Angular Correlation Apparatus of Positron Annihilation and Application to the Study on Copper Alloys

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Abstract
The angular correlation apparatus of positron annihilation was constructed for the study of the Fermi surfaces (F.S.) in various materials under various conditions. This apparatus has the advantages in the aspects that the `crossslit geometry' is involved and that the study of liquid state as well as solid state is possible. Its application to the study on several Cu-based alloys has shown satisfactory performance for our purpose. The angular correlation curves of β'-brass, 0.8 Cu-0.2 Ni and 0.6 Cu-0.4 Ni single crystals were measured. In the preliminary experiments, the following results were obtained: (1) the F.S. of β'-brass has the necks in directions, (2) in 0.8 Cu-0.2 Ni, the radius of the neck seems to be about 0.5 mrad., so that about 0.4 electrons per atom of Ni may be contributed to the conduction band. Further, the possibility of the production of much stronger 58 Co positron source was discussed.