Side-Mounted Scintillator Photodetector Layout for Time Resolution
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Solution Overview
Problem
Existing radiation detectors with scintillators and semiconductor photodetectors struggle to achieve high time resolution due to the detection of scintillation lights with significant time differences when they are incident on different end surfaces, leading to reduced accuracy.
Innovation Solution
The radiation detector design includes a scintillator with a specific shape and orientation, where the semiconductor photodetector is positioned on a side surface, allowing simultaneous detection of scintillation lights with minimal time difference, and incorporates avalanche photodiodes operating in Geiger mode with quenching resistors for improved light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the semiconductor photodetector is disposed on another end surface of the scintillator, then the scintillator can absorb radiation in the high energy range, but the time resolution deteriorates
Solution Approach 1:
The patent transitions from placing the photodetector on the end surface (one-dimensional approach) to placing it on the side surface (two-dimensional approach), changing the spatial dimension of detection. This allows simultaneous capture of scintillation lights from different paths without the large time differences that occur when detecting lights incident on opposite end surfaces
Solution Approach 2:
The patent positions the photodetector specifically on the side surface rather than uniformly across all surfaces. This localized placement optimizes the detection of scintillation lights that pass through the scintillator body, capturing both directly incident and reflected lights with minimal time difference while maintaining reliable radiation absorption
2Reliability
If the scintillator is longer in the first direction, then radiation absorption is improved, but the time difference between detecting scintillation lights increases
Solution Approach 1:
By placing the photodetector on the side surface rather than the end surface, the patent changes the detection geometry. This allows the longer scintillator length in the first direction to be utilized for improved radiation absorption while the side surface detection captures scintillation lights with minimal time difference, as lights from different paths converge at the same detection point
3Adaptability or versatility
If the semiconductor photodetector detects scintillation lights from multiple paths, then detection coverage is improved, but the time resolution deteriorates
Solution Approach 1:
The patent positions the photodetector on the side surface where it can detect scintillation lights from multiple paths (directly incident and reflected lights) with minimal time difference. This localized placement provides broad detection coverage while maintaining high time resolution, as all detected lights arrive at the photodetector nearly simultaneously
Solution Approach 2:
By moving the detection point to the side surface, the patent enables the photodetector to capture scintillation lights from various paths in the scintillator volume. This spatial repositioning allows simultaneous detection of multiple light paths without the large time differences that would occur with end surface detection
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 configuration enhances the time resolution of the radiation detector by reliably detecting scintillation lights with minimal time difference, increasing the amount of light detected and reducing reflection attenuation, thus improving overall detection accuracy.
Implementation Method 1
the scintillator generates a scintillation light in response to entry of radiation
Implementation Method 2
a plurality of avalanche photodiodes arranged to operate in Geiger mode
Implementation Method 3
a plurality of avalanche photodiodes arranged to operate in Geiger mode
Data Source
AI summary
A radiation detector includes: a scintillator including a pair of end surfaces opposing each other in a first direction and one side surface coupling the pair of end surfaces; and a semiconductor photodetector including a semiconductor substrate. A length of the scintillator in the first direction is longer than a length of the scintillator in a second direction orthogonal to the one side surface. A length of the one side surface in the first direction is longer than a width of the one side surface in a third direction orthogonal to the first direction and the second direction. The semiconductor substrate includes a photodetection region disposed in a first portion and a first electrode and a second electrode disposed in a second portion. The photodetection region includes a plurality of avalanche photodiodes arranged to operate in Geiger mode and a plurality of quenching resistors.