Complex fragment emission in the 200-MeV ${}^4{\mathrm{H}\mathrm{e}+}^{\mathrm{nat}}\mathrm{Ag},$ ${}^{197}\mathrm{Au}$ reactions

Spectra, angular distributions, and cross sections have been measured for $Z=3\mathrm{}–14$ fragments produced in 200-MeV ${}^4\mathrm{He}$-induced reactions on ${}^{\mathrm{nat}}\mathrm{Ag}$ and ${}^{197}\mathrm{Au}$ targets. In addition, isotopic yields were measured at forward angles. Two-component moving-source fits have been performed on the data to evaluate the relative contributions of nonequilibrium and equilibrium emission mechanisms. At forward angles, the complex fragment yields are dominated by nonequilibrium emission, with IMF energies extending from the emission barrier to momenta in excess of the incident beam. Backward of 90° the yields are nearly isotropic and exhibit spectra consistent with emission from an equilibrated composite nucleus.