Hybrid Multi-Layer Sensor for High-Fluence Dosimetry
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Solution Overview
Problem
Existing dosimetry and fluxmetry sensors, such as Phoswich and Hybrid Pixel detectors, saturate quickly and fail to accurately discriminate radiation species in high-fluence environments like nuclear reactors and particle accelerators, limiting their effectiveness in harsh conditions.
Innovation Solution
A hybrid multi-layer sensor with a scintillator and photosensor separated by a visible EM spectrum filter, using fiber-coupled spectrophotometry and microwave detection to correlate scintillator spectrum structure and microwave probed photoconductivity for particle species and energy discrimination, allowing for contactless dosimetry and fluxmetry in harsh environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Phoswich detectors use thin scintillator layers to detect low-energy particles, then detection efficiency is improved, but the ability to detect penetrative high-energy particles deteriorates
Solution Approach 1:
The detector is divided into multiple scintillator layers with different thicknesses and material compositions. Each layer is optimized for detecting specific energy ranges of particles, allowing the system to simultaneously detect both low-energy particles (using thinner layers) and penetrative high-energy particles (using thicker layers), resolving the contradiction between detection efficiency and adaptability across energy ranges
Solution Approach 2:
The detector employs composite scintillator materials with different luminescence characteristics (e.g., fast and slow scintillators) arranged in specific layer configurations. This composite structure enables the detector to distinguish between different particle types and energy levels while maintaining high detection efficiency across the full energy spectrum, addressing both detection precision and versatility requirements
2Measurement precision
If Phoswich detectors use multiple thin scintillators tightly bound together, then spectral discrimination is improved, but manufacturing complexity increases
Solution Approach 1:
The scintillator assembly is segmented into distinct layers that can be independently manufactured and then assembled using standardized coupling mechanisms. This segmentation allows for simplified fabrication of individual layers while maintaining the spectral discrimination capability through the layered structure, reducing overall manufacturing complexity
Solution Approach 2:
An optical coupling medium or reflective layer is introduced as an intermediary between the scintillator layers to enhance light collection efficiency and spectral discrimination. This intermediary element improves the performance of the multi-layer structure without requiring complex tight-binding fabrication techniques, thus reducing manufacturing complexity while maintaining measurement precision
3Measurement precision
If Hybrid Pixel detectors are used for dosimetry, then measurement precision is improved, but device cost and radiation damage resistance deteriorate
Solution Approach 1:
The detector uses scintillator materials and photodetectors that can be replaced if damaged, rather than relying on expensive and fragile hybrid pixel semiconductor structures. The scintillator layers and optical components are designed to be replaceable modules, providing cost-effective dosimetry with acceptable radiation hardness, avoiding the need for expensive radiation-hardened semiconductor devices
Solution Approach 2:
The detector replaces the semiconductor-based charge-collection mechanism of hybrid pixel detectors with an optical detection system using scintillators and photodetectors. This substitution eliminates the vulnerability of semiconductor electronics to radiation damage while maintaining dosimetry precision through optical signal measurement, which is less sensitive to radiation-induced degradation
4Measurement precision
If Phoswich detectors use PMTs for signal detection, then sensitivity is improved, but signal saturation occurs under high-fluence irradiation
Solution Approach 1:
The detection system is segmented into multiple independent photodetector channels, each reading from a specific scintillator layer. This segmentation allows the system to handle high-fluence irradiation by distributing the signal load across multiple channels, preventing saturation in any single channel while maintaining high sensitivity through the combined signal from all layers
Solution Approach 2:
The detector employs dynamic signal processing that adapts to the intensity of incident radiation. The system can switch between different reading modes (e.g., single-channel vs. multi-channel) and adjust gain settings based on the detected signal level, preventing saturation under high-fluence conditions while maintaining sensitivity for low-fluence measurements
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
Enables fast and reliable measurement of high-intensity radiation, avoiding signal saturation and reducing costs compared to existing technologies, with the ability to operate in contactless mode and provide simultaneous particle species identification.
Implementation Method 1
a top layer (2) as GaN scintillator... generates a scintillation spectrum inherent for definite radiation dose
Implementation Method 2
a depth-scan layer (4) made of the high purity silicon (HP-Si) layer (4) acting as a stopping range scanner or microwave-probed photo-conductor
Implementation Method 3
microwave probed photoconductivity amplitude and decay lifetime
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
This invention discloses a hybrid multi-layer sensor (1) and methods for large fluence dosimetry and fluxmetry by using this sensor. The sensor (1) comprises scintillator sensors (2) and a photosensor (4) operating in the pulse-mode as well as in DC-mode, which is separated from the photosensor (2) by the visible spectrum filter (3) made of large conductivity Si-layer. During dosimetry and fluxmetry, the scintillator (2) and the photosensor (4) are scanned by external apparatuses - a fiber-coupled spectrophotometer (8) and the microwave needle-tip antenna connected to a microwave detection system (7). The discrimination of particle species and the particle energies is performed by correlating signals of the scintillator (2) spectrum structure and the microwave probed photoconductivity amplitude and decay lifetime, where the multi-layered scintillator (2) and the photosensor (4) act as the complementary detectors. This multi-layer sensor (1) is designed for contactless dosimetry and fluxmetry, and is complemented with reading apparatuses (7, 8, 14) and irradiation measurement methods for monitoring of harsh radiation facilities and control of mixed particle beams in nuclear reactors, in storages of nuclear fuel waste, in large particle accelerators and neutron spallators.