Segmented Neutron and Gamma Ray Detector
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Solution Overview
Problem
Existing radiation detectors are inadequate for effectively detecting shielded radioactive weapons of mass destruction, such as 'dirty bombs,' uranium-based atomic bombs, and plutonium-based atomic bombs, due to limitations in selectivity, efficiency, and portability, failing to meet Homeland Security needs.
Innovation Solution
A novel radiation detection apparatus comprising a combination of light guides and scintillator materials that selectively detect neutrons and gamma rays, using thermalizing hydrogenous materials to capture fast neutrons and distinguish them from gamma rays through optical detectors and a processor for classification, allowing for handheld operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional radiation detectors are used, then detection of unshielded gamma rays and neutrons is possible, but detection efficiency and selectivity for shielded radioactive weapons is insufficient
Solution Approach 1:
The detector is segmented into distinct functional regions: a neutron detection region containing hydrogenous material and neutron-sensitive scintillator, and a gamma ray detection region containing high-Z scintillator material. This segmentation allows each region to specialize in detecting specific radiation types, improving overall detection efficiency and selectivity for shielded weapons while maintaining manageable structural complexity through modular design.
Solution Approach 2:
The detector employs composite material structures combining hydrogenous materials (for neutron moderation), neutron-sensitive scintillators (for neutron detection), and high-Z scintillator materials (for gamma ray detection). These composite materials enable simultaneous detection of both neutron and gamma radiation with enhanced efficiency, directly addressing the reliability improvement while the integrated composite structure prevents excessive complexity increase.
2Reliability
If conventional neutron detectors are used, then thermal neutron detection is possible, but fast neutron detection efficiency and portability are insufficient
Solution Approach 1:
The detector incorporates hydrogenous material that performs preliminary thermalization of fast neutrons before they reach the neutron-sensitive scintillator region. This preliminary action converts high-energy fast neutrons into thermal neutrons in advance, enabling efficient detection by the scintillator without requiring complex external moderation systems, thus improving portability while maintaining detection efficiency.
Solution Approach 2:
The detector merges the neutron moderation function (typically requiring separate bulky components) with the detection function by integrating hydrogenous material directly within the detector structure. This merging eliminates the need for separate moderation chambers and associated complex packaging, improving both fast neutron detection efficiency and portability while avoiding excessive structural complexity.
3Reliability
If high efficiency gamma ray detectors are used, then gamma ray detection is possible, but detection of shielded gamma rays and selectivity from background radiation is insufficient
Solution Approach 1:
The detector applies local quality by using high-Z scintillator material specifically in the gamma ray detection region to enhance gamma ray interaction probability and detection efficiency for shielded sources. Simultaneously, the neutron detection region uses hydrogenous material with specific properties optimized for neutron moderation. This localized optimization of material properties in different regions improves gamma ray detection efficiency while the distinct regional functions prevent background radiation interference, maintaining measurement precision.
Data Source
AI summary
An apparatus for selective radiation detection includes a neutron detector that facilitates detection of neutron emitters, e.g. plutonium, and the like; a gamma ray detector that facilitates detection of gamma ray sources, e.g., uranium, and the like. The apparatus comprises a first light guide, optically coupled to a first optical detector; a second light guide, optically coupled to a second optical detector a sheet of neutron scintillator, opaque for incoming optical photons, said sheet of neutron scintillator sandwiched between the first and the second light guides. The second light guide comprises a gamma ray scintillator material.