A dosimeter is any device used to measure an individual's exposure to a hazardous environment, particularly when the hazard is cumulative over long intervals of time, or one's lifetime. This article pertains to a radiation dosimeter and the science of dosimetry, but other dosimeters also exist, such as sound dosimeters. A pocket watch, a device used to tell time Look up time in Wiktionary, the free dictionary. ... This article or section includes a list of works cited or a list of external links, but its sources remain unclear because it lacks in-text citations. ... Dosimetry is the measurement of absorbed dose in matter and tissue resulting from the exposure to ionizing radiations. ... A sound dosimeter or noise dosimeter is a device used to measure an individuals exposure to possibly damaging levels of environmental noise. ...

A radiation dosimeter is a pen-like device that measures the cumulative dose of radiation received by the device. It is usually clipped to one's clothing to measure one's actual exposure to radiation. Magnifying lenses (a low-power microscope) and an illumination lens allow one to directly read the dose by aiming the illumination lens at a light source and looking into the device. Radiation as used in physics, is energy in the form of waves or moving subatomic particles. ...

For personal use, this is the most useful device to measure radiation, because biological damage from radiation is cumulative.

Dosimeters must be periodically recharged. One's dosimeter is usually read before it is charged, and the dose is logged, to chart one's exposure. In many organizations, possession of the recharger is limited to health physicists to prevent falsification of exposures.

A dosimeter is a very rugged form of a device called an electrometer. It has two electrodes which are charged through an external connection. Since they are the same charge, they repel each other. As ionizing radiation passes between the electrodes and the electrically conductive case, the charge on the electrodes is neutralized. When the charge reduces, an electrode moves away from the zero calibration. The magnifier displays this motion against a scale. An electrometer is an electrical instrument for measuring electric charge or electrical potential difference. ... Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... Radiation hazard symbol. ... Calibration refers to the process of determining the relation between the output (or response) of a measuring instrument and the value of the input quantity or attribute, a measurement standard. ...

The charger is a small box, usually powered by a battery. It contains an electronic circuit that steps the battery voltage up to several thousand volts. The box has a fixture that requires one to press the end of the dosimeter on the charging electrode. Some chargers include a light to illuminate the measurement electrode, so that measurement, logging and recharging can occur with one routine motion. An electrode is an electrical conductor used to make contact with a metallic part of a circuit (e. ...

Dosimeters are made in different ranges. Peace-time occupational exposure ranges usually measure up to 500 mrem (5 mSv), which exceeds the normal US yearly dose of 360 mrem (3.6 mSv). War-time fallout meters measure up to 500 rem (5 Sv), roughly the lethal dose. The Röntgen equivalent man or rem (symbol rem) is an obsolete unit of radiation dose. ...

A similar device, used with the same charger, is a rate meter. This is an inexpensive method for civil defense persons to measure radiation rates. One measures the rate of change of the rate meter for a timed exposure after charging the rate meter. Usually one measures heavy fallout of a thirty-second period, and light fallout over a ten-minute period. The rate meter has two internal scales that read the radiation flux directly in rems for each period.

An inexpensive alternative to the electronic dosimeter is the film badge dosimeter, a plastic badge containing a small piece of photographic film. Radiation exposure gradually exposes the film, which is periodically removed and developed, and the developed film's optical density correlated to a cumulative dosage measurement. Another inexpensive passive dosimeter is the thermoluminescent dosimeter, which contains a small crystal (typically lithium fluoride or calcium fluoride) which absorbs gamma or neutron radiation and is heated in a specialized reader to determine the applied radiation dose. The film badge dosimeter, or film badge, is a dosimeter used for monitoring exposure to ionizing radiation. ... This article or section does not cite any references or sources. ... This article or section does not cite its references or sources. ... Optical density is the absorbance of an optical element for a given wavelength λ per unit distance: Where: Although absorbance does not have true units, it is quite often reported in Absorbance Units or AU. Accordingly, optical density is measured in ODU, which are equivalent to AU cm−1. ... A Thermoluminescent dosimeter is a small device used to measure radiation exposure by measuring the amount of visible light emitted from a crystal in the detector when the crystal is heated. ... For other uses, see LIF. Lithium fluoride is a chemical compound of lithium and fluorine. ... Calcium fluoride (CaF2) is an insoluble ionic compound of calcium and fluorine. ...

See also

• Geiger counter
• scintillometer
• Richard Rosenthal.

This article or section does not cite any references or sources. ... A Scintillometer is a scientific device used to measure atmospheric optical disturbances called scintillations, which are caused by fluctuations of the refractive index of air. ... Richard R Rosenthal, MD (born April 5, 1939) is an allergist and immunologist practicing in the Washington D.C. area. ...

External links

• A photographic list of radiation dosimeters