A new primary emanation standard for Radon-222

Röttger, Stefan; Röttger, A.

doi:10.1016/j.apradiso.2019.108928

Cited by 16 publications

(24 citation statements)

References 20 publications

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“…On the downside, we still observe very low 226 Ra adsorption yield from the initial 226 Ra stock solution (< 10-30%) and low emanation power that suggests the need for further research. [5] Electrodeposition Stainless steel disk 0.6-0.9 < 2% BJ [20] Coprecipitation-chemisorption Complex silica gels 0.4-0.97 -HL [21] Coprecipitation-coevaporation Ba-stearate 0.998 (thoron) - The environment related goals to reduce waste, energy consumption and chemicals can be achieved by applying the MnO 2 disk source preparation approach. The procedure needs limited resources: few basic lab wares, MnO 2 disk, stirrer, about 100 mL water and depending on the required activity maximum few mL of standardised 226 Ra solution.…”

Section: Resultsmentioning

confidence: 99%

“…The two main emanation source preparation methods, considered at the beginning of the project, were electrodeposition and co-precipitation. Since PTB (Physikalisch-Technische Bundesanstalt, Germany) chose to develop electrodeposited sources [5] and LNHB (Laboratoire National Henri Becquerel, France) focused in barium stearate co-precipitated source preparation [3], JRC studied drop deposition and chemisorption preparations of radon sources to avoid duplication of the work by other project partner.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of multi-purpose radon emanation sources

Jobbágy

Marouli

Stroh

2021

J Radioanal Nucl Chem

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The aim of this work was to prepare reference radon emanation sources traceable to primary standards to be used for radon-in-air as well as radon-in-water experiments. The feasibility of making stable radon emanation sources by drop deposition and chemisorption was studied. Experimental emanation coefficients for sources made by drop deposition and chemisorption ranged from 0.10 to 0.74 and from 0.18 to 0.25, respectively. These relatively low emanation coefficient values suggest that further method developments would be desirable. Proposals are made to improve chemisorption yield during source preparation and to obtain more accurate measurements on radon emanation coefficient.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation of multi-purpose radon emanation sources

Jobbágy

Marouli

Stroh

2021

J Radioanal Nucl Chem

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“…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.…”

Section: Resultsmentioning

confidence: 99%

“…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.…”

Section: Introductionmentioning

confidence: 99%

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

Röttger¹,

Röttger²

2021

SMSI 2021 - Measurement Science

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A new approach to assess the emanation of 222 Rn from 226 Ra sources based on measurements of the residual 222 Rn is presented. The method incorporates the dynamics into the inference procedure, rather than resorting to previously available steady-state approximations. The algorithm is based on approximate Bayesian filtering in a switched linear dynamical system to identify regimes of changing emanation behavior from a time-series of spectral data.

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“…For calibrations at such remarkably low activity concentrations, decaying reference atmospheres of 222 Rn, e.g., produced by the method of Picolo et al [ 15 ], are generally unsuitable for statistical reasons. Relatively recently, an alternative was found in the use of so-called 222 Rn emanation sources [ 16 , 17 , 18 ], which are 226 Ra sources constructed with such physicochemical properties that a known or measurable amount of 222 Rn is released per unit time, which enables calibration at static or even dynamic activity concentrations. Since the processes resulting in this release are generally linked to the physicochemical properties of the source material, the 222 Rn emanation from such sources must be expected to vary with environmental parameters such as humidity, temperature, and pressure.…”

Section: Introductionmentioning

confidence: 99%

Development of 222Rn Emanation Sources with Integrated Quasi 2π Active Monitoring

Röttger

2022

IJERPH

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In this work, a novel approach for the standardization of low-level 222Rn emanation is presented. The technique is based on the integration of a 222Rn source, directly, with an α-particle detector, which allows the residual 222Rn to be continuously monitored. Preparation of the device entails thermal physical vapor deposition of 226RaCl2 directly onto the surface of a commercially available ion implanted Si-diode detector, resulting in a thin-layer geometry. This enables continuous collection of well resolved α-particle spectra of the nuclei, decaying within the deposited layer, with a detection efficiency of approximately 0.5 in a quasi 2π geometry. The continuously sampled α-particle spectra are used to derive the emanation by statistical inversion. It is possible to achieve this with high temporal resolution due to the small background and the high counting efficiency of the presented technique. The emanation derived in this way exhibits a dependence on the relative humidity of up to 15% in the range from 20% rH to 90% rH. Traceability to the SI is provided by employing defined solid-angle α-particle spectrometry to characterize the counting efficiency of the modified detectors. The presented technique is demonstrated to apply to a range covering the release of at least 1 to 210 222Rn atoms per second, and it results in SI-traceable emanation values with a combined standard uncertainty not exceeding 2%. This provides a pathway for the realization of reference atmospheres covering typical environmental 222Rn levels and thus drastically improves the realization and the dissemination of the derived unit of the activity concentration concerning 222Rn in air.

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A new primary emanation standard for Radon-222

Cited by 16 publications

References 20 publications

Preparation of multi-purpose radon emanation sources

Preparation of multi-purpose radon emanation sources

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

Development of 222Rn Emanation Sources with Integrated Quasi 2π Active Monitoring

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