Research On High Sensitivity And Wide Range Adaptive Charge Sensitive Amplifiers

Current intensity is one of the most basic parameters of beam flow,and it is necessary to monitor it during accelerator debugging and operation.The Faraday tube detector is the most commonly used device for measuring beam current intensity.On the heavy ion Research Facility in Lanzhou,Faraday cylinder detectors are distributed on the whole accelerator beam transmission line.Due to the different beam intensities at their locations,the amount of charge collected by the detectors will also have a large span,about 1p C～30n C.The weak and large-scale charge signal poses challenges for subsequent signal amplification and acquisition.Currently,there is no charge sensitive amplifier suitable for this dynamic input range.Therefore,this article focuses on the measurement requirements of the 1p C～30n C output charge signal of Faraday tube detectors,and develops a high sensitivity and wide range adaptive charge sensitive amplifier.The specific research content is as follows:(1)Aiming at the problem of Faraday cylinder detector collecting the beam intensity of the heavy ion device in Lanzhou,a wide range adaptive charge sensitive amplifier is proposed to amplify and process the output charge signal of the detector.At the same time,the research status and development trend of charge sensitive amplifiers at home and abroad were summarized,and targeted research on the input charge signal range was conducted based on the parameters of commercial charge sensitive amplifiers.(2)The overall hardware structure of the charge sensitive amplifier is composed of primary amplification circuit,secondary amplification circuit,comparison circuit,ADC acquisition circuit,and STM32 control circuit.LT-spice is used for circuit simulation of each module to determine the optimal parameters of the circuit system.Finally,the development of the circuit board is achieved using EDA software.(3)Based on the hardware circuit design of the charge sensitive amplifier,the minimum mean square criterion and least squares criterion are used for adaptive data processing to ensure signal linearity output.Secondly,the stable output of the charge sensitive amplifier system signal was achieved by fitting and processing the output data of the range channel overlap area.Finally,in response to remote control requirements,design an application programming IAP(In Application Programming)for software program debugging and system updates.(4)Build a testing platform for charge sensitive amplifiers,conduct experimental research and performance testing on the circuit system.The circuit waveform test results show that within the dynamic range of the input charge signal,the measured waveforms of the primary and secondary amplification circuits of the charge sensitive amplifier are consistent with the simulation results.Finally,perform linear fitting on the measured data of each range to ensure good linearity of the range channel,and then fit the overall data curve.The results indicate that the output signal of the charge sensitive amplifier designed in this project is stable and meets the measurement requirements.