Estimation of yields of hydroxyl radicals in water under various energy heavy ions

This article reports the determination of yields of OH (hydroxyl) radicals in water irradiated with helium, carbon, neon and argon ions ranging from 2 to 18 MeV/nucleon. The yields of the OH radicals depend on the atomic number and energy of the incident ion and the reaction time just after the irradiation based on the track structure theory. The yields of the OH radicals estimated by analyzing the yields of the irradiation products from phenol were at almost 0 to 3.1 per 100 eV absorbed energy on a time scale from 0.75 to 300 ns and were lower than the corresponding ones after exposure to low-LET radiation. The yields of OH radicals decreased with decreasing specific energy for each ion, with increasing atomic number of each ion at a similar specific energy, and with the average reaction time after irradiation. In addition, Monte Carlo simulations were conducted and compared with the OH radical yields obtained experimentally.