Protons d'interaction directe émis à partir des cibles Ag et Au bombardées par des protons de 156 MeV et de 91 MeV
Angular and energy distributions have been measured on prompt protons emitted between 4 and 150 MeV after the bombardment of Ag and Au targets by 156 and 91 MeV protons. The experimental device is a telescope made of 4 d E/d x and E solid state counters. The energy distributions obtained in the forward angles are compared with the results obtained after Monte-Carlo calculations on a large number of nucleon-nucleon quasi-elastic collisions inside the nuclear matter. Three models have been used to start on the calculation. The impulse approximation is assumed for all three. The first one is based on a square well potential (carré). Both model 2 and model 3 assume a diffuse edge nucleus. Model 2 (step) takes account of transmission coefficients by a classical refraction approximation. Model 3 (step no) does not include any effect of refraction or reflexion. The comparison with experimental data shows that prompt cascade protons are emitted at a large rate even for an incident energy of 91 MeV. The proportion of compound nucleus is much lower than the calculated value by model 2. In many respects the best fit seems to be obtained with model 3, so called "step no". The complete set of experimental data might stimulate more elaborated calculations on the direct process.