In such a thermal equilibrium, a neutron is as likely to gain kinetic energy upon scattering from a.

In such a
thermal equilibrium, a neutron is as likely to gain kinetic energy upon
scattering from a rapidly moving nucleus as it is to lose energy upon
scattering from a slowly moving nucleus. Such neutrons are referred to as
thermal neutrons. At room temperature, 293 K, the average kinetic energy of
thermal neutrons is 0.025 eV corresponding to a neutron speed of about 2200
m/s. This is a minuscule energy compared to the energy released in nuclear
reactions induced by such slow moving neutrons.