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 intrinsic detection efficiency of (4.39±0.22)%. The detection efficiency was characterized as a function of the neutron incidence angle, showing a monotonic increase. For fast neutrons, 100 µm diodes coupled to polypropylene layers of varying thicknesses were characterized using an AmBe source. The results showed that the intrinsic detection efficiency increased with converter thickness, reaching a maximum value of (0.57±0.04)% 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.