A collaborative team of physicists from Germany, Finland, India, and Japan has identified a new isotope of the synthetic element Seaborgium.
Mossat et al. Report on the discovery of the new isotope Seaborgium-257. Image credit: P. Mossat, GSI/Fair.
Seaborgium is a synthetic chemical element with the symbol SG and atomic number 106.
This element was first synthesized in 1974, and currently, there are 14 known isotopes. The most stable isotope, Seaborgium-271, has a half-life of about 2.4 minutes.
The newly discovered isotope, Seaborgium-257, decays through spontaneous fission and alpha particle emission, possessing a half-life of 12.6 ms.
“Our progress is hindered by a scarcity of high-quality lead-206 targets necessary for the production of Seaborgium-257, using a powerful beam of Chromium-52 from the GSI/Fair Linear Accelerator Unilac,” they explained.
Utilizing the advanced gas-filled recoil separator TASCA (transactinide separator and chemical device), researchers recorded a total of 22 decays of Seaborgium-257.
“Our findings regarding Seaborgium-257 provide intriguing insights into the shell effects influencing the fission properties of ultra-heavy nuclei,” they mentioned.
“One significant outcome suggests that the next lightweight yet unknown isotopes may undergo nuclear fission within a brief timeframe of 1 nanosecond to 6 microseconds.
“This upper limit for the anticipated half-life is close to the current experimental capabilities unless a so-called K-extra-character state exists.”
“This excited state, stabilized by quantum effects, exhibits extended fission lifetimes and potentially allows for the exploration of short-lived nuclei.”
“Recently, notable advancements were achieved with the discovery of the 60-NS Rutherford 252 through a long-lived K-amplitude state, edging towards the stability threshold.”
“The quest for the isotopic limits of elements is a natural extension of these experiments, mapping the boundaries of hyper-heavy nuclear stability.”
“To date, no K-atroscopy states have been identified in Seaborgium isotopes.”
Nonetheless, in this current experiment, the team also irradiated a lead-208 target and found strong evidence of a K-isomer state in Seaborgium-259.
“Our results concerning the K-Crossic state of Seaborgium-259 open avenues to investigate the K-isomer phenomena in other isotopes, paving the way for the synthesis of short-lived Seaborgium-256 isotopes.”
The team’s results were published in the journal Physical Review Letters.
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P. Mossat et al. 2025. Investigating the shell effect in fission: a new hyperstable nucleus 257SG. Phys. Rev. Lett. 134, 232501; doi:10.1103/s7hr-y7zq
Source: www.sci.news
