采用反康普顿γ谱仪对85Kr样品进行活度标定作为工作参考,通过自行设计的Kr气体收集装置和液闪制样装置,建立了一种85Kr气体样品的液闪测量方法.结果表明:以甲苯为溶剂、1,4-双-2-(4-甲基-5苯基噁唑基)(POPOP)和2,5-2苯基噁唑(PPO)为溶质的闪烁液,当体积为20 mL,硅胶加入质量为1.0g时,能够完全溶解0.5 m3空气中的Kr气,且样品液闪测量无需进行淬灭校正;对于85Kr活度小于1 Bq的样品,液闪测量相对偏差绝对值小于7％;制备的样品放置20 h以内计数率稳定.该方法适用于环境大气中85Kr放射性水平的测量.%With a known activity of 85Kr standardized by Anti-Compton γ spectrometer as working standards,and with a set of self-designed Kr collection and liquid scintillation sample preparation device,the radioactive measurement method of 85 Kr by liquid scintillation was established.Experimental results show that,under the condition of toluene used as solvent,PPO and POPOP used as solute,and 1.0 g silicone added into the liquid,Kr sample can be completely dissolved in 20 mL scintillation liquid and its activity can be determined without quenching correction.The absolute value of relative error less than 7％ can be reached when 85 Kr activity is lower than 1 Bq in the sample.The sample stability is proved by compared with the counting of sample measurements in the interval 20 h.The device and method established can be applied to the measurement of environmental atmospheric 85Kr activity concentration.
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