The newly-discovered isotope, plutonium-227, has a half-life of 0.78 seconds, according to a team of physicists from China.
The region of the nuclear chart 87≤Z≤97 and 112≤N≤136 shows the new isotope plutonium-227 (red star) and the 12 nuclides (blue star) that were discovered at the Institute of Modern Physics at the Chinese Academy of Sciences. Image credit: Huabin Yang.
“The magic numbers of protons and neutrons, such as 2, 8, 20, 28, 50, 82, and 126, are correlated with shell closures,” said Dr. Zaiguo Gan from the Institute of Modern Physics at the Chinese Academy of Sciences and colleagues.
“Past studies revealed a persistent weakening of the neutron shell closure of 126 up to uranium, making it fascinating to explore whether shell closures fade in the transuranium region.”
“We discovered the presence of the shell closure in neptunium isotopes through a series of experiments.”
“However, due to the absence of experimental data, the robustness of this closure in plutonium isotopes remains unknown.”
To probe unknown plutonium isotopes, the authors carried out their experiment at the gas-filled recoil separator SHANS (Spectrometer for Heavy Atoms and Nuclear Structure).
Using the fusion evaporation reaction, they were able to synthesize a very neutron-deficient plutonium isotope: plutonium-227.
“Plutonium-227 is the 39th new isotope discovered by the Institute of Modern Physics,” they noted.
From the nine observed decay chains, the physicists then measured the alpha-particle energy and half-life of plutonium-227 to be about 8,191 keV and 0.78 seconds, respectively.
“These data fit quite well with the systematics of known plutonium isotopes,” they said.
The researchers now plan to investigate more plutonium isotopes, aiming to gain a deeper understanding of shell evolution in plutonium.
“The newly discovered plutonium-227 is still seven neutrons away from the magic number of 126,” said Dr. Huabin Yang, also from the Institute of Modern Physics at the Chinese Academy of Sciences.
“To study the robustness of the shell closure in plutonium, it is necessary to continue research on even lighter plutonium isotopes, including plutonium-221 to plutonium-226.”
The team’s work appears in the journal Physical Review C.
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H.B. Yang et al. 2024. Alpha-decay of the new isotope 227Pu. Phys. Rev. C 110 (4): 044302; doi: 10.1103/PhysRevC.110.044302
Source : Breaking Science News