4. METHOD OF SOLUTION
The formulas for the excitation function are analytical expressions. Therefore no numerical techniques are required. They have been derived based on an evaporation model considering preequilibrium emission. Some primary approximations are as follows:
1. The pre-equilibrium emission only occurs at the state of exciton number n=3.
2. There is only one competing reaction of (n,n').
3. Secondary particle emission was omitted.
4. A complex particle such as d, t, 3He or alpha is regarded as an exciton which is priorly formed in the target nucleus with a probability P(g). In this work, we took P(alpha)=0.2 and P(d P(t) and P(3He)<<1.
5. The penetration factor of a rectangular-well potential is used t describe the effects of Coulomb barrier.
6. The energy level density of the compound nucleus is taken in the form of constant temperature.