free-air ionization chamber


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free-air ionization chamber

[¦frē ¦er ‚i·ə·nə′zā·shən ‚chām·bər]
(nucleonics)
An ionization chamber in which the ionizing radiation is limited by a diaphragm, so that ionization is detected in a region of accurately known volume, away from the electrodes and other internal parts of the equipment.
References in periodicals archive ?
The NIST Attix free-air ionization chamber [4] was also used to directly measure the air-attenuation corrections for various sources.
The PTB x-ray air kerma measurements were made using the PK100 primary standard free-air ionization chamber.
DeWerd, Mammography exposure standard: Design and characterization of free-air ionization chamber, Rev.
Mobility of the active material in the seeds does not appear to be an important factor in the primary standardization of the seeds, where good geometry measurements are made with a standard free-air ionization chamber, but movement of the active material affects the reproducibility of measurements in [pi] geometry, as in the re-entrant ionization chamber used as a laboratory standard.
I/m is the mass ionization current as measured by the free-air ionization chamber,