An article about the synthesis of the darmstadtium isotopes with mass numbers 273 and 275 and the investigation of their decay properties was published in the Physical Review C journal. The authors are scientists of the Laboratory of Nuclear Reactions and Laboratory of Theoretical Physics at JINR, Institute of Modern Physics (China), Gumilyov Eurasian National University (Kazakhstan), and Palacký University Olomouc (Czech Republic).

The ²³²Th(⁴⁸Ca, 5n)²⁷⁵Ds and ²³⁸U(⁴⁰Ar, 5n)²⁷³Ds reactions were studied at the DGFRS-2 Gas-Filled Separator at the Superheavy Element Factory at the Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research. For the first time, a new isotope ²⁷⁵Ds with a half-life of 0.43^+0.29_-0.12 ms and α-particle energy of 11.20±0.02 MeV was synthesised in the ⁴⁸Ca-induced reaction with the actinide nucleus and identified by measuring correlated α decays ending in known nuclei.

Superheavy Element Factory

The decay properties of nuclei originating from ²⁷³Ds and ²⁷⁵Ds were compared with theoretical calculations, and decay schemes were proposed. The cross sections of the ²³²Th(⁴⁸Ca, 5n)²⁷⁵Ds reaction of 0.11 +0.46 -0.09 and 0.34^+0.59_-0.16 pb were measured at excitation energies of the ²⁸⁰Ds compound nucleus E^* = 51 and 56 MeV, respectively. The cross section of the 5n-evaporation channel of the ²³⁸U+⁴⁰Ar reaction at E^* = 49 MeV of 0.18^+0.44_-0.12 pb turned out to be comparable to that for ²⁷⁵Ds at close excitation energy.

The research co-authors are Y.T. Oganessian, V.K. Utyonkov, M.V. Shumeiko, F.S. Abdullin, G.G. Adamian, S.N. Dmitriev, D. Ibadullayev, M.G. Itkis, N.D. Kovrizhnykh, D.A. Kuznetsov, O.V. Petrushkin, A.V. Podshibiakin, A.N. Polyakov, A.G. Popeko, I.S. Rogov, R.N. Sagaidak, L. Schlattauer, V.D. Shubin, D.I. Solovyev, Y.S. Tsyganov, A.A. Voinov, V.G. Subbotin, N.S. Bublikova, M.G. Voronyuk, A.V. Sabelnikov, A.Yu. Bodrov, N.V. Aksenov, A.V. Khalkin, H.B. Yang, and others.

The research was supported with a grant No. 075-10-2020-117 by the Ministry of Science and Higher Education of the Russian Federation, by a JINR Directorate grant, and by the Strategic Priority Research Programme of the Chinese Academy of Sciences.