The Four Basic Types of Ionizing Radiation

DOE-HDBK-1130-98

The positively charged atom and the negatively charged electron are called an "ion

pair."

Ionization should not be confused with radiation. Ions (or ion pairs) produced as a

result of the interaction of radiation with an atom allow the detection of radiation.

Ionizing radiation

Ionizing radiation is energy (particles or rays) emitted from radioactive atoms, and some

devices, that can cause ionization. Examples of devices that emit ionizing radiation are X-

ray machines, accelerators, and fluoroscopes.

It is important to note that exposure to ionizing radiation does not necessarily result

in contamination of the worker.

Radiation is a type of energy, and contamination is radioactive material that is

uncontained and in an unwanted place.

Non-ionizing radiation

Electromagnetic radiation that doesn't have enough energy to ionize an atom is called

"non-ionizing radiation."

Examples of non-ionizing radiation are radar waves, microwaves, and visible light.

C. The Four Basic Types of Ionizing Radiation

The four basic types of ionizing radiation of concern in the DOE complex are alpha particles,

beta particles, gamma or X rays, and neutrons.

Alpha particles

Physical characteristics

The alpha particle has a large mass and consists of two protons, two neutrons,

and no electrons.

It is a highly charged particle (charge of plus two) that is emitted from the

nucleus of an atom.

The positive charge causes the alpha particle (+) to strip electrons (-) from

nearby atoms as it passes through the material, thus ionizing these atoms.

Range

The alpha particle deposits a large amount of energy in a short distance of travel.

This large energy deposit limits the penetrating ability of the alpha particle to a

very short distance.