航空伽玛测量稳谱电路设计

The Design of stabilizing circuit for the airborne gamma-ray spectrometric survey

摘要:

在航空伽玛能谱测量中，接收伽玛射线的NaI(Tl)晶体与光电倍增管电路特性，容易受到环境温度的影响，能谱测量数据会随着环境温度的改变而发生数据记录道数的非线性漂移。电路稳谱技术对于保证航空伽玛能谱测量数据准确性有着非常重要的作用，航空伽玛能谱测量稳谱电路设计，采用控制光电倍增管高压方式调整信号增益，以及信号脉冲叠加电平的方法平移脉冲信号幅度，利用软件程序控制稳谱电路工作，调整环境温度变化引起的能谱脉冲记录道数的非线性漂移，实现了能谱测量数据自动稳谱的功能；在能谱测量数据实验中，稳谱电路特征峰位调整控制明显，稳谱速度快，对于1024道测量总谱最大峰漂小于1.5道，达到了设计要求。

Abstract:

In the airborne gamma-ray spectrometric survey, the NaI(Tl) crystal and photomultiplier circuit are easily affected by the changes of ambient temperature, which will result in non-linear peak drift in the number of channels. Thus, the circuit stabilization technology plays a significant role in ensuring the accuracy of airborne gamma-ray spectrometric data. The airborne gamma-rayspectrometric stabilization circuit is designed by controllingthe high voltage of photomultiplier tube to adjustthe signal gain and signal pulse superposition level to shift the pulse signal amplitude.The developed program controls the operation of the spectrum stabilization circuit to adjust the nonlinear peak drift caused by the change of ambient temperature, realizing the function of automatic spectrometric stabilization.According the experiments, the characteristic peak position controlled by the stabilization circuit is obvious, and the stabilization speed is fast.The maximum peak drift is less than 1.5 channels for 1024-channel full spectrum measurements, which meets the design requirements.