A computer-controlled system for slow positron implantation spectroscopy

Abstract
The design and construction of a computer-controlled beam transport system and its application to slow positron implantation spectroscopy is described. The control features include the facility to vary the positron beam energy, observe visually the associated spatial movement of the beam profile, and change the beam position so as to hit the sample centrally at all energies selected. This procedure allows the automatic collection of annihilation gamma ray energy spectra and calculation of lineshape parameters as a function of incident positron energy. Examples of such measurements for metallic and semiconductor samples are used to illustrate the performance of the system.
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