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Section 3.1．Is there more than one kind of ionising radiation?


There are many types of ionising radiation. The four most common types are

Neutrons Neutrons Neutrons do not carry any electric charge and are constituents of atomic nuclei.
Alpha particles
Alpha (α) particles Alpha particles are positively charged particles. Each of them consists of two protons and two neutrons, identical to a helium nucleus.
Beta particles
Beta (β) particles Beta particles are high speed electrons or positrons.
Gamma rays Gamma (γ) rays Gamma rays are high energy electromagnetic waves arising from the radioactive decay of atomic nuclei.


Section 3.1．Is there more than one kind of ionising radiation?

Penetrating power of different types of ionizing radiation Penetrating power of different types of ionizing radiation
Neutrons have very high penetrating power and can only be stopped by hydrogen-rich materials, such as water or paraffin.
Fast-moving neutrons are produced by fission in a nuclear reactor. Water is commonly used to moderate and control the speed of neutrons.

Section 3.2．Ionising radiation warning symbol

There are two internationally recognised warning symbols for ionising radiation:


Traditional trefoil ionising radiation warning symbol Traditional trefoil ionising radiation warning symbol

Supplementary ionising radiation warning symbol Supplementary ionising radiation warning symbol


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