Prospects for the discovery of the next new element: Influence of projectiles with Z > 20

The possibility of forming new superheavy elements with projectiles having Z > 20 is discussed. Current research has focused on the fusion of ⁴⁸Ca with actinide targets, but these reactions cannot be used for new element discoveries in the future due to a lack of available target material. The influence on reaction cross sections of projectiles with Z > 20 have been studied in so-called analog reactions, which utilize lanthanide targets carefully chosen to create compound nuclei with energetics similar to those found in superheavy element production. The reactions ⁴⁸Ca, ⁴⁵Sc, ⁵⁰Ti, ⁵⁴Cr + ¹⁵⁹Tb, ¹⁶²Dy have been studied at the Cyclotron Institute at Texas A&M University using the Momentum Achromat Recoil Spectrometer. The results of these experimental studies are discussed in terms of the influence of collective enhancements to level density for compound nuclei near closed shells, and the implications for the production of superheavy elements. We have observed no evidence to contradict theoretical predictions that the maximum cross section for the ²⁴⁹Cf(⁵⁰Ti, 4n)²⁹⁵120 and ²⁴⁸Cm(⁵⁴Cr, 4n)²⁹⁸120 reactions should be in the range of 10-100 fb.