Probabilities forM-shell ionization in intermediate-velocity collisions of medium-mass atoms with4He2+ions

Abstract

High-resolution measurements of the $K{\ensuremath{\beta}}_{2}$ diagram line and its ${M}^{1}$ satellite were performed for zirconium, molybdenum, palladium, and praseodymium. The x-ray spectra were induced by impact with 28-, 40-, 65-, and 100-MeV \ensuremath{\alpha} particles and measured with a transmission-type bent crystal spectrometer in modified DuMond slit geometry. From the relative yields of the $K{\ensuremath{\beta}}_{2}{M}^{1}$ satellites the experimental average $M$-shell ionization probabilities for nearly central collisions were deduced. They are compared with theoretical predictions from the semiclassical independent particle approximation using either hydrogenlike wave functions (SCA-HWF) or Dirac-Hartree-Fock wave functions (SCA-DHF), pointing out the relevance of the use of DHF wave functions instead of hydrogenlike wave functions in the SCA model. Moreover, the experimental energy shifts of the satellite transitions with respect to the diagram lines are compared to results of extensive multiconfiguration Dirac-Fock calculations.