Design And Implementation Of Detector Module And Spectrum Analysis For A Portable Gamma-ray Spectrometer

With the rapid development of nuclear science and technology in recent years,nuclearsafety is drawing more and more people’s attention. Energy spectrum analysis of gamma-ray is a critical method to detect and analyse nuclear materials. The portable gamma-rayspectrometer, based on the technology of gamma-ray energy spectrum analysis,is just theinstrument to realize onsite radiation dose rate monitoring, radioactive source finding,nuclide identification and radioactive activity analysis. This paper has implemented thedetector, data acquisition circuit and the spectrum analysis algorithm of a portable gamma-ray spectrometer. To meet the relevant standards of IAEA and IEC,the GM tube and theLaBr3scintillation detector are chosen as the detectors. GM tube is used to measurethe dose rate and LaBr3scintillation,which has good energy resolution,is used todetect the energy spectrum of gamma-ray.The output pulses of the detector are amplified and shaped by the data acquisitioncircuit, then are digitalized by a high-speed ADC. Compared with the tradetionalmethod, which holds the pulse peak to obtain the energy, our method has the followingadvantages:(1)more convenient to calibrate the baseline,(2) easier to get rid of theunwanted pulses,(3) shorter dead time,(4) lower noise.The analysis of the energy spectrum is achieved by smoothing the spectrum curve, sear-ching the peaks, eliminating the background, calculating area of the net peaks and so on.Meanwhile, the system stability is assured by using the138La nuclide in the LaBr3detectoras a reference source.The dose rate of the prototype is calibrated in the institute of nuclear metrology,and therelevant parameters have satisfied the national standards. Furthermore, nuclide identi-fication and spectrum analysis have been evaluated using two radiation isotopes,andexcellent results are achieved.