Many-Body Effects Observed in the Positron Annihilation Experiment

G. Kontrym-Sznajda and H. Sormannb aInstitute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 937, 50-950 Wrocław 2, Poland bInstitut für Theoretische Physik - Computational Physics, Technische Universität Graz, Petersgasse 16, 8010 Graz, Austria

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Received: 20 09 2004;

This paper is devoted to study many-body effects in the positron annihilation experiment, both electron-positron (e-p) and electron-electron (e-e) correlations. Various theories of the e-p interaction in real solids were used to verify them by comparing theoretical and experimental e-p momentum densities in Cu and Y. We show that the lattice potential has an essential influence on the e-p correlation effects, i.e. their proper description must be done via periodic lattice potential as e.g. in the Bloch modified ladder theory. Moreover, it is not true that the dynamic parts of the direct e-p and e-e interactions cancel each other because e-e correlations are observed not only in the Compton scattering but also in the positron annihilation experiments.

DOI: 10.12693/APhysPolA.107.562 PACS numbers:78.70.Bj, 78.70.Ck, 74.25.Jb