The distribution of neon ions that result from ionization by x rays has been measured with a coincidence time-of-flight mass spectrometer. Radiation from an aluminum target, filtered through a beryllium foil, was used so that in more than 95% of the events a $K$ electron was removed. The observed charges, including $L$ ionization, are distributed as follows: ${\mathrm{Ne}}^{1+}$=3%; ${\mathrm{Ne}}^{2+}$=66%; ${\mathrm{Ne}}^{3+}$=24%; ${\mathrm{Ne}}^{4+}$=6%; ${\mathrm{Ne}}^{5+}$=0.8%. On the average 2.4 electrons are removed per interaction. The charge spectrum has also been computed using calculated $K-\mathrm{LL}$ Auger transition rates and electron shake-off probabilities as given by the ${\beta }^{-}$ decay of ${\mathrm{Ne}}^{23}$. The assumptions of the models used as well as the applicability to the present study have been examined. Comparison of the calculations with the experimental data indicates the presence of other modes of ionization.

• Received 3 September 1963

DOI:https://doi.org/10.1103/PhysRev.133.A385