Single, double and triple ionization of Ne, Ar, Kr and Xe by 30 - 1000 keV impact

Abstract

Experimental data for single, double and triple ionization of Ne, Ar, Kr and Xe by 30-1000 keV antiproton impact are presented and compared with existing proton data. It is found that the current phenomenological understanding of ionization developed from studies of light targets generally apply to heavy atomic targets as well. Inner-shell ionization followed by Auger decay is found to be an important channel for multiple ionization of the heaviest targets, and the projectile charge dependence of their multiple ionization cross sections must be understood as stemming from the underlying inner-shell ionization cross sections.

Empirical formulas for direct double ionization by bare ions:Z=−1to 92

“…In agreement with the findings of Knudsen et al, they found that for larger Z/v the ratios increased as v −2 but were velocity independent as Z/v → 0. Antiproton and proton impact data were compared [10][11][12][13] with the observed differences in the double ionization being attributed to quantum interference, in accordance with the McGuire model. For a synopsis of the antiproton and proton studies see [11] and references therein.…”

“…Our analysis is based on a large database of published experimental cross sections and double-ionization ratios [7][8][9][10][11][12][13][26][27][28][29][30][31][32][33][34][35][36][37][38]. To simplify the interpretation, only data for the direct ionization channel, i.e., only data where there are no contributions from the electron-capture channel, and fully stripped projectile impact were used.…”

“…(3) and our fitting parameters compared to experimental data from Refs. [8][9][10][11][12][13]26,27,36]. The dotted curves show σ int and σ 2 determined using the fit to the antiproton single-ionization cross sections.…”

“…For this purpose, single-and double-ionization cross sections for proton, antiproton, and multiply charged ion impact on helium, neon, and argon were used (He target references are provided above, Ne target data are from Refs. [12,28,36], and Ar target data are from Refs. [11][12][13]26,27]).…”

On the measurement of ionization cross sections for antiproton impact on atoms and molecules

“…Here is shown the single ionization cross section measured on neon for impact of antiprotons [6]. These data are compared with experimental proton data [7].…”