Demonstrations for the effect of composite electric fields of molecular ions on the motion of secondary electrons due to ion irradiation

Moribayashi, Kengo

Cancer therapy using carbon ions has a powerful therapeutic effect. This is based on the fact that relative biological effectiveness (RBE) of carbon ions is higher than that of protons and X-rays. A hypothesis has been proposed that clustered DNA damage is highly relevant to RBE values. However, it remains largely unknown how clustered DNA damage is generated after irradiation. We proposed and quantified that the electric field traps the emitted electrons near a radiation track, which, in turn, may lead to a clustering of DNA lesions. We have found that plasma with low electronic temperature and high density appears near the track of the incident ion in the irradiation of a carbon ion. The electrons in this plasma may more often interact with DNA which is located near the track and may produced the larger number of clustered DNA damages than the case where electric field is not considered and plasma is not formed.