Development of a low-level radon reference atmosphere

D3.3 Approximate Sequential Bayesian Filtering to Estimate Rn-222 Emanation from Ra-226 Sources from Spectra

“…Figure 1 shows the raw-counts that were computed from the spectra (input data), the relative humidity inside the chamber as measured by a SHT-35 sensor (red curve), the inferred filtering distributions and the results that would have been obtained from the method in [1,2]. It can be observed from these results that once the dynamics of ingrowth are modeled in this way it becomes apparent that the methods in [1,2] lead to deviations from the true value. The new method extends the validity to regimes of nonconstant 𝜂𝜂 and allows for an estimate of the naturally expected increased uncertainty in these regimes.…”

“…Emanation sources are 226 Ra sources constructed so that some fraction of the generated 222 Rn is released from them. In [1,2], an approach to measure the released amount of 222 Rn based on measuring the residual 222 Rn in the source is presented. However, this approach is only valid for times in which steady state has been reached.…”

A primary standard source of radon-222 based on the HPGe detector

“…Thus, the components of the radon reference chamber are made of stainless steel. Therefore, there is no chance for any additional source of radon to enter (Linzmaier, and Röttger 2013). For this procedure, if the radon gas emanation is constant, the emanation factor χ is calculated using: (1)…”

Development of a transfer standard for the measurement of low Rn-222 activity concentration in air

“…To reduce the measurement uncertainty and the limited statistics of the count rate, a low level radon reference chamber with specific measurement equipment was set up (Linzmaier, 2012 andLinzmaier andRöttger, 2013). Therefore, a large volume detector was developed as a transfer standard for the realization of the unit Bq/m 3 .…”