U.S. patent application number 11/641583 was filed with the patent office on 2008-06-19 for detection of peroxides and superoxides with fast neutrons.
This patent application is currently assigned to Pratt & Whitney Rocketdyne, Inc.. Invention is credited to Gregory A. Johnson, Andrew J. Zillmer.
Application Number | 20080142722 11/641583 |
Document ID | / |
Family ID | 39526024 |
Filed Date | 2008-06-19 |
United States Patent
Application |
20080142722 |
Kind Code |
A1 |
Zillmer; Andrew J. ; et
al. |
June 19, 2008 |
DETECTION OF PEROXIDES AND SUPEROXIDES WITH FAST NEUTRONS
Abstract
A system for detecting a compound in a sample includes a neutron
source, at least one gamma ray detector positioned proximate the
sample, and a signal processor. The neutron source directs a
neutron beam toward the sample. The gamma ray detector collects
gamma rays emitted from the sample and the signal processor
determines the compounds in the sample based on the gamma rays
collected by the gamma ray detector. The compound is selected from
the group consisting of peroxides and superoxides.
Inventors: |
Zillmer; Andrew J.;
(Woodland Hills, CA) ; Johnson; Gregory A.;
(Camarillo, CA) |
Correspondence
Address: |
KINNEY & LANGE, P.A.
THE KINNEY & LANGE BUILDING, 312 SOUTH THIRD STREET
MINNEAPOLIS
MN
55415-1002
US
|
Assignee: |
Pratt & Whitney Rocketdyne,
Inc.
Canoga Park
CA
|
Family ID: |
39526024 |
Appl. No.: |
11/641583 |
Filed: |
December 19, 2006 |
Current U.S.
Class: |
250/390.04 |
Current CPC
Class: |
G01N 23/222 20130101;
G01N 2223/106 20130101; G01N 33/0036 20130101; G01N 2223/0745
20130101; G01N 2223/639 20130101 |
Class at
Publication: |
250/390.04 |
International
Class: |
G01N 23/00 20060101
G01N023/00 |
Claims
1. A system for detecting an oxidizer in a container, the system
comprising: a neutron source for directing a neutron beam toward
the container; at least one gamma ray detector positioned proximate
the sample container for collecting gamma rays emitted from the
oxidizer; and a signal processor for determining the oxidizer in
the container from the gamma rays collected by the gamma ray
detector; wherein the oxidizer to be detected is selected from the
group consisting of superoxides.
2. The system of claim 1, and further comprising a shield
surrounding at least a portion of the neutron source wherein the
oxidizer to be detected is further selected from the group
consisting of metal superoxides.
3. The system of claim 1, and further comprising a shield
surrounding at least a portion of the neutron source and a beam
dump positioned downstream of the sample.
4. The system of claim 1, and further comprising a plurality of
gamma ray detectors.
5. The system of claim 1, wherein the neutron beam is directed
toward the sample at an energy of at least 6 Million Electron
Volts.
6. The system of claim 1, wherein the gamma ray detector is a high
purity germanium crystal detector.
7. The system of claim 1, wherein the gamma ray detector is a
thallium-doped sodium iodide detector.
8. A system for detecting a superoxide oxidizer in a closed
container, the system comprising: a neutron source for directing a
neutron beam toward the closed container at an energy of at least 6
Million Electron Volts; at least one gamma ray detector positioned
proximate the closed container for detecting gamma rays produced by
the superoxide oxidizer; and a signal processor for analyzing the
gamma rays detected by the gamma ray detector.
9. The system of claim 8, wherein the superoxide oxidizer is an
inorganic chemical that forms an explosive fuel when mixed with an
organic chemical.
10. The system of claim 8, and further comprising a shield for
directing the neutron beam from the neutron source in one direction
and a beam dump positioned to intercept the neutron beam downstream
of the sample.
11. The system of claim 8, and further comprising a plurality of
gamma ray detectors.
12. The system of claim 8, wherein the superoxide oxidizer is a
metal superoxide.
13. The system of claim 12, wherein the metal superoxide is
selected from the group consisting of sodium superoxide, potassium
superoxide. cesium superoxide and rubidium superoxide.
14. The system of claim 8, wherein the gamma ray detector is a high
purity germanium crystal detector.
15. The system of claim 8, wherein the gamma ray detector is a
thallium-doped sodium iodide detector.
