Super Heavy Element Factory in Dubna & New Gas Filled separators for synthesis, spectroscopy and chemistry of SHE in Dubna

Sergey Dmitriev & Andrey Popeko (FLNR/JINR Dubna)

The Joint Institute for Nuclear Research (JINR) is an international intergovernmental organization established for investigations in the areas of particle physics, nuclear physics and condensed matter physics. JINR comprises seven laboratories and the university centre.

The scientific activity of the Flerov Laboratory (FLNR) founded by Academician G.N. Flerov in 1957 is concentrated on the synthesis and study of nuclear and chemical properties of superheavy elements, nuclear properties of light exotic nuclei, mechanisms of reactions induced by beams of accelerated stable and radioactive isotopes, radiation effects and physical bases of nanotechnology,accelerator physics and technic.

The main achievement of FLNR during the past 20 years is the discovery of the superheavy elements 114 – 118 named “flerovium”, “moscovium”, “livermorium”, “tennessine” and “oganesson”.

In accordance with the development program, the first in the world Superheavy Element Factory is being built at the Laboratory based on the new high current cyclotron DC-280. The main task of the Factory is the synthesis of the new chemical elements with atomic numbers 119 and higher, as well as the detailed study of the previously discovered superheavy isotopes.

The DC-280 isochronous cyclotron designed at the Flerov Laboratory will deliver beams of accelerated ions from He to U. The energy of the ions extracted from the cyclotron may be smoothly varied from 4 up to 8 MeV/amu. The expected beam intensity of ions with the masses around 50 is 10 pμA (6∙10¹³s^-1), and the maximum beam power is 2.5 kW.

The first test beam of ⁸⁴Kr¹⁴⁺ions was transported up to the extraction radius by the end of 2018, and on 17 January 2019, the beam was extracted and delivered to the switching magnet distributing the beams between five transportation channels. Now the fine-tuning of accelerator systems is under way.

As the first experimental set-up for experiments on the synthesis and study of superheavy elements, the gas-filled separator GFS-II has been chosen. The separator comprises the Q-D30-Q-Q-D10 ion optical scheme. The main analyzing magnet D30 with a deflection angle of 30° and a gap of 120 mm focuses the particles by the rotated rear pole face. The dipole D10 with a deflection angle of 10° reduces the background from elastically scattered gas atoms, i.e., hydrogen (protons) or helium (alpha-particles).

The separator had been manufactured by the firma SigmaPhi (Vannes, France) and installed at the beam line №3 of the cyclotron DC-280 in an experimental hall designed in compliance with class II radiation safety requirements for work with high active targets made of transuranium isotopes.

During the first stage of testing the properties of the separator, the detection and data acquisition systems will be studied using reactions Ar+Dy, O+Pb, Ca+Pb. Tests will continue using Ca+Pu and Ca+Am thick targets. Several hundreds decay events of flerovium and moscovium isotopes are expected to be recorded. After completion of these tests, it is planned to start the synthesis of new superheavy elements in reactions of ⁵⁰Ti and ⁵⁴Cr ions with ²⁴⁸Cm, ²⁴⁹Bk and ^249-251Cf isotopes. The experiments will be conducted in a broad international cooperation.

Practical information:

11h00 GANIL Guest House (Maison d’Hôtes)
Coffee will be served 15mn before