Scientists have taken a major step toward explaining how the universe makes gold. A team led by researchers at the University of Tennessee reported new measurements that clarify how unstable atomic nuclei break apart during the rapid neutron-capture process, or r-process. That chain of reactions helps create heavy elements such as gold and platinum in extreme cosmic events.
Astrophysicists have long known that heavy elements form when stars collapse, explode, or collide. In those violent settings, atomic nuclei absorb neutrons very quickly, grow unstable, and then decay into other forms. But many of the nuclei involved are so rare and short-lived that scientists cannot easily study them in the lab. That has left a key gap in models of how the universe makes gold.
CERN Experiments Focused on a Rare Isotope
To investigate the problem, the team studied indium-134 at the ISOLDE Decay Station at CERN. The facility produced large numbers of the isotope and used laser separation to isolate it. When indium-134 decays, it creates excited forms of tin-134, tin-133, and tin-132.
Using a neutron detector built at the University of Tennessee, the researchers made what they called the first measurement of neutron energies from beta-delayed two-neutron emission. That decay mode occurs only in exotic nuclei and has been difficult to resolve because neutrons can scatter in ways that make it hard to distinguish between one- and two-emission events. The team said the result opens a new line of study into nuclei along the r-process pathway.
The work also produced a second major result. Researchers observed, for the first time, a long-predicted single-particle neutron state in tin-133. According to the study, physicists had searched for this state for about 20 years. Its detection helps complete the structural picture of the nucleus and improves the calculations used in nuclear models.
A Third Result Challenges Current Theory
The study’s third finding may be the most disruptive for theory. The team observed what it described as a non-statistical population of the newly identified state. In simple terms, the state was populated during decay in a way that did not match the patterns scientists usually expect.
That matters because many nuclear models assume these decays follow statistical behavior. The new result suggests those assumptions may fail in very unstable nuclei, especially farther from the region of nuclear stability. The researchers argue that more advanced theoretical approaches may now be needed to explain why some decays release one neutron, and others release two.
The paper, led by Peter Dyszel as first author, appeared in Physical Review Letters. The collaboration included researchers from the University of Tennessee and several international institutions.
Why the Findings Matter Beyond One Isotope
The new measurements do not mean scientists have fully solved the origin of gold. But they do sharpen a part of the nuclear sequence that had remained uncertain for years. Better data on exotic decays can improve computer models of the stellar events that forge heavy elements and help physicists predict the behavior of nuclei that are otherwise out of reach.
That is why the study matters beyond one rare isotope. When researchers refine the decay steps within the r-process, they improve the broader picture of how the universe makes gold and other heavy elements. In a field where many crucial reactions occur too fast to watch directly, even a single new measurement can reshape the map.