Thermal and cold neutron counting with microchannel plates, invited

摘要

A wide range of applications, from fundamental physics to homeland security, relies on efficient detection of neutrons. The absolute neutron detection efficiency, as well as background radiation rejection, have always been key parameters defining the effectiveness of various neutron detection schemes that have been implemented over the years. Recent progress in neutron sensitive microchannel plate (MCP) detectors, now enables some interesting and novel applications, given the rapid advance in the neutron counting ability of MCPs, which offer very high spatial and timing resolution at very low background rates. Among those applications are high resolution neutron radiography and tomography, providing images with contrast levels not attainable using conventional X-ray imaging. There are now numerous areas in neutron research which can benefit from the enhanced capability provided by MCP neutron detection. As small sample can be mentioned here: neutrons can penetrate many thick metals to reveal internal hydrogenous structures, allowing studies of operating fuel cells, or fuel and oil distributions within combustion engines and injection nozzles; studies of geological samples at high resolution, or ancient archaeological artifacts; new pulsed neutron sources combined with neutron-sensitive MCP detectors, can enable transmission Bragg edge spectroscopy to be done, allowing nondestructive studies of phase, texture and even strain within certain materials, as well as the compositional content of imaged objects. The very low sensitivity to background gamma radiation when operated in ultrafast timing coincidence, coupled with virtually noise-free readout technology, bring new capabilities in detection of special nuclear materials for homeland security applications.