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- With the continuous radon/thoron operation mode, the AlphaGUARD
generates useful results in 10 min cycle up to a mix ratio between thoron
and radon of 1:5 and vice versa (5:1). With bigger differences in ratio,
the
uncertainties of individual results on the part of the gas with the lower
concentration b
ecomes too large in order to deliver qualified data for the
respective parameter.
- Operating the AlphaGUARD in radon/thoron mode the build
-up of the
thoron progeny Po212 is determined and the results of radon and thoron
are corrected accordingly. After swit
ching from the RnTn mode to the
conventional radon modes (diffusion or flow) the correction of Po212 is lost.
For subsequent measurements,
this may lead to overestimating the radon
concentration due to remaining Po212 activity in the chamber. Hence,
after
measuring high thoron concentrations, it is recommended to allow
residual activity to decline and resume radon measurements only a couple
of days later.
-
In case the flow rate is set to a different value, the flow rate will be changed
to 1 l/min resp. 2 l/
min according to the selected Radon/Thoron
discrimination mode. After deactivating the Radon/Thoron discrimination
mode, the originally selected flow rate will be set back.
- It has to be ensured that the thread between chamber
entry window and diffusion / flow adapter is always
lubricated. For lubricating the thread ordinary lubricants
can be used like silicon oil or Vaseline.
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