Cold 86Kr valley in superheavy Z = 104-120 nuclei

Abstract

Based on the cold fusion reaction valleys, referring tothe minima in the potential energy surfaces calculated on quantummechanical fragmentation theory, some of us andcollaborators suggested the use ofa 86Kr beam or its neighbouring nuclei in theirvery first publications of 1976-7. More recently, one of us (RKG) andcollaborators stressed its use again in 1993-4. In view of the veryrecent experiments, reporting the use ofa 86Kr beam for the coldsynthesis of theZ = 118 element, here we havere-investigated this problem for a large number of Z = 104-120 nuclei.We find that the use of a 86Kr beam for cold fusion reactions is asappropriate as the Pb and Ca nuclei and the optimum targets are174Yb, 184W and 208Pb, respectively, for synthesizing the260106Sg, 270110 and 294118 nuclei. The 86Kr + 208Pb is the reaction used in the above-mentioned Berkeley and GSIexperiments. For other elements, lighter than Z = 118, the34Se beamis found to compete withthe 36Kr beam, whereas for Z>118 elements38Sr is shown to be a natural choice.32Ge and 40Zrare found to be more suitable for the production of neutron-rich isotopes,thereby requiring the use of radioactive nuclear beams. The radioactivenuclear beams (and targets) are predicted to be of great use for manyother nuclei. The role of 86Kr(being similar to the doubly magic208Pb or 48Ca) is perhaps related to the recently predictedstrong shell stabilizing effects of 76Kr in cluster decay studies.