The neutron detection temperature, also called the neutron energy, indicates a
free neutron
The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beha ...
's
kinetic energy
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its a ...
, usually given in
electron volt
In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum ...
s. The term ''temperature'' is used, since hot, thermal and cold neutrons are
moderated in a medium with a certain temperature. The neutron energy distribution is then adapted to the
Maxwell distribution
Maxwell may refer to:
People
* Maxwell (surname), including a list of people and fictional characters with the name
** James Clerk Maxwell, mathematician and physicist
* Justice Maxwell (disambiguation)
* Maxwell baronets, in the Baronetage of ...
known for thermal motion. Qualitatively, the higher the temperature, the higher the kinetic energy of the free neutrons. The
momentum
In Newtonian mechanics, momentum (more specifically linear momentum or translational momentum) is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If is an object's mass ...
and
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...
of the neutron are related through the
de Broglie relation. The large wavelength of slow neutrons allows for the large cross section.
Neutron energy distribution ranges
But different ranges with different names are observed in other sources.
The following is a detailed classification:
Thermal
A thermal neutron is a free neutron with a kinetic energy of about 0.025
eV (about 4.0×10
−21 J or 2.4 MJ/kg, hence a speed of 2