Threshold for dissipative fission

We examine the empirical domain of validity of statistical theory, as applied to fission data on prefission neutron, charged particle, and γ-ray multiplicities. Systematics are found in the threshold excitation energy for the appearance of nonstatistical fission. From the data on systems with not too high fissility,, the relevant phenomenological parameter is the ratio of the threshold temperature ${\mathit{T}}_{\mathrm{thresh}}$ to the (temperature dependent) fission barrier height ${\mathit{E}}_{\mathrm{b}\mathrm{a}\mathrm{r}\left(\mathit{T}\right)}$. The statistical model reproduces the data for ${\mathit{T}}_{\mathrm{thresh}}$/${\mathit{E}}_{\mathrm{b}\mathrm{a}\mathrm{r}\left(\mathit{T}\right)<\mathrm{}0.26\mathrm{}}$±0.05 but underpredicts the multiplicities at higher ${\mathit{T}}_{\mathrm{thresh}}$/${\mathit{E}}_{\mathrm{b}\mathrm{a}\mathrm{r}\left(\mathit{T}\right)}$ independent of mass and fissility of the systems.