A pulse signal self-stable peak nuclear radiation detection system based on FPGA

Abstract

The application discloses a kind of nuclear radiation detection systems based on FPGA of pulse signal self-stable peak, including integrated in FPGA main control module, signal generation module, pulse width measurement module, pulse width discrimination module and counting output module;The signal generation module and the pulse width measurement are respectively with the pulse width discrimination module electric connection, the pulse width discrimination module with the counting output module electric connection;The main control module is respectively with the signal generation module, the pulse width measurement module, the pulse width discrimination module and the counting output module electric connection;The nuclear radiation energy spectrum of the present application is generated using relative threshold pulse width, can exclude the baseline drift caused by the count change error caused by device temperature drift and the baseline drift caused by counting rate change.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of pulse signal technology, and more particularly to a pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA. BACKGROUND

[0002] In nuclear radiation signal detection, the temperature characteristics of the detector and the amplifier, the stability of the high-voltage power supply, and the limit drift caused by the change of the nuclear radiation signal count rate will all affect the output pulse amplitude of the detector, causing the drift of the energy spectrum peak position. In order to obtain accurate counting, a peak stabilizing circuit is often used. A typical peak stabilizing circuit uses 3-4 comparators to divide the spectrum peak into upper and lower half peaks, and the count difference is used as a correction signal to adjust a feedback self-stabilizing system, so that the peak position drift is greatly reduced, and the count rate measurement value is more accurate.

[0003] If there are many detectors in the system or a detector array is used, each detector needs a peak stabilizing circuit and a corresponding feedback self-stabilizing system, resulting in an overly complex system, which is unacceptable in terms of size and power consumption. If a spectrum measurement method is used to identify the corresponding nuclear radiation signal, the system will be more expensive and complicated.

[0004] Therefore, how to reduce the number of peripheral components and provide a small size, low power consumption, multi-channel self-stabilizing peak circuit based on FPGA is a problem that needs to be solved by those skilled in the art. SUMMARY

[0005] Therefore, the present application provides a pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA, which can eliminate the count change error caused by baseline drift due to device temperature drift and count rate change when generating nuclear radiation energy spectrum using a relative threshold pulse width.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] A pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA, comprising a main control module, a signal generation module, a pulse width measurement module, a pulse width discrimination module and a count output module, all integrated in FPGA;

[0008] The signal generation module and the pulse width measurement module are electrically connected to the pulse width discrimination module, and the pulse width discrimination module is electrically connected to the count output module; the main control module is electrically connected to the signal generation module, the pulse width measurement module, the pulse width discrimination module and the count output module.

[0009] Further, the signal generation module is used to generate a reference sampling pulse signal;

[0010] The pulse width measurement module is used for receiving the nuclear radiation detection pulse signal processed by the voltage comparator, measuring the high level duration of the pulse signal by the reference sampling signal, and obtaining a relative threshold pulse width value;

[0011] The pulse width discrimination module is used for calculating the detection pulse width signal amplitude according to the relative threshold pulse width, obtaining the nuclear radiation energy spectrum by cumulative calculation, obtaining the nuclear radiation photoelectric peak in the nuclear radiation energy spectrum, and confirming the low pulse width value and the high pulse width value corresponding to each nuclear radiation photoelectric peak according to the half peak width; and adjusting the energy spectrum drift caused by various reasons, realizing internal tracking adjustment of peak position drift, and locking the radiation signal photoelectric peak.

[0012] The counting output module is used for accumulating the number of detection pulse amplitude signals whose relative threshold pulse widths are located between the low pulse width value and the high pulse width value, and obtaining the final photoelectric peak count.

[0013] Further, the FPGA master control module controls the overall logic, and calculates the low pulse width value and the high pulse width value corresponding to the nuclear radiation photoelectric peak by using the measured relative threshold pulse width.

[0014] Further, the calculation of the pulse width signal amplitude according to the relative threshold pulse width is specifically as follows:

[0015]

[0016] Wherein, V Y is the selected threshold voltage, V0 is the detection pulse width signal amplitude, t Y is the signal high level duration, i.e. the relative threshold pulse width.

[0017] Further, the pulse width measurement module comprises a plurality of signal input interfaces for obtaining a plurality of the nuclear radiation detection pulse signals.

