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一、引言 在电子-正电子湮灭中,由于质心的运动,在实验室系中测得的511keV湮灭光子能谱会有一个多普勒加宽。同时,在湮灭时由于正电子已接近于热化状态,其动量与电子动量相比可以忽略,因此,多普勒加宽谱实际上表征了与正电子发生湮灭的电子的动量分布。由于这类分布与材料的电子结构以及各种缺陷都有密切的联系,因此,近年来,湮灭多普勒加宽谱的测定方法已开始在固体物理研究中有了实际的应用。 本工作用高分辨率的Ge(Li)谱仪,对正电子在几种金属中的多普勒加宽谱进行了实验测定。根据所测得的全能峰的谱形,应用最小二乘分析法,在PDP-11小型计算机上进行了实验数据的拟合,由此给出了
I. INTRODUCTION In electron-positron annihilation, there is a Doppler broadening of the 511 keV annihilation photon spectrum measured in the laboratory due to centroid motion. At the same time, the positron possesses negligible momentum compared with the electron momentum at the time of annihilation. Therefore, the Doppler broadening spectrum actually characterizes the momentum distribution of the electron annihilating with positrons. Since these kinds of distribution are closely related to the electronic structure and various defects of the materials, the determination of annihilation Doppler broadening spectrum has started to have practical application in solid state physics in recent years. In this work, high-resolution Ge (Li) spectrometer was used to measure the Doppler broadening spectrum of positrons in several metals. Based on the measured spectrum of the all-powerful peak, the experimental data fitting was performed on a PDP-11 minicomputer by using the least-square analysis method, thereby giving