Sper Scientific 840024 Digital Radiation Meter - Manual (Page 18)

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RADIATION AND
RADIOACTIVITY
Alpha Particles
An alpha particle is identical to a
Helium nucleus having two protons and
two neutrons. When ionized by
radiation the ratio of neutrons to
protons is changed in the atom. This
causes atoms to restore the balance by
emitting alpha particles. Alpha particles
are large atoms that travel slowly in air
and lose energy rapidly after a few
inches or centimeters. This energy is
low enough to be stopped by a piece of
paper therefore alpha particles can
only be detected with specialized
equipment. Model 840024 cannot
detect alpha particles.
Common Alpha Emitters Energy MeV
Americium-241 5.48
Uranium-238 4.27
Radium-226 4.87
Radon-222 5.48