Figure 3.

(left) Bi-dimensional z-$\theta$ efficiency map for ${\alpha }_1$-$_{}^{12}\text{C}$ coincidence events. Values of $\theta$ are expressed in an arbitrary reaction chamber reference frame. Unitary coincidence efficiency is safely achieved in a broad z and $\theta$ domain. This plot is used to center the forward telescope with the $_{}^{12}{\text{C}}^{\star }$ (4.44 MeV) kinematic emission cone. (right) Schematic layout of the experiment. In their nominal positions, the backward telescope is placed at $\theta ={90}^{\circ }$, while the forward telescope is placed at $\theta =64.8^{\circ }$ with respect to the $_{}^2\text{H}$ beam direction.