In this chapter, the equipment and methods used for measuring ionizing radiation will be discussed. There are two types of instruments: counting equipment (used to determine the number of becquerels and the radiation quality) and dosimeters (used to determine the radiation dose). Both types of equipment require that the radiations result in observable changes in a compound (whether gas, liquid or solid). Measuring equipment consists of two parts that usually are connected. The first part consists of a sensitive volume, consisting of a compound that experiences changes when exposed to radiation. The other component is a device that converts these changes into measurable signals. The qualities of radiation that we want to measure are: • Activity. The activity or strength of a source is measured in becquerel. The
concentration is usually given in Bq/kg (solid) or Bq/m3 (liquid or gas). In considering pollution of an area Bq/m2 is used. Some countries still use Ci/km2.