The production of shell-stabilized, spherical nuclei has received significant attention in recent years due to the discovery of new superheavy elements with these characteristics.  Reactions of 48Ca, 45Sc, 50Ti, and 54Cr with lanthanide targets produce shell-stabilized, spherical nuclei near the N = 126 shell, and excitation functions for the xn and pxn exit channels have been measured using the MARS spectrometer at Texas A&M University.  The peak cross sections for the 4n evaporation channels in the 48Ca-induced reactions are substantially larger than for the other projectiles, and in some cases the p3n cross sections of the 45Sc-induced reactions are larger than the corresponding 4n cross sections.  The data have been described theoretically by a simple model that incorporates an angular momentum-dependent fission barrier, and that excludes rotational energy from the energy available to emit neutrons.  This work demonstrates that the production of nuclei near the N = 126 shell using fusion-evaporation reactions is heavily influenced by the atomic number of the projectile, and that cross sections for evaporation residues formed using projectiles with Zp > 20 may be substantially reduced relative to 48Ca-induced reactions.  This talk will summarize the most recent experimental results, discuss the theoretical model, and give some observations on the likelihood of future new element discoveries.

Survival of shell-stabilized, spherical nuclei and prospects for discovery of the next new element

247th National Meeting (2014)

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