We are concerned here with collisions involving two identical nuclei either in the entrance or in the exit channels (or in both) for which the differential cross section reads dσ/dΩ ∝‖f(θ)${\mathrm{\Vert }}^2$+‖f(π-θ)${\mathrm{\Vert }}^2$+2α Re[f(θ)${\mathit{f}}^{\mathrm{*}}$(π-θ)]. We propose a simple graphical method for obtaining the parameter α directly from the measured angular distribution.

• Received 22 February 1988

DOI:https://doi.org/10.1103/PhysRevC.38.543