ANGULAR-DISTRIBUTION OF PHOTON-INDUCED M(2,3)-N(1)N(1) AUGER ELECTRONS IN ATOMIC CALCIUM

The angular distribution of photon-induced M2,3-N1N1 Auger transitions in calcium has been measured in the region of the Cooper minimum of t he 3p photoionization cross section. As expected from theory, the M2-N 1N1 transition is isotropic whilst the angular distribution parameter of the non-isotropic M3-N1N1 transition shows a large variation. This variation is analyzed in terms of the alignment of the photoionized st ate and compared with theoretical calculations which consider the many -electron interactions for the 3p photoionization cross section in dif ferent approximations. Good agreement is found with the energy-adapted results from a relativistic random-phase approximation calculation.