Synthesis of new superheavy elements using the Dubna Gas-Filled Separator: The complex of technologies

Abstract

All the new isotopes of superheavy elements in the reactions with 48Ca ions and actinide targets, synthesized at the Flerov Laboratory of Nuclear Reactions (FLNR), have been obtained at the Dubna Gas-Filled Recoil Separator (DGFRS). Success was achieved with the use of several techniques, algorithms and approaches with record performance in their area. The most sophisticated of them are rare event detection technology, methods of measuring the effective equilibrium charges of heavy ions and nuclei in hydrogen at low pressure, modified approaches to evaluation of probabilistic characteristics of detected multichain events, beam-free test methods of detection equipment, and some other ones. The author analyzes the approaches that have led ultimately to a real breakthrough and an advance in experiments on the synthesis of superheavy elements. The development of detection systems also attracts the authors’ attention. Contributions from some facilities—such as SHIP, TASCA, and GARIS (RIKEN)—to synthesis experiments are partially noted. Under consideration are methods of automation of similar experiments, including the development of control and shielding systems for operation with highly active actinide targets. Some techniques for detecting α decay of heavy nuclei that came before the current experiments with electromagnetic separators are reviewed briefly. The methods, algorithms and hardware presented cover a more than twenty-year period of commissioning and application in long-term experiments at FLNR DGFRS.