Antiproton, proton and electron impact multiple ionization of rare gases

Abstract

We present a study on multiple ionization of Ne, Ar, Kr and Xe by antiproton, proton and electron impact. Four different aspects are involved in this work. First, the theoretical calculations of ionization probabilities by impact of antiprotons and protons, in an extended energy region (25 keV to 10 MeV), using the continuum distorted-wave eikonal initial state approximation and the first Born approximation. Second, the inclusion of Auger-type post-collisional contributions through experimental photoionization branching ratios. These contributions to multiple ionization are very important in the high-energy region. Third, the comparison with the available experimental data on multiple ionization by protons and antiprotons in the extended energy range, and by electrons for high-impact velocities, where proton, antiproton and electron impact results are expected to converge. It is also the energy region where direct ionization does not explain the experimental results, and the post-collisional ionization is the main contribution to multiple ionization. And fourth, total ionization cross sections are calculated and compared with the antiproton, proton and electron experimental data, showing the importance of Auger-type multiple ionization for heavy targets even at the level of total cross sections. Gross and count cross sections are scrutinized.

Influence of inner-shell electron removal on the multiple ionization of Kr and Xe by protons

“…The method has been successfully applied to the quadruple, quintuple and sextuple ionization of Kr and Xe targets by protons and electrons, taking into account the removal of deep-core electrons, namely from the 2s and 2p subshells (besides the M and N shells) of Kr and from the 3s, 3p and 3d subshells (besides the N and O shells) of Xe, providing in general a very good agreement with experiment and thus solving some of the discrepancies previously observed in the calculations of Montanari and co-workers [20] which did not include these contributions.…”

“…As expected, the effects due to post-collisional emission increase as the target final charge state increases. [20] without the inclusion of post-collisional electron emission. Experimental data for protons: solid triangles, [8] (Kr and Xe) and solid stars, [40] (Kr).…”

“…In the present calculations we have considered the removal of L, M and N electrons of Kr and M, N and O electrons of Xe. The inclusion, for the first time, of deep-core electrons, namely from the 2s and 2p subshells of Kr and from the 3s, 3p and 3d subshells of Xe, has the aim of solving the discrepancies previously observed in [20]. The paper is organized as follows.…”

Multiple ionization of rare gases by hydrogen-atom impact

“…Two kind of time orders are possible; the corresponding probabilities are (15) (ionization followed by capture), and (16) (capture followed by ionization). We symmetrize the probabilities by taking the average of P (1) and P (2) . In a similar way, the time order of the different processes was taken into account in deriving the probabilities of higher ionization degrees with and without assuming single electron capture.…”

“…The simplest and cleanest dynamics occurs at antiproton impact: in this case the only reaction channel is pure ionization. A comprehensive overview of multiple ionization induced by antiprotons, protons, and electrons in rare gases has been published recently by Montanari et al [1].…”