ABSTRACT
This chapter reviews the concepts of atomic and nuclear physics relevant to radiation measurements. It should not be considered a comprehensive discussion of any of the subjects presented. The special theory of relativity developed by Einstein in 1905 is based on two simple postulates: First Postulate: The laws of nature and the results of all experiments performed in a given frame of reference (system of coordinates) are independent of the translational motion of the system as a whole. Second Postulate: The speed of light in vacuum is independent of the motion of its source. To the best of knowledge today, every atom consists of a central positively charged nucleus around which negative electrons revolve in stable orbits. This chapter discusses the energetics of α, β, and γ decays, demonstrating how the kinetic energies of the products of the decay can be calculated from the masses of the particles involved.
