Tagged Neutron API Subsurface Location

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Solution Overview

Problem

Current neutron-gamma analysis methods face challenges in accurately locating subsurface objects with high signal-to-noise ratio and non-destructive measurement capabilities, particularly for carbon-based materials.

Innovation Solution

The development of an Associated Particle Imaging (API) system using a neutron generator that emits tagged neutrons, which interact with target materials to produce nucleus-specific gamma rays, allowing for non-invasive measurement of elemental content by constructing alpha-gamma timing spectra and correlating energy and timing data to determine the location and depth of buried objects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional neutron-gamma analysis methods are used, then measurement capability is provided, but signal-to-noise ratio is insufficient and location precision is poor

Engineering Contradiction:

Improvelocation precisionVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent segments the gamma ray detection by applying energy windowing to isolate specific nucleus-specific gamma ray energies (e.g., 4.44 MeV for carbon-12). This energy segmentation allows the system to filter out background radiation and focus only on gamma rays from the target material, thereby improving signal-to-noise ratio and location precision simultaneously

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces time-correlated single photon counting (TCSPC) as an intermediary measurement technique that correlates gamma ray detection with the known emission time of tagged neutrons. This intermediary time-correlation mechanism enables precise determination of gamma ray origin location by calculating time-of-flight, resolving the contradiction between measurement capability and location precision

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If non-invasive measurement is used, then target material integrity is preserved, but detection sensitivity is reduced

Engineering Contradiction:

Improvedetection sensitivityVSAvoidinvasiveness

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the measurement parameters by using tagged neutrons with specific energies (e.g., 14 MeV from D-T fusion) and correlating them with nucleus-specific gamma ray energies. This parameter change enables non-invasive detection while maintaining high sensitivity through the unique energy signature matching between incident neutrons and emitted gamma rays

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback through the coincidence detection system that requires both alpha particle detection (from the neutron source) and gamma ray detection within a specific time window. This feedback mechanism confirms that the detected gamma rays originate from the tagged neutron interaction, thereby maintaining high detection sensitivity without invasive contact

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The API system effectively identifies buried target materials by enhancing the signal-to-noise ratio and enabling precise location and depth determination of carbon-based objects, demonstrating improved sensitivity and minimal detectable level compared to traditional methods.

Implementation Method 1

Multiple tagged neutrons are emitted from the associated particle imaging system neutron generator. The tagged neutrons penetrate a target material and interact with the target material nucleus—which emits nucleus-specific gamma rays.

Methodology Applied

Scientific EffectNuclear inelastic scattering:

Implementation Method 2

An alpha-gamma timing spectrum is constructed for all detected gamma rays. Based on the peaking time of the gamma rays (due to tagged neutrons interaction with the target material nucleus) in the alpha-gamma timing spectrum for the specific energy level, the distance from the neutron generator to the target material can be calculated.

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS11402338B2System and method of using energy correlated timing spectra to locate subsurface objects

Publication Date: 2022.08.02 THE GOVERNMENT OF THE UNITED STATES OF AMERICA AS REPRESENTED BY THE SECRETARY DEPARTMENT OF HEALTH & HUMAN SERVICES

AI summary

Multiple tagged neutrons are emitted from an associated particle imaging neutron generator. The tagged neutrons penetrate a target material and interact with the target material nucleus—which emits nucleus-specific gamma rays. A gamma ray detector detects all gamma rays—including the nucleus-specific gamma rays. An alpha-gamma timing spectrum is constructed for all detected gamma rays. For a specific energy level (MeV) corresponding with the target material nucleus, a peak in the alpha gamma timing spectrum indicates the presence of the target material. Based on the peaking time of the gamma rays (due to tagged neutrons interaction with the target material nucleus) in the alpha-gamma timing spectrum for the specific energy level, the distance from the neutron generator to the target material can be calculated. The nucleus-specific gamma ray spectrum data can be effectively collimated by programming the system to detect the gamma rays in a time window corresponding to the peaking time.