Publications

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A wide range of NSC (Neutron Scatter Camera) activities were conducted under this lifecycle plan. This document outlines the highlights of those activities, broadly characterized as system improvements, laboratory measurements, and deployments, and presents sample results in these areas. Additional information can be found in the documents that reside in WebPMIS.

We have developed a mobile fast neutron imaging platform to enhance the capabilities of emergency responders in the localization and characterization of special nuclear material. This mobile imager of neutrons for emergency responders (MINER) is based on the Neutron Scatter Camera, a large segmented imaging system that was optimized for large-area search applications. Due to the reduced size and power requirements of a man-portable system, MINER has been engineered to fit a much smaller form factor, and to be operated from either a battery or AC power. We chose a design that enabled omnidirectional (4π) imaging, with only a ~twofold decrease in sensitivity compared to the much larger neutron scatter cameras. The system was designed to optimize its performance for neutron imaging and spectroscopy, but it does also function as a Compton camera for gamma imaging. This document outlines the project activities, broadly characterized as system development, laboratory measurements, and deployments, and presents sample results in these areas. Additional information can be found in the documents that reside in WebPMIS.

A series of laboratory experiments were undertaken to demonstrate the feasibility of two dimensional time-encoded imaging. A prototype two-dimensional time encoded imaging system was designed and constructed. Results from imaging measurements of single and multiple point sources as well as extended source distributions are presented. Time encoded imaging has proven to be a simple method for achieving high resolution two-dimensional imaging with potential to be used in future arms control and treaty verification applications.

This project aims at the development of advanced low-threshold Ge detection technology and proof of its applicability to reactor monitoring via the as-yet undetected coherent neutrino nucleus scattering (CNNS) process.

A spallation based multiplicity detector has been constructed and deployed to the Kimballton Underground Research Facility to measure the cosmogenic fast neutron flux anti-coincident from the initiating muon. Two of the three planned measurements have been completed (~380 and ~600 m.w.e) with sufficient statistics. The third measurement at level 14 (~4450 m.w.e.) is currently being performed. Current results at ~600 m.w.e. compare favourably to the one previous measurement at 550 m.w.e. For neutron energies between 100 and 200 MeV measurements at ~380 m.w.e. produce fluxes between 1e^-8 and 7e^-9 n/cm²/s/MeV and at ~600 m.w.e. measurements produce fluxes between 7e^-9 and 1e^-11 n/cm²/s/MeV.

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Time-encoded imaging (TEI) is a new approach to directional detection of energetic radiation that produces images by inducing a time-dependent modulation of detected particles. TEI-based detectors use single-scatter events and have a low channel count, reducing complexity and cost while maintaining high efficiency with respect to other radiation imaging techniques such as double-scatter or coded aperture imaging. The scalability of TEI systems makes them a very promising detector class for weak source detection. Extension of the technique to high-resolution imaging is also under study. With a prototype time-encoding detector, we demonstrated detection of a neutron source at 60 m with neutron output equivalent to an IAEA significant quantity of WGPu. We have since designed and built a full-scale detector based on the time-encoding concept. We will present results from characterization of very large liquid scintillator cells, including pulse shape discrimination, as well as from studies of the detector system performance in weak source detection scenarios. © 2013 SPIE.

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