K-Shell to K-Shell Charge Transfer in Collisions of Bare Decelerated S Ions with Ar

The impact parameter dependence of the single and double K-shell to K-shell charge transfer probabilities was studied by measuring triple coincidences between two K X-rays and the scattered projectiles for 16 MeV S 16+-Ar. It was found that the data are internally consistent with independent electron assumptions, but cannot be reproduced by different calculations of single electron transfer probabilities applying the independent electron model. Also a calculation of double K-vacancy transfer including electron correlations which described the He2+-He charge transfer probabilities well is not in good agreement with the authors data. The data also allow a more sensitive test of various calculations on K to K charge transfer than recent experimental studies on collision systems with hydrogen-like projectiles