Zhang reported in April, 2021 that a flyweight isotope of uranium helps to shed light on a fundamental form of nuclear decay. The creation of the lightest uranium atom ever gives scientists a better understanding of a fundamental type of radioactive decay. All elements have one or more isotopes, which differ from each other in the number of neutrons in their nuclei. Almost all naturally occurring uranium atoms contain either 143 or 146 neutrons.
Zai-Guo Gan at the Chinese Academy of Sciences in Lanzhou and his colleagues have produced a uranium isotope with only 122 neutrons by firing a beam of argon at a tungsten target until atoms of each element fused together — an extremely rare event that formed uranium atoms. The team then extracted the 122-neutron isotope using a magnetic device called a separator.
All uranium isotopes undergo α-decay, a process whereby an atom loses two protons and two neutrons. Unexpectedly, the authors found that their ultralight isotope and a previously detected uranium isotope containing 124 neutrons decay more easily than do light isotopes of other elements. This suggests that interactions between protons and neutrons in atomic nuclei can have a greater role in α-decay than previously thought.
More technically, a new α-emitting isotope 214U, produced by the fusion-evaporation reaction 182W(36Ar,4n)214U, was identified by employing the gas-filled recoil separator SHANS and the recoil-α correlation technique. More precise α-decay properties of even-even nuclei 216,218U were also measured in the reactions of 40Ar, 40Ca beams with 180,182,184W targets. By combining the experimental data, improved α-decay reduced widths δ2 for the even-even Po-Pu nuclei in the vicinity of the magic neutron number N=126 are deduced. Their systematic trends are discussed in terms of the NpNn scheme in order to study the influence of proton-neutron interaction on α decay in this region of nuclei. It is was found that the reduced widths of 214,216U are significantly enhanced by a factor of two as compared with the NpNn systematics for the 84≤Z≤90 and N<126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the π1f7/2 and ν1f5/2 spin-orbit partner orbits, which is supported by the large-scale shell model calculation.
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