High-sensitivity scintillating-fiber imaging detector for high-energy neutrons

Abstract

We have created a detector to image the neutrons emitted by imploded inertial-confinement fusion targets. The 14 MeV neutrons, which are produced by deuterium-tritium fusion events in the target, pass through an aperture to create an image on the detector. The neutron radiation is converted to blue light (430 nm) with a 20 cm2 array of plastic scintillating fibers. Each fiber is 10 cm long with a 1 mm2 cross section; approximately 35 000 fibers make up the array. The resulting blue-light image is reduced in size and amplified by a sequence of fiber-optic tapers and image intensifiers, then acquired by a charge-coupled device camera. The fiber-optic readout system was tested separately for overall throughput and spatial resolution; the throughput was 0.22 electrons/photon, and the resolution was 0.8 mm. We also characterized the overall efficiency of the detector using the DT-fusion neutrons emitted by inertial confinement targets; the measured value was 14 electrons/pixel/neutron. Several neutron images of laser-fusion targets have been obtained with the detector. We describe the detector, present characterization results, and give examples of the neutron images. © 1995 American Institute of Physics.