Elastic n-d Scattering Phases

Abstract

A large volume of both experimental and theoretical work has been devoted to the study of elastic scattering of neutrons by deuterons. The reason for this is that the n + d system is the simplest nuclear system involving more than two nucleons. Studies of the properties of this system at low energies should therefore yield more detailed information about nuclear forces than can be obtained from analyses of the two-nucleon system. It is usually assumed in the analysis of n-d scattering at low energies that there is no spin-orbital interaction, and that the total spin S of the system and the orbital angular momentum l are good quantum numbers. This is in agreement with measurements of the polarization of neutrons scattered elastically by deuterons [1,2,3]. However, even in this case, the scattering phases cannot be unambiguously determined from the angular distributions. The angular distributions in n-d scattering have been measured by Elwin et al. [3] with good accuracy at low energies. They have reported two sets of phases which are in equally good agreement with the experimental differential cross sections. In both sets, the s phases were fixed and the p and d phases were obtained from the best fit to the experimental data. In the first set, the s phases correspond to those obtained by Christian and Gammel [4], and in the second set they correspond to the phases obtained by Buckingham et al. [5].