What has 122 neutrons, 92 protons, a half-life of .52 milliseconds, and it is the lightest version of this element? The answer is Uranium-214. It has only 122 neutrons compared with the 146 neutrons found in Uranium-238, which makes up > 99% of the world’s naturally occurring uranium.
Isotopes of a particular element always have the same number of protons but differ by their number of neutrons, and they are labeled by the total number of protons and neutrons their nuclei contain. Thus, in this case 122 + 92 = 214, making this isotope – Uranium-214 – the lightest of all Uranium isotopes.
Researchers in China just recently produced this lightest version of Uranium. Zhiyuan Zhang at the Chinese Academy of Sciences and his colleagues produced this new isotope through a time-consuming process that involved the blasting of tungsten samples with powerful beams of argon and calcium until the atoms fused together. Afterward, using a magnetic device called a separator, they picked the Uranium-214 atoms out of the sample.
“The production of these atoms is very difficult, because not every collision can produce what we want,” says Zhang. “About 1018 beam particles were delivered to collide with the target, but only two nuclei of Uranium-214 were produced successfully and separated.”
The researchers watched those nuclei decay and determined that the half-life of Uranium-214 was .52 milliseconds. Half-life is the length of time until half of the nuclide has decayed – radioactively. In this particular case, Uranium-214 undergoes alpha decay – the atom releases two protons and two neutrons. Similar experiments with Uranium-216 and Uranium-218, revealed half-lives of ~ 2.25 milliseconds and 0.65 milliseconds, respectively.
Based on their research they believe that the interactions between protons and neutrons in these atoms are more powerful than in other isotopes. “Our finding might be the first experimental evidence that the strong proton-neutron interaction can play an important role in alpha decay in [heavy nuclei],” Zhang says.