Observation of Anisotropy in the Temperature Dependence of the Positron-Annihilation Spectrum from a Single Crystal of Cadmium

Abstract
Measurements have been made on the Doppler broadening of the 511-keV photons resulting from positron annihilation in a single cadmium crystal over the temperature range 4-590 K. They show that the temperature dependence in the prevacancy region (150-350 K) is markedly different in the cases of emission in the [0001] and [101¯0] directions.