[0018] Further, the pulse width discrimination module comprises a plurality of discrimination sub-modules for performing pulse width discrimination on the pulse signals received by the corresponding respective signal input interfaces.

[0019] Further, the counting output module comprises one or more output ports, and the output port is USART or SPI.

[0020] Further, a box body is further included, a female seat and a power socket are arranged at the top end of the box body, and a signal input interface, a power switch and a running indicator light are arranged on the front face of the box body.

[0021] The present application has the following beneficial effects:

[0022] Compared with the prior art, the pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA provided by the application can realize the exclusion of interference factors such as temperature drift and baseline drift of the output signal of the nuclear radiation detector array, and can obtain accurate nuclear radiation photopeak counting, thereby improving the stability and nuclear sensitivity of the detection system. The parallel capability of the FPGA can be applied to simultaneously access multiple signals, and only one comparator circuit is required for each nuclear radiation signal, and the TDC pulse width measurement, photopeak position judgment, high-low pulse width value adjustment and counting output and other functions of the multiple signals are completed in parallel in the FPGA, thereby saving 2-3 comparators and feedback adjustment circuits for each signal compared with a typical peak stabilization circuit, greatly reducing the number of components for the detector array, saving instrument space, and reducing energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0024] Figure 1 The accompanying drawings are a structural schematic diagram of a pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA provided by an embodiment of the present application.

[0025] Figure 2 The accompanying drawings are a structural schematic diagram of a pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA provided by an embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0027] The embodiment of the present application discloses a pulse signal self-stabilizing peak nuclear radiation detection system based on FPGA, which comprises a main control module, a signal generation module, a pulse width measurement module, a pulse width discrimination module and a counting output module integrated in the FPGA.

[0028] The signal generation module and the pulse width measurement module are electrically connected with the pulse width discrimination module, and the pulse width discrimination module is electrically connected with the counting output module. The main control module is electrically connected with the signal generation module, the pulse width measurement module, the pulse width discrimination module and the counting output module.

[0029] In one embodiment, the signal generating module is configured to generate a reference sampling pulse signal;

[0030] The pulse width measuring module is configured to receive the nuclear radiation detection pulse signal processed by the voltage comparator, measure the high level duration of the pulse signal with the reference sampling signal, and obtain a relative threshold pulse width value;

[0031] The pulse width discriminating module is configured to calculate the detection pulse signal amplitude according to the relative threshold pulse width, obtain a nuclear radiation energy spectrum through cumulative calculation, and obtain nuclear radiation photopeaks in the nuclear radiation energy spectrum, and confirm the low pulse width value and the high pulse width value corresponding to each nuclear radiation photopeak according to the half peak width;

[0032] The counting output module is configured to count the number of detection pulse amplitude signals whose relative threshold pulse widths are between the low pulse width value and the high pulse width value, and obtain a final photopeak count.

[0033] In one embodiment, the pulse width measuring module measures the relative threshold pulse width value of the nuclear radiation signal based on TDC time-to-digital conversion according to the reference square wave signal.

[0034] In one embodiment, the calculation formula of the relative threshold pulse width is as follows:

[0035]

[0036] wherein, V Y is a selected threshold voltage, V0 is a selected voltage amplitude, i.e., the amplitude of the reference pulse signal; t Y is the amplitude of the detection pulse signal. After the circuit parameters are determined, τ and V Y are fixed values, therefore, the fixed threshold pulse width t Y is in a linear relationship with the logarithmic value of the pulse signal amplitude V0.

[0037] Therefore, the fixed threshold pulse width of the measured pulse signal can correspond to the corresponding pulse amplitude, the wider the pulse width, the greater the pulse signal amplitude, and the higher the corresponding nuclear radiation energy. The measured pulse value corresponds to a spectrum, which can be considered as an energy spectrum compressed by logarithm.

[0038] According to the calculation formula of the relative threshold pulse width, when the pulse width measuring module measures the known relative threshold pulse width, the detection pulse signal amplitude is calculated.

[0039] In this embodiment, after the received nuclear radiation is converted into a pulse electrical signal and amplified by the preamplifier and the linear amplifier, an approximately unipolar exponential decay waveform is output, and the expression is as follows:

[0040] V(t)=V0e -t / τ

[0041] Wherein: V(t) is the voltage value at t time, V0 is the pulse amplitude, tau is the time constant of the amplifier circuit, tau=RC, R is the input resistance value of the circuit, C is the coupling capacitance value constant.