16. A method of detecting inorganic superoxides in a container, the
method comprising: passing fast neutrons through the container;
detecting gamma rays released from the inorganic superoxides in the
container; and analyzing the gamma rays released from the inorganic
superoxides in the container; wherein the fast neutrons are passed
through the source at energies of at least 6 Million Electron
Volts.
17. The method of claim 16, wherein detecting gamma rays comprises
detecting the number of gamma rays released from the sample.
18. The method of claim 16, wherein detecting gamma rays comprises
detecting the intensity of gamma rays released from the sample.
19. The method of claim 16, wherein the inorganic superoxides to be
detected in the sample metal superoxides.
20. The method of claim 16, wherein the inorganic superoxides to be
detected in the sample form explosive fuels when mixed with organic
chemicals.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention generally relates to the field of
detecting compounds in a sample. In particular, the invention
relates to detecting peroxides and superoxides in a sample.
[0002] Although peroxides and superoxides by themselves can be
inert chemicals, they can pose a large threat when mixed with other
chemicals. The combination of peroxides and superoxides with other
chemicals, such as organics, can be used to make explosives. For
example, a mixture of hydrogen peroxide and acetone is capable of
producing an unstable, explosive reaction. Because organics, such
as acetone, are present in numerous household products, it is more
efficient to monitor the presence of peroxides and superoxides in
sealed containers. By detecting and prohibiting large amounts of
oxidizers in sensitive areas, the threat of mixing two chemicals to
form an explosive fuel can be greatly reduced.
[0003] A method currently being used to detect explosives is to use
a small neutron source to detect the presence of nitrogen. Nitrogen
in a sample can indicate nitrates, which is a common oxidizer in
explosives. As the neutrons hit atoms in the sample, they react
with the atoms and produce gamma rays. The energy, number, and
intensity of gamma rays produced from the sample are measured to
determine whether the sample contains specified amounts of
nitrogen. If necessary, the sample can then be pulled and examined
for explosive potential. However, this technique of detecting
nitrogen is not capable of detecting peroxides or superoxides. The
ability to quickly and accurately detect oxidizers being housed
within sealed containers can help prevent explosive chemicals from
being carried onto vehicles such as airplanes, trains, buses,
etc.
BRIEF SUMMARY OF THE INVENTION
[0004] A system for detecting a compound in a sample includes a
neutron source, at least one gamma ray detector positioned
proximate the sample, and a signal processor. The neutron source
directs a neutron beam toward the sample. The gamma ray detector
collects gamma rays emitted from the sample and the signal
processor determines the compounds in the sample based on the gamma
rays collected by the gamma ray detector. The compound is selected
from the group consisting of peroxides and superoxides.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a schematic view of a detection system used to
detect peroxides and superoxides in a sample.
[0006] FIG. 2 is a diagram of a method of detecting peroxides and
superoxides in a sample.
DETAILED DESCRIPTION
[0007] FIG. 1 shows a schematic view of detection system 10 used to
detect peroxides and superoxides in sample 12. Detection system 10
generally includes neutron source 14, shield 16, gamma ray
detectors 18, beam dump 20, and signal processor 22. Detection
system 10 allows for quick and accurate detection of hazardous
chemicals in sample 12, which may be, for example, a closed
container. In particular, because peroxides and superoxides can be
used in combination with other chemical compounds to form
explosives, detecting peroxides and superoxides can significantly
help prevent the threat of explosions. Examples of peroxides that
are potentially dangerous include, but are not limited to: hydrogen
peroxide and acetone peroxide. Examples of superoxides that are
potentially dangerous include, but are not limited to: sodium
superoxide, potassium superoxide, cesium superoxide, and rubidium
superoxide. Although FIG. 1 is discussed in terms of detecting
peroxides and superoxides, detection system 10 may be used to
detect any number of compounds or elements, including nitrogen
atoms.
[0008] Neutron source 14 is positioned upstream of sample 12 and
directs fast neutrons toward sample 12. Shield 16 surrounds neutron
source 14 to help minimize radiation close to personnel and to
prevent damage to objects in close proximity to neutron source 14.
Shield 16 has an opening 24 that aligns a beam of neutrons 26 from
neutron source 14 with sample 12. Neutron beam 26 is sent from
neutron source 14 toward sample 12 at energies sufficient to
produce gamma rays from hydrogen atoms and oxygen atoms, the
primary constituents in peroxides and superoxides. In one
embodiment, neutron source 14 directs neutron beam 26 at energies
greater than at least 6 Million Electron Volts (MeV). As neutron
beam 24 strikes sample 12, the neutrons react with the atoms in
sample 12 and produce gamma rays at discrete energies based on the
atoms present in sample 12. Neutron source 14 may include, but is
not limited to: a compact neutron source, a fusion neutron source,
or a nuclear reactor with a fast neutron spectrum.
