&Bullet; physics 14, p43
Researchers have observed the lightest isotope of uranium to date and offer insights into models of the core structure.
Discovering new isotopes is like collecting postage stamps in physics, but the consequences of adding it to the set are much wider. A research team using the heavy ion research facility in Lanzhou, China, has now expanded the collection to include the discovery of the lightest uranium isotope to date  . The finding could have implications for our understanding of a particular type of radioactive decay that, despite more than a century of work, remains a mystery.
Uranium is an inherently unstable element. All isotopes are radioactive, with the most common having a half-life between 150,000 and 4.5 billion years (roughly the age of the earth). Naturally occurring uranium contains between 140 and 146 neutrons. The newly discovered isotope has only 122, one less than the previous record for the element.
The team created the isotope in a “fusion vaporization” reaction that involved firing a beam of argon at a tungsten target and monitoring the products of the fusion. They identified two previously discovered light uranium isotopes – uranium-216 and uranium-218 – as well as the new uranium-214 with a half-life of 0.5 ms.
The number of neutrons in this isotope is close to what is known as a magic neutron number, especially 126, which makes it interesting for studying nuclear stability. Magic isotopes are unusually stable, and observing their close neighbors provides an opportunity to study how the nuclear structure affects radioactive decay processes. In this case, measurements of the three uranium isotopes observed indicate that they have an enhanced proton-neutron interaction compared to isotopes of other elements. This stronger interaction influences the formation of alpha particles in the nucleus, a complex quantum many-body problem, the details of which are still unknown.
– Katherine Wright
Katherine Wright is the assistant editor of physics.
- ZY Zhang et al., “New
and abnormal improvement of
-Particle clusters in the lightest uranium isotopes ” Phys. Rev. Lett.126152502 (2021).