Development Of Rutherford Scattering Experiment Data Acquisition System

In the teaching process of nuclear physics or related majors, the Rutherford scattering experiment has strong instructive significance for cultivating students' physics thinking and experiment operating skills. With the development of integrated circuit technology and the wide application of embedded system, a set of Rutherford scattering experiment data acquisition system is designed in this dissertation. The system is featured for low power consumption, high integration, low cost and simple operation, which can be used in college physics laboratories and replaces the heavy outdated equipment.The principle of a-particle Rutherford scattering experiment is described in this dissertation. The straight thin a-rays are emitted through the collimator from the 241 Am bombarding on the gold foil and then scattered. The scattering particles are captured by the Au-Si surface barrier semiconductor detector and converted into charge signal output. In order to study the experimental results under different scattering angles, the receiving angle of the detector from scattering can be changed by the turning of the target controlled by the step motor drive. The charge sensitive pre-amplifier converts the charge signal into voltage signal and amplifies. The main-amplifier consists of polarity conversion circuit, pole-zero cancellation circuit, amplifying circuit, integration filter circuit, and so on, which be used to choose signals'polarity, removal of accumulation, change the gain and filter into a quasi gaussian signal output. The multi-channel pulse amplitude analyzer designed based on the STM32F4 series microprocessor will identify and broaden the signals, convert the signal amplitude into digital quantity through the build-in ADC for further analysis and processing.The output signals'rise time of the charge sensitive pre-amplifier is less than 200ns. The scattering angle controlling system has three kinds of step angle, which respectively arel°,5°nd10°. The main-amplifier uses differential input and the polarity of the output pulse can be changed. The main-amplifier features high common-mode rejection, which can be used to restrain the disturbance introduced by the long input cable. Furthermore, the main-amplifier has five kinds of gain. And the time constant is 1?s.