Inside the Facility for Rare Isotope Beams at Michigan State University, Priyarshini Ghosh and her team just did something no one has ever done before: they measured chromium-52 cosmic rays in a laboratory setting, unlocking secrets about how our galaxy was built.
When stars die, they don't go quietly. Their explosions scatter elemental nuclei across space at nearly the speed of light—cosmic rays that have been traveling toward us ever since. For over a century, scientists have been trying to piece together where these elements come from and what happens to them on their long journeys through the galaxy. But a critical piece of the puzzle has always been missing: we didn't know exactly how these elements transform when they collide with hydrogen atoms as they race through space. That uncertainty has left fundamental questions about the Milky Way's chemical composition frustratingly unanswered—until now.
The breakthrough came from an elegantly simple idea: recreate the cosmic collisions in a controlled laboratory environment. When cosmic ray nuclei like chromium-52 zip through the galaxy, they undergo a process called "proton spallation," where they smash into hydrogen atoms and shatter into lighter elements. Iron from a supernova might break apart into sodium and other particles. By measuring these exact interactions, researchers can finally confidently trace detected elements back to their origins and understand the galaxy's true chemical history.
Ghosh's experiment, which ran for 43 hours earlier this month, generated a beam of chromium-52 nuclei using a clever workaround. Enriched chromium-52 itself costs approximately $150,000 for a sample the size of a chocolate square—prohibitively expensive for most research. Instead, FRIB created the chromium-52 by smashing a beam of nickel-58 against a carbon target, producing exactly what the team needed. They then fragmented this beam and recorded what happened when it collided with a liquid hydrogen target designed to mimic the hydrogen floating through space. In those 43 hours, the team successfully collected data on 50 to 60 isotopes of interest—the byproducts of element collisions and fragmentation that illuminate how the universe works.
"Nuclear data acts as a translator from the data collected by missions like Voyager 1 and 2, converting it into a meaningful understanding of our galaxy," Ghosh explains. That translation work is critical. Space telescopes and probes send back raw information about which elements exist in the cosmos, but without knowing precisely how those elements scatter and transform during their journeys, scientists can't reliably interpret what they're seeing.
What makes this research particularly significant is its rarity. The experiments needed to collect this kind of nuclear data are expensive, time-consuming, and demand access to specialized facilities like FRIB. The data Ghosh's team gathered will now undergo nearly a year of analysis, but the payoff promises to be substantial. By filling in these missing measurements, researchers expect to improve the precision of astrophysical models and finally understand the chemical fingerprint of the Milky Way itself.
"One of the most exciting aspects of this project is that FRIB offers unique opportunities to reproduce under control a very specific process occurring in the universe," noted Jorge Pereira, FRIB's magnetic spectrometer operation group leader. It's a reminder that sometimes the best way to understand the cosmos is to bring a small piece of it down to Earth.