On 27 February 2023, the previously unknown darmstadtium-275 isotope was observed for the first time at the Superheavy Element Factory of the Laboratory of Nuclear Reactions JINR.

As explained by the Scientific Secretary of the Laboratory of Nuclear Reactions JINR Alexander Karpov, the ²⁷⁵Ds nucleus was obtained at the DGFRS-II Separator of the Superheavy Element Factory (SHE) in the interaction of the calcium-48 beam with the thorium-232 target material. The main purpose of the experiment was to prepare for the future synthesis of chemical element 120.

Gas-Filled Recoil Separator DGFRS-II

The first successful synthesis of darmstadtium isotopes in the ⁴⁸Ca – ²³²Th reaction was carried out at the JINR SHE Factory in 2022. As a result, three previously unknown isotopes were discovered: darmstadtium-276, hassium-272, and seaborgium-268. In 2023, the experiment was continued at a higher beam energy. Scientists found one formation event of darmstadtium-276 and one of darmstadtium-275 in it.

The new darmstadtium-275 isotope decayed with the formation of hassium-271 through alpha decay. The half-life of ²⁷⁵Ds was 62 microseconds. Scientists will continue the study of this reaction.