Spatial resolution of Medipix-2 device as neutron pixel detector

Nowadays, promising digital active pixel detector systems are available and make real time imaging with high sensitivity and broad dynamic range possible. The hybrid silicon pixel detector device Medipix-2 was originally designed for single X-ray photon detection. The device consists of a sensor chip with 256×256 square pixels of 55 μm size. The detector can be adapted for neutron detection by deposition of a converter layer to its surface. Thermal neutrons are converted in the layer into the secondary radiation which can be subsequently detected by the pixel detector. Different types of converter materials were examined with the aim to reach maximal spatial resolution at reasonable detection efficiency. The results demonstrate superior properties of the Medipix-2-based thermal neutron imager with a 6LiF converter in terms of spatial resolution, signal-to-noise ratio, linearity and dynamic range. Several images of real objects demonstrating the capabilities of the device are presented. The performance of the imager was compared with several types of contemporary neutron imaging systems (Medipix-1, CCD camera, imaging plates).