bandy@lll-lcc.UUcp (Andrew Scott Beals) (05/08/86)
[sorry I couldn't followup to the original article, something in this computer is flaking out horribly, and it's not rn (it's /bin/sh's fault..)] Newsgroups: ba.general Subject: Re: Query: Radioactive measurments? In article <348@tolerant.UUCP> waynet@tolerant.UUCP (Wayne Thompson) writes: > Hey, I'm confused. We hear of RAD's, Roentgen's(sp?) per (time unit), and >REM's. Could someone please break these down into comparable units. THANX. [From: "The Effects of Nuclear Weapons", third edition [1977], US Gov't Printing Office] [we just happened to have it lying around the office] Rad: A unit of absorbed dose of radiation; it represents the absorption of 100 ergs of nuclear (or ionizing) radiation per gram of absorbing material, such as body tissue. Rem: A unit of biological dose of radiation; the name is derived from the initial letters of the term "roentgen equivalent man (or mammal)". The number of rems of radiation is equal to the number of rads absorbed multiplied by the RBE of the given radiation (for a specified effect). The rem is also the unit of does equivalent, which is equal to the product of the number of rads absorbed and the "quality factor" of the radiation. See _Dose, Dose equivalent, Rad, RBE_. RBE (or Relative Biological Effectiveness): The ratio of the number of rads of gamma (or X) radiation of a certain energy which will produce a specified biological effect to the number of rads of another radiation required to produce the same effect is the RBE of the latter radiation. Roentgen: A unit of exposure to gamma (or X) radiation. It is defined precisely as the quantity of gamma (or X) rays that will produce electrons (in ion pairs) with a total charge of 2.58e-4 coulomb in 1 kilogram of dry air. An exposure of 1 roentgen results in the deposition of about 94 ergs of energy in 1 gram of soft body tissue. Hence, an exposure of 1 roentgen is approximately equivalent to an absorbed dose of 1 rad in soft tissue. See _Dose, Rad_. Dose: A (total or accumulated) quantity of ionizing (or nuclear) radiation. The _absorbed dose_ in rads represents the amount of energy absorbed from the radiation per gram of specified absorbing material. In soft body tissue, the absorbed dose in rads is essentially equal to the exposure in roentgens. The biological dose (also called the _RBE dose_) in rems is a measure of biological effectiveness of the absorbed radiation. See _Exposure, Rad, RBE, Rem Roentgen_. Dose Equivalent: In radiation protection associated with peacetime nuclear activities, the does equivalent in rems is a measure of the biological effectiveness of absorbed ionizing radiation. It is similar to the biological dose which is used in connection with the large radiation exposures that might accompany a nuclear explosion. See _Dose, Rem_. Exposure: A measure expressed in roentgens of the ionization produced by gamma (or X) rays in the air. The _exposure rate_ is the exposure per unit time (e.g., roentgens per hour). See _Dose, Dose rate, Roentgen_. Dose Rate: As a general rule, the amount of ionizing (or nuclear) radiation which an individual or marterial would recieve per unit of time. It is usually expressed as rads (or rems) per hour or in multiples or submultiples of these units, such as millirads per hour. The dose rate is commonly used to indicate the level of radioactivity in a contaminated area. See _Survey meter_. -- Amu, ne armu! Andy Beals bandy@lll-crg.arpa {ihnp4,seismo,ll-xn,qantel,pyramid}!lll-crg!bandy LLNL, P.O. Box 808, Mailstop L-419, Livermore CA 94550 (415) 423-1948 -- Amu, ne armu! Andy Beals bandy@lll-crg.arpa {ihnp4,seismo,ll-xn,qantel,pyramid}!lll-crg!bandy LLNL, P.O. Box 808, Mailstop L-419, Livermore CA 94550 (415) 423-1948