Radiation Pulse Detector Count Rate Estimation Under Pulse Pileup
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Solution Overview
Problem
Existing methods for estimating input count rate in radiation pulse detectors, such as those involving dead time corrections, fail to provide accurate measurements at high count rates due to pulse pileup and sensitivity issues, leading to underestimation and complexity.
Innovation Solution
A method that selectively uses only reliable intervals between detected pulse arrivals by choosing start times that ensure no undetected pulses are included, using a specified detection gap to compute an unbiased estimator of the input count rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional dead time correction methods are used to estimate input count rate, then the measurement can be performed with existing techniques, but the accuracy deteriorates at high count rates due to pulse pileup
Solution Approach 1:
The method segments the detected pulse arrivals into reliable and unreliable intervals based on a specified detection gap parameter. By dividing the count rate estimation into segments (using only intervals greater than the detection gap), the method eliminates the influence of pulse pileup on the estimation accuracy while maintaining simplicity.
Solution Approach 2:
The method intentionally uses only a partial subset of the detected pulse intervals for estimation - specifically, only those intervals that exceed the specified detection gap. This partial action approach discards potentially unreliable data (intervals shorter than the gap) to ensure the accuracy of the remaining estimation, trading some data utilization for improved precision.
2Measurement precision
If all detected pulse intervals are used for count rate estimation, then the statistical accuracy improves, but the bias increases due to inclusion of unreliable piled-up pulse intervals
Solution Approach 1:
The method performs a preliminary filtering action before the actual count rate estimation by establishing a detection gap criterion. Intervals shorter than this gap are pre-identified and excluded from the estimation calculation, ensuring that only reliable intervals contribute to the final result. This preliminary action prevents biased estimation while maintaining computational efficiency.
Solution Approach 2:
The detection gap parameter is determined based on the intrinsic characteristics of the detector system and pulse shapes, allowing the method to self-adjust and identify reliable intervals without requiring external calibration or complex modeling of detector dead time. The system uses its own operational parameters to define the estimation window.
3Reliability
If a specified detection gap is introduced to ensure reliable intervals, then the unbiased estimation is achieved, but the number of usable data points decreases
Solution Approach 1:
The method introduces a variable detection gap parameter that can be adjusted based on the specific application requirements, detector characteristics, and desired balance between reliability and data quantity. By changing this parameter, users can optimize the trade-off between using more data points (smaller gap) and ensuring higher reliability (larger gap) for their specific needs.
Data Source
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AI summary
The invention provides a method of estimating an input count rate of a radiation pulse detector from a detector signal where some individual signal pulses making up the detector signal are closely spaced in time less than a minimum reliable detection gap (104,105; t c , t d ). In one aspect, the individual signal pulses are detected using a detection algorithm and a plurality of interval start times (s k ) are defined each interposed with at least one of the detected individual signal pulse arrival times ( t k ), each interval start time (s k ) being later by at least the minimum reliable detection gap than a corresponding most recent detected individual signal pulse arrival time ( t k -1). A corresponding plurality of individual signal pulse arrival intervals are calculated between each of the interval start times (s k ) and a corresponding next detected individual signal pulse arrival time ( t k ).