Radon Glossary F-P
Field Blank: A quality control measurement made using a detector which has not been exposed to radon or progeny. The purpose of this procedure is to determine the bias associated with the storage and shipping of devices.
Follow Up Measurements: Measurements made to evaluate typical long term radon concentrations. They are conducted after an initial measurement indicates the potential for unacceptable radon levels.
Gamma radiation: Short-wavelength electromagnetic radiation of nuclear origin, with energies between 10 keV to 9 MeV.
Gamma Rays: Gamma rays are an example of electromagnetic radiation, as is visible light. Gamma rays originate from the nucleus of an atom. They are capable of traveling long distances through air and most other materials. Gamma rays require more "shielding" material, such as lead or steel, to reduce their numbers than is required for alpha and beta particles.
Geiger Counter: A device for detecting beta and gamma radiation.
Half-Life: The time required for a population of atoms of a given radionuclide to decrease, by radioactive decay, to exactly one-half of its original number is called the radionuclide's half-life. No operation, either chemical or physical, can change the decay rate of a radioactive substance. Half-lives range from much less than a microsecond to more than a billion years. The longer the half-life the more stable the nuclide. After one half-life, half the original atoms will remain; after two half-lives, one fourth (or 1/2 of 1/2) will remain; after three half-lives one eighth of the original number (1/2 of 1/2 of 1/2) will remain; and so on.
Ionizing radiation: Any type of radiation capable of producing ionization in materials it contacts; includes high-energy charged particles such as alpha and beta rays, and nonparticulate radiation such as gamma rays and X-rays. In contrast to wave radiation (e.g., visible light and radio waves) in which waves do not ionize adjacent atoms as they move.
Non-Ionizing Radiation: Low energy radiation such as radio and television waves.
Passive radon/radon decay product measurement device: A radon or radon decay product measurement system in which the sampling device, detector, and measurement system do not function as a complete, integrated unit. Passive devices include electret ion chamber devices, activated carbon or other adsorbent systems, or alpha track devices, but does not include continuous radon/radon decay product monitors, or grab radon/radon decay product measurement systems.
PicoCurie (pCi): One pCi is one trillionth of a Curie, 0.037 disintegrations per second, or 2.22 disintegrations per minute.
PicoCurie per liter (pCi/L): A unit of radioactivity corresponding to one decay every 27 seconds in a volume of one liter, or 0.037 decays per second in every liter of air.
Plating Out: The process whereby small particles or dust attach to walls, carpets, furniture, lung tissue, and so forth.