First Coincident Measurement of the Energies of Positron-Induced Secondary Electrons and Corresponding Positron Annihilation-Induced Gamma Photons*

A novel spectroscopic technique utilizing a recently completed positron beam has been developed at the University of Texas at Arlington. The technique employs a positron annihilation-induced Auger electron spectroscopy system to measure the flight times of Auger electrons in coincidence with gamma photons measured by a high purity Ge gamma detector. Described herein as gamma-gamma-Auger coincidence, the integrated technique is applied to the study of the doppler-broadened spectra of gamma photons emitted during a particular positron-electron annihilation event which results in the emission of an Auger electron. The ability to identify specific gamma energies alongside the Auger electron energies to which they are associated will allow the acquisition of electronic, structural, and chemical information from the top-most surfaces of thin films and nanostructures.