Neutron temperature

Neutron Temperature

Maxwell-Boltzmann distribution of neutron speeds.

Neutron temperature is a concept used in nuclear physics to describe the kinetic energy of neutrons in a given environment. It is an important factor in nuclear reactions, as the energy of neutrons affects their interaction with atomic nuclei. Neutron temperature is often expressed in terms of the temperature of a hypothetical gas of neutrons in thermal equilibrium.

Classification of Neutrons by Temperature

Neutrons can be classified based on their kinetic energy, which is related to their temperature. The main categories are:

Cold Neutrons

Cold neutrons have very low kinetic energy, typically less than 0.025 eV. They are produced in neutron moderators and are used in various applications such as neutron scattering experiments.

Thermal Neutrons

Thermal neutrons are in thermal equilibrium with their environment and have energies around 0.025 eV at room temperature. They are crucial in nuclear reactors as they are more likely to induce nuclear fission in certain isotopes, such as uranium-235.

Epithermal Neutrons

Epithermal neutrons have energies between thermal and fast neutrons, typically ranging from 0.025 eV to 1 keV. They are less likely to be absorbed by nuclei compared to thermal neutrons.

Fast Neutrons

Fast neutrons have high kinetic energy, typically greater than 1 keV. They are produced in nuclear reactions and are important in fast neutron reactors.

Relativistic Neutrons

Relativistic neutrons have extremely high energies, often exceeding 1 MeV. They are encountered in high-energy physics experiments and cosmic ray interactions.

Neutron Moderation

Neutron moderation is the process of reducing the kinetic energy of fast neutrons to convert them into thermal neutrons. This is achieved using materials known as moderators, such as water, heavy water, or graphite. Moderation is essential in thermal nuclear reactors to sustain a controlled chain reaction.

Applications of Neutron Temperature

The concept of neutron temperature is applied in various fields:

• In nuclear reactor design, understanding neutron temperature helps in optimizing the reactor's efficiency and safety.
• In neutron scattering techniques, different neutron temperatures are used to probe the structure of materials at the atomic level.
• In nuclear medicine, neutron temperature is considered in the design of boron neutron capture therapy (BNCT) for cancer treatment.

Related Pages

• Neutron
• Nuclear reactor
• Neutron scattering
• Nuclear fission
• Neutron moderator