2-D Position-Sensitive Scintillation Detector for Neutrons

A 2-di mensional neutron-position scintillation detector, based on the well-proven principle of the Anger γ-ray camera, has been developed. A 6Li-loaded, Ce-activated glass scintilator is coupled via a unique 44 mm thick light guide to a closely spaced hexagonal array of nineteen 5 cm diameter photomultipliers. The 1 mm thick x 22 cm diameter glass scintillator is made up of four optically cemented quadrants. The location of a scintillation is determined by calculating the X and Y centroids using a resistor weighting scheme. A spatial FWHM resolution of 2-3 mm was obtained. At 0.025 eV (1.8 A) the efficiency of the glass is 80% and the FWHM pulse height resolution is 14%. These characteristics in combination with low γ-ray sensitivity in the thin scintillator provide for excellent background rejection. Drift in the photomultipliers' gain results in output change of <0.05 mm/°C. The detector was evaluated in experiments at the pulsed spallation neutron source ZING-P'. In an experiment with a single crystal diffractometer a Laue pattern from a NaCl crystal was obtained. In a resonance radiography experiment Au and in, contained in a test object, were graphically resolved. For these applications the scintillation detector has several inherent advantages over a gas proportional counter.