Alpha, beta and gamma rays (Basic science review)

There are three types of “rays” that are discussed in nuclear physics:

• alpha (α) rays
• beta (β) rays
• gamma (γ) rays

Alpha rays

An alpha ray is emitted from a heavy nucleus during a process called alpha decay. An alpha ray is a particle made of two protons and two neutrons; this turns out to be a helium nucleus.

In fact, helium (like in helium balloons) is found in pockets underground. It is created through alpha decay from radioactive elements within the earth.

Beta rays

A beta ray is an electron emitted from a heavy nucleus during a process called beta decay.

(If a positron is emitted instead of an electron, the process is called β⁺ decay, since a positron has a positive charge.)

Gamma rays

Unlike alpha rays and beta rays, gamma rays are not particles. They are extremely energetic photons of electromagnetic radiation.

Comparison

Ray	Symbol	Charge	Composition	Danger
alpha	α	+2	Helium nucleus	Does not penetrate skin; dangerous if swallowed
beta	β–	-1	Electron	Does penetrate skin
gamma	γ	0	Photon	Most dangerous; difficult to shield against