STATISTICAL EMISSION OF DEUTERONS AND TRITONS FROM HIGHLY EXCITED COMPOUND NUCLEI

Statistical model calculations, employing optical model transmission coefficients for particle emission, have been able to describe in a satisfactory way n, p, d, t, and a emission properties of compound nuclei at excitation energies below 100 MeV. Recent experimental data have shown that the same model systematically overpredicts the deuteron and triton yields observed at higher excitation energies up to 405 MeV. The predictions of the statistical model with transmission coefficients derived from an ingoing-wave boundary condition and a direct reaction approach to fusion method are discussed. It is shown that a description of the deuteron and triton data is possible, provided that the corresponding inverse cross sections are reduced from the optical model predictions. For deuteron emission in particular, the required reduction is found to be consistent with experimental deuteron fusion cross sections. The breakdown of the traditional approach is attributed to the large percentage of nonfusion components contained in the optical model absorption cross section.