A study of radiative double electron capture in bare chromium ions at the ESR.

Radiative double electron capture is a fundamental atomic process which should be observed in collisions of bare ions with atoms, albeit with a much smaller cross-section than single radiative electron capture. A new experiment-to observe this rare process under single-collision conditions-has been performed at the internal gas jet target of the experimental storage ring at GSI in Darmstadt. X-ray spectra associated with single and double charge exchange have been observed in 30MeV u(-1) collisions of bare chromium ions (Cr24+) with helium and nitrogen target gases.