Dynamic Pulse Shaping Circuit for Ionizing Radiation Detectors
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Solution Overview
Problem
Ionizing radiation detectors face challenges in maintaining energy resolution and accuracy at high counting rates, particularly with low-volume detectors exposed to intense radiation, where pulse stacking occurs, leading to unreliable energy estimates.
Innovation Solution
A method involving a processing circuit with two shaping durations, where the second shaping duration can be greater or less than the first, and a correction factor is applied to ensure reliable energy estimation by compensating for temporal drift in conversion gain, using a comparison of amplitudes from pulses shaped with different durations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the shaping time is reduced to limit pulse stacking at high counting rates, then the occurrence of pile-ups is limited, but the energy resolution deteriorates
Solution Approach 1:
The patent applies dynamics by making the shaping time variable rather than fixed. The processing circuit dynamically adjusts the shaping duration based on the detected pulse amplitude: longer shaping times are applied to smaller pulses to improve energy resolution, while shorter shaping times are applied to larger pulses to prevent stacking artifacts. This dynamic adaptation allows the system to optimize both energy resolution and stacking rejection simultaneously.
Solution Approach 2:
The patent changes the parameter of shaping time from a static value to a variable parameter that depends on pulse characteristics. By modifying the shaping duration parameter according to the pulse amplitude, the system resolves the contradiction between maintaining good energy resolution and preventing pulse stacking at high counting rates.
2Measurement precision
If the shaping time is increased to improve energy resolution, then the energy resolution is improved, but pulse stacking occurs more frequently at high counting rates
Solution Approach 1:
The system dynamically selects the appropriate shaping time constant based on the pulse amplitude. For small pulses where energy resolution is critical, longer shaping times are used. For large pulses that are more prone to stacking, shorter shaping times are applied. This dynamic behavior allows the system to maintain high counting rates while preserving energy resolution where needed.
Solution Approach 2:
The shaping time parameter is changed from a fixed value to a variable that adapts to the pulse characteristics. This parameter change enables the system to optimize the trade-off between energy resolution and stacking rejection on a pulse-by-pulse basis, thereby improving both measurement precision and productivity simultaneously.
3Device complexity
If a single shaping circuit with fixed shaping time is used, then the device complexity is low, but it cannot maintain reliable energy estimation under varying counting rates
Solution Approach 1:
The patent introduces dynamic adaptability into the shaping circuit by making the shaping time variable based on pulse amplitude. This dynamic feature allows a single circuit to effectively handle varying counting rates and pulse conditions, maintaining reliable energy estimation without requiring multiple fixed shaping circuits for different operating conditions.
Solution Approach 2:
The processing circuit achieves multi-functionality by incorporating variable shaping time capability into a single circuit design. This universal circuit can adapt to different pulse conditions and counting rates, replacing the need for multiple specialized circuits while maintaining or improving energy estimation reliability across varying operational conditions.
Data Source
Figure 1A~2B
Figure 2C~3D
Figure 4A~4B
AI summary
The invention is a method for processing a pulse (S) generated by an ionizing radiation detector (10), the detector (10) being capable of interacting with ionizing radiation (5) to generate said pulse, the amplitude (A) of which depends on an energy released by the ionizing radiation during its interaction in the detector, the method comprising the following steps: a) exposing the detector to a source of ionizing radiation (2) so as to obtain, at a measurement instant (t), a pulse (S), called the measurement pulse; b) shaping the measurement pulse, considering a first shaping time (δt1), and determining a first amplitude (A'1) of the pulse thus shaped; c) correcting the first amplitude measured in step b), taking into account a correction factor (n); the correction factor being determined by taking into account pulses, called pulses of interest (S1 ... .SN,Scalib), formed by the detector during exposure to the source or to a calibration source, during a time range of interest (Δt).