Optimization of an ultra-fast silicon detector for proton and carbon beams using GEANT4 Monte Carlo toolkit

The purpose of this study was to investigate the crosstalk effects between adjacent pixels in a thin silicon detector with 50 um thickness.

There are some limitations in the applications of detectors in hadron therapy. So it is necessary to have a detector with concurrent excellent time and resolution. In this work, the GEANT4 toolkit was applied to estimate the best value for energy cutoff in the thin silicon detector in order to optimize the detector.

GEANT4 toolkit was applied to simulate the transport and interactions of particles. Calculations were performed for a thin silicon detector (2 cm × 2 cm×0.005 cm) irradiated by proton and carbon ion beams. A two-dimensional array of silicon pixels in the x-y plane with 100 um × 100 um × 50 um dimensions build the whole detector. In the end, the ROOT package is used to interpret and analyze the results.

It is seen that by the presence of energy cutoff, pixels with small deposited energy are ignored. The best values for energy cutoff are 0.01 MeV and 0.7 MeV for proton and carbon ion beams, respectively. By applying these energy cutoff values, efficiency and purity values are maximized and also minimum output errors are achieved.

The results are reasonable, good and useful to optimize the geometry of future silicon detectors in order to be used as beam monitoring in hadron therapy applications.