  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 $nd\to
p(nn)$ scattering of proton to the angle $\theta$ 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.
