Thermal neutron

Thermal neutrons are in thermodynamic equilibrium, i.e. moving with the same mean kinetic energy, with their surroundings.  At room temperature, their mean energy is about 0.025 eV, and their speed about 2.2×10³ m s^-1.  

Under these conditions, further scattering does not change their average kinetic energy, equal to (3/2)kT, where k is the Boltzmann constant (1.3806×10^-23 J K^-1) and T is the absolute temperature. 

See slow neutrons.