Recent work has demonstrated that the production of nuclei near the N = 126 shell using fusion-evaporation reactions is heavily influenced by the atomic number of the projectile.  In experiments at Texas A&M University, excitation functions for the xn and pxn exit channels in the reactions of 48Ca, 45Sc, 50Ti, and 54Cr with lanthanide targets have been measured using the MARS spectrometer.  The peak cross sections for the 4n evaporation channels in the 48Ca-induced reactions are substantially larger than for the other projectiles.  The compound nuclei in these reactions are shell-stabilized and spherical, and the sharp decrease in cross section for 45Sc-, 50Ti-, and 54Cr-induced reactions is attributed to an enhancement of the fission level density along with a smaller change in the probability of compound nucleus formation.  This talk will discuss the most recent results in the context of neutron binding energies, fission barriers, and the energy available for neutron emission.  The data suggest that cross sections for evaporation residues formed using projectiles with Z > 20 may be substantially reduced relative to 48Ca, and this may affect the likelihood of future superheavy element discoveries.

Production of shell-stabilized spherical nuclei using projectiles with <i>Z</i> > 20

246th National Meeting (2013)

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Production of shell-stabilized spherical nuclei using projectiles with Z > 20