When an $\alpha$ -particle with kinetic energy k = 14 MeV collides with a stationary lithium nucleus, the following nuclear reaction takes place.
${ }^{4}He+{}^{7}Li\to {}^{10}B+n$
The Q-value of this reaction is E=-2.9 MeV and the neutron is outgoing at right angle to the incoming direction of the $\alpha$ -particle. If kinetic energy of the neutron and the boron nucleus are $K_{1}MeV$ and $K_{2}MeV$ respectively.