S.E. International Inspector EXP Specifications download pdf (Page 13)

Ionizing Radiaon

Ionizing radiaon changes the structure of individual atoms by ionizing them. The ions produced in turn

ionize more atoms. Substances that produce ionizing radiaon are called radioacve. Radioacvity is a natural

phenomenon. Nuclear reacons take place connuously on the sun and all other stars. The emied radiaon

travels through space and a small fracon reaches the Earth. Natural sources of ionizing radiaon also exist in

people and in the ground. The most common sources of ground radiaon are uranium and its decay products

Types of Ionizing Radiaon

X-Rays

X-rays are man made radiaon produced by bombarding a metallic target with electrons at a high speed in

a vacuum. X-rays are electromagnec radiaon of the same nature as light waves and radio waves, but at

extremely short wavelength, less than 0.1 billionth of a cenmeter. They are also called photons. The energy of

X-rays are millions of mes greater than that of light and radio waves. Because of this high energy level, X-rays

penetrate a variety of materials, including body ssue.

Electromagnec radiaon (photons) of higher frequency and energy than visible and ultraviolet light. X-rays are

photons emied by interacons involving orbital electrons rather than atomic nuclei. X-rays and gamma rays

have the same basic characteriscs. The only dierence between them is their source of origin.

Gamma Rays

Gamma rays are almost idencal to X-rays. Gamma rays generally have a shorter wavelength than X-rays.

Gamma rays are very penetrang and thick lead shielding is generally required to stop them.

Short wavelength electromagnec radiaon higher in frequency and energy than visible and ultraviolet light.

Gamma rays are emied from the nucleus of an atom. These high energy photons are much more penetrang

than alpha and beta parcles.

Beta Radiaon

A beta parcle consists of a negavely charged electron emied from an atom. It has more mass and less

energy than a gamma ray, so it doesn’t penetrate maer as deeply as gamma and X-rays.

Beta parcles have a mass and charge equal to that of an electron. They are very light parcles (about 2,000

mes less mass than a proton) and have a charge of -1. A few millimeters of aluminum will stop most beta

parcles.

Alpha Parcles

Alpha radiaon is a parcle that consists of two protons and two neutrons, the same as the nucleus of a

helium atom.

Alpha parcles are posively charged parcles emied from the nucleus, are relavely large, and very heavy.

Due to this strong posive charge and large mass, an alpha parcle cannot penetrate far into any material. It

generally can travel no more than 1 to 3 inches in air before stopping, and can be stopped by a piece of paper.

Chapter 6: Basics of Radiaon and Its Measurement

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S.E. International Inspector EXP Specifications Page 13