Does DSB increase or decrease with increasing LET?, 1; A Statement from the "increase"

Yokoya, Akinari

We have measured the yield of DSB induced in hydrated pUC18 plasmid as a model DNA. TIARA in JAEA-Takasaki and HIMAC in NIRS were used as He, C and Ne ion beam sources. The track structures are different among the ions if they have the same LET values. Hence we have investigated the yield of DSB by systematically changing LET of identical ion. The obtained results show that (1) there is a minimum around 20 keV/m for He ion irradiation, and the DSB yield increases precipitously toward 120 keV/m, and then decreases again above the LET value, (2) similarly the yield of DSB increases with increasing level of LET of C ion in 80500 keV/m though the trend is not noticeable rather than He ion irradiation, (3) the DSB yield does not significantly depend on LET for Ne ion irradiation. These results suggest that the DSB yield increases with increasing level of LET, though the trend of increase strongly depends on ion species.