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在~(14)C年龄测定工作中,将微处理计算机Lecroy—3500接入双道液体闪烁谱仪。在线~(14)C年龄测定系统不但能测量~(14)C计数,而且能测出~(14)C能谱和有较低的本底计数率。由于~(14)C样品测量时间较长(1000分钟),故进行精确年龄测量时,必须对仪器稳定性进行监察。从~(14)C能谱,在线~(14)C年龄测定系统能够监察仪器的稳定性。本系统在国内首先解决了这个问题。液体闪烁谱仪有1/2—1/3的本底是来自串光本底计数。双道液体闪烁谱仪中,Ⅰ道脉冲辐度V_Ⅰ,Ⅱ道脉冲辐度V_Ⅱ。对~(14)C信号V_Ⅰ～V_Ⅱ,对串光本底信号V_Ⅰ(?)V_Ⅱ或V_Ⅱ(?)V_Ⅰ。利用这一差别,系统软件可灵活地选择BT值,有效地消除串光本底计数。本系统提出了监察液体闪烁谱仪和降低串光本底的新途径。本系统不但可以给出上述各参数,而且可以直接给出样品年龄,标准偏差等数据。
In ~ (14) C age determination work, the micro-computer Lecroy-3500 access dual-channel liquid scintillation spectrometer. The online ~ (14) C age determination system can not only measure the ~ (14) C count, but also the ~ (14) C spectrum and the lower background count rate. Because ~ (14) C samples take longer to measure (1,000 minutes), the instrument stability must be monitored for accurate age measurements. From ~ (14) C spectrum, online ~ (14) C age determination system can monitor the stability of the instrument. The system in the country first to solve this problem. Liquid scintillation spectrometry with 1 / 2-1 / 3 background is derived from the string light background count. In dual-channel liquid scintillation spectroscopy, the amplitude of Ⅰ-channel pulse is V_Ⅰ, and the amplitude of II-channel pulse is V_Ⅱ. For ~ (14) C signals V_I ~ V_II, the background signal V_I (?) V_II or V_II (?) V_I. Using this difference, the system software has the flexibility to select the BT value, effectively eliminating the Crosstalk background count. The present system proposes new ways of monitoring liquid scintillation spectrometry and reducing the background of string light. The system can not only give the above parameters, but also directly gives the sample age, standard deviation and other data.