Ionization and fragmentation of RNA base molecule uracil in collisions with carbon ions of energies between 100 keV and 60 MeV

We report here the first measurement of absolute single ionization cross-section of uracil (C4H4N2O2, m=112) in collisions with highly charged C ions of energy ranging between 100 keV to 60 MeV i.e. in the range of Bragg peak which is relevant for high energy hadron therapy. An ECR based low energy accelerator along with a 14 MV Pelletron accelerator were used to obtain a wide range of energies. Energy and charge state (representing perturbation strength) dependence of ionization cross-section has been studied using a ToF mass spectrometer. In the low energy range, cross-section increases with energy and then saturates while in the high energy range it decreases with energy. Ionization cross-section found to increase linearly with charge-state. The CTMC and CDW-EIS models are used to compare with the data. The complementary experiment was also carried out to measure the low energy electron emission spectrum at different angles.