Plastic Scintillating Fiber with Graded Fluorescent Core

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Solution Overview

Problem

Scintillating fibers with a rectangular cross-section are difficult to produce, leading to high costs and poor optical performance due to unsatisfactory total reflection conditions, which limits their use in elongated or high-sensitivity detectors.

Innovation Solution

A plastic scintillating fiber with a circular cross-section is developed, where the concentration of fluorescent agents in the core increases from the center to the outer periphery, and a multi-clad structure is used to enhance light transmission and reduce light emission variations across the fiber's cross-section.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If scintillating fibers with rectangular cross-section are used, then detection sensitivity can be improved, but manufacturing difficulty increases and production cost rises

Engineering Contradiction:
Improvedetection sensitivityVSAvoidmanufacturing difficulty
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent applies local quality by creating a non-uniform concentration distribution of fluorescent agents within the core, with higher concentration at the center and lower concentration at the periphery. This localized variation in material properties optimizes light emission for radiation crossing at different positions, achieving uniform detection sensitivity across the circular cross-section without requiring complex rectangular geometry.

Inventive Principle:
Principle #3Local quality

2Measurement precision

If scintillating fibers with rectangular cross-section are used, then detection sensitivity can be improved, but production cost increases

Engineering Contradiction:
Improvedetection sensitivityVSAvoidproduction cost
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent changes the concentration parameter of fluorescent agents from uniform to non-uniform distribution. By adjusting the concentration gradient (higher at center, lower at periphery), the system achieves uniform light emission across the cross-section, maintaining detection sensitivity while using a simple circular cross-section that is cheaper to manufacture.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If scintillating fibers with rectangular cross-section are used, then detection sensitivity can be improved, but optical performance deteriorates due to unsatisfactory total reflection conditions

Engineering Contradiction:
Improvedetection sensitivityVSAvoidoptical performance
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent employs a circular cross-section instead of rectangular, utilizing the curved geometry to achieve superior total internal reflection conditions. The circular shape ensures consistent optical path and reflection angles, maintaining high optical performance while combining it with non-uniform fluorescent agent distribution to achieve uniform detection sensitivity.

Inventive Principle:
Principle #14Spheroidality (Curvature)

4Ease of manufacture

If uniform concentration of fluorescent agents is used in circular scintillating fibers, then manufacturing is simplified, but light emission amount varies depending on radiation crossing position

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidlight emission uniformity
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies local quality by creating a non-uniform concentration distribution of fluorescent agents within the core, with higher concentration at the center and lower concentration at the periphery. This localized variation in material properties optimizes light emission for radiation crossing at different positions, achieving uniform detection sensitivity across the circular cross-section without requiring complex rectangular geometry.

Inventive Principle:
Principle #3Local quality

5Power

If high concentration of fluorescent agents is added, then wavelength conversion efficiency is improved, but self-absorption increases and transparency deteriorates

Engineering Contradiction:
Improvewavelength conversion efficiencyVSAvoidself-absorption
Core Design Contradiction:
PowerVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating a non-uniform concentration distribution of fluorescent agents within the core, with higher concentration at the center and lower concentration at the periphery. This localized variation in material properties optimizes light emission for radiation crossing at different positions, achieving uniform detection sensitivity across the circular cross-section without requiring complex rectangular geometry.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the concentration parameter of fluorescent agents from uniform to non-uniform distribution. By adjusting the concentration gradient (higher at center, lower at periphery), the system achieves uniform light emission across the cross-section, maintaining detection sensitivity while using a simple circular cross-section that is cheaper to manufacture.

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 suppresses light emission variations depending on the radiation crossing position, improving detection sensitivity and reducing the formation of insensitive regions, even in detectors with circular scintillating fibers.

Implementation Method 1

one or more organic phosphors are dissolved in the core substrate so as to convert an ultraviolet light emitted by the core substrate under a radiation into a visible light

Methodology Applied
Scientific EffectWavelength conversion: Fluorescence

Implementation Method 2

the first fluorescent agent, which absorbs light having a wavelength of about 300 nm and emits a light having a wavelength of about 350 nm to perform wavelength conversion

Methodology Applied
Scientific EffectAbsorption: Absorption (EM radiation)

Implementation Method 3

a scintillating light generated inside a core 11 propagates toward the respective ends of the scintillating fiber 1 while repeatedly undergoing total reflection at the core 11-clad 12 interface

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP3557288B1Method of producing a plastic scintillation fiber
Publication Date: 2024.08.28 KURARAY CO LTD
  • EP3557288B1 patent drawingFigure 1
  • EP3557288B1 patent drawingFigure 2
  • EP3557288B1 patent drawingFigure 3

AI summary

Provided is a plastic scintillating fiber having a circular cross-section, in which a reduction in light emission amount depending on the radiation crossing position can be suppressed. A plastic scintillating fiber (1) according to one aspect of the present invention is a plastic scintillating fiber having a circular cross-section, the plastic scintillating fiber including: a core (11) which contains a fluorescent agent having ultraviolet absorption and luminescence properties; and a clad (12) which covers the outer peripheral surface of the core (11) and has a lower refractive index than that of the core (11). The concentration of the fluorescent agent in the core (11) is distributed such that it increases from the center toward the outer periphery in a cross-section of the core (11).