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Hamburg 2009 – scientific programme

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A: Fachverband Atomphysik

A 34: Poster II

A 34.20: Poster

Thursday, March 5, 2009, 16:30–19:00, VMP 9 Poster

Spin-resolved electron scattering from lead (Pb) and europium (Eu) atoms — •Volker Hamelbeck and G. Friedrich Hanne — Physikalisches Institut, 48149 Münster, Germany

The interactions between low-energy spin-polarised electron beams and atomic as well as molecular targets have comprehensively been studied in our group. An interesting aspect of this field are collision experiments on heavy open-shell metal atoms such as Pb and Eu where spin-orbit and exchange effects occur simultaneously. This is still a difficult task for theory.
For a description of these processes, the scattering parameters SP, SA, T and U are introduced. Through the polarisation function SA the spin-dependence of the DCS is quantified. The other parameters are determined by measurement of P and P′, the electron polarisation before and after scattering respectively. These cover distinct effects such as exchange (Tx,Ty,Tz) and rotation (Uxz,Uzx) of the electron spin during scattering.
In our experiments, the spin-polarised electron beam is guided from a GaAs source to the collision centre where it hits the heavy metal vapour emanating from an oven. A rotatable spectrometer is used to collect the scattered electrons whose spin polarisation is determined in a Mott-detector, subsequently.
In the case of low energy electron scattering from Pb, the angular distribution of the spin asymmetry function SA shows a significant dependence on the energy between 11 eV and 14 eV. For Eu, first results of SA and the exchange parameter Ty are presented.

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