AmBe

AmBe, short for americium-beryllium, is a compact sealed radioactive neutron source used in research, industry, and education. It consists of a small quantity of americium-241 embedded in a beryllium-containing matrix. Americium-241 decays by alpha emission to neptunium-237; the emitted alpha particles interact with 9Be nuclei to produce neutrons via the 9Be(alpha,n)12C reaction. The source emits fast neutrons and, from the americium decay, a gamma-ray component, most notably the 59.5 keV gamma line.

Neutron energy and emission: The neutrons have energies in the fast range (roughly 2–7 MeV) with a broad spectrum. The neutron yield is fixed by the source design and gradually declines with time as Am-241 decays. The gamma radiation from Am-241 is relatively low-energy and is accompanied by higher-energy gammas from reaction products; shielding is used to reduce exposure to both neutrons and gammas.

Applications: AmBe sources are used for detector calibration, neutron activation analysis, prompt gamma neutron activation analysis, and educational demonstrations. They have also been employed in oil-well logging and various laboratory experiments where portable neutron sources are advantageous. They are valued for their compactness and simplicity but are regulated as sealed radioactive sources.

Safety and regulation: Because they contain long-lived radioactivity and emit both neutrons and gamma rays, AmBe sources are subject to strict regulatory control. Handling, transportation, storage, and disposal require appropriate licensing, shielding, and containment. Radiation-protection measures commonly include neutron moderators (like polyethylene), gamma shielding (lead or concrete), and regular integrity and contamination checks.

See also: sealed radioactive source, neutron source, americium-241, beryllium.