Fission of Gold with 112-MevC12Ions: A Yield-Mass and Charge-Distribution Study

Abstract

Fission-product cross sections have been measured radiochemically and mass-spectrometrically for gold bombarded with 112-Mev ${\mathrm{C}}^{12}$ ions. Cross sections for 43 nuclides have been measured for elements from nickel to barium. Thirty-six yields are either primary fission-product yields (independent yields) or have been corrected (with less than 25% correction) so as to represent independent yields. The independent yields have been empirically systematized, and a yield-mass curve has been constructed. The yield-mass curve is compared with the yield-mass curves obtained from the fission of bismuth with 22-Mev and 190-Mev deuterons. The yield systematics indicate that the sum of the mass numbers of complementary fission products is 13\ifmmode\pm\else\textpm\fi{}1 amu less than that of the compound nucleus, and the sum of the charges of complementary fission products is 2-units less than that of the compound nucleus. By thermodynamic arguments it is shown that the loss of charge was carried by an alpha particle, not by protons.The most probable charge of the fission products as a function of mass number has been determined empirically and compared with theoretical prediction. The charge-dispersion curve (fraction chain yield vs $Z\ensuremath{-}{Z}_{p}$) may be fitted well by the Gaussian $y=\frac{\mathrm{exp}[\ensuremath{-}\frac{{(Z\ensuremath{-}{Z}_{p})}^{2}}{0.9}]}{{(0.9\ensuremath{\pi})}^{\frac{1}{2}}}$. Experimental yields on both sides of $Z\ensuremath{-}{Z}_{p}=0$ support the symmetry of the charge-dispersion curve that many workers have assumed.