Implementation of a Deceleration Beamline for the Investigation of Charge Exchange Processes using Highly Charged Ions

A new experimental beamline has been constructed at the Heidelberg Electron Beam Ion Trap (EBIT) for the investigation of charge exchange processes between slow Highly Charged Ions (HCIs) and a neutral gas target, which are measurements of astrophysical relevance. In order to study this process in detail in the laboratory, the new experiment is designed to decelerate ions extracted from the EBIT. The ion optical properties of the new beamline and the properties of decelerated ions have been simulated using the program SIMION. Simulations show that ions are decelerated without any major broadening of their kinetic energy distribution, whereas angular distribution increases with deceleration voltage. The deceleration potential as a function of focal distance is shown to follow a parabolic relationship. Performance tests of the new beamline support the results of the simulation and qualitatively demonstrate the ion optical-like properties of the deceleration system. First experiments with Ar18+ and Ar17+ incident upon a neutral argon target have been successfully completed, with the observation of the K- peak and higher order transitions in both cases. The decay of the metastable state 3S1 of Ar16+ could be identi ed as an important decay channel using coincidence spectroscopy. Calculated hardness ratios for the spectra (0:186 +/- 0:010 for Ar18+ and 0:090 +/- 0:005 for Ar17+) are lower than those found in previous experiments by di erent groups. This deviation is most likely a consequence of lower background events as a result of the coincidence spectroscopy technique employed