Double-differential cross section for ionization of H2O molecules by 4-MeV/u C6+ and Si13+ ions

S. BHATTACHARJEE; S. BISWAS; J. M. MONTI; R. D. RIVAROLA; L. C. TRIBEDI

PHYSICAL REVIEW A - ATOMIC, MOLECULAR AND OPTICAL PHYSICS

AMER PHYSICAL SOC

Lugar: New York; Año: 2017 vol. 96 p. 527071 - 5270710

1050-2947

Double-differential cross section (DDCS) for electrons ejected in collisions of fast C6+ and Si13+ projectiles, with a H2O vapor target, were measured. The electrons were detected over an energy range of 1?600 eV and an angular range of 20◦?160◦. The obtained DDCS spectra, for both the ions, were compared with the CDW-EIS model. Occasional reference has been made to the DDCS data for the case of 3.75-MeV/u O8+ colliding on the same molecule for an overall comparison. A reasonable agreement with theoretical results was seen for the case of C6+ and O8+ projectiles. However, between C6+ and O8+ projectiles, the deviation from theory is largerfor the case of the carbon projectile. Substantial deviation starts to show up for the case of the Si13+ projectile. By numerical integration of the DDCS data, the single-differential cross section (SDCS) and total cross section (TCS) were obtained and compared with theoretical models. The present TCS data alongwith the other available data for p, He, and C ions were plotted together. A clear and gradual deviation from the Bethe-Born predicted q2 scaling was observed, where q is the projectile charge state. From all the data we find TCS varies as qn where n = 1.7 ± 0.1. The provided data set will be valuable in order to help model the radiation damage in hadron therapy, particularly in the Bragg peak region.