Polyhedral Neutron Spectrometer with Segmented Detectors
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Solution Overview
Problem
Current neutron dosimetry instruments, such as neutron monitors, cannot provide spectral information and require multiple exposures and long setup times, limiting their ability for continuous real-time monitoring and are often bulky, costly, and dependent on scarce materials like Helium-3.
Innovation Solution
An active neutron spectrometer with a polyhedral moderator body and distributed thermal neutron detectors, along with surface inserts of high atomic number materials, enabling isotropic response and sensitivity across the energy spectrum, and allowing for single exposure measurements and real-time monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single spherical moderator with distributed detectors is used, then spectral measurement capability is achieved, but the device becomes bulky and heavy (25-30 cm diameter, over 10 kg)
Solution Approach 1:
The spherical moderator is segmented into multiple polyhedral units (e.g., octahedrons or icosahedrons) that are arranged in a specific geometric configuration. Each polyhedral unit contains a subset of detectors, and the collective arrangement maintains the isotropic response characteristic of a sphere while reducing the size and weight of individual components, making the overall device more compact and portable.
2Measurement precision
If multiple detectors are distributed in a spherical geometry, then isotropic response is achieved, but the construction complexity increases due to the internal spherical lead shell
Solution Approach 1:
The spherical moderator is segmented into multiple polyhedral units (e.g., octahedrons or icosahedrons) that are arranged in a specific geometric configuration. Each polyhedral unit contains a subset of detectors, and the collective arrangement maintains the isotropic response characteristic of a sphere while reducing the size and weight of individual components, making the overall device more compact and portable.
Solution Approach 2:
Instead of using a uniform spherical geometry with an internal lead shell, the invention employs polyhedral units with detectors positioned at specific locations (vertices, faces, or edges). This local optimization allows each detector to be strategically placed for maximum efficiency while simplifying the overall construction by eliminating the need for complex internal spherical shells.
3Measurement precision
If a single neutron sensor is used, then sensitivity is improved, but the device requires high voltage polarisations and expensive materials like Helium-3
Solution Approach 1:
The single neutron sensor is divided into multiple detectors distributed across the polyhedral units. This segmentation allows the use of alternative, more economical detector materials and technologies (such as semiconductor detectors or gas proportional counters) while maintaining or even improving overall sensitivity through the combined response of multiple detectors. The distributed arrangement also eliminates the need for expensive Helium-3 gas.
4Measurement precision
If Bonner spheres with multiple detectors are used, then spectral information is obtained, but long setup and exposure times are required
Solution Approach 1:
The polyhedral detector array is designed to provide continuous real-time monitoring capability, eliminating the need for sequential multiple exposures required by Bonner spheres. The multiple detectors operating simultaneously capture spectral information continuously, allowing for immediate measurement and analysis without repeated setup and exposure cycles.
Solution Approach 2:
The invention transitions from the traditional spherical Bonner sphere geometry to a polyhedral arrangement with detectors positioned in three-dimensional space along orthogonal axes. This dimensional reconfiguration allows for more efficient detector placement and signal collection, reducing measurement time while maintaining spectral resolution.
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 spectrometer achieves continuous real-time monitoring, reduced weight and cost, improved sensitivity, and portability, while simplifying construction and eliminating the need for complex spherical geometries and expensive materials.
Implementation Method 1
a polyhedral moderator body of hydrogenated material
Implementation Method 2
moderator body of hydrogenated material having a centre and an external surface
Implementation Method 3
thermal neutron detectors housed in channels which are arranged along said first main axis
Implementation Method 4
channels which extend in the direction that goes from said centre to the centre of said flat faces for the possible housing of inserts of a high atomic number
Data Source
AI summary
The active neutron spectrometer (1) comprises a polyhedral moderator body (2) of hydrogenated material having a first, a second and a third orthogonal main axis (X1, X2; Y1, Y2; Z1, Z2), a first series of thermal neutron detectors (3a1, 3a2, 3a3, 3a4, 3a5, 3a6, 3b1, 3b2, 3b3, 3b4, 3b5, 3b6) arranged along the first main axis (X1, X2), a second series of thermal neutron detectors (4a1, 4a2, 4a3, 4a4, 4a5, 4a6, 4b1, 4b2, 4b3, 4b4, 4b5, 4b6) arranged along the second main axis (Y1, Y2), and a third series of thermal neutron detectors (5a1, 5a2, 5a3, 5a4, 5a5, 5a6, 5b1, 5b2, 5b3, 5b4, 5b5, 5b6) arranged along the third main axis (Z1, Z2).