Alkaline-Earth Halide Scintillator Sm2+ Co-Doping
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Solution Overview
Problem
Existing scintillators face challenges in achieving large volume with minimal self-absorption, which affects energy resolution, and often contain radioactive isotopes that interfere with precise radiation measurements.
Innovation Solution
A crystalline alkaline earth halide scintillator doped with Samarium (Sm2+) is co-doped to shift the scintillation emission wavelength beyond 670 nm, reducing self-absorption and eliminating intrinsic radioactivity, allowing for high light intensity and transparency to its own emitted light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If rare earth halides such as LaBr3:Ce or LaCl3:Ce are used as scintillators, then high light intensity is achieved, but radioactive isotopes interfere with precise radiation measurements
Solution Approach 1:
The invention changes the chemical composition parameters by using alkaline earth halides (SrI2, BaI2, CaI2) instead of rare earth halides, and by co-doping with specific concentrations of Sm2+ (0.1-5 mol%) and Eu2+ (0.1-5 mol%). This parameter change eliminates intrinsic radioactivity while maintaining high light intensity through the activator-doped crystal structure.
Solution Approach 2:
The invention creates a composite scintillator material by combining alkaline earth halide matrix with multiple dopants (Sm2+ and Eu2+). This composite approach allows the material to achieve both low radioactivity (from the alkaline earth base) and high light intensity (from the activator dopants), resolving the contradiction between these two properties.
2Volume of moving object
If scintillator volume is increased to greater than 1 cm3 for effective radiation detection, then detection capability is improved, but self-absorption of emitted light increases
Solution Approach 1:
The invention changes the optical parameter by shifting the emission wavelength to beyond 670 nm through Sm2+ co-doping. This wavelength shift reduces the overlap between emission spectrum and absorption spectrum, thereby reducing self-absorption losses and enabling large volume scintillators to maintain high light transmission efficiency.
3Loss of energy
If emission wavelength is shifted beyond 670 nm through Sm2+ co-doping, then self-absorption is reduced, but photodetector sensitivity requirements increase
Solution Approach 1:
The invention optimizes the emission wavelength parameter to the range beyond 670 nm (specifically 750-850 nm for Sm2+). While this requires photodetectors sensitive to these wavelengths (such as red-extended PMTs or SiPMs), the significant reduction in self-absorption losses more than compensates for the photodetector requirement, resulting in net improved detection efficiency.
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 results in a scintillator with improved energy resolution and reduced self-absorption, enabling precise ionizing radiation detection without interference from intrinsic radioactivity, using a photodetector sensitive to the shifted emission wavelength.
Implementation Method 1
The scintillator material receives ionizing radiation, which causes it to emit scintillation light
Implementation Method 2
Rare earth halides such as LaBr3:Ce or LaCl3:Ce... are scintillators with high light intensity
Implementation Method 3
The scintillators used may in particular be made of a single crystal of sodium iodide doped with thallium... cesium iodide doped with thallium or sodium... which is then transformed into an electrical signal using a photodetector such as a photomultiplier
Data Source
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AI summary
The invention relates to a scintillator material for an ionising radiation detector, comprising a crystalline alkaline-earth halide including at least one alkaline earth selected from among Mg, Ca, Sr, Ba, said alkaline-earth halide being doped with at least one scintillation activator dopant different from Sm2+, and co-doped with Sm2+, said alkaline-earth halide comprising at least one halide selected from among Br, Cl, I.