Vol 25, No 1 (2020)
Original research articles
Published online: 2020-01-01

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

Mohsen Mashayekhi1, Ali Asghar Mowlavi12, Sayyed Bijan Jia3, Hossein Ghayoumizadeh4
DOI: 10.1016/j.rpor.2019.12.020
Rep Pract Oncol Radiother 2020;25(1):109-112.



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

Materials and Methods

GEANT4 toolkit was applied to simulate the transport and interactions of particles. Calculations were performed for a thin silicon detector (2cm×2cm×0.005cm) irradiated by proton and carbon ion beams. A two-dimensional array of silicon pixels in the x-y plane with 100um×100um×50um 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 0.01MeV and 0.7MeV 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.

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Reports of Practical Oncology and Radiotherapy