EPR Investigation of Radical-Production Cross Sections for Sucrose and L-alanine Irradiated with X-rays and Heavy-ions

Using electron paramagnetic resonance (EPR), we investigated stable radical-production cross sections (σ) of sucrose and L-alanine radicals produced by heavy-ion irradiations with various linear energy transfers (LET). The heavy-ion irradiation results were compared with those of X-ray irradiation at the same dose. The EPR signal areas for the two compounds showed a linear relation with the absorbed dose, as well as a logarithmic correlation with the LET. Further analysis was carried out for the radical-production cross section, which showed that stable radicals of the two compounds were produced through collisions of several particles with a single molecule. The relative σ value of sucrose for C ion irradiation was (1.29 ± 0.64) × 10⁻¹² μm². The σ value of alanine for C ion irradiation was (6.83 ± 0.42) × 10⁻¹³ μm². Considering the structural molecular sizes of sucrose and alanine, the σ values are similar. In addition, a comparison of the EPR results for the C ions and X-rays at 50 Gy dose was made. Sucrose spin concentrations produced by C ions at the LET value of 13.1 keV/μm and X-rays were similar unlike alanine. Thus, the noble EPR results with X-ray and heavy-ion irradiations imply that sucrose can be useful as a radiation indicator.