Study On The Application Of Digital Gauss Shaping Technology In Air Pulse Ionization Chamber

Gas detector is one of the earliest detectors used in nuclear science and technology.It plays an important role in the development of nuclear physics.The pulse ionization chamber is widely used in the field of radiation continuous monitoring forits advantages of high energy response,high stability and low background.Pulse ionization chamber operates in the saturation region where collecting voltage can completely absorb ions produced by particles in the gas,but its output signal is relatively weakand vulnerable to the influence of noise,ballistic deficit and pulse stacking.When the pulse signal is shaped into a signal with the Gauss waveform,the signal to noise ratio can be improved,the loss of the trajectory can be reduced,and the energy resolution of the detector can be improved.F.S.Goulding theoretically proved that the Gauss formation technique could make the final energy resolution of the detector closest to its intrinsic resolution.From the beginning of the last century in 90 s,with the rapid development of electronic technology and chip manufacturing,the design and development of nuclear instrument are used these technologies more,the digital nuclear instrument will become the mainstream in the future.Digital pulse shaping technology is the most important technology and the most attractive direction in the field of nuclear instrument design and manufacture.It is easy to realize pulse signal shaping with digital technology to improve the overall stability of the measuring system and the scalability and maintainability of the measurement system.In addition,the simulation system is also difficult to achieve the real Gauss forming theory which can achieve the anti causal effect.In order to meet the needs of the digital nuclear instrument,the study on data acquisition,digital nuclear pulse signal amplification and shaping technology of signal to implement a digital Gauss shaping scheme based on Sallen-Key filter,and use FPGA chip to realize the design requirements and finally applied to air pulse ionization chamber.This dissertation studies the Sallen-Key filter based on discrete components,establishesthe voltage transfer model by using Kirchhoff's current law,uses the numerical recursive method to achieve the digital Gauss shaping of nuclear signal,and simulates nuclear signal by using MATLAB software tools with Gauss shaping digital recursivemodel to complete thecomputer verification of digitalGaussshaping method.The performance test shows that it is feasible to apply the Gauss shaping on air pressure ionization chamber.