Partially depleted operation of 250 m-thick silicon carbide neutron detectors

Fusion experiments put many challenges on the neutron detection methods, since they require fast neutron counters and spectrometers with good energy resolution capable of operating in harsh environments under a large range of neutron flux intensities. Recently, SiC detectors were proposed for these roles due to their outstanding properties. Among those, the operation of SiC with partial polarization is of interest since it might allow for a fast neutron detector with efficiency tunable online, which would allow a good functionality under a large range of flux intensities. This paper describes the characterization of a series of SiC detectors operated with a fraction of the polarization needed to achieve full depletion. The characterization is performed through I/V measurements, alpha irradiation in vacuum and neutron irradiation. A functionality with excellent detection characteristics is demonstrated, reaching an energy resolution of 1.05 % for 5.5 MeV alphas and 2.05 % for 14 MeV neutrons. Some limitations on the maximum bias will be also discussed, pointing out some challenges for the manufacturing of thick SiCs in the future.