Measurements and Calculations of the ³⁹K and ⁴⁰Ca(n,) Cross Sections at E_n = 4.5 to 6.5 MeV

Cross sections, angular distributions, and double-differential cross sections were measured for ³⁹K(n,)³⁶Cl reactions at E_n = 4.5, 5.5, and 6.5 MeV and for ⁴⁰Ca(n,)³⁷Ar reactions at E_n = 5.0 to 6.0 MeV, using a twin-gridded ionization chamber, and the experimental data were analyzed with the UNF code. The results indicate that the optical model parameters employed in the calculation are appropriate in the energy region. The energy level densities used in our calculations are a little different from the findings of Gilbert and Cameron, and the pair corrections of some nuclei are much smaller than what was determined by them. The experiment and model calculation results indicate that in the energy region below 7 MeV, the compound nuclear mechanism is predominant; at 6.5 MeV, the preequilibrium emission is ~12%.