Photoionization of atomic Ca in the26–120-eV photon-energy range

We present detailed experimental results for the resonance structure of atomic Ca in the region of the 3p threshold, from 26 to 40 eV, as manifested in the partial cross sections of the 4s^-1 and 3p^-1 main photoelectron lines and several of their satellites, including satellite--to--main-line branching ratios. We also present partial photoionization cross sections for the 4s^-1, 3p^-1, and 3s^-1 main lines up to 120 eV photon energy. Finally, we give a qualitative, theoretical discussion of the resonance structure and decay mechanisms, and compare the measured 4s, 3p, and 3s photoionization cross sections with theoretical results within the framework of random-phase approximation and many-body perturbation theory.