A new two-dimensional scintillation detector system for small-angle neutron scattering experiments

A new two-dimensional position-sensitive detector system for small-angle ne utron scattering experiments is under development. It is based on a 60 x 60 cm(2) large Li-6-glass scintillator for the neutron capture and dispersion of the emitted light on an array of photomultiplier tubes for the derivati on of the event position. For subthermal neutrons of 8 Angstrom, an efficie ncy of 96% and a spatial resolution of 8 mm are to be achieved. Major impro vements have been made in the signal- and data-processing branch, which aim s at an electronical dead time of 1 mus. A fast digitalization method using free-running analog-to-digital converters for each photomultiplier combine d with field-programmable gate arrays for a parallel event detection in all channels has been applied. A subsequent farm of up to 16 floating-point di gital signal processors is used to provide enough computing power for an im proved reconstruction of the event position according to a maximum likeliho od method.