Sub-pixelated Radiation Detector Charge Sharing Correction
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Solution Overview
Problem
CZT pixelated radiation detectors face challenges in accurately resolving gamma-ray energy due to charge sharing between pixels, which results in inefficiencies and errors in measured spectra, particularly due to inter-pixel gap charge loss and variations in surface passivation.
Innovation Solution
The method involves subdividing each pixel into sub-pixel detectors and using processing circuitry to measure and correct for charge sharing effects by determining a sub-pixel charge sharing correction factor, which is applied to energy measurements from simultaneous detection events across multiple sub-pixels, thereby improving the accuracy of gamma photon energy spectra.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If pixels are subdivided into sub-pixel detectors to reduce dark current, then dark current is reduced, but charge sharing between sub-pixels increases
Solution Approach 1:
Each pixel is divided into multiple sub-pixel detectors (e.g., 2x2 or 3x3 arrangement), reducing the area of individual detector elements and thereby reducing dark current generation in each sub-pixel while maintaining the overall pixel functionality
Solution Approach 2:
The system detects simultaneous coincidence events across multiple sub-pixels and applies a charge sharing correction factor to the summed energy measurements, using feedback from the detection pattern to correct for charge sharing losses and recover accurate photon energy information
2Measurement precision
If charge sharing correction is applied to improve energy resolution, then measurement precision improves, but device complexity increases
Solution Approach 1:
Processing circuitry acts as an intermediary that receives signals from multiple sub-pixels, detects simultaneous coincidence events, sums energy measurements, applies correction factors, and outputs corrected energy spectra, thereby managing the complexity of charge sharing correction in a systematic manner
3Measurement precision
If sub-pixel simultaneous detection events are summed to recover full energy, then measurement precision improves, but loss of information increases due to charge sharing
Solution Approach 1:
The system uses feedback from detecting simultaneous coincidence events across sub-pixels to identify charge sharing patterns, then applies correction factors based on these patterns to recover the full photon energy that would otherwise be lost due to charge sharing in the inter-sub-pixel gaps
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 energy resolution and efficiency of gamma-ray detection by compensating for charge sharing, reducing dark current, and accounting for inter-pixel gap charge loss, leading to more accurate spectral measurements and improved detector performance.
Implementation Method 1
The electrical signal generated by solid state radiation detectors, such as CZT detectors, results from gamma-rays exciting electrons in the atoms of the material that eject electrons from their orbits and into a conduction band of the bulk material
Implementation Method 2
Each electron ejected into the conduction band leaves behind a net positive charge that behaves like a positively charged particle known as a 'hole' that migrates through the material in response to an electric field applied between a cathode and an anode
Data Source
AI summary
Various aspects include methods of compensating for issues caused by charge sharing between pixels in pixel radiation detectors. Various aspects may include measuring radiation energy spectra with circuitry capable of registering detection events occurring simultaneous or coincident in two or more pixels, adjusting energy measurements of simultaneous-multi-pixel detection events by a charge sharing correction factor, and determining a corrected energy spectrum by adding the adjusted energy measurements of simultaneous-multi-pixel detection events to energy spectra of detection events occurring in single pixels. Adjusting energy measurements of simultaneous-multi-pixel detection events may include multiplying measured energies of simultaneous-multi-pixel detection events by a factor of one plus the charge sharing correction factor.