Sandia Corporation

Nicholas Mascarenhas

James S Brennan

Peter Marleau

Mark Gerling

Stanley Mrowka

Charles H Greenberg

Robert Lee Cooper

Kevin D Krenz

An instrument that will directly image the fast fission neutrons from a special nuclear material source wherein the neutron detection efficiency is increased has been described. Instead of the previous technique that uses a time-of-flight (TOF) between 2 widely spaced fixed planes of neutron detectors to measure scatter neutron kinetic energy, we now use the recoil proton energy deposited in the second of the 2 scatter planes which can now be repositioned either much closer together or further apart. However, by doubling the separation distance between the 2 planes from 20 cm to a distance of 40 cm we improved the angular resolution of the detector from about 12&#xb0; to about 10&#xb0;. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6&#xb0; without adding additional detectors or ancillary electronics. The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular resolution of this new configuration, therefore, is increased at the expanse of detection sensitivity. However, the diminished sensitivity may be acceptable for those applications where the detector is able to interrogate a particular site for an extended period.

Method for improving the angular resolution of a neutron scatter camera

An instrument that will directly image the fast fission neutrons from a special nuclear material source wherein the neutron detection efficiency is increased has been described. Instead of the previous technique that uses a time-of-flight (TOF) between 2 widely spaced fixed planes of detectors to measure scatter neutron kinetic energy, we now use the recoil proton energy deposited in the second of the 2 scatter planes which can now be repositioned much closer together. Allowing the 2 planes to be placed closer together has been shown to provide up to about a &#x2dc;170% improvement in detection efficiency without adding additional detectors and ancillary electronics. The distance between planes also may be dynamically changed using a suitable common technique such as a gear- or motor-drive to toggle between the various positions. The angular resolution of this new configuration is diminished but this loss of resolution may be acceptable for those applications where only modest directionality is sufficient to identify a threat.

Neutron scatter camera for improved neutron detection

An instrument that will directly image the fast fission neutrons from a special nuclear material source has been described. This instrument can improve the signal to background compared to non imaging neutron detection techniques by a factor given by ratio of the angular resolution window to 4&#x3c0;. In addition to being a neutron imager, this instrument will also be an excellent neutron spectrometer, and will be able to differentiate between different types of neutron sources (e.g. fission, alpha-n, cosmic ray, and D-D or D-T fusion). Moreover, the instrument is able to pinpoint the source location.

Neutron scatter camera

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Livermore, CA, United States of America

Nicholas Mascarenhas