How does a spinning charged particle move

The fundamental mirror symmetry law requires that a particle in a central potential should move on a flat trajectory. We have observed a deviation from the flat trajectory for a spinning charged particle - electron moving in a Coulomb potential of a nucleus. Such an observation is not possible in a typical scattering experiment, since the observable macroscopic electron directions before and after the collision always lie in one plane. However, in order to probe the electron dynamics during the collision, we have observed the bremsstrahlung x-ray emitted when the electron passes near the nucleus. The angle of x-ray linear polarization is correlated with the direction of the electron in this moment. We saw that the plane of polarization does not coincide with the reaction plane when spin-oriented electrons are used. While this effect is very small and difficult to detect, we were able to improve the angular resolution of x-ray polarimetry ten times as compared to the previous best measurement which made this observation possible. The results are important for understanding of relativistic electron dynamics in the strongest electromagnetic field experimentally available - in the field of the nucleus. They can also be applied for polarimetry of relativistic electron beams.

Measurement of the Correlation between Electron Spin and Photon Linear Polarization in Atomic-Field Bremsstrahlung
S. Tashenov, T. Bäck, R. Barday, B. Cederwall, J. Enders, A. Khaplanov, Yu. Poltoratska, K.-U. Schässburger, and A. Surzhykov
Phys. Rev. Lett. 107, 173201 (2011)
DOI: 10.1103/PhysRevLett.107.173201

Bremsstrahlung polarization correlations and their application for polarimetry of electron beams
S. Tashenov, T. Baeck, R. Barday, B. Cederwall, J. Enders, A. Khaplanov, Yu. Fritzsche, K.-U. Schaassburger, A. Surzhykov, V.A. Yerokhin, and D. Jakubassa-Amundsen
Physical Review A 87 (2013) 022707
DOI: 10.1103/PhysRevA.87.022707