Relative multiple ionization cross sections of neon by projectiles in the 1-2-MeV/amu energy range

Abstract

The change in the $K\ensuremath{\alpha}$ x-ray spectra of neon is studied as a function of projectiles of ${\mathrm{C}}^{+3,+4,+5,+6}$, ${\mathrm{N}}^{+4,+6,+7}$, ${\mathrm{O}}^{+4,+5,+6,+7,+8}$, and ${\mathrm{F}}^{+9}$ having an energy between 1 and 2 MeV/amu. The spectra are observed using a curved crystal spectrometer. Combined with previous measurements data are obtained for projectiles from carbon to argon. X rays are observed from different ionization states of Ne designated by $K{L}^{n}$ for $n=1\ensuremath{-}7$. An 81% correction between the $K{L}^{5}$ peak and $K{L}^{6}$ peak is derived. Semiempirical fluorescence yields are applied to the relative x-ray intensities to obtain relative multiple ionization cross sections. These cross sections are fitted by a binomial distribution as predicted by Coulomb ionization. All cases give good fits except for the ${\mathrm{F}}^{+9}$ induced spectra. A possible explanation is that a different excitation mechanism may exist for this near-symmetric collision case.