Study on the dynamic energy spectra of mev heavy ions penetrating biological sample

In order to study the probability for heavy ions to have a long projectile range in botanic sample, transmission energy spectra of 1.5 MeV F⁺, 3 MeV F²⁺ and 1.5 MeV H⁺ penetrating 100 µm seed cotyledon samples were measured as a function of ion dose. Results show that very fewer ions can penetrate through the samples, though their theoretical ranges are much shorter than sample thickness. Besides, the measured energy spectra of 1.5 MeV and 3.0 MeV F ions change dynamically while increasing the ion dose, they extend to the high energy direction and the count rates of the transmission ions increases quickly. These phenomena can be understood with the special composition and structure of the biological material.