Low-energy electrons emitted in collisions of heavy ions with solid state targets

Detailed knowledge of low-energy electron emission in collisions of swift ions with solids and gases is of utmost importance for the modeling of the dose distributions and track structures at small distances (<20 nm) in mixed radiation fields, particularly for the Local Effect Model, LEM, developed and used at GSI for the prediction of ion radiation effects in ion radiotherapy and related fields. At GSI, we have launched a project aimed at systematic investigations of the energy and angular distributions of low energy (sub-keV) electrons emitted from solids. We have commissioned an electrostatic toroidal spectrometer at the UNILAC accelerator, and we have developed a method to identify, study and analyze problems caused by the condition and constitution of the target foils and their surfaces. For this, we combined measurements of electrons emitted in collisions of low-energy electron beams (500 eV, 1 keV) with results of dedicated Monte Carlo simulations. We utilized the findings of these studies for the investigation of electrons emitted from the same targets in ion-atom collisions for the data analysis, and we report on results of our first measurements with carbon projectiles.