Differential mode signal processing method and system for liquid scintillation spectrometer

Abstract

The invention discloses a differential mode signal processing method for a liquid scintillation spectrometer, which comprises the following steps of: performing nuclear decay on a sample in the liquid scintillation spectrometer, and exciting scintillation liquid to flicker to generate an optical signal; the N detectors capture optical signals and output the optical signals in the form of N differential mode signals; amplification processing is completed through a differential mode amplification circuit; respectively carrying out differential comparison processing and N-path addition processing, and respectively inputting the processed signals into the FPGA chip; and the FPGA chip completes counting and multi-channel function output spectral line processing. The invention also discloses a liquid scintillation spectrometer differential mode signal processing system based on the method. The system comprises N detectors, a differential mode amplification circuit, a conversion circuit and an FPGA chip. Compared with circuit processing such as complex signal adjustment, multi-stage amplification, alignment, discrimination and peak holding of traditional liquid flash, the liquid flash detection device is more economical, efficient, stable and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear radiation measurement, and in particular, to a differential mode signal processing method and system for a liquid scintillation spectrometer. Background Art

[0002] In the nuclear radiation measurement industry, as a β-ray detection device, the liquid scintillation spectrometer has a wide range of applications, such as archaeological determination of the age of items, radioactive detection of nuclear wastewater, nuclear pollution detection of seafood, medical physical examinations, etc., and has an irreplaceable position.

[0003] The liquid scintillation mainly consists of two parts: one is the counting function part that counts the number of signal pulses, and the other is the multi-channel function part that extracts the amplitude of the signal pulses. The counting function needs to identify as many real signals as possible, while the multi-channel function needs to accurately extract the amplitude of the real signal as much as possible. Due to the characteristics of the measurement method used by the liquid scintillation, the energy amplitude forms a continuous energy spectrum diagram distributed according to a certain law from zero to the maximum energy of the measured nuclide. Therefore, the corresponding signal amplitude near the absolute zero amplitude will inevitably be submerged by noise. In this case, the larger the signal amplitude, the smaller the possibility of the signal being submerged by noise, and the higher the detection efficiency.

[0004] Most of the traditional liquid scintillation detector designs use a general photomultiplier tube design, and the general photomultiplier tube design is single-ended output. The so-called single-ended output means that with the reference ground as the zero potential, the output signal either changes to the positive polarity and is called a positive signal, or changes to the negative polarity and is called a negative signal. Both the positive signal and the negative signal are single-ended output signals. As Figure 2 shown, since the 3 detectors 3 need to be fixedly installed at a certain angle in the sample chamber 1 and need to be close to the sample 2 to be measured, the output signal of the photomultiplier tube often needs to be output a certain distance to the signal processing unit, generally requiring a wire length of 2 to 3 meters. The signal wire is prone to electromagnetic interference when running in the air. To avoid this electromagnetic interference, most liquid scintillation manufacturers use high-speed shielded wires for output, relying on the grounded shielding layer to resist external electromagnetic interference. However, due to the large-area grounding of the system, it is easy to introduce noise through the ground wire, resulting in an increase in the basic noise. When the signal undergoes amplitude extraction through the multi-channel function, the noise superimposed on the signal will affect the accuracy of amplitude extraction. In the actual hardware implementation of the traditional liquid scintillation design, a series of circuit designs such as isolation, adjustment, amplification, and coupling have to be carried out to condition the signal quality. Therefore, the basic noise of the traditional liquid scintillation design increases continuously with the generation and transmission of the signal. Until the end, both the counting function and the multi-channel function only have the ability to reduce noise, but do not have the ability to cancel noise.

[0005] For the above reasons, traditional liquid scintillation designs often have to improve the performance of photomultiplier tubes, select photomultiplier tubes with high amplification factors and good energy linearity performance, and use the high performance of photomultiplier tubes to improve the signal-to-noise ratio, so as to achieve the purpose of being able to collect more signals in the low-energy region. However, this increases the cost and the difficulty of selecting photomultiplier tubes.

