A simulation study of a high-resolution fast neutron imaging detector based on liquid scintillator loaded capillaries

Background: At present, the highest spatial resolution of a fast neutron imaging detector, mainly determined by the range of secondary particles generated by fast neutrons, is about hundreds of microns. In view of the above inherent spatial resolution limitation, a capillary-based scintillation detector that can improve the spatial resolution of fast neutron imaging by recording and reconstructing the recoil proton track was developed. Purpose: The purpose of this paper is to develop a detector for recognizing recoil proton events, reconstructing particle track and improving the position resolution with track reconstruction method to reconstruct the position of interaction. Methods: The proposed detector consists of a 1000 × 1000 array of glass capillaries loaded with a high refractive index liquid scintillator. Each glass capillary was 10 μm in diameter and 5 cm in length. The recoil protons generated by the incident neutrons move within the detector and produce scintillation light within each capillary that they traverse. The light emitted from the capillary array can be recorded by employing an intensified CCD camera. We used Geant4 to simulate the detector performance and CERN ROOT analysis framework to record physical information of recoil proton, including position, energy deposition in each capillary and track length. Based on Hough transform, a rapid, computerized and efficient proton track reconstruction procedure was developed. Conclusion: The recoil proton events display a continuous extended structure. The 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.