Abstract
Although water is one of the most ubiquitous molecules as well as a main component of human body, understanding of water radiolysis especially with heavy ions is not always sufficient. Among many types of ionizing radiations, heavy ions deposit their energies very densely and categorized as high LET radiations. Due to the high LET feature, following chemical and biological processes become distinctive compared to low LET radiations such as x-rays and γ-rays. Comprehension of water radiolysis itself is essential to consider indirect actions of ionizing radiations because OH radicals produced in water radiolysis is assumed to participate as a trigger of the action. Moreover, energy deposition distributions in water is strongly related to that in/on biomolecules including DNA, proteins, and so on, and spatial distributions and temporal behaviors of water radicals give a clue to think over the fate of initial DNA damages produced within several ns.
However, it is almost impossible to observe radiation tracks in water directly because track structure is very small and it changes its shape and size very rapidly, normally within μs.
In this presentation, yield measurements of water decomposition products which are employed as a measure to see radiation track indirectly will be shown. The yields of hydrated electrons, hydroxyl radicals, and hydrogen peroxides have been measured for many types of heavy ions provided at HIMAC. One of the most advanced Monte-Carlo simulations developed by a group of University of Sherbrooke is also utilized complementally to discuss track structure from the microscopic viewpoint which is not attainable experimentally.
