海水放射性传感器温度漂移校正方法研究

Research on temperature drift correction method of seawater radioactivity sensor

基于NaI(Tl)闪烁晶体探测方法研制而成的海水放射性传感器是目前国内外开展海洋放射性核素原位自动监测的主要技术手段,但海水放射性传感器在海上长期连续运行时,测量得到的海水伽马能谱数据会受到环境温度影响而发生漂移。开展环境温度梯度变化条件下的海水放射性传感器测量实验,分析海水放射性传感器测量得到的伽马能谱数据随环境温度变化而发生的漂移规律,通过将峰位道址漂移表达为温度的二次函数关系,进而提出了基于环境温度变化的伽马能谱漂移校正方法。经实验室空气环境和水体环境实验验证,空气环境校正后峰位道址漂移不超过±2道,水体环境校正后峰位道址漂移不超过±3道,可以满足海水放射性传感器连续测量伽马能谱的温度漂移校正需求。

The seawater radioactivity sensor developed based on NaI(Tl)scintillation crystal detection method is the main technological means to carry out in situ automatic monitoring of marine radionuclides at home and abroad.Nevertheless,when the seawater radioactivity sensor is continuously operating at sea for a long time,the measured seawater gamma spectrum data will drift due to the influence of ambient temperature.In this paper,the seawater radioactivity sensor measurement experiment is carried out under the condition of environmental temperature gradient change,and the drift law of the gamma spectrum data calculated by the seawater radioactivity sensor which occurs with the environmental temperature change is analyzed.When the ambient temperature is lower than 15℃,channel address corresponding to the characteristic energy peak increases with the increase of temperature;on the contrary,when the ambient temperature is higher than 15℃,the channel address corresponding to the characteristic energy peak decreases with the increase of temperature.The gamma spectrum peak channel address shift can be expressed as a quadratic function of temperature,and further a correction method of gamma spectrum shift based on ambient temperature change is proposed.It is verified by laboratory experiments on air and water environment that the peak channel address drift of characteristic peak after air environment correction is not more than±2 channels,and the peak channel address drift after water environment correction is not more than±3 channels,which meets the requirements of temperature drift correction for continuous measurement of gamma spectrum by the sensor.