Röttger Stefan, Röttger Annette, Mertes Florian, Morosch Viacheslav, Ballé Tanita, Chambers Scott
Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany.
Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany.
Appl Radiat Isot. 2023 Jun;196:110726. doi: 10.1016/j.apradiso.2023.110726. Epub 2023 Feb 24.
In the framework of the EMPIR project traceRadon, stable atmospheres with low-level radon activity concentrations have to be produced for calibrating radon detectors designed to measure outdoor air activity concentrations. The traceable calibration of these detectors at very low activity concentrations is of special interest to the radiation protection, climate observation, and atmospheric research communities. Radiation protection networks (such as the EUropean Radiological Data Exchange Platform (EURDEP)) and atmospheric monitoring networks (such as the Integrated Carbon Observation System (ICOS)) need reliable and accurate radon activity concentration measurements for a variety of reasons, including: the identification of Radon Priority Areas (RPA); improving the sensitivity and reliability of radiological emergency early warning systems (Melintescu et al., 2018); for more reliable application of the Radon Tracer Method (RTM) to estimate greenhouse gas (GHG) emissions; for improved global "baseline" monitoring of changing GHG concentrations and quantification of regional pollution transport (Chambers et al., 2016), (Chambers et al., 2018); and for evaluating mixing and transport parameterisations in regional or global chemical transport models (CTMs) (Zhang et al., 2021), (Chambers et al., 2019). To achieve this goal, low activity sources of radium with a variety of characteristics were produced using different methods. Sources ranging from MBq Ra down to several Bq Ra were developed and characterised during the evolution of production methods, and uncertainties below 2 % (k=1) were achieved through dedicated detection techniques, even for the lowest activity sources. The uncertainty of the lowest activity sources was improved using a new online measurement technique for which the source and detector were combined in the same device. This Integrated Radon Source Detector device, henceforth an IRSD, reaches a counting efficiency approaching 50 % through detection under quasi 2π sr solid-angle. At the time of this study the IRSD was already produced with Ra activities between 2 Bq and 440 Bq. To compare the working performance of the developed sources (i.e., to establish a reference atmosphere), study the stability of the sources, and to establish traceability to national standards, an intercomparison exercise was carried out at the PTB facility. Here we present the various source production techniques, the determination of their radium activity, and determination of their radon emanation (including assigned uncertainties). This includes details of the implementation of the intercomparison set-up, and a discussion of the results of the source characterisations.
在“EMPIR项目traceRadon”的框架下，必须生成具有低水平氡活度浓度的稳定大气，以校准用于测量室外空气活度浓度的氡探测器。在极低活度浓度下对这些探测器进行可溯源校准，对辐射防护、气候观测和大气研究领域尤为重要。辐射防护网络（如欧洲放射性数据交换平台（EURDEP））和大气监测网络（如综合碳观测系统（ICOS））出于多种原因需要可靠且准确的氡活度浓度测量值，包括：确定氡优先区域（RPA）；提高放射应急预警系统的灵敏度和可靠性（梅林泰斯库等人，2018年）；更可靠地应用氡示踪法（RTM）来估算温室气体（GHG）排放；改进对不断变化的温室气体浓度的全球“基线”监测以及区域污染传输的量化（钱伯斯等人，2016年），（钱伯斯等人，2018年）；以及评估区域或全球化学传输模型（CTM）中的混合和传输参数化（张等人，2021年），（钱伯斯等人，2019年）。为实现这一目标，使用不同方法制备了具有各种特性的低活度镭源。在生产方法的演变过程中，开发并表征了活度范围从MBq镭到几Bq镭的源，即使对于最低活度的源，通过专用检测技术也实现了低于2%（k = 1）的不确定度。使用一种新的在线测量技术提高了最低活度源的不确定度，该技术将源和探测器组合在同一设备中。这种集成氡源探测器设备，此后称为IRSD，通过在准2π sr立体角下进行检测，计数效率接近50%。在本研究开展时，已经生产出镭活度在2 Bq至440 Bq之间的IRSD。为比较所开发源的工作性能（即建立参考大气）、研究源的稳定性并建立与国家标准的可溯源性，在德国物理技术研究院（PTB）设施进行了一次比对试验。在此，我们介绍各种源生产技术、其镭活度的测定以及氡析出率的测定（包括指定的不确定度）。这包括比对设置的实施细节以及源表征结果的讨论。
