A new sensor for thermal neutron imaging

Thermal neutrons serve as a useful tool in probing macromolecular structures in protein crystallography and in investigations of new materials. However, neutron techniques are underutilized due to the lack of high performance digital, position sensitive detectors. The primary limiting factor in current detectors is the converter screen which converts the neutron signal into visible light. Here we report on a new type of neutron sensitive screen for use in digital imaging systems. The screen consists of a pixelated, microstructured CsI(Tl) scintillator film sandwiched between two neutron converting layers of GdF₃. To increase the effective surface area of the GdF₃ conversion layer and to enhance the contrast resolution of the images, the CsI(Tl) layer is pixelated using micromachining techniques. For testing their imaging performance, the sensors were optically coupled to a CCD system to form an imaging detector. The system was subjected to imaging tests at a thermal neutron port of the University of Massachusetts Lowell Research Reactor. The results of these preliminary imaging experiments are presented here.