Gamow states in a realistic two-center potential and nucleon emission in heavy-ion collisions

For a realistic finite-depth two-center potential with fixed spherical Woods-Saxon wells adiabatic bound and Gamow states have been calculated by representing each potential in a harmonic oscillator basis in momentum representation. Numerical results for the real and complex energy eigenvalues of the single-particle states as a function of the distance between the centers of the wells are presented for a neutron in a 16O + 16O potential. Due to the neglect of volume conservation and of any shape degrees of freedom the considerations are restricted to separation regions with a small overlap of the density distributions only. The matrix elements for the coupling of adiabatic states due to non-adiabatic effects in the collective relative motion of the potentials during a heavy-ion collision have been calculated for bound-bound as well as bound-continuum transitions. Neglecting the rotational coupling, from the population of Gamow states a differential neutron emission spectrum has been computed, which for a peripheral 17O + 16O reaction shows distinct peaks at the position of low-lying asymptotic adiabatic states and a decreasing high-energy tail connected with emission from quasistationary states, pushed up in energy when the collision partners are coming in contact. An appreciable fraction of the particle emission appears as a sequential decay of the excited fragments after separation. (orig.)