  Two detection systems based on optical readout were developed:
  a. Integrative optical detector A 2nd generation of Time-Resolved Integrative
Optical Neutron (TRION) detector was developed. It is based on an integrative
optical technique, which permits fast-neutron energy-resolved imaging via
time-gated optical readout. This mode of operation allows loss-free operation
at very high neutron-flux intensities. The TRION neutron imaging system can be
regarded as a stroboscopic photography of neutrons arriving at the detector on
a few-ns time scale. As this spectroscopic capability is based on the
Time-of-Flight (TOF) technique, it has to be operated in conjunction with a
pulsed neutron source, such as an ion accelerator producing 1-2 ns wide beam
pulses at MHz repetition rates. TRION is capable of capturing 4 simultaneous
TOF frames within a single accelerator pulse and accumulating them over all
pulses contained within a finite acquisition time. The detector principle of
operation, simulations and experimental results are described.
  b. Fibrous optical detector A fast neutron imaging detector based on
micrometric glass capillaries loaded with high- refractive-index liquid
scintillator has been developed. Neutron energy spectrometry is based on
event-by-event detection and reconstruction of neutron energy from the
measurement of the recoil proton track projection length and the amount of
light produced in the track. In addition, the detector can provide fast-neutron
imaging with position resolution of tens of microns. The detector principle of
operation, simulations and experimental results obtained with a small detector
prototype are described. Track-imaging of individual recoil protons from
incident neutrons in the range of 2-14 MeV are demonstrated as well as
preliminary results of detector spectroscopic capabilities.
  Keywords: Fast neutron resonance radiography; Time-of-Flight; Fast neutron
imaging; Energy-resolved imaging; Neutron spectrometry; Capillary array; Liquid
scintillator
