TYPES OF RADIATION
The radioactive sources in the gauge produce four types of
radiation:
Alpha particles
Beta particles
Gamma rays (photons)
Neutrons
The alpha and beta particles are stopped by the source capsule.
Therefore, they present no external hazard to personnel. Only the
gamma and neutron radiation from sealed sources contribute to any
occupational radiation exposure.
Gamma rays (photons) are a type of electromagnetic radiation, like
X rays, radio waves, and visible light. Photons have no mass or
electrical charge, and travel at the speed of light. Gamma rays are
energetic and penetrating. Dense materials (such as lead, tungsten,
and so on) provide the best shielding against gamma radiation.
Neutrons are a form of particulate radiation but, unlike alpha and
beta particles, they have no electrical charge. This makes neutron
radiation very penetrating. Fast neutrons lose energy primarily by
so-called “billiard ball” elastic collisions with the nuclei of low
atomic number atoms, especially hydrogen. The best shielding
materials for fast neutrons are those with a high hydrogen content,
such as water, concrete, and polyethylene.
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