井下直接铀定量γ能谱仪中铅屏蔽层的应用效果评价

Evaluation on the Application Effect of Lead Shielding Layer in Downhole Direct Uranium Quantitativeγ-Spectrometer

研制井下直接铀定量γ能谱仪过程中,为降低信号采集的死时间及康普顿散射对于低能段γ能谱数据应用的影响,研究了新型CeBr3探测器组合铅屏蔽层技术,并针对0~3000 keV能量范围,从死时间、谱峰特征以及1001 keV能量特征峰在不同地层铀含量的响应等几方面对其应用效果进行了评价。研究结果表明在标准模型井中组合厚度为3 mm的铅屏蔽层时,在铀含量1.0%模型系统实测死时间由7.94%降低为3.73%;0~500 keV能量段的屏蔽计数占96%以上,高能段影响较小;1001 keV能量特征峰在不同铀含量时响应呈线性分布,达到预期目标。

In the process of developing a downhole direct uranium quantitativeγ-spectrometer,to reduce the dead time of signal acquisition and the influence of Compton scattering on the application of low-energyγ-spectroscopy data,a new lead shielding layer combined CeBr3 detector was studied for the energy range of 0~3000 keV,its application effects are evaluated in terms of dead time,spectral peak characteristics,and the response of 1001 keV energy characteristic peaks in different uranium content formations.The research results showed that when a lead shielding layer with a thickness of 3 mm is combined in a standard model well,the measured dead time of the uranium content 1.0%model well is reduced from 7.94%to 3.73%;the shielding count of the 0~500 keV energy range accounts more than 96%,the high-energy section has little effect;the response of the characteristic peak of 1001 keV energy at different uranium content showed a linear distribution which reaches the expected research goal.