针对便携式X荧光光谱仪,设计了紧凑型Si-PIN探头低温控制电路.低温制冷器采用微型半导体电制冷片,其恒流控制电路利用低噪声的线性稳压器来避免引入电子学噪声,并利用闭环控制保证温度的稳定性.前级供电采用高效率的DC-DC电路稳压,以降低探测器的整体热耗散.Si-PIN探测器安装在制冷片的陶瓷电路板上,并真空封装在TO-8管座内来维持低温制冷效果.实验测试结果表明,探测器可稳定保持在-35 ℃的低温工作环境,对59.5 keV能量获得的能量分辨率从常温下的2.70%提高到1.47%.
This paper designed a compact Si-PIN detector module with low-temperature control circuit for portable X-ray fluorescence spectrometer.The cooler uses a miniature Peltier thermoelectric cooler.Its constant-current circuit uses a low-noise low dropout linear regulator to prevent electronic noises and uses closed-loop control to ensure the stability of temperature.The front-stage power supply uses a high-efficiency DC-DC switch circuit to reduce the overall heat dissipation of the system.The Si-PIN detector is installed on the ceramic circuit board which put above the Peltier thermoelectric cooler,and all of them are packaged in the vacuum TO-8 tube to maintain the low temperature.The experimental test results show that the compact Si-PIN detector module can maintain a low-temperature working environment stably at-35 ℃,and the energy resolution obtained by 59.5 keV energy has increased from 2.70%at normal temperature to 1.47%at low temperature.