Two-electron one-photon transitions into the doubly ionized<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>K</mml:mi></mml:math>shell

Abstract

Correlated two-electron transitions into the doubly ionized $K$ shell have been observed in Al-Al, O-Ca, Ca-Ca, Fe-Fe, Fe-Ni, Ni-Fe, and Ni-Ni collisions at beam energies between 24 and 40 MeV. In these transitions one photon carries away the entire two-electron transition energy. The cross sections for the characteristic radiation and the two-electron radiation have been determined. The measured branching ratios between the single- and double-electron transition into the doubly ionized $K$ shell are compared with various theoretical predictions. The theoretical and experimental results are found to be in qualitative agreement.