Position sensitive detection of thermal neutrons with solid state detectors (Gd Si planar detectors)

Recent advances in the technology of position sensitive silicon detectors and the corresponding electronics allow the construction of fast time response thermal neutron detectors. These detectors also exhibit excellent position resolution by combination of silicon detectors with thin Gd converter foils. We constructed several one- and two-dimensional prototype detectors, using DC and AC coupled silicon strip detectors, pad detectors and different VLSI readout electronics. The position resolution and the detector efficiency for different converters at wavelengths from 1.1 to 3.3 Å were determined at the TRIGA reactor in Vienna and at the ILL in Grenoble. Spatial resolutions of less than 100 μm and efficiencies up to 40% have been achieved. The results of these measurements are compared with a Monte Carlo simulation of the detector operation. These detectors can also be used for phase topography experiments using perfect crystal neutron interferometers. In certain cases an increase of the sensitivity in the order of 100 can be anticipated compared to beam attenuation radiography.