Relation between biomolecular dissociation and energy of secondary electrons generated in liquid water by fast heavy ions

Tsuchida, Hidetsugu*; Kai, Takeshi   ; Kitajima, Kensei*; Matsuya, Yusuke  ; Majima, Takuya*; Saito, Manabu*

Fundamental study of interaction between biomolecules and heavy ions in water is very important to predict an initial stage of radiation biological effects. A heavy ion irradiation experiment into droplet target assumed as a biological system in a vacuum was performed to measure production yields of cations and anions for glycine, which was ejected from the droplet target to the vacuum. However, the production mechanisms have been unknown. The PHITS code adapting ion track structure mode was used to analyze the production mechanisms from the dose evaluation at the surface between the vacuum and the water. It is found that induction yields of ionization and excitation, and dissociative electron attachment involved in the secondary electrons were correlated with the production yields of cations and anions of the glycine. The results provide us newly scientific insights to predict an initial stage of radiation biological effects.