Experimental Evaluation of Silicon Carbide P-N Detectors Under Thermal and Fast Neutron Irradiation at the RA-6 Nuclear Research Reactor

Silicon carbide (SiC) detectors present key advantages for neutron detection in harsh radiation environments, including high radiation hardness, low leakage current, and excellent thermal stability. In this work, we report on the characterization of SiC P–N diodes manufactured at the Institute of Microelectronics of Barcelona (IMB-CNM-CSIC) for both thermal and fast neutron detection. For thermal neutron measurements, 50 μm and 100 μm SiC diodes coupled to a 6LiF conversion layer were tested at the RA-6 Nuclear Research Reactor, San Carlos de Bariloche, Argentina. The detectors exhibited a linear response with reactor power up to 500 kW, with no evidence of saturation or dead-time effects, and an average detection efficiency of (4.42±0.09)%. The angular dependence of the efficiency confirmed the expected increase with incidence angle, reaching a maximum around 90°. For fast neutrons, 100 μm diodes coupled to polypropylene layers of varying thicknesses were characterized using an AmBe source. The results showed that the detection efficiency increased with converter thickness, reaching a maximum value of 0.57% for an 800 μm layer. PHITS Monte Carlo simulations reproduced the experimental data, validating the interpretation of the measured spectra. These results confirm the potential of SiC-based detectors for reliable monitoring of thermal and fast neutrons in environments with high gamma background, including radiotherapy, nuclear reactors, and others.