A computer-controlled system for slow positron implantation spectroscopy

The control features of this system 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 the 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 system's performance. (Original abstract-amended)