Boosting neutron numbers will be the purview of Michigan’s $730 million Facility for Rare Isotope Beams (FRIB), which broke ground last March. FRIB will unleash neutron-rich beams at both conventional and unconventional elemental targets, making longer-lasting, neutron-loaded superheavies.
FRIB’s beams will consist of large, yet common, atoms, like uranium-238, accelerated to half the speed of light. The targets in this case are smaller atoms, which shatter the larger particles upon collision. The resulting atomic shards will be carefully separated on the fly, using electromagnetic fields and other tricks to corral and store the radioactive, neutron-dense isotopes of interest that emerge from the collision.
After it opens in 2022, FRIB should also spawn about 1,000 new isotopes and useful quantities of 3,500 known isotopes — which together make up 80 percent of all the isotopes thought possible between hydrogen and uranium. “If scientists want an isotope, FRIB would be a good place to get it,” says Brad Sherrill, chief scientist at FRIB.
Among the most desired isotopes will be those of elements heavier than iron, including gold and silver. Theory holds that supernovas, the explosive deaths of giant stars, forge these heavy elements. Yet our finest supercomputer models of supernovas fail to produce the right mix of gold, silver and numerous other familiar metals. “The elements in people’s jewelry? We don’t know where those came from,” says Sherrill. FRIB will produce the short-lived precursors to such elements in quantity, and the results could solve that astrophysical mystery.
More down to Earth, FRIB could also unveil new radioactive isotopes for zapping cancer. These isotopes could have chemistries that favor binding to delivery agents, thus packing potent, tumor-directed punches. Another benefit could be helping scientists at work on innovative nuclear power plants better understand the exotic new neutron-laden materials they might be working with, resulting in more efficient and less wasteful reactors.
Overall, the coming crop of new superheavy elements and novel isotopes looks set to revamp our understanding of nature at the atomic level. “In nuclear physics, there are many frontiers,” says Sherrill. “This is a story where we don’t know the ending.”
[This article originally appeared in print as "Forging New Elements."]