Physicists detect 188At, the heaviest known proton emitter, changing our understanding of nuclear decay.
New isotope 188At reveals rare proton emission and reshapes nuclear decay models
Nuclear physicists have detected the radioactive disintegration of a rare isotope of astatine for the first time. This shows that the heaviest element found in nature may be modified a lot, maybe even destroyed, in a way that scientists didn't predict. That oddball radioactive decay with 85 protons and 103 neutrons is almost (but not quite) a nuclear species that we would call stable. The finding was made by researchers at the University of Jyväskylä in Finland, and it's a major development for nuclear physics. It describes something that just shouldn't be and then shows us what the forces are that make for heavy atomic structures.
Rare Proton Decay in 188At Sheds Light on Extreme Nuclear Shapes and Stability Limits
As per a report published in Nature Communications on May 29, 2025, the isotope was produced using a fusion-evaporation reaction that entailed the irradiation of a natural silver target with strontium-84 ions. The exotic nucleus, 188 At, has a pronouncedly prolate form (of a ”watermelon” type) generated by the neutron and proton normal and attractive interaction in the inner shells of heavy nuclei experienced as a projectile in our case study.
Henna Kokkonen, the doctoral researcher who made the discovery, has mentioned that the proton emitted allows an unstable nucleus to progress towards stability by getting rid of a proton. The 190 At isotope was found by Kokkonen with the investigation of rare decay in the heavy nucleus, the rare interaction in the binding energy of the proton, and presumably a tendency change in the heavy atom region.
The team of the theory and experiment workshop pointed out the importance of exploring new decay modes and testing predictive models at the extremes of the periodic table. They also talked about how technology has improved in making and studying isotopes with short lifetimes.
Isotope discoveries of this scale remain rare in modern nuclear physics. Kokkonen expressed pride in contributing to a global effort that deepens our understanding of atomic structure. Each such finding helps refine our knowledge of nuclear forces, elemental formation, and the fundamental limits of matter. The breakthrough underscores how even after a century of nuclear science, the field continues to yield surprises from the smallest building blocks of the universe.
