Hydrogen peroxide yields in water radiolysis by high-energy ion beams at constant LET

The radiolytic yields of hydrogen peroxide in aqueous solution irradiated with ion beams at constant linear energy transfer (LET) values ranging from 2.5 keV/mum (30 MeV protons) to 30 keV/mum (1140 MeV carbon ions) and with Cs-137-gamma-rays, where the mean LET is 0.53 keV/mum, were determined. They are compared with those in the literature. The evolution of hydrogen peroxide yields is studied as a function of radical scavenger concentration. The radical-scavenging curves are discussed in terms of radical spatial distribution around the tracks. This distribution depends on both the type and the energy of radiation. This study also shows that the probing of the spatial structure for the proton track can be achieved by nitrate/methanol systems where the role of the nitrate is to protect hydrogen peroxide from the attack of hydrated electron. (C) 2002 Elsevier Science Ltd. All rights reserved.