ABSTRACT
This chapter provides the reader with the fundamentals of radioactivity, radiation, and radiation detection. Radiological contamination in the environment is of concern to human health because, if left uncontrolled, the contamination could lead to adverse health effects such as cancer. When considering environmental contamination, the most relevant forms of radiation include alpha particles, beta particles, X rays, and gamma rays. An alpha particle is basically an energetic helium nucleus, consisting of two protons and two neutrons. Alphas are emitted from the nucleus of an atom typically with energies in the million-electronvolt range. Beta particles are emitted from the nucleus of an atom and can have energies in the million-electronvolt range. Unlike alpha particles that are emitted with discrete energies, beta particles are emitted with energies ranging from 0 eV to a maximum value characteristic of the radioisotope. An X ray occurs when an electron drops from a high energy level to a lower energy level as it orbits a nucleus.
