High Energy Resolution (e, 2e) Spectrometer Data Acquisition System Development And Its Application

In this dissertation a multi-parameter data acquisition system for the high energy resolution (e, 2e) spectrometer in our laboratory has been designed and constructed. And the software with good user interface, which is suitable to the data acquisition system, has been developed under the LabVIEW environment. The data acquisition system can process 8 signals in parallel under coincident measurement. Furthermore, a new method for data correcting has been proposed, and data processing software has been modified and consummated. The binding energy spectra and momentum distributions of Ar atom and CF2Cl2 molecule measured by high energy resolution (e, 2e) spectrometer have been used to verify the data acquisition system and the modified data processing software.This dissertation includes the following five chapters:In the first chapter, the theoretical background, the experimental arrangement, and the research progress of electron momentum spectroscopy have been introduced simply. In addition, the newly developed high energy resolution (e, 2e) spectrometer in our lab is described in detail.In the second chapter, the design of data acquisition system has been disserted in detail. Firstly we analyzed the requirement of data acquisition system and offered the main principle of design. Then the hardware and software of data acquisition system have been constructed. The data acquisition system can process 8 signals in parallel under the measurement in coincidence with 30K sample/sec rates. Finally we tested the data acquisition system by using the experiment of Ar 3p orbital ionization. The results show the data acquisition system works normally and satisfies the demand of high resolution (e, 2e) spectrometer.In the third chapter, we have presented the experimental data processing and analyzing process including how to calibrate the relation of energy (angle) and position, how to obtain the binding energy spectra and momentum distributions, etc. In order to decrease the influence of the fluctuations of detected efficiencies, a new method to correcting efficiency by using the single background of two detectors and triangle background counts has been proposed, and compared with the other method by employing accidental coincident background. The applicable area of two methods of efficiency correction has been achieved.In the forth chapter, the experiment of CF2Cl2 carried out by the high energy resolution (e, 2e) spectrometer has further verified the data acquisition system and the data processing software. The experimental binding energy spectra and momentum distributions have been acquired by using the modified data process software with two different methods of efficiency correction, and compared with those without correction, as well as the corresponding theoretical calculations. The results show that the data acquisition system works well, the data processing software is reliably and the efficiency correcting methods is feasible.In the last chapter, the distortion in the edge of the measured image of the position sensitive detector (PSD) has been shown clearly in a simple way by using electric pulses instead of input charge cloud. A mapping relation was established between the distorted image and the original one. The spatial distortion of another measured image was corrected according to this relation and the correction results were evaluated. After the correction, the barrel distortion was obviously improved and the integral nonlinearity decreased to 0.59% from 2.1% along x-axis.