Charge Sharing Correction for Pixelated Radiation Detector Arrays

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Solution Overview

Problem

Charge sharing between pixels in pixilated CZT radiation detectors leads to inaccuracies in energy measurement and efficiency losses due to charge loss in the inter-pixel gap, which varies with surface passivation quality and temperature, making it difficult to achieve precise energy resolution and detector efficiency.

Innovation Solution

A method to compensate for charge sharing by calculating a charge sharing correction factor based on peak energy values from single and multi-pixel events, adjusting energy measurements of coincident events, and combining these to create a corrected energy spectrum, which involves determining the charge sharing correction factor as (Vpeak1−Vpeak2)/Vpeak2 and applying it to the energy measurements of multi-pixel events.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If charge sharing correction is applied to multi-pixel events, then energy measurement accuracy is improved, but device complexity increases due to additional processing steps and correction factor calculations

Engineering Contradiction:

Improveenergy measurement accuracyVSAvoidprocessing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The charge sharing correction factor is pre-calculated and stored in a lookup table during system calibration, eliminating the need for complex real-time calculations. The processing system simply retrieves the pre-computed correction factor from the table based on the event characteristics, significantly reducing operational complexity while maintaining high measurement accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of performing complex mathematical operations to determine charge sharing corrections, the system uses pre-computed correction factors that replicate the results of complex calculations. These correction factors are derived from simulated or measured charge sharing characteristics and stored as reference data, allowing rapid application without repeating the complex analysis each time.

Inventive Principle:

Principle #26Copying

2Productivity

If charge sharing correction factor is calculated using peak energy values from single and multi-pixel events, then detector efficiency is improved, but measurement processing time increases

Engineering Contradiction:

Improvedetector efficiencyVSAvoidprocessing time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The correction factor is determined in advance through calibration procedures or simulation, with the results stored in a lookup table. During actual operation, the system simply queries the pre-computed correction factor from the table rather than performing time-consuming calculations in real-time, thus maintaining high detector efficiency while minimizing processing time delays.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces complex real-time computational operations with simpler data retrieval operations from pre-computed lookup tables. This substitution of calculation-based processing with data-based processing dramatically reduces processing time while preserving the accuracy and efficiency benefits of charge sharing correction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 method improves the accuracy of energy spectra and detector efficiency by correcting for charge sharing, resulting in a 40-50% increase in efficiency while maintaining energy resolution, and can be calibrated during manufacturing and service to account for variations in inter-pixel gap charge loss.

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 ejects electrons from their orbits and into a conduction band of the bulk material

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

Each gamma-ray will generate many electron-hole pairs, depending upon the energy of the photon. For example, the ionization energy of CZT is 4.64 eV, so absorbing the energy of a 140 keV gamma ray from Technetium will generate about 30,000 electron-hole pairs

Methodology Applied

Scientific EffectIonization: Ionisation

Implementation Method 3

Charge sharing between pixels in pixilated CZT radiation detectors leads to inaccuracies in energy measurement and efficiency losses due to charge loss in the inter-pixel gap

Methodology Applied

Scientific EffectCharge sharing:

Data Source

PatentUS10928527B2Charge sharing correction methods for pixelated radiation detector arrays

Publication Date: 2021.02.23 REDLEN TECH

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.