Development Of A PMT-BASE Digital Energy Spectrometer With Embedded Automatic Spectrum Stabilization

In nuclear radiation measurements,energy spectrum measurement is one of the most important components.Through the analysis results of energy spectrum measurement,we can directly or indirectly reveal the important information such as the geometric structure and the kinds of constituent elements of the measured substance.Nuclear radiation measurement technology has been widely used in industry,agriculture,safety,radiation protection,environmental monitoring and other fields due to its advantages of higher sensitivity,fewer damage and higher accuracy.Scintillator detector is one of the most widely used nuclear radiation detectors because of its mature manufacturing process,wide selection and low price.The nuclear radiation measurement system composed of scintillator and photomultiplier tube occupies a large proportion in the gamma-ray measurement,but the temperature effect of the measurement system is serious.In long-term measurement it is easy to cause the spectrum drift,which leads to the difficulty of spectrum analysis and the deviation of intensity measurement.The spectrum stabilization function can reduce the contribution of temperature change to spectral drift.This paper starts with a hardware and software two aspects of the PMT-BASE integrated digital energy spectrometer which embedded automatic stabilization.In the hardware design,a hybrid charge-sensitive preamplifier with RC self-discharge and reset discharge is developed,and the analog and digital circuits of the low-noise multichannel pulse amplitude analyzer are designed and implemented.POE hardware standard is used for communication between energy spectrometer and host computer.Power supply and data communication can be completed simultaneously by using only one network cable,which reduces the number of cables used and improves the usability.In terms of spectrum stability,the spectrometer designed in this paper uses an ²⁴¹Am low-energy gamma rays source as a reference,and uses a 16-bit high-speed ADC combined with high-precision spectrometer analog circuit to measure ²⁴¹Am low-energy gamma rays.Dynamic peak correction is performed by using area ratio peak finding algorithm in embedded software.Finally,the linearity of embedded high voltage is 0.99997,the linearity of the energy response is 0.999999,the integral nonlinearity is about 0.08%,and the differential nonlinearity is about 0.33%.The energy resolution of 662 keV gamma-ray is 6.77%by using NaI?Tl?scintillator and 2.88%by using LaBr₃?Ce?scintillator with the energy spectrometer.The energy resolution of 59.5keV gamma-ray is 12.84%by using NaI?Tl?scintillator.When the ²⁴¹Am gamma ray stabilizer is turned on,the spectrum drift can be less than±2 channels of its average peak position in the temperature range of 0?to 50?.