Three-body model of deuteron breakup and stripping, II

Abstract

A previously investigated three-body model of the deuteron-nucleus system, limited to relative angular momentum l = 0 for the two active nucleons, is reevaluated. Full attention is given to self-consistency between elastic and breakup channels. Introduction of the reaction of breakup on the elastic channel now reduces the elastic reflection coefficients in low partial waves by nearly a factor of 2 and causes substantial shifts in phase. Breakup amplitudes in low partial waves are also greatly reduced. As before, the breakup part of the wavefunction contains a broad spectrum of n- p continuum states. The breakup part of the wavefunction at zero n- p separation is localized at small radii, within and just outside the target nucleus, where it is comparable in magnitude with the projected elastic channel wavefunction. As a result, the projected elastic channel wavefunction is a poor approximation to the full wavefunction at n- p coincidence. Deuteron stripping theories that use the projected elastic wavefunction in a truncated waves Born series must correspondingly be quite misleading. To investigate deuteron stripping further, the exact result of the coupled channels calculation is compared with several standard approximate models. Although there is a close qualitative resemblance among the results of all the approaches, the best single approximation to the coupled channels result is found from the familiar phenomenological approach, in which a local optical potential is fitted to the elastic scattering “observed” in the coupled channels calculation. The coupled channels results are also used to analyze the approximations in the Johnson-Soper method. Several formal aspects of the three-body model are discussed.