Finnish physicists have discovered the heaviest nucleus known to emit a proton, called 188-astatine, which could significantly alter our understanding of atomic nuclei.

The discovery was made using advanced detection techniques with the RITU recoil separator, which helped identify this new isotope.

This breakthrough was achieved at the University of Jyväskylä in Finland, marking the first observation of proton emission from the heaviest nucleus since 1996.

The nucleus 188-astatine contains 85 protons and 103 neutrons, and was produced through a fusion-evaporation reaction involving a silver target and an 84Sr ion beam.

This research builds on previous work, including the 2023 discovery of a new isotope, 190-astatine, and is part of a doctoral thesis by Henna Kokkonen, published in Nature Communications.

The findings, published in Nature Communications on May 29, 2025, involve an international team of nuclear physicists and represent a major milestone in understanding the limits of matter.

These results contribute to our knowledge of nuclear structure and the boundaries of nuclear stability, marking a significant scientific advancement.

Proton emission is a rare radioactive decay process, and studying such exotic nuclei provides new insights into nuclear interactions, despite the challenges posed by their short lifetimes and low production rates.

The study suggests a change in the binding energy trend of the valence proton, indicating unprecedented nuclear interactions, with the nucleus described as strongly prolate or 'watermelon-shaped'.