Implications for statistical theories of fragmentation from measurements ofAg(p, He3)andAg(p, He4)at intermediate proton energies

Energy spectra and angular distributions measured for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ emitted from an Ag target bombarded with 210, 300, and 480 MeV protons are analyzed in terms of rapidity and relativistically invariant cross section. This analysis yields constraints on the possible velocities of any systems assumed to be deexciting by statistical processes. Constraints on the masses of emitting systems follow from kinematics, with implications for statistical theories: e.g., independent of the model used, the concept of evaporation is shown by this analysis to be insufficient to explain all of the data.