1. National Institute of Metrology, Beijing 100029, China
2. Guangdong Provincal Insititute of Metrology, Guangzhou Guangdong 510405, China
3. Nuclear and Radiation Safety Center of Ministry of Environment Protection, Beijing 100082, China
4. China University of Geosciences, Beijing 100083, China
Abstract：Based on a large-area gas flow proportional counter, a 2π alpha and 2π beta particle emission rate measurement system is established. Performance test is executed and the results show that the plateau length of 600～800V, the optimal average plateau incline of 0.2%/100V for alpha plane sources, and the plateau length of 350～400V, the optimal average plateau incline of 0.23%/100V for beta plane sources are achieved. Uniformity for counting is measured by 239Pu alpha point source to be 0.45% in the central region of 100mm×150mm. Corrections including the background, dead time and the discrimination threshold are executed, and the absolute measurement of particle emission rate for the alpha and beta plane sources are realized. The expanded uncertainty of measurement result are better than 0.9% (k=2) for alpha sources and better than 1.1% (k=2) for beta sources. Comparisons of emission rate of 9 importing sources including 233U and 241Am etc. are executed between 2πα、2πβ primary standard equipment and new built emission rate measurement system, and the measurement results are equivalent in expanded uncertainties limits.
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2016, Vol. 37 
