Ionizing Radiation Division

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Basic Standards and Calibrations

222Rn-in-air Measuring System

A secondary measuring system for 222Rn-in-air is used to transfer calibrations between laboratories. The system is based on measurements of the photon emission rate of radon samples contained in spherical 35 mL glass ampoules with a NaI(Tl) well counter. The system is calibrated against the NIST pulse-ionization-chamber national radon measuring system and has an overall uncertainty of approximately 2 percent.

Reference: An International Radon-in-Air Measurement Intercomparison Using a New Transfer Standard. J.M.R. Hutchinson, J. Cessna, R. Collé, and P.A. Hodge. Appl. Radiat. Isot. 43, 175 (1992).

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Online: November 1997   -   Last update: March 1999