Radiative double electron capture (RDEC) by bare fluorine ions on a nitrogen target.*

Unlike radiative electron capture (REC), in which a single photon is emitted due to capture of a single electron from the target to the projectile, radiative double electron capture (RDEC) involves two electrons accompanied by the emission of a single photon. Hence, RDEC can be considered as the inverse of double photoionization and used to study the role of electron correlation in causing the process. We report recent results obtained for 40 MeV F$^{\mathrm{9+}}$ ions incident on a nitrogen target, in which counts were observed in the calculated RDEC region (2.8-4.4 keV) for the system. Based on these observations an approximate value for the total RDEC cross section was estimated. Compared with the data obtained for 38 MeV O$^{\mathrm{8+}}$ ions incident on a carbon foil target$^{\mathrm{1}}$, the present value is considerably smaller than the value found for carbon, but in better agreement with recent theory$^{\mathrm{2}}$. *Supported in part by NSF. $^{\mathrm{1}}$A. Simon et el., PRL \textbf{104}, 123001 (2010); $^{\mathrm{2}}$ E. A. Mistonova et el., Phys. Rev. A \textbf{87}, 034702 (2013).