[en] Creation of DC-280 cyclotron, the basic facility of the Factory of Superheavy Elements (SHE), is complete. The project is based on both new and experimentally tested engineering decisions of the JINR FLNR. Planned beam intensities up to 10 p · μA for ions with average masses (A ∼ 50) are one order higher than those reached so far at the U-400 cyclotron. From 2016 to 2018 installation and adjusting of the DC-280 cyclotron equipment have been done. The first beam of ⁸⁴Kr¹⁴⁺ ions was accelerated in the DC-280 on December 26, 2018 and extracted to the ion transport channel on January 17, 2019. In March 2019, beams of accelerated ⁸⁴Kr⁺¹⁴ ions with an intensity of 1.36 p · μA and ¹²C⁺² ions with an intensity of 10 p · μA were extracted from the DC-280 to the beam transport channel with energy about 5.8 MeV/nucleon. The main task of the new accelerator is implementation of the long-term program of researches on the SHE Factory aimed at synthesis of new elements (Z≥119) and detailed studying of nuclear-physical and chemical properties of earlier opened 112-118 ones.

No abstract available

[en] This paper presents the study of mass-energy distributions of quasi-fission fragments obtained in the reactions ³⁶S, ⁴⁸Ca, ⁶⁴Ni+²³⁸U at energies below and above the Coulomb barrier. To describe the quasi-fission mass distribution the simple model has been proposed. This model is based on the driving potential of the system and time dependent mass drift. This procedure allows to estimate QF time scale from the measured mass distributions. (authors)

[en] Mass and energy distributions of binary reaction products obtained in the reactions ²²Ne+²⁴⁹Cf,²⁶Mg+²⁴⁸Cm,³⁶S+²³⁸U and ⁵⁸Fe+²⁰⁸Pb leading to Hs isotopes have been measured. At energies below the Coulomb barrier the bimodal fission of Hs*, formed in the reaction ²⁶Mg+²⁴⁸Cm, is observed. In the reaction ³⁶S+²³⁸U the considerable part of the symmetric fragments arises from the quasifission process. At energies above the Coulomb barrier the symmetric fragments originate mainly from fusion-fission process for both reactions with Mg and S ions. In the case of the ⁵⁸Fe+²⁰⁸Pb reaction the quasifission process dominates at all measured energies. The pre- and post-scission neutron multiplicities as a function of the fragment mass have been obtained for the reactions studied.

[en] Results of the study of mass-energy distributions of binary fragments for a wide range of nuclei with Z = 82-122 produced in reactions with heavy ions at energies close and below the Coulomb barrier are reported. The role of the shell effects, the influence of the entrance channel asymmetry and the deformations of colliding nuclei on the mechanism of the fusion-fission and quasifission processes are discussed. The observed peculiarities of the mass and energy distributions of reaction fragments are determined by the shell structure of the formed fragments. (paper)

[en] Mass and energy distributions of fission fragments for spontaneous and low energy fission of nuclei with Z = 98-112 are discussed. The dependence of fragment characteristics (symmetric and asymmetric mass, low and high kinetic energy, bimodal) on nucleon composition of the compound nucleus and on the structure of fission fragments is investigated. (authors)

[en] Investigation of the decay properties and formation cross sections of the heaviest isotopes of element 112 with atomic numbers 282 and 283 has been performed at the FLNR (JINR) with the use of the extracted high intensity ⁴⁸Ca beams. Using a ²³⁸U target at the beam energy E_targ=231±3 MeV (E*=31 MeV) two spontaneous fission events have been detected which corresponds to the cross section of 5.0±2 pb. The result could be explained as spontaneous fission of the even-odd isotope ²⁸³112 with the half-life T_1/2=117.2_-48.5^+252.9 seconds. The probability of the α decay of ²⁸³112 is not excluded and the possible branching ratio could be b_a≅b_sf≅50%

[en] Two components in the M_γ(M) distribution were established in detailed measurements of mean γ -ray multiplicities from fission fragments of ²²⁶Th . For the first time in the M_γ(M) dependencies we were able to distinguish two components associated with primary and the final (after the neutron evaporation) fission fragments, and show that at the scission point M_γ is extremely sensitive to symmetric and asymmetric modes of fission. Theoretical calculations of the pre-scission shapes of the fissioning nuclei confirm our conclusions

[en] Future development of the FLNR accelerator complex (project DRIBs-III) includes modernization of existing cyclotrons, construction of a new experimental hall, creation of a new high current cyclotron and of next generation experimental set-ups. Realization of the project is planned for 2010-2016.

[en] Mass-energy distributions, as well as capture cross-section of fission-like fragments for the reactions ⁶⁴Ni+²³⁸U and ⁵⁸Fe+²⁴⁴Pu leading to the formation of superheavy compound system with Z = 120 and N 182 at energies near the Coulomb barrier have been measured. Fusion-fission cross sections were estimated from the analysis of mass and total kinetic energy distributions. It was found that the fusion probability is about one order of magnitude higher for the reaction ⁵⁸Fe+²⁴⁴Pu than that for the reaction with ⁶⁴Ni-ions.