We discuss the conjecture that a determination of the axis of symmetry in a sequential decay provides the necessary information to select the reaction mechanism. Experimental results and a distorted-wave Born approximation analysis are given for the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}\mathrm{}(d,n)\mathrm{}{}_{}{}^{13}{}_{}{}^{}\mathrm{N}_{}^{*}{}_{}{}^{}\mathrm{}\left(p\right)\mathrm{}{}_{}{}^{12}{}_{}{}^{}\mathrm{C}$.

• Received 3 January 1972

DOI:https://doi.org/10.1103/PhysRevLett.28.623