Possibility of transient effects during the emission of intermediate mass fragments

Multiplicity distributions of intermediate mass fragments observed in the reactions ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ ${+}^{\mathrm{nat}}$Ag and ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ ${+}^{197}$Au at E/A=84 MeV are compared to statistical model calculations. The emission of intermediate mass fragments from a highly excited ($E_x$/A≥6 MeV) A=100 nucleus is found to be suppressed compared to the predictions of a sequential statistical evaporation model. This deficiency may be interpreted as resulting from dynamical constraints imposed by the finite time necessary to emit complex fragments.