Excitation functions for production of heavy actinides from interactions ofCa40andCa48ions withCm248

Excitation functions have been measured for production of isotopes of Bk through Fm in bombardments of ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ with 234- to 294-MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ ions and with 239- to 318-MeV ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ ions. The maxima of the isotopic distributions for these elements occur at only 2 to 3 mass numbers larger for ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ than for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ reactions. The shapes of the distributions and the half-widths of about 2.5 mass numbers are quite similar to those observed previously for reactions of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, and ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ with ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$. In general, the excitation functions for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ show maxima near the Coulomb barrier while those for ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ are about 20 MeV above the barrier. The cross sections decrease rather slowly with increasing projectile energy over the energy range studied, indicating that the additional projectile energy is not manifested as excitation energy of these actinide products.