[0042] The comparator processes the pulse output by the amplifier, selects a threshold voltage V Y , and outputs a high level pulse with a width of t Y . According to the above formula, we have:

[0043]

[0044] Finally, the pulse width calculation formula is derived.

[0045] In an embodiment, the pulse width measurement module comprises a plurality of signal input interfaces for acquiring a plurality of nuclear radiation detection pulse signals.

[0046] In an embodiment, the pulse width discrimination module comprises a plurality of discrimination sub-modules for discriminating the pulse width of the pulse signals received by the corresponding signal input interfaces.

[0047] In an embodiment, the counting output module comprises one or more output ports, and the output port is a USART interface or a SPI interface.

[0048] In an embodiment, a box body is further included, a female seat and a power socket are arranged at the top end of the box body, and a signal input interface, a power switch and a running indicator light are arranged on the front face of the box body.

[0049] The application uses the PLL of FPEG to generate a 200-400Mhz square wave as a sampling pulse; the pulse width value of the input nuclear radiation signal is measured, the pulse width value of the nuclear radiation signal relative to the fixed threshold value is related to the amplitude of the nuclear radiation signal, the measured pulse width value can obtain the amplitude of the nuclear radiation signal, the cumulative signal amplitude can obtain the response nuclear radiation spectrum, the signals in the photoelectric peak range are statistically discriminated and accumulated, and the photoelectric peak count of the nuclear radiation can be obtained, so that the counting change error caused by the baseline drift caused by the device temperature drift and the counting rate change is excluded.

[0050] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same and similar parts between the embodiments can be referred to each other. For the device disclosed by the embodiments, since it corresponds to the method disclosed by the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0051] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An FPGA-based pulse signal self-stabilizing peak nuclear radiation detection system, characterized in that, The main control module, the signal generation module, the pulse width measurement module, the pulse width discrimination module and the counting output module are integrated in the FPGA. The signal generation module and the pulse width measurement module are electrically connected with the pulse width discrimination module, and the pulse width discrimination module is electrically connected with the counting output module. The signal generation module is used for generating a reference sampling pulse signal. The pulse width measurement module is used for receiving the nuclear radiation detection pulse signal processed by the voltage comparator, measuring the high-level duration of the pulse signal with the reference sampling signal to obtain a relative threshold pulse width value. The pulse width discrimination module is used for calculating the detection pulse signal amplitude according to the relative threshold pulse width, obtaining the nuclear radiation energy spectrum through cumulative calculation, obtaining the nuclear radiation photoelectric peak in the nuclear radiation energy spectrum, and confirming the low pulse width value and the high pulse width value corresponding to each nuclear radiation photoelectric peak according to the half peak width. The counting output module is used for accumulating the number of detection pulse amplitude signals with the relative threshold pulse width between the low pulse width value and the high pulse width value to obtain the final photoelectric peak count. ； wherein τ is the time constant of the amplification circuit, is a selection threshold voltage, is a detection pulse width signal amplitude, is a signal high level duration, i.e. the relative threshold pulse width; The main control module controls the overall logic, and calculates the low pulse width value and the high pulse width value corresponding to the nuclear radiation photoelectric peak by using the measured relative threshold pulse width. The pulse width measurement module includes a plurality of signal input interfaces for obtaining a plurality of nuclear radiation detection pulse signals. 2.The FPGA-based pulse signal self-stabilizing peak nuclear radiation detection system according to claim 1, wherein, The pulse width discrimination module includes a plurality of discrimination sub-modules for performing pulse width discrimination on the pulse signals received by the corresponding signal input interfaces. 3.The FPGA-based pulse signal self-stabilizing peak nuclear radiation detection system according to claim 2, characterized in that, The counting output module includes one or more output ports, and the output port is USART or SPI.

4. The FPGA-based pulse signal self-stabilizing peak nuclear radiation detection system according to claim 1, characterized in that, The box further includes a box body, a female seat and a power socket are arranged at the top end of the box body, and a signal input interface, a power switch and a running indicator lamp are arranged on the front face of the box body.

5. The FPGA-based pulse signal self-stabilizing peak nuclear radiation detection system according to claim 1, characterized in that, ​

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