Neutron temperature

Neutron temperature is a term used in nuclear physics to describe the kinetic energy of neutrons in a system. It is an important concept in various fields such as nuclear engineering, nuclear fusion, and nuclear fission.

Overview

Neutron temperature is not a measure of heat, but rather a measure of the average kinetic energy of the neutrons in a system. It is typically measured in electron volts (eV), a unit of energy. The neutron temperature of a system can be determined by the speed and direction of the neutrons.

Thermal Neutrons

Thermal neutrons are neutrons in thermal equilibrium with a surrounding medium. They have a neutron temperature similar to the actual temperature of the medium. Thermal neutrons have a speed of about 2200 meters per second at room temperature.

Fast Neutrons

Fast neutrons are high-energy neutrons with energies above 1 MeV. They are produced in nuclear reactions and have a higher neutron temperature than thermal neutrons. Fast neutrons are important in nuclear fission as they can cause the fission of certain heavy nuclei.

Cold Neutrons

Cold neutrons are neutrons that have been moderated to energies below thermal energies. They have a lower neutron temperature than thermal neutrons. Cold neutrons are used in neutron scattering experiments and in neutron radiography.

Neutron Moderation

Neutron moderation is the process of slowing down fast neutrons to thermal energies. This is achieved by the neutrons colliding with a moderator, which is a material that slows down the neutrons without absorbing them. The neutron temperature after moderation is dependent on the type of moderator used.

Applications

Neutron temperature is a critical parameter in nuclear reactor design. The neutron temperature affects the rate of nuclear reactions, the efficiency of the reactor, and the safety of the reactor. In nuclear fusion research, the neutron temperature is important in determining the conditions for achieving a sustained fusion reaction.