Neutron Detection Threshold Adjustment for Fiber Degradation

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Solution Overview

Problem

The detection accuracy of neutron beams is degraded due to the deterioration of optical fibers, which affects light transmittance, leading to potential erroneous detection of gamma rays as neutron beams.

Innovation Solution

A neutron beam detection apparatus that includes a scintillator, an optical fiber for transmitting light, and a discrimination section that adjusts the determination threshold value based on the wave height distribution to differentiate between neutron beam and gamma ray signals, even when the optical fiber deteriorates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If an optical fiber is used to transmit light from the scintillator, then the detection device can be compact and flexible, but the light transmittance is degraded due to deterioration caused by radial rays

Engineering Contradiction:
Improvecompactness and flexibilityVSAvoidlight transmittance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent changes the physical-chemical parameters of the optical fiber by introducing a specific coating layer with light-reflecting properties and modifying the fiber structure to create a light-guiding configuration that compensates for transmittance degradation while maintaining compactness

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If the determination threshold value is fixed, then the discrimination section can operate simply, but detection accuracy is degraded when the optical fiber deteriorates

Engineering Contradiction:
Improvesimplicity of discrimination sectionVSAvoiddetection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic determination threshold value that automatically adjusts based on the detected light intensity level. The threshold is set as a percentage (e.g., 10-30%) of the maximum detected signal, allowing the discrimination section to maintain high detection accuracy while adapting to optical fiber deterioration without increasing system complexity

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system uses feedback from the detected signal distribution to automatically adjust the determination threshold. By monitoring the light intensity patterns and using statistical methods (such as setting threshold at mean + 2σ), the system compensates for optical fiber degradation and maintains accurate neutron beam detection

Inventive Principle:
Principle #23Feedback

3Measurement precision

If the determination threshold value is lowered to account for light transmittance degradation, then detection sensitivity is maintained, but gamma ray signals may be erroneously detected as neutron beam signals

Engineering Contradiction:
Improvedetection sensitivityVSAvoiddetection accuracy
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

Rather than using a fixed lowered threshold, the patent implements a dynamic threshold that scales with the detected signal distribution. The threshold is calculated as a percentage of the maximum signal or using statistical parameters (mean + 2σ), which automatically adapts to maintain both sensitivity and accuracy even when optical fiber transmittance changes

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the threshold determination method from a fixed value to a relative value that depends on the signal distribution characteristics. This parameter change allows the system to maintain optimal detection performance across different conditions including optical fiber deterioration

Inventive Principle:
Principle #35Parameter changes

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

This approach prevents the degradation of neutron beam detection accuracy by dynamically adjusting the threshold value, ensuring accurate discrimination between neutron beam and gamma ray signals even with deteriorated optical fibers.

Implementation Method 1

a scintillator configured to generate light when a radial ray is incident thereon

Methodology Applied
Scientific EffectScintillation: Scintillation

Implementation Method 2

an optical fiber configured to cause the light generated in the scintillator to be transmitted therethrough

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3006961B1Neutron radiation detection device and neutron capture therapy device
Publication Date: 2019.02.27 SUMITOMO HEAVY IND LTD
  • EP3006961B1 patent drawingFigure 1
  • EP3006961B1 patent drawingFigure 2
  • EP3006961B1 patent drawingFigure 3

AI summary

A neutron beam detection apparatus includes a scintillator configured to generate light when a radial ray is incident thereon, an optical fiber configured to cause light generated in the scintillator to be transmitted therethrough, and a discrimination section configured to receive light transmitted through the optical fiber and to discriminate a detection signal from a signal related to a neutron beam when a wave height of a detection signal related to the received light exceeds a determination threshold value Qth. The discrimination section adjusts the determination threshold value in accordance with deterioration of the optical fiber.