F

Fast Neutron

Quick Reference
Also Known AsHigh-energy neutron, fission neutron, MeV neutron

What is Fast Neutron?

A fast neutron is a neutron with kinetic energy greater than 1 MeV (megaelectronvolt), typically produced by nuclear fission or fusion reactions. Unlike thermal (slow) neutrons, fast neutrons have not been moderated to thermal energies and travel at high velocities. They are important in nuclear reactor physics and weapons design.

Properties & Characteristics

Kinetic energy: > 1 MeV (typically 1–20 MeV). Speed: ~14,000 km/s (5% speed of light). Mass: 1.675 × 10⁻²⁷ kg. Charge: 0 (neutral). Penetrating power: high. Less likely to cause fission in U-235 than thermal neutrons.

Uses & Applications

Fast breeder reactors (generate more fissile material than consumed). Nuclear physics research. Neutron radiography and imaging. Cancer treatment (fast neutron therapy). Materials testing by activation analysis.

Safety Information

Extremely hazardous radiation — penetrates most materials. Causes radiation sickness at high doses. Can activate non-radioactive materials. Lead shielding less effective; hydrogen-containing materials (water, polyethylene) better for moderation. Exposure must be minimized.

Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.

Key Facts

Term Fast Neutron
Synonyms High-energy neutron, fission neutron, MeV neutron

Frequently Asked Questions

A fast neutron is a neutron with kinetic energy greater than 1 MeV (megaelectronvolt), typically produced by nuclear fission or fusion reactions. Unlike thermal (slow) neutrons, fast neutrons have not been moderated to thermal energies and travel at high velocities. They are important in nuclear reactor physics and weapons design.

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