Antiproton, proton and electron multiple ionization of rare gases

C. C. MONTANARI; J. E. MIRAGLIA

Fort Worth, Texas

Congreso; 22st International Conference in the Application of Accelerators in Research and Industry; 2012

University of North Texas and Sandia National Laboratories

Multiple-ionization is one of the most challenging subjects within the field of the atomic collisions. Experimental measurements require highly advanced techniques to get absolute values of all possible channels and final states. For positive ions, they must separate pure ionization from capture channels, which enhance the data in the intermediate energy region [1]. The case of antiproton impact is quite different. Despite the experimental difficulty to achieve a low energy antiproton-beam, it is the simplest ionization dynamic to describe [2]: no possible capture channel or electron exchanges to consider. On the other hand, the study of antiproton impact ionization has the additional interest of being projectiles produced in high-energy physics sources. We present a theoretical study on multiple-ionization [3], which involves four different aspects: i) the theoretical calculations, using the CDW-EIS and the first Born approximation, in an extended energy region (50 keV-15 MeV). ii) the inclusion of Auger-type post-collisional contributions through experimental photoionization data. iii) the comparison with the available experimental values on multiple-ionization by protons and antiprotons,  but also by electron impact for high impact velocities. In this energy region direct ionization does not explain the experimental results, and the post-collisional ionization is the main contribution to multiple-ionization. iv) the review of the  total ionization cross sections, gross and count,  showing that  Auger-type contributions should be included in total-ioniization cross sections too. Our results demonstrate that this contribution is very small for Ne or Ar but increases with the target atomic number, being 30 % for total-ionization of  Xe at high energies [3]. [1] DuBois R D, Phys. Rev. Lett. 52, 2348-2351 (1984). [2] Kirchner T and Knudsen H, J. Phys. B: At. Mol. Opt. Phys.  44, 122001 (2011). [3] Montanari C C and Miraglia J E  J. Phys. B: At. Mol. Opt. Phys.  45, in press (2012).