Thermal neutrons have the same kinetic energy as the surrounding material.

Thermal neutrons have the same kinetic energy as the surrounding material.

• A. True
• B. False
• C. Sometimes
• D. Not applicable

Answer: (A)

Thermal neutrons are those that have come into thermal equilibrium with the surrounding material, usually a moderator. When a neutron is in this state, its velocities follow the Maxwell-Boltzmann distribution at the temperature of the material, so its kinetic energy is set by that temperature. At room temperature, that energy scale is on the order of a few hundredths of an electron volt (kT ≈ 0.025 eV; the most probable energy is about kT, with the mean energy around (3/2)kT). So the energies are characteristic of the surrounding material rather than being fixed to a single value. That’s why the statement is true: thermal neutrons have kinetic energies comparable to the thermal energy of the surrounding material, with a distribution tied to its temperature.

Thermal neutrons are those that have come into thermal equilibrium with the surrounding material, usually a moderator. When a neutron is in this state, its velocities follow the Maxwell-Boltzmann distribution at the temperature of the material, so its kinetic energy is set by that temperature. At room temperature, that energy scale is on the order of a few hundredths of an electron volt (kT ≈ 0.025 eV; the most probable energy is about kT, with the mean energy around (3/2)kT). So the energies are characteristic of the surrounding material rather than being fixed to a single value. That’s why the statement is true: thermal neutrons have kinetic energies comparable to the thermal energy of the surrounding material, with a distribution tied to its temperature.