The activity concerns the study and optimization of a 3D simulation code of the electrostatic potential and of the dynamics of the mobile carriers in the volume of semiconductor detectors in conditions of high injection levels.

The main motivation of this activity originates in the field of new detection systems for FEL (Free Electron Laser) sources of X rays featuring ultra-high brilliance and for the modern nuclear physics experiments with exotic beams.

As an example, at the European XFEL facility in Hamburg (D) generation levels up to 3×107 electron–hole pairs are foreseen in spots smaller than one pixel in the silicon X-ray imagers, with time intervals between beam pulses as short as 200ns. The correct simulation of Coulomb “explosion” and plasma effects, of charge sharing effects and collection times, as well as how all this impacts on the shape of the signals are key aspects to optimize detector performances. The application areas are manifold: mapping with atomic details viruses and proteins, film chemical reactions, study the state of matter deep inside planets, etc.

The work starts from an existing code and needs to extend its application to the range of high injection levels, taking care of studying, implementing and validating appropriate numerical techniques suitable to simulate the evolution of high-density charge clouds since the first instants after generation. The final goal is a first version of the simulation code, that can run on small workstations. If feasible, it will be possible to participate in experimental campaigns for a first validation of the developed code in the frame of international collaborations.

The activity requires sufficient skills in scientific programming / numerical computation.

Info: Prof. A.Castoldi, Dip. Elettronica Informazione e Bioingegneria (andrea.castoldi@polimi.it)