Distributed sensing of fusion neutrons by plastic scintillating fibers

A flexible one-dimensionally distributed fast neutron sensor using plastic scintillating fibers (PSFs) is proposed for measuring neutron emission profile from plasmas, where the PSFs are set up around the fusion device and neutron flux distribution along the PSFs is measured by applying the time of flight (TOF) technique to the scintillated light propagation. From the performance test of this system with 5 m long PSF for 14 MeV neutrons, the counting efficiency was evaluated to be about 1.8 × 10 - s counts per incident neutron into the PSF core, and spatial resolution was reached up to about 15 cm (full width at half maximum). An experiment using a 14 MeV point neutron source was also made for demonstrating the feasibility of this system to measure neutron emission profile, where the PSF was set up in a circle of 60 cm diameter and the neutron distribution around a 14 MeV neutron source was measured by changing the position of the PSF circle relative to the neutron source. The results showed that the TOF spectrum along the PSF is sensitive enough to measure the neutron source position inside the circle.