Alpha, Beta and Gamma

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In physics there are three main types of radioactive particles. These are alpha, beta, and gamma particles. They are emitted by unstable atomic nuclei during radioactive decay. Ernest Rutherford identified the alpha and beta particles and Paul Villard discovered gamma rays.

Specification of the particles

Particle	Charge	Symbol
Alpha	+2	$\alpha$ or ${}_2^4\text{He}$
Beta	-1	$\beta$ or ${}_{-1}^0\text{e}$
Gamma	0	$\gamma$

Penetration of the particles

Each type has its own penetration power:

• Alpha: A sheet of paper or a few cm of air.
• Beta: A few mm of aluminium.
• Gamma: Several cm of lead or several m of concrete.

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See also

• Alpha-particle scattering experiment

References

• 31.1 Nuclear Radioactivity - College Physics 2e WEB
• The Physics Book DK Books (Pages 238-239) BOOK
• A Level Physics OCR (Pages 484) BOOK