Multifaceted radiation detection and classification system

Patent metadata

Field	Value
Publication number	US-11009622-B2
Application number	US-201916417324-A
Country	US
Kind code	B2
Filing date	May 20, 2019
Priority date	May 18, 2018
Publication date	May 18, 2021
Grant date	May 18, 2021

Abstract

A system identifying a source of radiation is provided. The system includes a radiation source detector and a radiation source identifier. The radiation source detector receives measurements of radiation; for one or more sources, generates a detection metric indicating whether that source is present in the measurements; and evaluates the detection metrics to detect whether a source is present in the measurements. When the presence of a source in the measurements is detected, the radiation source identifier for one or more sources, generates an identification metric indicating whether that source is present in the measurements; generates a null-hypothesis metric indicating whether no source is present in the measurements; evaluates the one or more identification metrics and the null-hypothesis metric to identify the source, if any, that is present in the measurements.

First claim

We claim:

1. One or more computing systems for identifying a source of radiation, the one or more computing system comprising:
one or more computer-readable storage mediums storing computer-executable instructions of:
a radiation source detector that:
receives measurements of radiation;
for one or more sources, generates a detection metric indicating whether that source is present in the measurements; and
evaluates the detection metrics to detect whether a source is present in the measurements; and

a radiation source identifier that, when the presence of a source in the measurements is detected,
for one or more sources, generates an identification metric indicating whether that source is present in the measurements;
generates a null-hypothesis metric indicating whether no source is present in the measurements based on analysis of the measurements and the one or more identification metrics; and
evaluates the one or more identification metrics and the null-hypothesis metric to identify the source, if any, that is present in the measurements; and

one or more processor for executing the computer-executable instructions stored in the one or more computer-readable storage mediums.

2. The one or more computing systems of claim 1 wherein the radiation source detector generates the detection metric for a source based on a detection source signature for that source and the radiation identification detector generates the identification metric for a source based on a plurality of identification source signatures for that source.

3. The one or more computing systems of claim 2 wherein the identification sources signatures for a source represent that source with different shieldings.

4. The one or more computing systems of claim 1 wherein the radiation source identifier identifies a radiation source class for an identified source.

5. The one or more computing systems of claim 1 wherein the measurements are calibrated to account for drift in the detector that collected the measurements.

6. The one or more computing systems of claim 1 wherein the radiation source identifier generates an aggregated metric for each source.

7. The one or more computing systems of claim 1 wherein the measurements with in a window are aggregated and radiation is detected and identified based on aggregated measurements.

8. A method performed by a computing system for detecting presence of a source of radiation from a measurement of radiation, the method comprising:
for one or more of sources,
for one or more detection algorithms,
generating a metric using that detection algorithm, the metric indicating similarity between a current measurement and a source signature for that source, that detection algorithm factoring in an estimate of background radiation generated based on prior measurements to the current measurement; and

generating an aggregated metric for that source from one or more metrics for that source;

analyzing the aggregated metric for one or more sources to determine whether a source is likely present in the current measurement; and
upon determining that a source is likely present in the current measurement, indicating that the presence of a source has been detected.

9. The method of claim 8 further comprising generating an estimate of background radiation based on prior measurements excluding prior measurements for which the presence of a source was detected.

10. The method of claim 9 wherein the estimate of background radiation is a weighted average based on a measurement and a prior estimate of background radiation.

11. The method of claim 8 wherein a source signature is associated with an identification of a source and a shielding of the source.

12. The method of claim 11 wherein for each detection algorithm, a metric is generated for each source signature associated with a source.

13. The method of claim 8 wherein a measurement is represented by a histogram of energy ranges with a count of photons for each energy range.

14. The method of claim 8 wherein a metric is generated for each of a plurality of windows measurements, each window including the current measurement and a number of adjacent prior measurement.

15. The method of claim 8 wherein a detection algorithm is associated with coefficients and further comprising dynamically adjusting the coefficients based on an estimate of background radiation.

16. The method of claim 8 wherein the analyzing of the aggregated metrics includes applying a classifier that is trained using training data that includes feature vectors with features that include detection algorithm, a window size, and an aggregated metric and a label for each feature vector indicating whether a source is present.

17. The method of claim 16 wherein the feature vectors are generated from collected measurements of radiation.

18. The method of claim 16 wherein the feature vectors are generated from simulated measurements of radiation.

19. The method of claim 18 further comprising calibrating the current measurement to account for drift associated with a detector used to collect the measurements.

20. A method performed by a computing system for identifying a source of radiation from a measurement of radiation, the method comprising:
receiving a current measurement for which presence of a source has been detected based on detection source signatures;
for each of a plurality of identification source signatures, generating a metric using an identification algorithm, the metric indicating similarity between a current measurement and a source signature for that source, the identification algorithm factoring in an estimate of background radiation generated when detecting the presence of the source, the identification source signatures being more comprehensive than the detection source signatures;
for each source, generating a source metric based on one or more metrics generated using a source signature for that source, wherein at least one source metric is generated based on more than one metric;
generating a null-hypothesis metric indicating similarity between the current measurement and the estimate of background radiation, the sources and the estimate of background radiation being targets, the source metrics and the null-hypothesis metric being target metrics; and
for each target, generating a target probability representing presence of that target in the current measurement, the target probability based on the target metric for that target.

21. The method of claim 20 further comprising, for each of a plurality of radiation source classes, generating a radiation source class probability that the current measurement represents a source of that radiation source class, the radiation source class probabilities generated based on target probabilities.

22. The method of claim 20 wherein the generating of a target probability factors in prior probabilities for each target.

23. The method of claim 20 wherein the identification algorithm is based on an orthonormal subspace projection matched filter algorithm.

24. A method performed by a computing system for generating a metric relating to a source of radiation in measurements of radiation, the method comprising:
accessing a source signature of the source, an estimated background, and background basis vectors;
generating a projection vector based on the source signature, estimated background, and the background basis vectors, and
accessing a measurement; and

Assignees

• L Livermore Nat Security Llc

Inventors

• Labov Simon E
• Nelson Karl E
• Seilhan Brandon S

Classifications

• G01T1/36

  Measuring spectral distribution of X-rays or of nuclear radiation {spectrometry (pulse selection circuits per se H03K; investigation of materials by radiation diffraction G01N23/20; spectrometer tubes H01J49/00)} · CPC title

• G01T7/00 Primary

  Details of radiation-measuring instruments · CPC title

• G01T1/167

  Measuring radioactive content of objects, e.g. contamination (whole body counters G01T1/163) · CPC title

• G01V5/0091

  Physics · mapped topic

• G01V5/0075 Primary

  Physics · mapped topic