Cross sections for bare and dressed carbon ions in water and neon

• The paper presents calculated cross sections for bare and dressed carbon projectiles of charge states q (0 to 6) with energies 1–104 keV/u impacting on molecular water and atomic neon targets. The cross sections of water are of interest for radiobiological studies, but there are very few experimental data for water in any phase or non-existent. The more extensive experimental database for the neon target made it possible to test the reliability of the model calculations for many-electron collision system. The current calculations cover major single and double electronic interactions of low and intermediate energy carbon projectiles. The three-body classical trajectory Monte Carlo (CTMC) method was used for the calculation of one-electron transition probabilities for target ionisation, electron capture, and projectile electron loss. The many-electron problem was taken into account using statistical methods: a modified independent event model was used for pure (direct) and simultaneous target and projectile ionisations; and the independent particle model for pure electron capture and electron capture accompanied by target ionisation. Results are presented for double differential cross sections (DDCS) for total electron emission by carbon projectile impact on neon. For the water target, we present: single differential cross sections (SDCS) and DDCS for single target ionisation; total cross sections (TCS) for electron emission; TCS for the pure single electronic interactions; equilibrium charge state fractions; and stopping cross sections. The results were found to be in satisfactory agreement with the experimental data in many cases, including DDCS and SDCS for the single target ionisation, TCS for the total electron emission, and TCS for the pure single electron capture. The stopping cross sections of this work are consistent with the other model calculations for projectile energies ≥800 keV/u, but smaller than the other calculations at lower energies. The discrepancy arises from the inclusion of all carbon charge states and coupling between electron capture and target ionisation channels, while other models use an average projectile charge. The CTMC model presented here provides a tool for cross section calculations for low and intermediate energy carbon projectiles. The calculated cross sections are required for Monte Carlo track structure simulations of full-slowing-down tracks of carbon ions. The work paves the way for biophysical studies and dosimetry at the cellular and subcellular levels in the Bragg peak area of therapeutic carbon ion beam.

Ämnesord

NATURVETENSKAP  -- Fysik -- Atom- och molekylfysik och optik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Atom and Molecular Physics and Optics (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Radiologi och bildbehandling (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Radiology, Nuclear Medicine and Medical Imaging (hsv//eng)

Nyckelord

CTMC

Carbon ions

Cross sections

Charge transfer

Stopping power

Track structure

medicinsk strålningsfysik

Medical Radiation Physics

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