DR is a two-step process. In the first step, a free electron is radiationlessly captured by an ion Aq+, the excess energy is used to excite a bound electron in the ion core simultaneously, by which a doubly excited intermediate state of the ion is formed. In the second step, the intermedia state stabilizes via emission photons.
The experimental cooler storage ring (CSRe) equipped with a 300 kV electron cooler (EC-300) which provides a broad detuning energy range of ±30 kV corresponding to relative energy at the center of mass frame to be ~1500 eV. By scanning the electron energy at the cathode of electron cooler and detecting the recombined ion beams after the first dipole magnet downstream the electron cooler EC-300,with further data analysis,the DR spectrum will be obtained. DR resonant technique at the CSRe can be used as a precision spectroscopy tool to test QED theory in strong field,study electron-electron correlation effects,and provide the opportunity for the DR spectroscopy research on radioactive ions.
