| Nuclide analysis is a key content of study in the field of nuclear science and technology.Nuclide analysis must rely on radioactive monitoring equipment,mostly energy spectrometers.With the development of digital electronic technology,the current circuit implementation of the energy spectrometer has shifted from analog to digital.Through the investigation,summary and induction of digital processing algorithms in digital gamma spectrometers at home and abroad,the specific research work made in this paper is as follows:(1)A set of virtual simulation experiment platform for digital gamma spectrometer was established.Monte Carlo simulation technology is used to quickly and accurately calculate the energy deposition ofγ-rays in the detector.According to the energy scale and half-height width data of the gamma spectrometer,the response law of the gamma spectrometer to the radioactive source is obtained.Nuclear pulse generation time and amplitude;combined with Matlab GUI software platform,to achieve fast analog-to-digital conversion of nuclear pulses,filter shaping,baseline recovery,amplitude extraction,and energy spectrum counting and display.At the same time,the simulation platform can also be used for the processing and analysis of measured nuclear pulses,providing a reliable platform for undergraduate experimental teaching and subsequent research.(2)In-depth study of the existing filter shaping algorithms.The theoretically derived digital recursive formulas for the Z-transform method and the convolution function method for trapezoidal(triangular)forming,the ideal Sallen-Key(S-K)circuit,and the CR-RC~mcombination circuit,and based on virtual simulation experiments of a digital gamma spectrometer The platform studies the influence of the parameters in the three digital filtering forming algorithms on the forming effect,and provides a reference for selecting the optimal forming parameters in hardware design.(3)Based on the attenuation law of the ideal single exponential nuclear pulse,and based on the idea of missing compensation,a digital recursive formula for the linear forming algorithm was established.Comprehensive comparison of linear shaping algorithm,trapezoidal(triangular)shaping algorithm,SK digital Gaussian filtering shaping algorithm and CR-RCm digital Gaussian filtering shaping algorithm is performed using four indicators:maintaining energy linearity,pulse stacking discrimination ability,algorithm simplicity and anti-noise ability Pros and cons,simulation results show that the straight-line forming algorithm is optimal.(4)A digital gamma spectrometer based on the straight-line forming algorithm was initially implemented.Based on AD9226 and EP4CE15F23C8N chip as the core,a digital gamma spectrometer hardware system was developed.In EP4CE15F23C8N chip,the straight-line forming algorithm,the minimum average method and the multipoint average method were used to extract the digital nuclear pulse amplitude.USB communication technology was used to achieve the upper and lower levels.The data of the computer is transmitted,and the software of the host computer is designed on the Matlab GUI platform,and a set of digital sodium iodide(Na I)gamma spectrometer is built.The actual test found that its energy resolution,short-term stability,and background count rate all meet the requirements of theγEnergy Spectrometer Verification Regulations(JJG 417-2006),and its energy nonlinearity is not greater than 2.1‰,confirming that its performance indicators can meet Requirements for practical applications. |
