Compound nuclear evaporation model calculations in the massA∼50andA∼80regions

Experimental excitation functions for the products of the reactions ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ + ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ + ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ + ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ + ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ were measured over the energy range from 65 to 99 MeV. The experimental excitation functions of the reaction products were then compared to the results obtained from compound nuclear evaporation model calculations. The generally better agreement obtained with one of the codes suggests the importance of angular momentum effects in the exit channel. Two-particle evaporations are badly underpredicted by both calculations in both mass regions. It is possible that part of these cross sections result from some reaction mechanism other than compound nuclear. The compound nuclear evaporation model calculations are also very sensitive to the level density parameters $a$, which are not well known in the mass $A\sim 50$ and $A\sim 80$ regions.