Neutron Detector With Nested Scintillators And Coincidence Circuit
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Solution Overview
Problem
Conventional neutron image detectors using ZnS/6LiF half transparent type scintillators and wavelength shift fibers face challenges in high detection efficiency and gamma ray sensitivity, particularly in vacuum environments, and are limited by the availability and cost of 3He gas, necessitating a more efficient and cost-effective alternative.
Innovation Solution
A neutron detector with a sandwich structure incorporating ZnS phosphor and 6Li or 10B converter materials, combined with coiled wavelength shift fibers, achieves high detection efficiency by using multiple scintillators and reducing gamma ray sensitivity through coincidence measurement, and is designed to operate without 3He gas, ensuring vacuum integrity and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional neutron image detectors using ZnS/6LiF half transparent type scintillators and wavelength shift fibers are used, then the detector can operate in vacuum environments, but the detection efficiency is limited and gamma ray sensitivity remains high
Solution Approach 1:
The patent implements a nested structure where multiple scintillator layers (first and second scintillators) are positioned around the optical fiber in concentric arrangements. The first scintillator is directly coupled to the optical fiber, while the second scintillator surrounds it, creating a nested detection system that increases neutron interaction probability without compromising vacuum compatibility
Solution Approach 2:
The detection system is segmented into multiple independent scintillator layers rather than using a single thick scintillator. This segmentation allows each layer to contribute to detection while maintaining optical fiber signal transmission capabilities, achieving high detection efficiency through cumulative effect of multiple segments
2Measurement precision
If the thickness of the scintillator is increased to improve neutron detection efficiency, then more neutrons can be detected, but gamma ray sensitivity increases and the half transparent type scintillator becomes less effective
Solution Approach 1:
The patent transitions from using a single thick scintillator layer to a multi-layer radial arrangement around the optical fiber. This dimensional change from one-dimensional thickness increase to three-dimensional radial nesting allows increased neutron detection probability while maintaining thin individual layers that are less sensitive to gamma rays
Solution Approach 2:
The system uses composite scintillator structures with different materials (ZnS/6LiF and other scintillator materials) arranged in multiple layers. Each material layer is optimized for specific detection requirements, creating a composite detection system that achieves high neutron efficiency while managing gamma ray sensitivity through material diversity
3Measurement precision
If 3He gas proportional counters are used to achieve high detection efficiency, then neutron detection performance is excellent, but the cost increases significantly and 3He gas availability decreases
Solution Approach 1:
The patent replaces expensive and increasingly scarce 3He gas with solid scintillator materials that are more abundant and cost-effective. The scintillator-based detection system achieves comparable detection efficiency using materials that do not face the same supply constraints and cost increases as 3He gas
Solution Approach 2:
The patent substitutes the gas-filled proportional counter mechanism with a solid-state scintillator optical detection system. This replacement eliminates the need for 3He gas while achieving similar or superior detection performance through light emission and optical fiber signal transmission
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 solution achieves a detection efficiency comparable to 3He gas proportional counters while minimizing gamma ray sensitivity and eliminating the need for expensive 3He gas, providing a stable and cost-effective neutron detection system suitable for high-vacuum applications.
Implementation Method 1
ZnS phosphor mixed with 6LiF is used as a neutron scintillator
Implementation Method 2
a neutron detection body which includes a ZnS phosphor and a neutron converter material which contains 6Li or 10B
Implementation Method 3
wavelength shift fibers, where two wavelength shift fibers are wound in parallel along the cylindrical substrate
Implementation Method 4
detecting it by a photomultiplier tube
Data Source
AI summary
A neutron detector with a unique neutron detecting element is disclosed. The neutron detecting element has an inner cylindrical neutron scintillator where a neutron detection body including a ZnS phosphor, and a neutron converter material which contains 6Li or 10B is arranged outside of the cylindrical substrate; a scintillator fluorescence detection body made by placing coiled wavelength shift fibers where two wavelength shift fibers are wound in parallel along the cylindrical substrate on said inner cylindrical neutron scintillator; and an outer cylindrical neutron scintillator where a neutron detection body is arranged inside of the cylindrical substrate, the outer cylindrical neutron scintillator being arranged on the scintillator fluorescence detection body. The fluorescence signals converted into pulse signals by two optical detectors are led to a coincidence circuit, and when two fluorescence signals are measured simultaneously during the predetermined period of time, a neutron signal is output.