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Time Encoded Radiation Imaging

Marleau, Peter M.; Brubaker, Erik B.; Gerling, Mark D.; Schuster, Patricia F.; Steele, John T.

Passive detection of special nuclear material (SNM) at long range or under heavy shielding can only be achieved by observing the penetrating neutral particles that it emits: gamma rays and neutrons in the MeV energy range. The ultimate SNM standoff detector system would have sensitivity to both gamma and neutron radiation, a large area and high efficiency to capture as many signal particles as possible, and good discrimination against background particles via directional and energy information. Designing such a system is a daunting task. Using timemodulated collimators could be a transformative technique leading to practical gamma-neutron imaging detector systems that are highly efficient with the potential to exhibit simultaneously high angular and energy resolution. A new technique using time encoding to make a compact, high efficiency imaging detector was conceived. Design considerations using Monte Carlo modeling and the construction and demonstration of a prototype imager are described.

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TYPE SAND Report YEAR 2011
OSTIDOI

Ground water and snow sensor based on directional detection of cosmogenic neutrons

Griffin, Patrick J.; Marleau, Peter M.

A fast neutron detector is being developed to measure the cosmic ray neutron flux in order to measure soil moisture. Soil that is saturated with water has an enhanced ability to moderate fast neutrons, removing them from the backscatter spectrum. The detector is a two-element, liquid scintillator detector. The choice of liquid scintillator allows rejection of gamma background contamination from the desired neutron signal. This enhances the ability to reconstruct the energy and direction of a coincident neutron event. The ability to image on an event-by-event basis allows the detector to selectively scan the neutron flux as a function of distance from the detector. Calibrations, simulations, and optimization have been completed to understand the detector response to neutron sources at variable distances and directions. This has been applied to laboratory background measurements in preparation for outdoor field tests.

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TYPE SAND Report YEAR 2011
OSTIDOI

Fast neutron resonance tomography using double scatter spectroscopy for materials identification

IEEE Nuclear Science Symposium Conference Record

Marleau, Peter M.; Brennan, James S.; Brubaker, Erik B.; Mengesha, Wondwosen M.; Mrowka, Stanley M.

Fast neutron based inspection systems are of interest in many Homeland Security applications because they offer the potential for elemental identification particularly for low Z elements which are the prime constituents of explosives. We are investigating a resonance tomography technique which may address some of the current problems found in fast neutron based inspection systems. A commercial off-the-shelf DT generator is used with an array of detectors to probe materials simultaneously over a large energy range and multiple viewing angles allowing for simultaneous 3-D imaging and materials identification. A prototype system has been constructed and we present here recent results for the identification of materials with differing H, C, N, O compositions. © 2011 IEEE.

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TYPE Conference YEAR 2011
ScopusOSTI

Results with a 32-element dual mode imager

Mascarenhas, Nicholas M.; Cooper, Robert L.; Marleau, Peter M.; Mrowka, Stanley M.; Brennan, James S.

We present advances with a 32 element scalable, segmented dual mode imager. Scaling up the number of cells results in a 1.4 increase in efficiency over a system we deployed last year. Variable plane separation has been incorporated which further improves the efficiency of the detector. By using 20 cm diameter cells we demonstrate that we could increase sensitivity by a factor of 6. We further demonstrate gamma ray imaging in from Compton scattering. This feature allows for powerful dual mode imaging. Selected results are presented that demonstrate these new capabilities.

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TYPE Conference YEAR 2010
OSTI

Applying the neutron scatter camera to treaty verification and warhead monitoring

Mascarenhas, Nicholas M.; Cooper, Robert L.; Mrowka, Stanley M.; Brennan, James S.; Marleau, Peter M.

The neutron scatter camera was originally developed for a range of SNM detection applications. We are now exploring the feasibility of applications in treaty verification and warhead monitoring using experimentation, maximum likelihood estimation method (MLEM), detector optimization, and MCNP-PoliMi simulations.

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TYPE Conference YEAR 2010
OSTI
Results 151–200 of 214
Results 151–200 of 214