Delta electron production

The difference in biological action between ions and photon is due to the different spatial distribution of the electrons and ionisation events. Photons produce stochastic distributed Compton, photo and pair electrons. Heavy ions dissipate their energy along their trajectories ionizing target atoms and producing free electrons. About two thirds of the dissipated energy is transformed into kinetic energy of the electrons. These so-called δ-electrons produce secondary and tertiary ionization processes around the ion's trajectory: the ion track.

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Toroidal electron spectrometer  

It is the energy spectrum of the emitted δ-electrons that determines the diameter and the local dose inside the track. These data are the input data for theoretical modeling (-> LEM) of the biological response.

At present there are two questions of importance for RBE calculation: First, the shape of the electron spectra and secondly, the possible difference in the electron spectra between gas target where up to now our information is from and condensed targets like waterfilms or thin plastic layers that ar more close to the biological situation.

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swift ions  

Using a toroidal electron spectrometer electron spectra from carbon foils are measured in collaboration with the GSI atomic physics group.

contact: S.Hagmanngsi.de