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A simplified geometrical approach to the fast abrasion model is proposed, in order to get simple analytical formulae for the most common physical observables in both inclusive and exclusive experiments. The obtained results are satisfactorily compared with predictions of the extended abrasion model of Dayras as well as with experimental results obtained at intermediate-energy heavy-ion collisions.

Excitation functions and angular distributions relative to elastic and inelastic (5/2+ at 0.44 MeV and 7/2+ at 2.08 MeV) scattering of α-particles from23Na have been measured in the energy range (12÷15) MeV. The experimental data have been analysed in terms of statistical and nonspherical optical models. In dealing with the optical model, the coupled-channel formalism has been used. The introduction of a hexadecapole parameter β4 and the coupling of the fourth low-lying level in the coupled-channel calculations have been crucial to obtain a reasonable fit of theoretical results to experimental data.

The relative fission cross-section of235U has been measured up to 200 keV with a nominal resolution of 1.0 ns/m. The data have been analysed in order to detect nonstatistical effects due to intermediate structure. The statistical tests which have been applied to this fission and similar total-cross-section data include calculation of the correlation serial coefficients, variance and Wald-Wolfwitz tests. The comparison of the results indicates the presence of intermediate-structure effects in fission cross-section which may be interpreted on the basis of the double-humped deformation potential. Under the assumption that the first not fully open channel is theKπ=2-, the energies of the outer barrier and of the shape isomer of this transition state are obtained.