An energy-loss model for low- and intermediate-energy carbon projectiles in water

To model interaction cross sections and energy loss for carbon projectiles C(0)-C(6+) of 1-10(4) keV/u (u: atomic mass unit) in water.

The classical trajectory Monte Carlo method was used to calculate the ionisation and charge-transfer cross sections. The excitation cross sections were scaled from proton data using equilibrium charges determined from the charge-transfer cross sections. Energy loss was obtained from the singly differential cross sections, and ionisation potentials of the target and projectile.

The calculated total ionisation cross sections are consistent with measured data, while the calculated electron-capture cross sections are larger than experimental data by a factor of 3. By scaling the latter to the measured data, the cross sections were made consistent with these data for 1-10 keV/u energies. The present stopping cross sections agree well with experimental data below 10 keV/u, and with other model calculations above 2 MeV/u. Deviation from the latter is found where electron capture is competitive with ionisation, and also arises from different energy-transfer calculations.

In this paper we report our efforts in the developments of full slowing-down Monte Carlo track structure calculations for carbon ions. Further development and refinement of the model are currently underway.