Charge-state dependence of the meanK- shell fluorescence yields ofSiq+ions

Projectile $K$ x-ray production cross sections have been measured for 15-60-MeV ${\mathrm{Si}}^{2+-11+}$ ions incident on a thin He gas target. The data are well reproduced by the plane-wave Born approximation theories of $K$- shell ionization in addition to $1s-2p$ excitation when charge-state dependent fluorescence yields ${\omega }^{\mathrm{}(q+1\mathrm{})\mathrm{}}$ are used as fitting parameters. After normalizing the mean fluorescence yield at the lowest charge state to the results obtained for neutral Si atoms, the ${\mathrm{Si}}^{\mathrm{q}+}$ fluorescence yields vary from 0.044 to 0.528 (±20%) for $2<q<\mathrm{}11\mathrm{}$.