PARAMETRIZATION OF A SPIN-POLARIZED (E,2E) EXPERIMENT

We use the density-matrix formalism to parametrize a spin-polarized (e ,2e) experiment where ap electron is ejected from a closed-shell syste m and the fine structure of the ion is resolved experimentally. This f ormulation allows a definition from general principles of the recently observed spin up-down asymmetry [X. Guo and co-workers, Phys. Rev. Le tt. 76, 1228 (1996); J. Phys. B 30, 4097 (1997)] due to the fine-struc ture effect [S. Jones et al., Phys. Rev. Lett. 72, 2554 (1994); G. F. Hanne, in Abstracts of Contributed Papers, XVIIth International Confer ence on the Physics of Electronic and Atomic Collisions, edited by W. R. MacGillivray, I. E. McCarthy, and M. C. Standage (Hilger, Bristol, 1992), p. 199] and the complete definition of potentially observable q uantities such as the polarization of the fast-and slow-emitted-electr on beams and the orientation of the ion beam after the collision. Thes e parameters are defined for the general case where the incoming-elect ron beam has an arbitrary polarization P=(P-x,P-y,P-z) and calculated in an asymmetric kinematic for the case where the initial-electron bea m is, respectively, unpolarized and polarized perpendicular to the sca ttering plane.