[0009] Gamma ray detectors 18 are positioned proximate sample 12
and detect the gamma rays released when neutron beam 26 strikes
sample 12. Gamma ray detectors 18 have energy resolutions that
allow gamma ray detectors 18 to measure the energy, number, and
intensity of the gamma rays produced by sample 12 based on the
specific energies of the neutrons in neutron beam 24. The energy,
number, and intensity of gamma rays are collected by gamma ray
detectors 18 and are used to determine the concentrations of
hydrogen and oxygen in sample 12. The ratio of gamma ray energies
can then be measured and compared to determine if sample 12 has a
higher concentration of peroxide or superoxide than an amount
predetermined as potentially dangerous. In one embodiment, gamma
ray detectors 18 may include, but are not limited to: high purity
germanium, cadmium zinc telluride, and thallium-doped sodium
iodide.
[0010] The number and intensity of the gamma rays produced by
sample 12 are then be sent to signal processor 22 and recorded.
Signal processor 22 analyzes the amounts, intensities, energies,
and ratios of gamma rays to determine the elements that make up
sample 12 and provide an output to a user. Because gamma ray
detectors 18 are capable of measuring the energy, number, and
intensity of atoms present in sample 12, signal processor 22 can
distinguish the presence of peroxides and superoxides from the
presence of other, less harmful compounds. This is because each
element produces gamma rays at particular energies and gamma ray
detectors 18 are capable of recording the particular energies and
intensities of the gamma rays produced to be analyzed by signal
processor 22. For example, the presence of peroxide, which is
composed of two hydrogen atoms and two oxygen atoms, can be
distinguished from the presence of water, which is composed of two
hydrogen atoms and one oxygen atom. Because water has a different
chemical composition than peroxide, the presence of water will give
a different signal than peroxide. Peroxides will have a higher
ratio of oxygen gamma rays to hydrogen gamma rays than water.
[0011] When neutron beam 24 reaches sample 12, some of the neutrons
will not strike sample 12. The neutrons in neutron beam 24 that
pass through sample 12 continue on to beam dump 20, which acts as a
shield and collects the neutrons to ensure that they do not
unintentionally strike personnel or other objects proximate
detection system 10.
[0012] FIG. 2 shows a diagram of a method 100 of detecting
peroxides and superoxides in sample 12. When a sample is to be
examined for peroxides or superoxides, neutron source 14 emits
neutron beam 24 through opening 22 of shield 16 toward sample 12,
Box 102. As neutron beam 24 strikes sample 12, the neutrons react
with the atoms present in sample 12 and gamma rays are released. A
plurality of gamma ray detectors 18 are positioned proximate sample
12 and detect the gamma rays produced from sample 12, Box 104. In
one embodiment, gamma ray detectors 18 measure the type, number,
and intensity of gamma rays released from sample 12. As depicted in
Box 106, the information collected from gamma ray detectors 18 is
then sent to signal processor 26, which uses the information to
determine the concentration of atoms present in sample 12. Signal
processor 26 may then provide an output detailing the make up of
sample 12 to a user. Any neutrons from neutron beam 24 that do not
strike sample 12 are subsequently collected in beam dump 20.
[0013] The detection system detects potentially dangerous
compounds, such as peroxides and superoxides, which may be housed
in a sealed container. Fast neutrons are emitted from a neutron
source toward the sample to be examined at energies high enough to
release gamma rays from hydrogen atoms and oxygen atoms. A shield
with an opening aligned with the sample is positioned around the
neutron source to protect personnel from the neutron beam. As the
neutron beam strikes the sample, gamma rays are released and
detected by a plurality of gamma ray detectors positioned proximate
the sample. The gamma ray detectors detect the energy, number, and
intensity of the gamma rays being released from the sample. The
energy, number, and intensity of gamma rays can be used to
determine the amount of hydrogen and oxygen atoms present in the
sample. Any remaining neutrons that do not strike the sample are
collected in a beam dump positioned downstream of the sample. The
quick and accurate detection of peroxides and superoxides in
samples may reduce the potential threat of explosives on
vehicles.
[0014] Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention.
* * * * *