Evaporation barriers for4He indicate very extended forms for many emitting nuclei

We have analyzed a large set of mean energies and angular anisotropies for evaporative4He emission to obtain barriers to evaporation,B. These exit channel barriers are often substantially smaller than the corresponding empirical s-wave fusion barriersE0. The differences (E0-B) are interpreted as indicators of the extent of distortion of the emitters. These distortions have in turn been characterized by the deformation parameter for a spheroid α20. ForZ=80 the dependence ofB or {α}20 on spin is somewhat suggestive of the superdeformed shapes predicted by the liquid drop model. ForZ>70 significant distortions are indicated for emitters of both large and small spin.