Positrons — an alternative probe to electron scattering
Faculty of Engineering, Trento University, 38050 Povo, Italy
Corresponding author: a email@example.com
Revised: 27 May 2005
Published online: 17 August 2005
Interaction of positrons with atoms and molecules differs from electron interaction due to the difference in polarity of the charge. This makes positrons an alternative tool to study atomic and molecular structure. Recent measurements of the total cross-sections for positron scattering at low energies on He, Ar, H2, N2, C6H6, C6H12, C6H7N carried out at Trento University [Karwasz et al., Acta Phys. Pol. 127, 666 (2005)] are discussed and compared to electron scattering results. All measured total cross-sections exhibit an increase with decreasing positron energy in the limit of zero energy; H2, N2, Ar, show regions of constant cross-section which are a few eV-wide, characteristic of scattering on a hard-sphere potential. Helium shows two resonant structures much below the positronium formation threshold. They may be attributed to virtual positronium formation. In conclusion, positron scattering is complementary to electron scattering. The total cross-sections do not show Ramsuaer minima but constant values, and new resonances appear.
PACS: 34.85.+x – Positron scattering / 39.90.+d – Other instrumentation and techniques for atomic and molecular physics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005