Preparation and Characterization of Standard Plane Source of ²¹⁰Po

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 1.0×10⁴ to 2.0×10⁵ 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.