| Decay (Radioactive): The decrease of radioactive material, specifically the emission of alpha and beta particles and gamma electromagnetic energy, with the passage of time. Decontamination (Radioactive): The reduction or removal of radioactive contamination from a structure, object or person. Detector (Radiation): A device that is sensitive to radiation and can produce a response signal suitable for measurement or analysis. A radiation survey meter. Dirty bomb: A radiological dispersal device (RDD). A device designed to spread radioactive material by conventional explosives for malevolent purposes. The objective of such a device would be to cause social disruption and panic. Dose/Dose Rate: The quantity of ionizing radiation deposited into a material, including an organ or tissue, expressed in the terms of the energy absorbed per unit mass of material. The basic unit of absorbed dose is the rad or its SI equivalent, the gray (Gy). The radiation dose delivered per unit of time. Dose equivalent: A quantity used in radiation protection to place all radiation on a common scale for calculating tissue damage. Dose equivalent is the absorbed dose in grays multiplied by the quality factor. The quality factor accounts for differences in radiation effects caused by different types of ionizing radiation. The sievert is the unit used to measure dose equivalent. Dosimeter: A small portable instrument such as a film badge or TLD for measuring and recording the total accumulated dose of ionizing radiation person receives. | 
