Experimental signature for statistical multifragmentation

Multifragment production was measured for the 60 MeV/nucleon ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ ${+}^{27}$Al, ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$, and ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Cu}$ reactions. The branching ratios for binary, ternary, quaternary, and quinary decays were determined as a function of the excitation energy E and are independent of the target. The logarithms of these branching ratios when plotted vs ${\mathit{E}}^{\mathrm{-}1/2}$ show a linear dependence that strongly suggests a statistical competition between the various multifragmentation channels. This behavior seems to relegate the role of dynamics to the formation of the sources, which then proceed to decay in an apparently statistical manner.