Avalanche Pixel Sensor Coincidence Logic for Ionizing Radiation Detection
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Solution Overview
Problem
Silicon photomultipliers used in detecting ionizing particles face challenges with signal linearity, leading to reduced detection efficiency due to indistinguishable signals from ionizing particles and thermal noise, causing issues in both intensity and coordinate detection modes.
Innovation Solution
The development of an avalanche pixel sensor with paired sensor elements on opposite surfaces of a substrate, interconnected with logic elements to distinguish between radiation-induced and dark signal events through Boolean logic operations, ensuring accurate detection of ionizing radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If silicon photomultipliers operate in breakdown mode to detect ionizing particles, then signal amplification is achieved, but signal linearity is lost making ionizing particle signals indistinguishable from thermal noise
Solution Approach 1:
The sensor is divided into multiple independent sensor elements (e.g., 6 elements) arranged in a matrix, where each element operates in breakdown mode independently. This segmentation allows individual elements to provide signal amplification while the collective arrangement enables noise discrimination through coincidence logic, resolving the contradiction between amplification and linearity.
Solution Approach 2:
A logic element acts as an intermediary between the sensor elements and the output, implementing coincidence logic to distinguish radiation-induced signals from thermal noise. The logic element receives signals from multiple sensor elements and determines whether they represent valid radiation detection, thereby preserving measurement precision while allowing breakdown mode operation for signal amplification.
2Measurement precision
If sensor elements are arranged in a matrix configuration, then coordinate detection capability is improved, but device complexity increases
Solution Approach 1:
The sensor elements serve multiple functions simultaneously: they detect ionizing particles, provide signal amplification through breakdown mode operation, and enable coordinate detection through their matrix arrangement. Each element is identical and can function independently or in combination with others, reducing overall device complexity through functional universality.
Solution Approach 2:
The sensor elements are integrated onto a single substrate in a matrix configuration, merging multiple detection functions into one compact device. The substrate integrates both the sensor elements and the logic element, combining coordinate detection and radiation detection capabilities in a unified structure that reduces complexity compared to separate systems.
3Reliability
If avalanche breakdown mode is used for signal detection, then detection sensitivity is enhanced, but dark rate pulses increase reducing detection efficiency
Solution Approach 1:
The logic element is configured to perform preliminary discrimination before final detection, using coincidence logic to identify and reject dark rate pulses that occur in single sensor elements. By anticipating and counteracting the noise problem in advance through logical operations, the system maintains high detection sensitivity while preserving detection efficiency.
Solution Approach 2:
The logic element provides feedback processing to the sensor element outputs, continuously monitoring signal patterns and applying coincidence logic to distinguish valid radiation signals from thermal noise. This feedback mechanism dynamically adjusts signal validation based on the operational state of multiple sensor elements, maintaining both sensitivity and 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
This approach enhances the detection efficiency by differentiating between radiation-induced and dark signals, improving the accuracy and precision of ionizing radiation detection, thereby overcoming the limitations of signal linearity and noise interference.
Implementation Method 1
When the charged particle passes the sensitive area of a silicon photomultiplier, it creates an electron hole pair due to ionization process
Implementation Method 2
Due to a high electric field inside the micro-cell, a drifting electron can generate a large number of electron-hole pairs via an avalanche process
Data Source
AI summary
According to an embodiment, an avalanche pixel sensor includes a substrate having opposite first and second surfaces, first sensor elements operating in breakdown mode situated on the first surface of the substrate for detecting ionizing radiation from a radiation-emission source, second sensor elements operating in breakdown mode situated on the second surface of the substrate, the second sensor elements each paired with a corresponding first sensor element to experience substantially coincident breakdown in response to ionizing radiation. Logic elements are each electrically interconnected to a respective pair of first and second sensor elements for receiving a signal or signal representing the substantially coincident breakdown of the respective pair to be distinguished from a dark signal even in either of the pair of the first and second sensor elements. Additionally, a detector array, a sensing apparatus, and a method of detecting ionization radiation using first and second sensor elements disposed on opposite sides of a substrate are also provided.