Need for new physics in statistical models of nuclear de-excitation

We have measured energy spectra and angular distributions of ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ from 190–MeV ${}_{}{}^{40}{}_{}{}^{}$Ar${+\mathrm{}}^{27}$Al reactions. Comparisons with statistical model calculations show that evaporation from spherical nuclei cannot account for both the energy spectra and angular distributions, using entrance channel spins and evaporation barriers derived from fusion data. Alterations are required in both the emission barriers and the moments of inertia. Extensive nuclear deformation could explain the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ data but discrepancies remain with the ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ spectra, suggesting that additional effects are needed in the models.