's heaviest elements are forged in the most extreme environments in the universe.