KT - nuclear physics and particle physics

KT.POV - Positron Annihilation: Coincidence Spectroscopy

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We demonstrate the positron life time spectroscopy using positrons from the decay of Na-22 into Ne-22. We measure the life time of positrons in metal samples and insulators with a time resolution of a few hundred picoseconds. The life time is an indicator for the existence of vacancies and voids in a material and also an indicator for the formation of positronium (e+-e-). We use different types of gamma detectors to detect gammas from the Na-22 decay and gammas from positron annihilation. We set up a time coincidence measurement using conventional nuclear spectroscopy modules and perform the time calibration and time resolution measurements. We also evaluate the angular correlation of the annihilation radiation using a coincidence setup.

II. Physikalisches Institut, D-1.119