What is Meant by Radiation

The word radiation was used until about 1900 to describe electromagnetic waves. Around the turn of the century, electrons. X-rays, and natural radioactivity were discovered and were also included under the umbrella of the term radiation. The newly discovered radiation showed characteristics of particles, in contrast to the electromagnetic radiation, which was treated as a wave. In the 1920s, DeBroglie developed his theory of the duality of matter, which was soon afterward proved correct by electron diffraction experiments, and the distinction between particles and waves ceased to be important. Today, radiation refers to the whole electromagnetic spectrum as well as to all the atomic and subatomic particles that have been discovered. 

One of the many ways in which different types of radiation are grouped together is in terms of ionizing and nonionizing radiation. The word ionizing refers to the ability of the radiation to ionize an atom or a molecule of the medium it traverses. 

Nonionizing radiation is electromagnetic radiation with wavelength A of about 10 nm or longer. That part of the electromagnetic spectrum includes radiowaves, microwaves, visible light (A = 770-390 nm), and ultraviolet light (A = 390-10 nm). 

Ionizing radiation includes the rest of the electromagnetic spectrum (X-rays, A 0.01-10 nm) and y-rays with wavelength shorter than that of X-rays. It also 

The material in this text refers only to ionizing radiation. Specifically, it deals with detection instruments and methods, experimental techniques, and analysis of results for radiation in the energy range shown in Table 1.1. Particles with energies listed in Table 1.1 are encountered around nuclear reactors, around installations involving production or use of natural or manufactured radioisotopes, and also around low-ener accelerators. Not included in Table 

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