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Title: Method for improving the angular resolution of a neutron scatter camera

Abstract

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.degree. to about 10.degree.. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6.degree. 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 tomore » interrogate a particular site for an extended period.« less

Inventors:
; ; ; ; ;
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1082134
Patent Number(s):
8,338,795
Application Number:
12/872,700
Assignee:
Sandia Corporation (Albuquerque, NM) SNL
DOE Contract Number:
AC04-94AL85000
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Mascarenhas, Nicholas, Marleau, Peter, Gerling, Mark, Cooper, Robert Lee, Mrowka, Stanley, and Brennan, James S. Method for improving the angular resolution of a neutron scatter camera. United States: N. p., 2012. Web.
Mascarenhas, Nicholas, Marleau, Peter, Gerling, Mark, Cooper, Robert Lee, Mrowka, Stanley, & Brennan, James S. Method for improving the angular resolution of a neutron scatter camera. United States.
Mascarenhas, Nicholas, Marleau, Peter, Gerling, Mark, Cooper, Robert Lee, Mrowka, Stanley, and Brennan, James S. Tue . "Method for improving the angular resolution of a neutron scatter camera". United States. doi:. https://www.osti.gov/servlets/purl/1082134.
@article{osti_1082134,
title = {Method for improving the angular resolution of a neutron scatter camera},
author = {Mascarenhas, Nicholas and Marleau, Peter and Gerling, Mark and Cooper, Robert Lee and Mrowka, Stanley and Brennan, James S.},
abstractNote = {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.degree. to about 10.degree.. A further doubling of the separation distance to 80 cm provided an addition improvement in angular resolution of the detector to about 6.degree. 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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 25 00:00:00 EST 2012},
month = {Tue Dec 25 00:00:00 EST 2012}
}

Patent:

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  • 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.pi.. 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.
  • A head for a scintillation camera has a planar scintillating crystal that responds to radiation stimuli by producing light events whose spatial distribution corresponds to the spatial distribution of the radiation stimuli, and a plurality of photomultipliers each having a photocathode facing the crystal and producing an output signal when a light event occurs. The photomultipliers are organized into a first group arranged in a cluster centrally positioned relative to the crystal and having smaller photocathodes than those in the second group which is arranged in an annular array surrounding the first group. The head of the camera is connectedmore » to signal processing circuitry for computing each of two spatial coordinates of a light event by forming analytical functions of the output signals. Such circuitry has two selective modes of operation. In the first, each spatial coordinate of a light event is computed by forming an analytic function of the output signals from only those photomultipliers in the first group. In the second mode of operation, each spatial coordinate of the light event is computed using an analytical function of the sum of the output signals of the first group of photomultipliers and the output signals from the second group. For light events falling within a first portion of the crystal defined by the envelope of the projection on the crystal of the photocathodes of the first group of photomultipliers, when the signal processing circuitry is operating in its first mode, the resolution achieved will be much better than the resolution achieved when the signal processing circuitry is operating in its second mode. 17 claims, 4 figures.« less
  • A method and apparatus for processing step-like output signals generated by non-ideal, nominally single-pole ("N-1P") devices responding to possibly time-varying, pulse-like input signals of finite duration, wherein the goal is to recover the integrated areas of the input signals. Particular applications include processing step-like signals generated by detector systems in response to absorbed radiation or particles and, more particularly, to digitally processing such step-like signals in high resolution, high rate gamma ray (.gamma.-ray) spectrometers with resistive feedback preamplifiers connected to large volume germanium detectors. Superconducting bolometers can be similarly treated. The method comprises attaching a set of one or moremore » filters to the device's (e.g., preamplifier's) output, capturing a correlated multiple output sample from the filter set in response to a detected event, and forming a weighted sum of the sample values to accurately recover the total area (e.g., charge) of the detected event.« less
  • A method and apparatus for processing step-like output signals (primary signals) generated by non-ideal, for example, nominally single-pole ("N-1P ") devices. An exemplary method includes creating a set of secondary signals by directing the primary signal along a plurality of signal paths to a signal summation point, summing the secondary signals reaching the signal summation point after propagating along the signal paths to provide a summed signal, performing a filtering or delaying operation in at least one of said signal paths so that the secondary signals reaching said summing point have a defined time correlation with respect to one another,more » applying a set of weighting coefficients to the secondary signals propagating along said signal paths, and performing a capturing operation after any filtering or delaying operations so as to provide a weighted signal sum value as a measure of the integrated area Q gT of the input signal.« less