Dresden 2011 – scientific programme
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ST: Fachverband Strahlen- und Medizinphysik
ST 7: Radiation Physics Measurements
ST 7.2: Talk
Thursday, March 17, 2011, 16:15–16:30, POT 112
Set up of a low-level radon reference chamber — •Diana Linzmaier1,2, Jörg Leppelt1, and Annette Röttger1 — 1Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig — 2Leibnitz Universität Hannover, Fakultät für Mathematik und Physik, 30167 Hannover
In order to calibrate measuring devices for the activity concentration of Rn-222 in air below 1000 Bq/m3, a low-level radon reference chamber is under construction. For the realisation of the unit Bq/m3 at such low radon activity concentrations, a high-sensitive transfer standard has to be developed.
The concept of the low-level radon chamber is based on the realisation of the atmosphere, in form of a standard vacuum chamber with an activity standard and a transfer standard (active large volume detector, serving as a secondary standard).
The realisation of the atmosphere consists of a reference volume of 0.5 m3 and a system for the radon emanation. A defined activity of Rn-222 diffuses out of a source and is transported through an noble gas leak-proof circuit to the reference volume to create a reference atmosphere.
The transfer standard is used for the spectrometry of α-particles. It is composed of a multi-wire pulse ionisation chamber with a detector volume of 10 l. To detect and amplify the signals, an optimised pre-amplifier is being built.
The concept of the reference chamber and first results will be presented and discussed.