Double ionization of helium by impact of fast protons.

In comparison with the electron impact case, fully differential cross sections for the double ionization of helium by proton impact have been little investigated. The reasons are quite simple: experimentally, the measurement requires a long time as the count rates are very low; theoretically, the full four-body problem poses a formidable challenge. The present theoretical investigation is a contribution towards understanding this process. We performed [1] ab initio first Born calculations for proton impinging with 6 MeV, in the experimental configuration investigated in [2]. We solve a three-body scattering driven equation with the Generalized Sturmian Functions method [3]. Using the asymptotic behavior of the solution, we extract directly the transition matrix and thus the corresponding fully differential cross section. A detailed comparison with the relative experimental data will be presented at the conference. [1] Ambrosio M J et al (2015) Phys. Rev. A 92, 042704. [2] Fischer D et al (2003) Phys. Rev. Lett. 90, 243201. [3] Gasaneo G et al (2013) Adv. Quantum Chem. 57, 153