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Double differential inelastic electron scattering cross sections of DNA components

29.09.2008

It is generally known that DNA is the radiation-sensitive target inside a cell and that the biological efficiency of ionizing radiation does not only depend on the absorbed dose but also on its track structure. The track structure is expressed in the different spatial distribution of the stochastic energy deposition in the area of the DNA. For the calculation of such a distribution, the interaction cross sections between the DNA components and the electrons, which are usually released in large quantities as secondary particles in the tissue during the passage of ionizing radiation, are indispensable.

In view of this fact, the electron scattering cross sections of tetrahydrofuran (C4H8O), which has a structure which is almost identical to deoxyribose, were measured. After last year's measurement of the differential elastic electron scattering cross sections, the double differential inelastic electron scattering cross sections of tetrahydrofuran were now also determined by experiment as a function of the scattering angle and of the secondary electron energy. The determination was performed for the primary energies T from 20 eV to 1000 eV for scattering angles between 5° and 135°. As an example, the figure shows the double differential inelastic scattering cross sections of tetrahydrofuran for 100 eV electrons. The measured scattering cross sections are an important data set for the modelling of the primary physical radiation damages in DNA with the aid of the Monte Carlo simulation.

Figure : Double differential inelastic electron scattering cross sections of tetrahydrofuran for 100 eV electrons as a function of the secondary electron energy for different scattering angles: (—) 20°, (--) 30°, (• • •) 60°, (- •• - •) 90°, (- • - •) 135°.