[0006] In addition, when the traditional liquid scintillation design performs the αβ separation function, it always encounters problems that are not easy to distinguish. The αβ separation function means that when the detector measures a sample, it may receive α signals or β signals. At this time, the liquid scintillation device should have the function of distinguishing these two signals and separating them on the spectrum line. Due to the characteristics of the liquid scintillation device, both α and β signals are continuous, so there are overlapping parts on the spectrum line. In the αβ separation function, it is often difficult to distinguish α and β signals with similar amplitudes. When the amplitudes of α and β signals are the same, their signal characteristics are very different and it is very difficult to distinguish. Traditional designs often use algorithms such as integration and logarithmic transformation to improve the discrimination.

[0007] Therefore, how to process liquid scintillation spectrometer signals efficiently, accurately, stably and economically is a technical problem that needs to be solved urgently at present. Summary of the Invention

[0008] To solve the deficiencies of the prior art, the present invention provides a method and system for processing differential mode signals of a liquid scintillation spectrometer, which outputs the captured photoelectrons in the form of differential signals, converts N differential mode signals into digital signals that can be recognized by an FPGA (Field Programmable Gate Array) chip through a comparison circuit, and adds the N differential mode signals through an addition circuit to obtain the total energy amplitude of N tubes. Using the signals obtained by the comparison circuit, the FPGA chip is used as a processor to complete N-tube coincidence judgment, N-1 tube coincidence judgment and single-tube judgment counting, and the total energy amplitude of N tubes passes through the digital multi-channel function composed of an ADC and an FPGA, so as to realize the extraction of the energy amplitude. Compared with the complex signal adjustment, multi-stage amplification, alignment, discrimination and peak holding and other circuit processes of traditional liquid scintillation, the present invention is more economical, efficient, stable and reliable.

[0009] The embodiments of the present invention provide the following solutions:

[0010] In a first aspect, an embodiment of the present invention provides a method for processing differential mode signals of a liquid scintillation spectrometer, the method comprising:

[0011] Step 1, a sample undergoes nuclear decay in a liquid scintillation spectrometer, exciting the scintillation liquid to scintillate and generate optical signals;

[0012] Step 2, N detectors of the liquid scintillation spectrometer capture the optical signals and output them in the form of N differential mode signals;

[0013] Step 3: Each of the N differential-mode signals is amplified through a differential-mode amplifier circuit.

[0014] Step 4: The N amplified signals are respectively subjected to differential comparison processing and N-way addition processing, and the processed signals are respectively input into the FPGA chip.

[0015] Step 5: The FPGA chip uses the signals after differential comparison processing and N-way addition processing to complete counting and multi-channel function output spectral line processing.

[0016] In an alternative embodiment, the optical signal described in Step 3 undergoes pre-amplification processing with resistance-capacitance filtering to form N differential-mode signals.

[0017] In an alternative embodiment, the differential comparison processing described in Step 4 includes respectively converting the N amplified signals through single-channel signal conversion and outputting N level signals to the FPGA chip.

[0018] In an alternative embodiment, the N-way addition processing described in Step 4 includes, after superimposing the N amplified signals, converting the analog signal into a digital signal through the ADC module and inputting it into the FPGA chip.

[0019] In an alternative embodiment, the counting and multi-channel function output spectral line processing described in Step 5 includes corresponding processing of N-way coincidence and N-way amplitude, as well as corresponding processing of N-1 tube coincidence and N-1 tube amplitude, so as to complete counting and multi-channel function output spectral line processing.

[0020] In a second aspect, an embodiment of the present invention further provides a differential-mode signal processing system for a liquid scintillation spectrometer based on the above method, including: N detectors, a differential-mode amplifier circuit, a conversion circuit, and an FPGA chip, wherein the differential-mode amplifier circuit includes N instrumentation amplifier modules respectively electrically connected to the N detectors; the conversion circuit includes 2 operational amplifier modules respectively connected to the output ends of each instrumentation amplifier module, namely a first operational amplifier module and a second operational amplifier module, wherein the N first operational amplifier modules are connected to the FPGA chip, and the N second operational amplifier modules are electrically connected to the FPGA chip through a signal superimposing module and an ADC module in sequence.

