PITT-**508**

**N. L. Manakov ^{*}, A. V. Meremianin^{*},
J. P. J. Carney
and R. H. Pratt
**

^{*}Department of Physics, Voronezh State University, Voronezh 394693, Russia

Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260

**15 June, 1999**

It is shown that a specific beyond-dipole-approximation
polarization effect in elastic photon-atom scattering,
resulting in circular dichroism (CD) when the scattered
photon has a suitable observed *linear* polarization,
has significance in the x-ray regime. Ground state atoms
are considered, assumed to be randomly oriented.
The cross section, given our assumptions, is written in
terms of photon Stokes parameters and four real
photon-polarization-independent atomic parameters
(which depend on the vectors of the problem and the two
invariant scattering amplitudes). Numerical results are
given for the case of scattering from ground-state atoms
with *Z*=29, *Z*=54 and *Z*=92. Attention is given to
determining the regime where the dichroism effect may be
experimentally observable. It is seen to be largest for
intermediate angles, high *Z* and high (hundreds of keV)
photon energies, increasing to an approximately 20%
effect in cross sections. The parameter determining this
effect is also responsible for the appearance of
elliptically polarized scattered photons for the case of
a suitable linearly polarized incident beam.

32.80.Cy

- Introduction
- Theory
- Numerical results
- Conclusions
- Acknowledgments
- Appendix
- Figures
- Bibliography
- About this document ...