Effective Atomic Number Determination via X-ray Scatter Ratio
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Solution Overview
Problem
Existing x-ray baggage scanners, including CT systems, fail to effectively discriminate between harmless materials and threat materials like plastic explosives due to limitations in x-ray diffraction identification systems, leading to a high false alarm rate.
Innovation Solution
A method and system that determine the effective atomic number of a substance by measuring the ratio of detected x-ray scatter photons in a diffraction profile, using an x-ray source, detector, and processor to analyze the diffraction profile and calculate the effective atomic number, thereby improving material discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If XRD identification systems are used to discriminate materials, then material discrimination capability is improved, but false alarm rate increases due to inability to identify certain explosive components
Solution Approach 1:
The patent combines XRD diffraction profile analysis with atomic number determination from Compton scattering data. The system merges two different physical measurement approaches: XRD provides structural information about crystalline materials, while Compton scattering provides atomic number information. By combining these complementary techniques, the system can identify materials that XRD alone cannot detect, reducing false alarms while maintaining discrimination capability.
Solution Approach 2:
The system performs multiple identification functions simultaneously: it analyzes diffraction profiles for crystal structure identification, determines atomic numbers from Compton scattering, and identifies material composition. This multi-functional approach allows the system to handle a broader range of material types including amorphous and crystalline substances, explosives, and narcotics, thereby reducing false alarms caused by inability to identify certain explosive components.
2Productivity
If existing X-ray baggage scanners are used for screening, then screening capability is provided, but discrimination between harmless and threat materials is insufficient
Solution Approach 1:
The patent replaces conventional X-ray transmission imaging with Compton scattering-based atomic number determination. Instead of relying on mechanical image processing and density thresholds, the system uses quantum mechanical Compton scattering to directly measure atomic number, providing superior material discrimination while maintaining screening productivity.
Solution Approach 2:
The system changes the measurement parameter from X-ray transmission intensity (used in conventional scanners) to Compton scattering cross-section (which depends on atomic number). This parameter change enables direct identification of material composition rather than relying on indirect density-based discrimination, significantly improving the ability to distinguish between harmless and threat materials.
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
This approach reduces false alarm rates by accurately identifying substances, including explosives, and determines whether a substance is a special nuclear material, enhancing security screening efficiency.
Implementation Method 1
a detector configured to detect primary and coherent scatter after the x-rays pass through the substance
Implementation Method 2
The method includes determining an effective atomic number of the substance based on a measured ratio of numbers of detected x-ray scatter photons in a diffraction profile
Data Source
AI summary
A method for determining a type of substance is described. The method includes determining an effective atomic number of the substance based on a measured ratio of numbers of detected x-ray scatter photons in a diffraction profile.