A High Spatial Resolution Sensor For Thermal Neutron Imaging

We are developing a new type of neutron-sensitive sensor with minimal gamma-ray sensitivity for use in digital imaging systems. It consists of a plastic scintillator loaded with boron or gadolinium atoms for enhanced sensitivity to thermal neutrons. To achieve high spatial resolution, the scintillator in a liquid form is introduced into a capillary array (fused glass capillaries with no interstices), and then polymerized. The scintillation light generated by a neutron interaction is confined within a capillary, without lateral spreading through the scintillator. This not only improves spatial resolution, but also enhances image contrast by minimizing the glare fraction. The sensors were optically coupled to a cooled, fiberoptic taper-based CCD system to form an imaging detector. The detector was subjected to characterization and imaging tests at the thermal neutron port of the University of Massachusetts Lowell Research Reactor. Here we present the results that confirm the high resolution, high efficiency, and low gamma-sensitivity of the sensor.