Photon-photon angular correlations in the radiative recombination of bare high-Z ions

The radiative recombination of a free electron into excited states of bare, high-Z ions and the subsequent photon decay are studied in the framework of the density matrix theory. Emphasis is placed, in particular, on the angular correlation between the recombination and the decay photons. The general expression for the photon-photon angular correlation function is. derived, based on Dirac's equation as appropriate for high-Z ions. Computations for the dependence of the photon-photon correlation function on the nuclear charge and the projectile energies are carried out for the capture into the 2p(3/2) level and the subsequent Lyman-alpha(1) (2p(3/2) --> 1s(1/2)) radiation.