Neutron Grid with Alternating Absorber Foils for Scattered Neutron Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In neutron radiography, scattered neutrons cause noise in transmission images, making it difficult to obtain clear images due to overlapping of scattered and original neutron signals, especially when using thermal neutrons.
Innovation Solution
A neutron grid with alternately arranged spacers and neutron absorbers, where the absorbers have a thermal neutron mass attenuation coefficient 100 times higher than the spacers, is used to absorb scattered neutrons, preventing them from reaching the image receptor and thus removing noise from the transmission image. The spacers and absorbers are designed to minimize thermal expansion coefficient differences and warpage, ensuring accurate transmission imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a grid is disposed between the specimen and the image-receiving body to remove scattered X-rays, then the clarity of transmission image is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the harmful scattered neutrons from the neutron beam before they reach the image-receiving body. By placing a neutron grid with absorber foils between the specimen and the image-receiving body, scattered neutrons are selectively absorbed and removed from the beam path, improving image clarity without adding complex processing systems
Solution Approach 2:
The neutron grid acts as an intermediary component between the specimen and the image-receiving body. The grid structure with alternating spacer and absorber foils serves as a mediator that selectively interacts with scattered neutrons, absorbing them while allowing primary neutrons to pass through, thus improving image quality without direct modification of the imaging system
2Measurement precision
If neutron absorbers with high thermal neutron mass attenuation coefficient are used to absorb scattered neutrons, then the noise removal efficiency is improved, but the absorption of primary neutrons increases reducing image intensity
Solution Approach 1:
The patent applies local quality by creating a non-uniform structure with alternating spacer foils and absorber foils. The absorber foils are strategically positioned and dimensioned to provide high neutron absorption capability only in the regions where scattered neutrons are present, while the spacer foils maintain openings that allow primary neutrons to pass through with minimal absorption
Solution Approach 2:
The absorber foils are designed with specific thickness and material composition to provide partial absorption of the neutron beam. This partial action allows the grid to absorb scattered neutrons effectively while maintaining sufficient transmission of primary neutrons to produce usable images, avoiding excessive absorption that would completely block the beam
3Measurement precision
If spacers and absorbers are arranged in alternating layers perpendicular to neutron irradiation direction, then scattered neutron absorption is improved, but manufacturing precision requirements increase
Solution Approach 1:
The neutron grid is segmented into multiple discrete components - individual spacer foils and absorber foils - that are arranged in alternating layers. This segmentation allows for modular manufacturing and assembly, where each layer can be fabricated and positioned separately, reducing the overall manufacturing precision requirements compared to creating a monolithic structure
Solution Approach 2:
The patent uses composite material structures combining different foil materials with complementary properties. The spacer foils are made from materials with low neutron absorption (such as aluminum or plastic) while absorber foils use high neutron absorption materials (such as boron, cadmium, or gadolinium). This composite approach allows each material to be optimized for its specific function while maintaining manufacturability
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 neutron grid effectively removes scattered neutrons, allowing for clear transmission images by selectively absorbing scattered thermal neutrons and other high-energy neutrons, thereby preventing image overlap and maintaining image clarity.
Implementation Method 1
a plurality of spacers (151) and a plurality of neutron absorbers (152) are alternately arranged along a first direction... the neutron absorber (152) is capable of absorbing at least a part of second neutrons which are scattered by the target
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A neutron grid, comprises: a grid including: a plurality of spacers through which at least a part of first neutrons from a target passes; and a plurality of absorbers to absorb at least a part of second neutrons scattered thorough the target, the spacers and the absorbers being alternately arranged along a first direction and extending along a second direction intersecting with the first direction; and a pair of covers through which at least a part of the first neutrons and at least a part of the second neutrons pass, sandwiching the grid along a third direction intersecting with the first and second directions. A thermal expansion coefficient difference between one of the spacers and one of the absorbers is ±9 × 10-6/°C or less, or Young's modulus of the spacer is 100 GPa or more.