Neutron Detectors for Detection of Nuclear Materials at LANL
Very Large Array Neutron Detector (VLAND); Development of large volume efficient neutron detectors for use in detection of small amounts (~ 1 gm) of U and Pu.
Might provide sufficient sensitivity to detect small amounts of U and Pu at truck monitoring ports. This would provide a new capability in homeland defense against illicit transport of nuclear materials.
Recent neutrino physics experiments have successfully instrumented from tens to thousands of tons of detector materials. Large-area photocathode photomultiplier technology is now mature enough that an eight inch diameter photo-multiplier tube (PMT) costs approximately a thousand dollars and can be expected to operate unattended for more than ten years. These PMT’s could be used along with the associated data acquisition and analysis technologies to build neutron detectors for counter terrorism applications. Specifically, the proposed detectors would be based on scintillators viewed by the PMT's. A trade study would select between scintillators comprised of gadolinium-loaded plastic or liquid, lithium-6 loaded inorganic phosphors, or unloaded plastic or liquid. The technologies developed for neutrino physics experiments could be applied to cost-effective neutron detector systems. The applications are in (a) detection of smuggled neutron-emitting special nuclear materials (SNM), such as weapons grade plutonium and certain uranium compounds, (b) terrorist nuclear weapon threat detection, and (c) weapon accountability. Since the likely targets of interest would emit low fluxes of neutrons, and need to be detected at relatively long distances with short dwell times, any effective neutron detection system would in turn need to have a large surface area. The concept involves employing panel-like neutron detection modules to provide significantly improved solid-angle coverage at reduced cost as compared to competing technologies. This would allow the detection of neutron emitting materials or devices in venues such as train stations, airport concourses or taxiways, tunnels, border crossings, and exits to weapons or nuclear facilities.
