Simulated and experimental angular response of a commercial MOSFET used as dosimeter

MOSFET transistors offer excellent qualities to be used as gamma dosimeters: small size, low power consumption, immediate readout and reproducibility. The main disadvantage of MOSFETs specifically designed for dosimetry is its high cost. In this work, we study the angular dependence of the radiation response of a general purpose commercial MOSFET, the 3N163 of Vishay-Siliconix. Monte Carlo simulations and experimental results are compared. MOSFETs were irradiated with photons beams generated by 60 Co and by a linear electron accelerator, using voltages of 6 MV and 18 MV. To reduce the computing time in the simulations, variance reduction techniques (the so-called splitting and Russian roulette) have been applied using an ant colony algorithm. The simulation times have been reduced by a factor 20. The experimental results are in reasonable agreement with those of the Monte Carlo simulations.