Gated truncated readout system
Inventors
Assignees
Jefferson Science Associates LLC
Publication Number
US-11694423-B2
Publication Date
2023-07-04
Expiration Date
2039-10-18
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Abstract
A gated truncated readout system for position sensitive or imaging detectors that improves resolution over traditional readout systems. The readout system includes two or more amplifiers that receive a multichannel output analog data from the detector. Analog gates control circuitry, included in the readout circuit, receives the signals from the amplifiers, determines a fractional value of the sum-integral of the signals, and enables analog gates operation around an area of interest, disabling all other channels where noise dominates the signal value and thereby improving interpolation accuracy of the signals centroid position and the detector resolution. Filtered signals are transmitted to a centroid interpolation signal processing device for computation of the centroid position. As a result disabling all channels where noise dominates the signal value, the gated truncated readout system provides better accuracy improved detector resolution.
Core Innovation
The present invention is a gated truncated readout system designed for position sensitive or imaging detectors, which improves resolution accuracy over traditional readout systems. The system receives multichannel output analog data from the detector via two or more amplifiers. It includes analog gates control circuitry that determines a fractional value of the sum-integral of the signals and enables operation of analog gates around an area of interest while disabling other channels where noise dominates the signal value. This gating process improves the interpolation accuracy of the signals' centroid position and thus enhances detector resolution.
The invention addresses the problem inherent in conventional center-of-gravity (COG) determination algorithms, where noise from remote or low-signal channels improperly receives weighting coefficients that pull the computed centroid position away from its true location, degrading accuracy. Thermal noise in channels outside the area of interest can cause false centroid positions. To solve this, the gated truncated readout system implements a fraction of sum rejection filter approach through analog gating, effectively gating out channels dominated by noise and focusing processing on the area of interest to improve position resolution.
The readout system circuit includes a summing amplifier producing an analog sum of all detector outputs, an analog stretcher circuit to hold this sum for signal processing duration, and a set of analog comparators controlled by a fraction adjustment divider. The comparators enable linear analog gates or switches for each channel only if the amplitude is above a selected fraction of the sum, thereby blocking channels dominated by noise. The gating logic is reset after each event acquisition cycle. This hardware-level noise rejection avoids nonlinearities or amplitude distortion within the area of interest signals, maintaining signal integrity while improving COG position accuracy.
Claims Coverage
The patent includes three independent claims covering the noise reduction system, the method for reducing noise in multichannel readout systems, and corresponding system components that provide improved position resolution.
Noise reduction system using analog sum and gating
A noise reduction system comprising a position sensitive device with analog output channels, analog data delay units per channel, an analog summing amplifier to create a sum signal, an analog stretcher circuit to extend the sum signal duration, an amplitude discriminator with adjustable threshold to trigger events, a noise rejection threshold varying proportionally to the sum amplitude to cut off low amplitude channels, analog comparators for each channel, and analog switches controlled by discriminator and comparator outputs.
Method for reducing noise to improve center of gravity determination
A method comprising providing position sensitive devices with analog outputs, amplifying analog signals per channel, delaying signals to allow gating triggers, summing all outputs, stretching the sum signal to enable processing, setting a fraction of sum threshold to cut off low amplitude outputs, using comparators and gates controlled by fraction of sum signal to open gates only for channels above threshold, creating event triggers via amplitude discriminator with noise rejection threshold, and adjusting said threshold to suppress noise and start each analog event.
The independent claims collectively cover the hardware and method for analog signal processing featuring summing, fraction-based gating, noise rejection thresholds, and time stretching to improve accuracy of position interpolation by selectively enabling only channels with signals above a fraction of the total summed signal.
Stated Advantages
Improves interpolation accuracy of signal centroid position resulting in better detector resolution.
Eliminates errors inherent in conventional center-of-gravity determinations caused by noise from remote or low-signal inputs.
Provides analog noise rejection at hardware level without introducing nonlinear gain or partial amplitude cutting of area of interest pulses.
Maintains signal shape and amplitude integrity within area of interest signals.
Expands sensitive area and improves image or position contrast for position sensitive detectors.
Documented Applications
Applicable to position sensitive detectors including radiation imaging detectors and 2-D position sensitive detectors.
Suitable for use with multi-anode or position sensitive photomultipliers (PS-PMTs), PMT arrays, semiconductor sensor arrays, and multi-output position sensitive solid state detectors.
Implemented with gamma cameras having arrays of photomultiplier tubes and pixelated crystal arrays to improve position resolution in image projections.
Applicable especially to SiPM or MPPC arrays which suffer from temperature-dependent random noise, improving their position resolution enhancement.
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