[0021] In an alternative embodiment, the N detectors are electrically connected to the differential-mode amplifier circuit through a resistance-capacitance filtering circuit.

[0022] In an alternative embodiment, the N detectors, the resistance-capacitance filtering circuit, and the differential-mode amplifier circuit are connected by shielded twisted pairs.

[0023] In an alternative embodiment, each differential-mode amplifier circuit is connected in parallel with a reference zero-potential operational amplifier circuit.

[0024] In an alternative embodiment, the signal superposition module is electrically connected to the FPGA chip through a first-stage operational amplifier module.

[0025] The beneficial effects of the present invention based on its technical solution are as follows:

[0026] (1) For a differential signal processing method and system of a liquid scintillation spectrometer provided by the present invention, the detector photomultiplier tube outputs a differential signal through pre-amplification processing. The differential signal is a positive and a negative signal with equal magnitude and opposite polarity relative to the reference zero potential, which has an improving effect on the counting function, αβ separation function, and multi-channel function of the liquid scintillation. In addition, it can be transmitted to the signal processing board through shielded twisted pair, and the magnetic fields around the signal lines cancel each other out to avoid mutual interference, which can directly suppress the transmission noise and electromagnetic interference noise of the signal, and improve the signal quality.

[0027] (2) When interference passes through the line, common-mode noise will be generated on the differential signal pair. The common-mode interference refers to the simultaneous increase or decrease of the signals on the two signal lines in the twisted pair. The interference that is serially connected to the signal from the ground is always superimposed on the differential signal at the same time to form common-mode interference. For a differential signal processing method and system of a liquid scintillation spectrometer provided by the present invention, an instrumentation amplifier circuit constructed by using a differential operational amplifier is used to realize the subtraction of the positive and negative input terminals of the signal and amplify their difference. After the differential signal passes through the instrumentation amplifier circuit, the output signal amplitude is equal to the sum of the positive and negative signal amplitudes, while the common-mode signal is cancelled out after passing through the instrumentation amplifier circuit. It can not only increase the magnitude of the signal itself, but also suppress noise interference, thus ensuring the continuity of differential anti-interference.

[0028] (3) For a differential signal processing method and system of a liquid scintillation spectrometer provided by the present invention, an operational amplifier is used to reconstruct a reference zero potential, so that the signal reference point of the entire differential system is isolated from the reference ground potential. Compared with the existing liquid scintillation that uses the reference ground potential as the signal reference, the reference zero potential can effectively isolate the interference serially connected due to the large-area use of the reference ground potential, and further resist signal noise interference.

[0029] (4) A method and system for processing differential-mode signals of a liquid scintillation spectrometer provided by the present invention convert N differential-mode signals into digital signals that can be recognized by a processor (FPGA chip) through a comparison circuit, and add the N differential-mode signals through an addition circuit to obtain the total energy amplitude of three tubes. The signals obtained through the comparison circuit use FPGA as the processor to complete triple coincidence judgment, double coincidence judgment and single tube judgment counting, while the total energy amplitude of three tubes passes through the digital multi-channel function composed of ADC and FPGA, so as to realize the extraction of energy amplitude. The so-called coincidence is the process of judging whether the currently received signal is the nuclear radiation signal of the measured sample. When only one photomultiplier tube receives a signal at the same time, it is called single tube coincidence. When two photomultiplier tubes receive signals at the same time, it is called double tube coincidence. When three photomultiplier tubes receive signals at the same time, it is called triple tube coincidence, and so on. Compared with the complex signal adjustment, multi-stage amplification, alignment, discrimination and peak holding and other circuit processing of traditional liquid scintillation, the present invention is more economical, efficient, stable and reliable. Brief Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present specification or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0031] Figure 1 It is a schematic flowchart of a method for processing differential-mode signals of a liquid scintillation spectrometer provided in Embodiment 1 of the present invention.

