中文摘要：

针对基于β射线法的大气颗粒物浓度测量仪设计过程中β射线源和滤膜的选择难题，运用MCNP建立大气颗粒物浓度测量仪模型。β射线能谱响应的MCNP模拟结果符合典型β射线能谱特征，与理论计算结果一致；对PTFE、PVC、玻璃纤维、PP4种常用大气颗粒物滤膜透射率、以及14C、85Kr、147Pm．204T1．90Sr-90Y5种β源对这4种滤膜透射率的模拟误差均小于2％。结果表明：（1）β源射线能量越高，对滤膜的透射效果越好；（2）β源的透射能力由强到弱依次为：90Sr-90Y〉204TI〉85Kr〉147Pm〉14C，与这五种放射源的最大β射线能量水平保持一致；（3）不同能量β射线对滤膜的透射能力由强到弱依次为：PP〉PVC〉PTFE〉玻璃纤维。综合考虑仪器安全性、设计与维护成本、材料性能等因素，大气颗粒物浓度测量仪采用14c源即可，并推荐优先采用透射率较高的PP滤膜。本工作的研究方法和结论可直接应用于大气颗粒物浓度测量仪的设计和开发。

英文摘要：

The atmospheric particulate concentration measurement system has been built via MCNP in this pa- per. Results for β rays spectrum response via MCNP are in accordance with the characteristics of β - Ray spec- trum, and consistent with theoretical results; The transmittance of filter materials in the system was calculated, such as FIFE, PVC, glass fiber and PP. So as the transmittance of the β sources 14C, 85Kr, 147pm, 204T1 and 90Sr - 90y for the four filter materials, and the calculation errors are less than 2%. The results showed that the high- er for the β source ＇ s energy, the bigger for the transmittance of the filters ; the transmission capacity of β sources is 90Sr - 9Oy 〉 204T1 〉 SSKr 〉 147 Pm 〉 14C, which is consistent with the maximum radiation level of these five sources＇ energy; the transmission capacity for β - rays of different energies to filter materials is PP 〉 PVC 〉 PTFE 〉 glass fiber; the β source X4C can be used to measure the atmospheric particulate matter concentra- tion. Considering the safety, cost and other factors, it is recommended that this type of instrument adopts PP filter. The methods and conclusions in this paper can provide a technical reference guide for choosing the filters and β sources, and the designing of atmospheric particulate matter concentration analyzer.