The thermal neutron response of miniature silicon carbide semiconductor detectors

Neutron response calibrations have been performed for miniature SiC semiconductor detectors based on a Schottky diode design in neutron fields maintained at the National Institute of Standards and Technology (NIST). The SiC diodes detect neutrons via neutron-induced charged particles (tritons) produced by the 6Li(n,α)3H reaction. The neutron response was calibrated at fluence rates from 1.76×104 to 3.59×1010 cm−2 s−1 in NIST neutron fields. The maximum deviation from linearity of the fit of the neutron response of the SiC detectors to the NIST-measured fluence rates is much less than 5%, which is the estimated uncertainty in the measured fluence rates. A direct comparison of the SiC count rates to count rates obtained with a NIST double fission chamber over limited ranges where the detector positions and configurations remain unchanged shows a relative precision of ±0.6%. In a separate set of calibrations, a SiC neutron detector that had been previously irradiated with a fast (E>1 MeV) neutron fluence of 1.3×1016 cm−2 was found to have an absolute neutron fluence rate response that was indistinguishable from that of a previously unirradiated detector.