Physicists at the University of Jyväskylä have made a groundbreaking discovery in nuclear physics by identifying the heaviest nucleus ever recorded to decay via proton emission. The newly discovered isotope, 188-astatine (188At), contains 85 protons and 103 neutrons and represents a significant advancement in our understanding of atomic stability limits.
Proton emission is a rare form of radioactive decay where an unstable nucleus ejects a proton to achieve greater stability. This phenomenon is particularly challenging to study due to the extremely short lifespans and low production rates of such exotic isotopes.
The research team produced this elusive nucleus through a fusion-evaporation reaction, bombarding a natural silver target with strontium ions (84Sr). Using specialized equipment called the RITU recoil separator, they were able to isolate and identify the 188At nucleus despite its fleeting existence.
Theoretical modeling revealed that the 188At nucleus has a strongly prolate (watermelon-shaped) structure rather than being spherical. This deformation significantly affects how the nucleus binds its outermost proton, revealing an unexpected shift in nuclear stability patterns that suggests a previously unobserved type of interaction in heavy nuclei.
The findings, published in Nature Communications, mark the first new proton emitter discovery in over thirty years and provide valuable insights into the fundamental forces that govern nuclear stability at the extremes of the periodic table.