核脉冲信号的高分辨率数字分离方法与高速实现技术研究

Digitization is an important direction of modern nuclear instrument system. And it will take decisive actions to improve the performance of the whole system such as accuracy, stability and reliability. Digitization of nuclear instrument system includes high-speed signal acquisition in real-time, digital signal shaping and separation of overlapping pulse. And the research achievements of nuclear signal acquiring techniques and digital shaping algorithm are abundant. But the high resolution digital separation method of overlapping pulses and high speed implementation techniques are still in the original stage. The mainly contents in the project are: ⑴Basing on the data acquisition system of high speed nuclear pulse signal, the hardware platform will be established. ⑵ After further investigation of nuclear pulse shaping algorithms signal such as Gauss, trapezoidal and triangle, the software platform of digital nuclear signal simulation system with high-speed and large-capacity can also be built. ⑶With the help of nuclear pulse signal shaping method, the separation method of overlapping pulse will be explored, such as the judgment of triangle shaping. ⑷Through repeated comparison between the digitization of the nuclear pulse signal and the simulation signal, the separation method of high resolution digital overlapping pulse will improved. Then determination of the correction factors, the high-speed algorithm will also be determined. Lastly, it will be implemented in the FPGA hardware platform.

核能谱测量是核安全监测，核物理、高能物理等基础研究以及核技术应用等常需获取的重要核信息之一，数字化是现代核能谱测量系统的重要发展方向，对提高系统精确性、稳定性、可靠性将取到决定性的作用。核测量系统的数字化包括高速信号的实时脉冲获取、高速数字成形、重叠脉冲分离等方面，其中核信号实时获取技术、数字成形算法等研究成果较为丰富，但重叠脉冲的高分辨率数字分离方法与高速实现技术尚处于研究的起步阶段。项目主要研究内容为：⑴研发高速核脉冲信号的数据采集系统，以构建研究所需的硬件平台；⑵建立大容量高速核信号数字模拟系统，以构建研究所需的软件平台；⑶完善核脉冲信号数字成形算法，基于脉冲信号的数字成形，探索重叠脉冲的高分辨率数字分离方法；⑷通过对核模拟信号和核脉冲实际信号的数字化，反复比较和逐步完善重叠脉冲的高分辨率数字分离方法，确定其修正参数，最终形成可硬件实现的高速算法，并在FPGA硬件平台上加以实现。

在核信号的数字化能谱获取中，核脉冲信号的高速实时获取、数字脉冲成形、堆积脉冲的分离是数字化能谱处理的关键，国内外对这类问题的研究很重视，高放高通量条件下的高分辨率的能谱测量一直是有待解决的问题。该项目针对高速数字脉冲成形、堆积脉冲分离技术进行了深入研究，获得了一系列研究成果。首先，提出了三路信号并行采集处理、两种触发采样模式方案，研发了高速核脉冲信号的数据采集系统，构建研究所需的硬件平台和软件平台，目前实现了100MHz采样频率的核脉冲信号的数据采集及处理；其次，研究了核脉冲信号的滤波放大调理电路的数学模型及数值分析算法，对高斯数字成形、梯形数字成形、单延迟线脉冲成形等成形技术进行了算法及参数研究，提出了适于FPGA的逆算法，实现了FPGA上堆积脉冲的高效分离；在以上研究基础上，进行了计数率校正方法研究，提出了快慢通道计数率校正方法。然后，基于研究成果，改进了高速核脉冲信号的数据采集系统的硬软件平台。研究过程中将研究成果应用于XRF分析、伽玛谱仪、大批量人群核辐射体内污染快速检测仪、L边密度计、乏燃料后处理中的铀浓度检测、录井等分析测试仪器中，取得了很好地应用效果。