Calculated electronic energy loss of swift proton and helium ion beams in liquid water

Paper submitted to the 9th International Conference on Applications of Nuclear Techniques, Crete, Greece, 8–14 June 2008.The electronic energy loss of swift proton and helium beams in liquid water is theoretically evaluated. Our model is based in the dielectric formalism, taking into account the charge exchange of the projectile during its travel through the target. The electronic properties of liquid water are described by the MELF-GOS model, where the outer electron excitations are represented by a sum of Mermin functions fitted to the experimental data in the optical limit, whereas the inner-shell electron excitations are modelled by the corresponding atomic generalized oscillator strength. The inverse mean free path, the stopping power and the energy loss straggling are calculated, showing a reasonably good agreement with the available experimental data.This work has been financially supported by the Spanish Ministerio de Educación y Ciencia (Contract Nos. FIS2006-13309-C02-01 and FIS2006-13309-C02-02). C.D.D. thanks the Spanish Ministerio de Educación y Ciencia for support under the Ramón y Cajal Program