Positronium Formation in Nanostructured Metals
J. Čížeka, O. Melikhova a, P. Hruška a, M. Vlček a, W. Anwand b, M.O. Liedke b, M. Novotný c and J. Bulíř c
aFaculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 18000, Praha 8, Czech Republic
bInstitute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden, Germany
cInstitute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague 8, Czech Republic
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Positronium formation in Au films was studied using a magnetically guided continuous slow positron beam with variable energy. Black Au film with porous morphology was compared with conventional smooth Au film. In the smooth Au film positronium is formed on the film surface only. The black Au film exhibits porous sub-surface region containing micro-cavities interconnected with surface. Positronium is formed on inner surfaces of micro-cavities in the sub-surface region and travels through interconnected cavities towards the surface. 3-γ annihilation of ortho-positronium leaves a clear signature in two-dimensional coincidence Doppler broadening spectra. Measures of 3-γ annihilation contribution calculated from single γ-ray and coincidence Doppler broadening spectra were calculated and compared.

DOI: 10.12693/APhysPolA.132.1579
PACS numbers: 78.70.Bj, 41.75.Fr, 36.10.Dr