[0032] Figure 2 It is a schematic diagram of a three-channel detector structure.

[0033] Figure 3 It is a schematic diagram of the module connection of a system for processing differential-mode signals of a liquid scintillation spectrometer provided in Embodiment 1 of the present invention.

[0034] Figure 4 It is a schematic diagram of the circuit connection of a system for processing differential-mode signals of a liquid scintillation spectrometer provided in Embodiment 1 of the present invention.

[0035] Figure 5 It is a schematic diagram of the signal processing process in Embodiment 1 of the present invention.

[0036] Figure 6 It is a schematic diagram of a four-channel detector structure.

[0037] In the figure: 1 - sample chamber, 2 - sample to be measured, 3 - detector, 3.1.1 - resistor-capacitor filter circuit, 3.1.2 - differential mode amplifier circuit, 3.1.3 - reference zero potential operational amplifier circuit, 3.2.1 - first operational amplifier module, 3.2.2 - second operational amplifier module, 3.3.1 - signal superposition module, 3.4.1 - first-stage operational amplifier module. Specific implementation mode

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope protected by the embodiments of the present invention.

[0039] Embodiment 1:

[0040] Taking the most common three-channel detector as an example for illustration. The embodiment of the present invention provides a method for processing differential mode signals of a liquid scintillation spectrometer. Referring to Figure 1 , the method includes:

[0041] Step 1, the sample undergoes nuclear decay in the liquid scintillation spectrometer, exciting the scintillator liquid to scintillate and generate optical signals.

[0042] Step 2, the three-channel detector of the liquid scintillation spectrometer captures the optical signals and outputs them in the form of three-channel differential mode signals after pre-amplification processing by a resistor-capacitor filter.

[0043] Step 3, each of the three-channel differential mode signals completes the amplification process through a differential mode amplifier circuit.

[0044] The signal amplitude of the differential mode signal (denoted as Vi) formed in Step 2 is relatively small, about ±2mV to ±30mV or so, and there is some crosstalk. It must be amplified and denoised to be better applied and processed. Therefore, each of the three-channel differential modes can complete the amplification of small signals, the cancellation of common mode interference, and the conversion of differential mode signals to single-ended signals through the differential mode amplifier circuit. For example, setting the amplification factor to 10 times (denoted as G = 10), at this time the output pulse amplitude Vo1 = 2 * Vi * G is about 40mV to 600mV.

[0045] Step 4, perform differential comparison processing and three-channel addition processing on the three amplified signals respectively, and input the processed signals into the FPGA chip respectively.

[0046] The differential comparison processing includes converting each of the three amplified signals through a single-channel signal conversion and outputting three-level signals to the FPGA chip.

[0047] The three-way addition process includes superimposing the three amplified signals, that is, the signal amplitude changes from Vo1 (40mV - 600mV) to Vo2 (120mV - 1800mV), which is exactly suitable for high-speed ADC acquisition. The analog signal is converted into a digital signal by the high-speed ADC module and input into the FPGA chip to achieve amplitude extraction. For example, the range of a 12-bit ADC is 0 - 2048mV, and the digital signal N corresponding to the input analog signal Vo2 (120mV - 1800mV) is N = Vo2 * 2^12 / 2048, and N is approximately 240 - 3600.

[0048] Step Five: The FPGA chip uses the signals after differential comparison processing and three-way addition processing to complete counting and multi-channel function output spectral line processing, including the corresponding processing of three-tube coincidence and three-tube amplitude, as well as the corresponding processing of two-tube coincidence and two-tube amplitude, so as to complete counting and multi-channel function output spectral line processing.

