210Po标准平面源的制备及表征

Preparation and Characterization of Standard Plane Source of 210Po

210Po的标准平面源用于检定流气正比计数器α射线对β射线的串道比,由于210Po的半衰期较短(138.4 d),检定用210Po标准平面源需定期更换。本工作采用色谱柱法,从210Pb的母子体溶液中分离出高纯度的210Po溶液,用γ谱仪确认了210Po溶液的核纯度;用电镀法制备了210Po平面源,用显微镜观察其表面形貌,并通过α谱仪测量了平面源的α能谱,符合α能峰单一的要求。用2πα、2πβ粒子发射率基准装置测量该平面源的2π表面粒子发射率,达到了检定规程中2π粒子发射率处于1.0×10^4~2.0×10^5 min-1之间、扩展不确定度在3.0%(k=2)以内的要求。建立了用210Pb溶液中的210Po制备210Po标准平面源的新方法,实现了可持续提供210Po标准平面源的目标。

The plane source of 210Po was used for verification of gas-flow proportional counter gross alpha and gross beta measure instruments, and it was needed to be replaced by new 210Po plane source because of its short half-life (138.4 d). High purity 210Po solution was extracted from raw 210Pb solution containing 210Bi and 210Po by resin before electroplating and its purity was confirmed by high purity germanium gamma spectrometer. The morphology of electroplating plane source of 210Po was checked by microscope and characterized by alpha spectrometer. There was a unique alpha peak in its alpha spectrum which was satisfied with the requirements well. The primary standard for 2πα and 2πβ particles emission rate was employed to verify the 2πα and 2πβ particle emission rate. The result is between 1.0×10^4 to 2.0×10^5 min^-1 and the expanded uncertainty is less than 3%(k=2), which show that the prepared standard plane source of 210Po meet the requirements of verification regulation well. A new approach of preparation of 210Po standard plane sources from 210Pb is established and the goal of supplying 210Po standard plane source constantly is achieved.