Opportunities for synthesis of new isotopes of superheavy elements


Valery Zagrebaev


Joint Institute for Nuclear Research, Dubna, Russia


Availability of different nuclear reactions (fusion of stable and radioactive nuclei, multi-nucleon transfers and neutron capture) for production of new isotopes of superheavy elements (SH) will be discussed in the talk.  Low values of the fusion cross sections and very short half-lives of nuclei with Z>120 put obstacles in synthesis of new elements.  However the fusion reactions of medium mass projectiles with different actinide targets still can be used for the production of the not-yet-synthesized SH nuclei.  The gap of unknown SH nuclei, located between the isotopes which were produced earlier in the cold and hot fusion reactions, could be filled in fusion reactions of 48Ca with available lighter isotopes of Pu, Am, and Cm.  Cross sections for the production of these nuclei are predicted to be rather large, and the corresponding experiments can be easily performed at existing facilities.  The use of heavier actinide targets give us a chance to produce more neutron enriched SH isotopes.  Moreover, for the first time, a narrow pathway is found to the middle of the island of stability owing to possible beta(+) decay of SH isotopes which can be formed in ordinary fusion reactions of stable nuclei.  Multi-nucleon transfer processes at near barrier collisions of heavy (and very heavy, U-like) ions seem to be quite realistic reaction mechanism allowing us to produce new neutron enriched heavy nuclei located in the unexplored upper part of the nuclear map.  The predicted cross sections, the angular and energy distributions of primary and survived reaction products should be useful for the design of appropriate experimental equipment and for carrying out experiments of such kind.  Neutron capture reactions can be also used for the production of the long-living neutron rich SH nuclei.  Strong neutron fluxes might be provided by pulsed nuclear reactors and by nuclear explosions in laboratory conditions and by supernova explosions in nature.  All these possibilities will be discussed in the talk.