Influence of coded mask rotation speed and central detector to imaging performance for time-encoded imager

Abstract

Time-encoded imaging could be useful for searching potential radioactive sources for preventing illicit transportation and trafficking of nuclear materials. A 2-D, dual-particle, time-encoded imager was developed for gamma-ray and neutron source imaging. The influence of central detector and coded mask rotation speed to imaging performance, such as angular resolution, signal-to-noise ratio and detection time, was investigated by Am–Be neutron source imaging experiments. The EJ276 plastic scintillator (Size: Φ5.08 cm × 5.08 cm) and CLYC scintillator (Size: Φ2.54 cm × 2.54 cm) couple to photomultiplier tubes was set as the central detector, respectively. Under the experiment conditions (Am–Be neutron source; 300 mCi; 1.8 m), for the neutron and gamma-ray images with EJ276 detector, the best horizontal and vertical angular resolution was (3.7°, 4.8°) and (5.9°, 6.6°), minimum detection time was 100 s and 600 s, respectively; for the neutron and gamma-ray images with CLYC detector, the best horizontal, vertical angular resolution was (3.1°, 3.1°) and (3.5°, 3.3°), minimum detection time was 2200 s and 1600 s, respectively. For different central detector, the results showed that the smaller volume of detector, the better angular resolution; the lower detection efficiency, the longer detection time. For different rotation speed, too fast rotation speed can lead to failure to locate the source.