Detection of fast neutrons with particle tracking detector timepix combined with plastic scintillator

摘要

Fast neutron imaging, spectroscopy and dosimetry are important tools for many applications. We are developing a fast neutron detector based on the combination of a thin plastic scintillator and the Timepix particle tracking detector. A fast neutron recoils a proton in the scintillator. The light in the scintillator is detected by a Silicon Photo-Multiplier (SiPM). The recoiled proton leaves the plastic scintillator, hits the tracking detector (256 × 256 pixels, 55 μm pitch, the total sensor area is 1.4 × 1.4 cm ~2, thickness is 300 μm) and generates a track. The track is analyzed and the energy and direction of the proton is recovered. That, together with the energy recorded by the SiPM, is used to reconstruct the energy or direction of the incoming neutron. The fast neutron detection process was studied by means of Monte-Carlo simulation. Description of the simulation and comparison of simulation results with a measurement is presented. Problems in the neutron energy reconstruction caused by protons passing through the 300 μm thick Silicon sensor are discussed, and a solution based on utilization of the detector response matrix is shown.