Digital Reconstruction Technique For Gamma Spectrum Detection

Simulated signal reconstruction technology is a kind of technical means which has important value in scientific exploration and engineering practice.In some of the world's greatest achievements,such as the first direct detection of gravitational wave event,signal reconstruction technology has played an important role.Signal reconstruction technique for nuclear spectrometry,as the inverse process of nuclear information acquisition and processing,can timely and effectively provide simulated test environment with known parameters when the devices of experiments are not yet ready or conditions of experiments are hardly to achieve.Therefore,nuclear signal reconstruction technology has a very wide range of applications in the verifying of nuclear signal processing methods,the evaluating of spectrum analysis algorithm and the designing and debugging of nuclear instruments.Nuclear signal reconstruction concerns the issue of radiation physics,radiation detection,nuclear electronics,nuclear spectroscopy,involving the time scale across more than a dozen orders of magnitude.In this paper,nuclear signal reconstruction technology is as a topic to focus on the discussion,the main contents include:1.Based on the discussion of the decay patterns of radioactive nuclides,the characteristics of the input signal of the time of the detector are analyzed.Based on the discussion of the interaction between the ray and the material,the forms of the information in the spectral distribution are analyzed.Based on the discussion of the energy conversion process in the nuclear radiation detector,the characteristics of the energy broadening of the instrument spectrum are analyzed,and the energy deposition process of the ray detector in the detector is simulated by the software of Monte Carlo simulation such as MCNP and Geant4.To achieve the reconstruction of the distribution of the gamma spectrum.2.Based on the discussion of the structure of the preamplifier,the characteristics of the waveform of the input signal of the nuclear instrument are analyzed.Based on the discussion of the characteristics of the electronic noise of the output signal of the preamplifier,the existences of the information of the nuclear signal are analyzed.Based on the discussion of the characteristics of the output signal of the scintillation detector,the characteristics of the rising time of the nuclear signal are analyzed.Based on the discussion of the process of the filtering and shaping,the problems concerned with acquiring the time and amplitude information of the nuclear instrument are analyzed.To achieve the reconstruction of the pulse waveform of the nuclear signal.3.The high-speed digitizer,high-speed SSD storage and high-speed arbitrary function generator are used to set up the high-speed streaming to disk system for nuclear signal,to achieve the off-line analysis of the nuclear signal.A group of information including nuclear signal waveform information,gamma spectrum distribution information,the data that covering the core signal acquiring and processing of the complete process.To achieve reproducible output of the nuclear signal.4.A nuclear signal generator for gamma spectrometry is designed,which can simulate the output signals of multiple types of preamplifiers.The pseudo-random number of the specific distribution can be generated using the FPGA to sample the stored data of the nuclear signal.The distribution of the time interval of the pulses,the distribution of the amplitude of the pulses,the distribution of the rising time of the pulses and the power density function of the noise are similar to those of the real nuclear signal.5.The signal reconstruction technique for gamma spectrum is applied in several examples.The method of the spectrum background estimation is evaluated by using the reconstructed distribution of the gamma spectrum.The method of the spectrum shifting correction is carried out by using the reconstruction of the nuclear pulse wave.Finally,an array detectors communication system is built,and its feasibility is verified by using the digital reconstruction technique for gamma spectrum detection.