Study On A High-resolution Fast Neutron Imaging Detector Based On Liquid Scintillator Loaded Capillaries

As one of the non-destructive testing,fast neutron photography can complete inspection tasks that X-ray and y-ray photography cannot complete.It has great development potential and wide application space.However,fast neutron imaging also has problems such as poor spatial resolution,low detection efficiency,and large scattering effects.In view of the limitation of the inherent spatial resolution of current detectors,a liquid scintillator detector based on capillaries is proposed.It not only has a high spatial resolution,but also can increase the neutron detection efficiency by increasing the thickness of the scintillator,and at the same time,it can obtain the track of the smallest ionized particles.On the other hand,some feature detection algorithms can be used to reconstruct the vertex positions of particle interactions,thereby further improving the spatial resolution of neutron imaging.The purpose of this paper is to develop a detector that can recognize recoil proton events and reconstruct particle track.And improving the position resolution with track reconstruction method to reconstruct the position of interaction.The detector consists of a 1000×1000 array of glass capillaries loaded with a high refractive index liquid scintillator is proposed.Each capillary was 10 μm in diameter and 5 cm in length.We used GEANT4 to simulate the detector performance,CERN ROOT Analysis Framework to record physical information of recoil proton,including position,energy deposition in each capillary traversed and track length.A rapid,computerized and efficient proton track recognition procedure based on Hough transform was developed,which applied to individual track and multi-track reconstruction to improve the spatial resolution of Fast Neutron Imaging.From the simulation results we have obtained,one can conclude that the neutron-proton conversion efficiency of glass capillary filled with liquid scintillator is much higher than the plastic scintillator fiber plate,which can reach～10%.Furthermore,the gamma track displays a spot,the Compton electronic track has an irregular linear structure,however,the recoil-proton events display a continuous extended structure.And,the energy deposition in capillary along its track with a Bragg peak,this makes reconstruction of neutron interaction with hydrogen possible.The Hough transform-based track reconstruction algorithms can reconstruct individual track precisely and when the counting rate was relatively low,the track reconstruction results were in good agreement with simulation data.Moreover,for intensive overlap conditions,this algorithm also reconstructs periphery tracks with high rate of accuracy.