Radiation Spectrum Digitization with Pulse-Synchronous Sampling
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Solution Overview
Problem
Conventional semiconductor-based radiation detectors face challenges in synchronizing sampling events with current pulse generation, leading to asynchronous sampling instants that can distort energy spectra, particularly at high photon count rates, requiring expensive and energy-intensive high sampling frequencies.
Innovation Solution
A processing and digitization chain that includes a synchronization circuit to generate pulses synchronous with current pulses from the detector, using a charge pre-amplification circuit, a delay line energy measurement circuit, and a sampler controlled by a discrimination circuit to ensure simultaneous charge counting and measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional asynchronous sampling is used, then the system is simple, but sampling instants do not correspond to maximum voltage peaks leading to measurement errors
Solution Approach 1:
The invention uses a feedback mechanism where the sampling instant is determined by the voltage peak detection itself. The sampling circuit samples the voltage at the moment when the peak detection circuit identifies the maximum voltage, creating a self-regulating system that ensures accurate timing without external synchronization signals.
Solution Approach 2:
The system uses its own output signal (the voltage pulse from the preamplifier) to control the sampling timing. The peak detection circuit monitors the voltage and automatically triggers sampling at the correct instant, eliminating the need for external synchronization hardware and making the system self-sufficient.
2Measurement precision
If sampling frequency is increased to mitigate asynchronous sampling errors, then measurement accuracy improves, but equipment cost and energy consumption increase significantly
Solution Approach 1:
The system performs preliminary detection of the voltage peak before sampling occurs. The peak detection circuit continuously monitors the voltage and prepares the sampling trigger in advance, ensuring that sampling happens at the optimal moment without requiring continuous high-frequency sampling of all signals.
Solution Approach 2:
The invention changes the timing parameter dynamically based on the actual voltage pulse characteristics. Instead of using a fixed high sampling frequency, the system adjusts the sampling instant to coincide with each voltage peak, adapting to the actual signal conditions and avoiding unnecessary high-frequency sampling.
3Measurement precision
If delay time is increased to ensure accurate energy measurement, then measurement accuracy improves, but counting rate capability decreases
Solution Approach 1:
The system uses dynamic timing where the delay is automatically adjusted based on the actual pulse arrival time. The sampling instant is determined by the peak detection circuit in real-time, allowing the system to adapt to varying pulse timings and maintain accurate measurement even at high counting rates where fixed delays would cause signal loss.
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 approach allows for accurate synchronization of digitization with current pulse generation, enabling high counting rates exceeding 10 Megaphotons per second while effectively eliminating pulses from charge stacks, thus improving the accuracy of energy spectrum measurement.
Implementation Method 1
The detector 12 is subjected to photon radiation, for example gamma photons or X photons, which ionize the semiconductor material. The charges thus produced then migrate towards electrodes (not shown) of the detector 12 due to the existence of the HV bias voltage.
Implementation Method 2
The preamplifier 20 includes an amplifier 26 high-gain, mounted in negative feedback with a parallel assembly of a capacity 28, of value C 1, and a resistor 30, of value R 1
Implementation Method 3
The circuit 22 energy measurement comprises a delay line 32, connected to the output of the preamplifier 20 and applying thereto a delay Δ t predetermined
Data Source
Figure 1~3
Figure 4
Figure 5~10
AI summary
The device has a preamplifier (20) connected to a semiconductor detector, and a sampler connected to an energy measuring circuit (22). A synchronization circuit (52) comprises a pulse current measuring circuit (56) connected to the preamplifier and realizes difference between an output and a derivative of the outlet of the preamplifier. A discrimination circuit (66) forms a binary signal based on an output of the circuit (22), where logic signal controls sampling instants of the sampler.