Electrons and positrons elastic collisions with pyrimidine and tetrahydrofuran

The present study shows results of theoretical calculations for positrons and electrons elastic scattering from pyrimidine and tetrahydrofuran over a broad energy range. The work has been motivated by the fact that very few experimental data exist for most of the nucleobases in particular for positrons. Concerning the theoretical tool, we have made improvements on the method using the independent atom-screened additivity rule by calculating differential elastic cross sections and its integrals in a straightforward manner. Moreover, elastic scattering of electrons and positrons by atoms of the biomolecule was evaluated by means of relativistic (Dirac) partial wave analysis. Results concerning the total elastic cross sections (ECS) for electrons and positrons are shown and discussed in comparison to existing experimental and theoretical data. As central result, our electron ECS from pyrimidine and tetrahydrofuran are in good agreement with existing experimental data in the range 10 eV to 1 keV. Another important improvement concerns our data for positron; as it will be shown in the present study, our positron ECS can be considered as a correction of existing data in the literature using the independent atom screened additivity rule. Parameterization of our electron and positron total ECS, elastic mean free paths, first elastic transport cross sections and first elastic transport mean free paths are provided for pyrimidine and tetrahydrofuran in the energy range 10 eV to 100 keV.