Separated by an ocean and more than a decade, innovative experiments with 31 tin isotopes having either a surplus or shortage of neutrons show how neutrons influence nuclear stability and element formation. The experiments, conducted between 2002 and 2012 at Oak Ridge National Laboratory and more recently at CERN, provide knowledge that impacts nuclear energy and national security applications.

The earlier, influential ORNL measurements contributed to the American Physical Society naming ORNL’s Holifield Radioactive Ion Beam Facility a historic physics site in 2016. Several resulting publications by ORNL scientists and collaborators examined nuclear energy transitions of isotopes of tin and its neighbors and established the “doubly-magic” nature of tin-132 —stability resulting from full outer shells of both protons and neutrons.

Recent laser spectroscopy measurements at CERN’s ISOLDE facility by a team of scientists, including Alfredo Galindo-Uribarri of ORNL, combined with ORNL’s earlier Holifield results, have helped physicists understand how nuclear properties change across isotopes. The results, which help theoretical physicists improve models, are published in the journal Physical Review Letters.