Cross sections and differential cross sections of K-39(n,alpha)Cl-36 at En=
4.5, 5.5, and 6.5 MeV, and that of Ca-40(n,alpha)Ar-37 at En=5 and 6 MeV we
re measured. These data and other available experimental data were used in
optical model calculations which contain a dispersion relation term. One se
t of parameters for dispersive optical potentials of K-39(n,n), (n,p), and
(n,alpha) reactions is determined, and subsequently used in the dispersive
optical model (DOM) calculations for Ca-40(n,n), (n,p), and (n,alpha) react
ions. A good description of the experimental data with DOM is achieved, and
the results are compared with that of the spherical optical model.