Single ionization of Ne, Ar and Kr by proton impact: single differential distributions in energy and angle

S. OTRANTO; J. E. MIRAGLIA; R. E: OLSON

Kalamazoo, Michigan

Conferencia; XXVI INTERNATIONAL CONFERENCE ON PHOTONIC, ELECTRONIC AND ATOMIC COLLISIONS; 2009

The study of single differential cross sections in energy and angle (SDCS) has been a topic of wide interest for experimentalists as well as theoreticians during the last four decades. Practical applications, like the evaluation of radiation damage or the estimation of radial dose distributions, highlights the need of information concerning secondary electron spectra. As a result, noble gases and some molecular reactants of particular interest and experimental tractability have been widely explored in different laboratories worldwide (see [1] for a review and references). Theoretical studies used over the years to describe the available data include the Binary Encounter Approximation, the CTMC, and several distorted wave models such as the PWBA, CDW-EIS etc. These models have been continuously improved to explore the available data, in principle, within the limitations of the computational technology available at the time. In this work, we employ a state-of-the-art CDW-EIS model in which for each state the central potential was determined from the Hartree-Fock wave functions and improved to achieve the best binding energy and moment of the position. Calculations are performed using an angular expansion in spherical harmonics and a numerical evaluation of the bound and continuum states for the emitted electron. In Figure 1, we show a SDCS in angle for 300 keV protons colliding with argon. The present CTMC model has been calculated using the same central potentials as in the CDW-EIS calculations. In this case, we see that the CTMC provides the closest agreement with the data collected in three independent laboratories. Although improving the description of the FBA (possibly due to its explicit inclusion of the two center effect), the CDW-EIS model leads to a description of the experimental data that is far from satisfactory at this impact energy. Furthermore, exploration of other collision energies in the range 100-1000 keV, shows a systematic overestimation of the low energy electron emission at large angles. 0 60 120 180 0.0 0.5 1.0 1.5 2.0 2.5 ds / dW (a.u.) q (deg) CTMC CDW-EIS Born Gabler and Stolterfoht Toburen Crooks and Rudd Fig. 1. SDCS in angle for the single ionization of Ar by 300 keV protons. Work at IAFE supported by ANPCyT, CONICET and UBA. Work at UNS supported by PGI 24/F038, PICT-2007-00887 (ANPCyT) and PIP 112-200801-02760 (CONICET). References [1] Rudd M E, Kim Y.-K., Madison D H and Gay T J 1992 Rev. Mod. Phys. 64 441. E-mail: sotranto@uns.edu.ar XXVI International Conference on Photonic, Electronic and Atomic Collisions IOP Publishing Journal of Physics: Conference Series 194 (2009) 082015 doi:10.1088/1742-6596/194/8/082015 c