3D Position-Sensitive Radiation Detection via Electron Drift Time
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current semiconductor radiation detectors, particularly CdZnTe detectors, face challenges with energy resolution due to hole trapping, material non-uniformity, and electron trapping, limiting their ability to accurately determine radiation characteristics in multiple-pixel events.
Innovation Solution
A method and system that utilize electron drift time data to calculate cathode-to-anode signal ratios, accessing calibration look-up tables to correct for energy deposition and account for crosstalk effects, interaction depth, and lateral positioning of pixels, enabling improved energy resolution in multiple-pixel events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If CdZnTe detectors are used for room-temperature gamma ray detection, then detection efficiency and energy resolution are improved, but electron trapping and material non-uniformity cause signal amplitude variation depending on interaction location
Solution Approach 1:
The patent transitions from two-dimensional charge sensing (coplanar anodes) to three-dimensional position sensing by measuring electron drift time in addition to charge distribution. This adds a temporal dimension (drift time measurement) to the spatial charge collection data, enabling depth resolution and correction of position-dependent effects throughout the detector volume.
Solution Approach 2:
The patent measures and utilizes electron drift time as an additional parameter to characterize charge carrier behavior. By measuring the time for electrons to drift from their creation point to the anode, the system can determine interaction depth and apply position-dependent correction factors to compensate for electron trapping and material non-uniformity effects.
2Measurement precision
If coplanar or pixellated anodes are used to minimize hole-trapping, then energy resolution improves for larger volume detectors, but material non-uniformity and spatially varying electron trapping still limit resolution
Solution Approach 1:
The patent implements a feedback mechanism where measured electron drift times and charge signals are used to calculate interaction position, which then informs the application of correction factors. The system continuously adjusts for position-dependent effects by using the measured drift time to determine the interaction location and applying appropriate correction factors from lookup tables or algorithms.
Solution Approach 2:
The patent pre-calculates and stores correction factors in lookup tables that account for electron trapping and material non-uniformity at different positions within the detector. These correction factors are determined in advance through calibration measurements and are ready for immediate application during data analysis, eliminating the need for complex real-time calculations.
3Measurement precision
If three-dimensional position information is measured for single-pixel events, then material non-uniformity and electron trapping effects are addressed, but multiple-pixel events cannot be correctly determined
Solution Approach 1:
The patent creates a universal correction framework that handles both single-pixel and multiple-pixel events through the same methodology. The electron drift time measurement and position-dependent correction approach works regardless of whether the event deposits energy in one pixel or multiple pixels, making the system adaptable to various event types without requiring separate processing algorithms.
Solution Approach 2:
The patent combines charge signal information from multiple anode pixels with electron drift time measurements to reconstruct the complete interaction history. By merging the spatial information from multiple pixel charges with the temporal drift time data, the system can determine interaction positions and apply corrections even when gamma rays interact with multiple pixels simultaneously.
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 approach enhances energy resolution by correcting for material non-uniformity and electron trapping, achieving better than theoretical limits in radiation detection, particularly for multiple-pixel events, and supports real-time 3-D CZT spectrometry.
Implementation Method 1
charge carriers (e.g., electrons) are generated via electron ionization
Implementation Method 2
Both negative and positive charge carriers, such as electrons and holes in a semiconductor device, then move toward, and are eventually collected by, an anode (a positively biased electrode)
Implementation Method 3
The induced signals on the electrodes are proportional to the number of charge carriers
Data Source
AI summary
Disclosed herein is a method of determining a characteristic of radiation detected by a radiation detector via a multiple-pixel event having a plurality of radiation interactions. The method includes determining a cathode-to-anode signal ratio for a selected interaction of the plurality of radiation interactions based on electron drift time data for the selected interaction, and determining the radiation characteristic for the multiple-pixel event based on both the cathode-to-anode signal ratio and the electron drift time data. In some embodiments, the method further includes determining a correction factor for the radiation characteristic based on an interaction depth of the plurality of radiation interactions, a lateral distance between the selected interaction and a further interaction of the plurality of radiation interactions, and the lateral positioning of the plurality of radiation interactions.