Liquid water radiolysis induced by secondary electrons generated from MeV-energy carbon ions

Tsuchida, Hidetsugu*; Tezuka, Tomoya*; Kai, Takeshi   ; Matsuya, Yusuke*  ; Majima, Takuya*; Saito, Manabu*

Although fast ion beams can damage DNA by chemical products such as secondary electrons produced by their interaction with water in living cells, the process of formation of these chemical products in the Bragg peak region used in particle therapy is not fully understood. To investigate this process, we performed experiments to evaluate the yields of radiolytic products produced when a liquid water jet in vacuum is irradiated with a MeV-energy carbon beam. In addition, ionization processes in water due to incident ions and secondary electrons were simulated using a radiation transport Monte Carlo code. The results indicated that the primary source of ionization in water is secondary electrons. Finally, we show that these elementary processes contribute to the development of radiation biophysics and biochemistry to study the formation mechanism of DNA damage.