Monte-Carlo simulation of fast neutron detection with timepix

The imaging semiconductor pixel detector Timepix allows the charge collected in each of its 256×256 pixels (55 ¿m pitch) to be measured. This feature makes it suitable for applications where the energy and position of incoming radiation needs to be determined. We are developing a fast neutron spectroscopy and radiography technique that is based on tracking protons recoiled by fast neutrons. The proposed setup consists of a hydrogen rich converter placed above the Timepix detector surface, which is irradiated by fast neutrons. The protons recoiled by neutrons interacting in the converter hit the detector and generate a track. Analysis of the tracks give the energies, positions and directions of flight of the protons. This information was used to reconstruct energy of the incoming neutrons. The neutron source position can be calculated as well. The converter can be replaced by an unknown hydrogen rich sample. In this case, the protons recoiled in the sample can be used for 3D reconstruction of the unknown sample. A Monte-Carlo simulation of the fast neutron detection process was prepared. The code was based on combination of the ROOT and SRIM/TRIM packages. The proton recoil and transport through the geometry was simulated and the energy deposited in the detector for each event was calculated. The results of the simulations compared with experiment are presented along with details of the neutron source spectrum/position and object 3D reconstruction.