[0049] Refer to Figure 3 and Figure 4 This embodiment also provides a differential-mode signal processing system for a liquid scintillation spectrometer based on the above method, including: three-way detectors, a differential-mode amplification circuit (3.1.2), a conversion circuit, and an FPGA chip. The differential-mode amplification circuit includes three instrumentation amplifier modules respectively electrically connected to the three-way detectors, namely the first instrumentation amplifier module, the second instrumentation amplifier module, and the third instrumentation amplifier module; the conversion circuit includes two operational amplifier modules respectively connected to the output ends of each instrumentation amplifier module, namely the first operational amplifier module (3.2.1) and the second operational amplifier module (3.2.2), where three first operational amplifier modules are connected to the FPGA chip, and three second operational amplifier modules are electrically connected to the FPGA chip through a signal superposition module (3.3.1) and a high-speed ADC module in sequence.

[0050] The three-way detectors are electrically connected to the differential-mode amplification circuit through a resistor-capacitor filter circuit (3.1.1).

[0051] The three-way detectors, the resistor-capacitor filter circuit, and the differential-mode amplification circuit are connected by shielded twisted pairs.

[0052] Each differential-mode amplification circuit is connected in parallel with a reference zero-potential operational amplifier circuit (3.1.3).

[0053] The signal superposition module is electrically connected to the FPGA chip through a first-stage operational amplifier module (3.4.1).

[0054] Refer to Figure 5, the signal processing procedure of this embodiment is as follows: The signals output by the three-way detectors are Vi(A+) and Vi(A-), Vi(B+) and Vi(B-), and Vi(C+) and Vi(C-), respectively. After being processed by the RC filter circuit 3.1.1, they are input to the signal input terminals of the corresponding differential-mode amplifier circuits 3.1.2 (in this embodiment, an instrumentation amplifier module is used), and then Vo1(A) = (Vi(A+) - Vi(A-)) * G is output from the output terminal of the instrumentation amplifier module. Since the magnitudes of A+ and A- are equal and the directions are opposite, Vo1 = 2 * Vi * G, which is equivalent to doubling the signal Vo1' = Vi * G of the traditional liquid scintillation device on the original signal. The reference zero-potential op-amp circuit 3.1.3 reconstructs a reference zero potential using an op-amp, isolating the signal reference point of the entire system from the reference ground potential. Compared with the traditional liquid scintillation using the reference ground potential as the signal reference, the reference zero potential can effectively isolate the interference introduced by the large-area use of the reference ground potential and further resist the signal noise interference. The subsequent circuit processes Vo1 in two paths. One path is used for counting after comparison by the first op-amp module 3.2.1, and the other path is subjected to signal following processing by the second op-amp module 3.2.2 and added to the signals after following processing of the other two paths through the signal superposition module 3.3.1. The added signal Vo2 = Vo1(A) + Vo1(B) + Vo1(C). Since the three detectors are placed in a completely symmetric design, the signal amplitudes of the three tubes should theoretically be the same. When the three tubes coincide, Vo2 = 3Vo1; when two tubes coincide, Vo2 = 2Vo1; when only a single tube exists, Vo2 = Vo1. Finally, the circuit is adjusted by a first-stage op-amp module 3.4.1 and then input to the ADC chip for amplitude extraction. After the above circuit processing, it can be obtained that when the ADC samples a signal amplitude, it is certain to obtain the corresponding count in the ABC three-way counting. If there are counts in all three tubes of ABC simultaneously, the FPGA increments the coincidence count of the three tubes by 1 at this channel number; if there are counts in AB or BC or AC simultaneously, the FPGA increments the coincidence count of the two tubes by 1 at this channel number; if there is a count in only A or B or C, the FPGA records the single-tube count and increments it by 1. The so-called channel number refers to dividing the full-scale amplitude of the ADC into n consecutive regions and numbering them 0 to n - 1, which is the channel number.

[0055] The present invention may be implemented by increasing or decreasing the photomultiplier tube detectors to achieve different applications and effects; it is also possible to increase the number of analog-to-digital converters (ADCs) to obtain more amplitude information of the detector signals and increase functions; it is also possible to replace with devices, FPGAs, and chips with better performance to achieve better effects.

