Researchers at the Chinese Academy of Sciences have reported in Physical Review Letters the lightest isotope of uranium ever produced. Uranium-214 was created by bombarding tungsten atoms with a beam of argon and calcium. The new version of the elements has a half-life of just 0.52 milliseconds – enough for scientists to do some pretty cool science with it.
Chemical elements are made of protons and neutrons in a nucleus, surrounded by a cloud of electrons. We distinguish each element by the number of protons it has. Hydrogen has one, helium two, and so on. But each element can have a different number of neutrons, which doesn’t change the chemical properties of the element, but might make it heavier or lighter. These versions are called isotopes.
Each element has isotopes – some are stable, and some are not, in which case the element decays radioactively and turns into a different isotope or a different element. Some isotopes are naturally occurring and others can only be created in the lab.
Uranium’s most common version is uranium-238, which is used in nuclear power plants for example. It is naturally occurring and makes up 99.3 percent of all uranium. It is made of 92 protons (like all uranium atoms) and a whopping 146 neutrons. The new version of uranium instead contains only 122 neutrons. That, plus 92 protons, makes 214 – hence the name uranium-214.
The importance of this atom comes from the way it decays. You might be familiar with the term gamma radiation, but there is also alpha radiation and beta radiation. Alpha radiation is the release of two protons and two neutrons together from the nucleus of atoms, and researchers are really unsure how this actually happens.
Uranium-214 decays by emitting this alpha-particle, and so do uranium-216 and uranium-218. The reason behind this is that having 126 neutrons is one of the so-called magic numbers of nuclear physics. Isotopes with that configuration tend to decay by releasing alpha radiation.
"The nuclei near the magic neutron number N = 126 provide an ideal place to probe how nuclear structure changes influence α-decay properties," lead author Zhang Zhiyuan from the Institute of Modern Physics at the Chinese Academy of Sciences said in a statement.
The team found that these uranium atoms are special compared to the isotopes of other elements with a similar number of neutrons. Properties related to the formation of the alpha particle are twice higher in the uranium isotopes than in other elements.
The study suggests that this enhancement might be even stronger for elements with a higher number of protons, such as plutonium.