Charge-exchange quasi-elastic process $nd\to p(nn)$ under $0^{\circ }$ in the frame of elastic $np\to np$ scattering to ${180}^{\circ }$

It is considered the problem of spin physics related with the difference of representation of the elastic interaction between the neutron and proton. In the first case the charge-exchange reaction $np\to pn$ under the angle $\theta$ is supposed, in the second — the simple elastic scattering of $np\to np$, when the neutron is going in opposite direction $\pi -\theta$. The transition from one representation to another is provided by the Majorana operator. In the framework of impulse approximation it is twice calculated the quasi-elastic charge-exchange reaction of a neutron on a deuteron. In the frame of $nd\to p(nn)$scatteringofprotontotheangle$\theta$ it gives the well-known Dean formula. Using other representation $nd\to (nn)p$ as a neutron elastic scattering under the angle $\pi -\theta$ (together with neutron-spectator in $nn$-pair) the alternative formula is presented.