Why Do Thermal Neutrons Use v = sqrt(2kT/m) Instead of v = sqrt(3kT/m)?

[sandon]

The most probable velocity of thermal neutrons can than be approximated by the Boltzmann constant and is given by the following:

v = sqrt (2kT/m)

where
k is the Boltzmann constant
T is the temperature
m is the mass of the neutrons

My question is why is the above equation not the following

v= sqrt(3kT/m)

 

[sandon]

Dont need an answer i got it