[0056] Embodiment 2:

[0057] Refer to Figure 6It is a schematic diagram of a four-channel detector structure. The difference between this embodiment and the first embodiment is that one more channel is added to the detector, and the numbers of the differential mode amplifier circuit 3.1.2, the first operational amplifier module 3.2.1, and the second operational amplifier module 3.2.2 are all correspondingly increased to 4, and finally, 4-channel signal addition processing is performed.

[0058] Those skilled in the art should understand that the embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes.

[0059] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (modules, systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded computers, or other programmable data processing devices to generate a machine, so that the instructions executed by the processors of the computer or other programmable data processing devices generate a machine for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0060] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including an instruction device, and the instruction device implements the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0061] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are performed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0062] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention.

[0063] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for processing differential mode signals of a liquid scintillation spectrometer, characterized in that: The method comprises: Step 1: The sample undergoes nuclear decay in a liquid scintillation spectrometer, which excites the scintillation liquid to generate a light signal; Step 2: The N-channel detectors of the liquid scintillation spectrometer capture the optical signal and output it in the form of N-channel differential mode signals; Step 3, each of the N differential mode signals is amplified through a differential mode amplifier circuit; Step 4: Perform differential comparison processing and N-way addition processing on the N-way amplified signals, and input the processed signals into the FPGA chip respectively; Step 5: The FPGA chip uses the signals after differential comparison processing and N-way addition processing to complete counting and multi-channel functional output spectrum line processing.

2. The liquid scintillation spectrometer differential mode signal processing method according to claim 1, characterized in that: The optical signal described in step 3 is processed by pre-amplification with resistor-capacitor filtering to form N differential mode signals.

3. The liquid scintillation spectrometer differential mode signal processing method according to claim 1, characterized in that: The differential comparison processing described in step 4 includes converting each of the N amplified signals into a single-channel signal and outputting N level signals to the FPGA chip.

4. The liquid scintillation spectrometer differential mode signal processing method according to claim 1, characterized in that: The N-channel addition processing described in step 4 includes superimposing the N-channel amplified signals, converting the analog signals into digital signals through the ADC module and inputting them into the FPGA chip.

5. The liquid scintillation spectrometer differential mode signal processing method according to claim 1, characterized in that: The counting and multi-channel functional output spectral line processing described in step 5 includes the corresponding processing of N-channel coincidences and N-channel amplitudes, and the corresponding processing of N-1 tube coincidences and N-1 tube amplitudes, thereby completing the counting and multi-channel functional output spectral line processing.

6. A liquid scintillation spectrometer differential mode signal processing system based on the method of claim 1, characterized in that: include: N-channel detectors, a differential mode amplifier circuit (3.1.2), a conversion circuit and an FPGA chip, wherein the differential mode amplifier circuit includes N instrument amplifier modules electrically connected to the N-channel detectors respectively; the conversion circuit includes two operational amplifier modules connected to the output end of each instrument amplifier module respectively, namely a first operational amplifier module (3.2.1) and a second operational amplifier module (3.2.2), wherein the N first operational amplifier modules are connected to the FPGA chip, and the N second operational amplifier modules are electrically connected to the FPGA chip via a signal superposition module (3.3.1) and an ADC module in sequence.

7. The liquid scintillation spectrometer differential mode signal processing system according to claim 6, characterized in that: The N-channel detectors are electrically connected to the differential mode amplifier circuit via a resistor-capacitor filter circuit (3.1.1).

8. The liquid scintillation spectrometer differential mode signal processing system according to claim 6 or 7, characterized in that: The N-channel detector, the resistor-capacitor filter circuit and the differential-mode amplifier circuit are connected by a shielded twisted pair cable.

9. The liquid scintillation spectrometer differential mode signal processing system according to claim 6, characterized in that: Each differential mode amplifier circuit is connected in parallel with the reference zero potential operational amplifier circuit (3.1.3).

10. The liquid scintillation spectrometer differential mode signal processing system according to claim 6, characterized in that: The signal superposition module and the FPGA chip are electrically connected via a first-level operational amplifier module (3.4.1).

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