New Superheavy Nucleus Discovered: Seaborgium-257

A team of physicists from Germany, Finland, India and Japan discovered a new isotope of the Synthetic Chemical Seorgium.

Mosat and al. Report on the discovery of the new isotope Seorgium-257. Image credit: P. Mosat, GSI / Fair.

Selorgium is a synthetic chemical element with an SG symbol and the atomic number 106.

The element was synthesized for the first time in 1974 and now has 14 isotopes; The most stable isotope, Selorgium-271, has a half-life of about 2.4 min.

The newly discovered isotope, Selorgium-257, is disintegrated by spontaneous fission and alpha-party emission with a half-life of 12.6 ms.

“For the production of Seaborgium-257, an intense beam of Chrome-52 from the Linear GSI / Fair Unilac accelerator involved the high quality-206 targets,” said physicist GSI / Fair physicist Pavol Mosat and his colleagues.

Using the very effective detection system of the decline filled with Tasca gas (transactinid separator and chemistry apparatus), the researchers observed a total of 22 Seorgium-257 disintegrations.

“Our results on Seaborgium-257 provide exciting clues to the impact of the effects of the shell on the fission properties of superhero nuclei,” they said.

“In a single consequence, it is possible that the lighter isotope, even unknown, could undergo a fission in a very short range of time of a nanosecond with six microseconds.

“The upper limit of this expected half-life beach is close or even just below the current experimental capacities-unless a so-called isomère state is.”

“Such excited states, stabilized by quantum effects, have longer fission lifes and open an indirect door to short -term nuclei.”

“Recently, significant progress towards the border of stability has been made by discovering the Rutherfordium-252 60-N via its state of isomer K in the longer term.”

“The exploration of the isotopic border for the Seorgium element is a natural continuation of these experiences, mapping the coast of the island of super-revocmer stability.”

“Until now, no isomeric state has been observed in the isotopes of the Seorgium.”

In the current experience, however, the authors have also irradiated a lead-208 target and observed solid evidence of the presence of an isomeric state K in the Seorgium-259.

“Our results on an i-isomeric state of the Seorgium-259 open a door to explore the K-Isomer phenomenon in other isotopes of the Seaborgium and to allow the synthesis of the short-term isotope of the Seorgium-256, if a K-isomeric state with long lifespan existing also in this nucleus, declared GSI / Fair Physist Khuyaga.

The results of the team were published in the newspaper Physical examination letters.

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P. Mosat and al. 2025. Probanty the effects of the shell on the fission: the new super-revocator nucleus 257SG. Phys. Rev. Lett 134, 232501; Doi: 10.1103 / S7HR-Y7ZQ