Estimation of the Fast-Neutron Fluence Rate With a 4H-SiC-Based Detector in a 14.1-MeV Mono-Energetic Field

Knowledge of neutron fluence rates and energy spectra is fundamental for nuclear installations such as fusion reactors, fission reactors, and beam lines. The constraints of hostile environments make solid sensors based on semi-conductors, and silicon carbide (SiC) in particular, a good candidate. Its use for fast neutron fluence rate monitoring is well-established, with threshold reactions and a linear sensor response to fluence rate. However, its use for quantitative fluence rate estimation at different locations and in a mixed field remains to be confirmed. Thus, our study introduces a technique for approximating fast neutron fluence rates within a mono-energetic environment using SiC-based sensors. A dedicated campaign on a 14-MeV neutron generator was performed to obtain energy spectra deposited in the sensor using on-line measurements in pulse mode. Interpretation of these measurements using a Monte Carlo transport code enabled the sensor response to be deconvoluted and the corrective terms needed to estimate a reaction rate to be evaluated. Our results showed that the experimentally estimated fluence rate is within the 1 sigma confidence interval of the reference fluence rate taken at the irradiation location, with a relative uncertainty of 29%.