Electron-Positron Interaction in Metals. Theory and Experiment

H. Stachowiak, and E. Boroński W. Trzebiatowski Institute for Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wrocław 2, Poland

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Received: 20 09 2004;

The electron-positron interaction greatly complicates the interpretation of positron annihilation data. The two-detector Doppler measurements of Mijnarends et al. as well as our theoretical calculations point at the conclusion that the local density approximation to e+-e- interaction is a good way of treating this problem in real metals, at least the simplest ones. This shows that e+-e- interaction in an electron gas is the key to understanding this phenomenon also in inhomogeneous systems. On the basis of dozens of experiments one comes to the conclusion that the well known formula of Boroński and Nieminen for the electron accumulation on the positron in jellium describes the best the positron lifetimes in metals. However, it is based on the calculations of Lantto which start from a physically oversimplified trial function. The results of Arponen and Pajanne, of Rubaszek and Stachowiak, and of Stachowiak and Lach lead to too short positron lifetimes in spite of using less controversial assumptions. The discrepancy is of the order of 8 to 15% for rs=2. This shows that we still do not fully understand e+-e- interaction even in an electron gas.

DOI: 10.12693/APhysPolA.107.541 PACS numbers:71.60.+z, 78.70.Bj