Semiquantal treatment of sequential two-nucleon transfer reactions induced by heavy ions

The WKB approximation is used to derive a semiquantal expression for the second-order DWBA amplitude of the sequential two-nucleon transfer process between two nuclei. The distorted waves are expanded in partial waves, and the radial matrix elements are converted into the contour integrals and further to the ordered double time integrals. The latter coincides with the semiclassical probability amplitude for the transfer along a classical trajectory of heavy ions. The relation with Brink's matching condition model is studied. (author)