Neutron energy spectrum measurement method and measurement system

Abstract

The invention relates to a neutron spectrum measurement method and system, and the method comprises the steps: obtaining a neutron signal obtained through the detection of an incident neutron beam through a plurality of detectors; after the neutron signal is processed, a processed signal is obtained; obtaining the neutron counting rate of each detector based on the processing signal; the initial neutron counting rate of the jth energy interval in the incident neutron beam is set as # imgabs0 #, the initial neutron counting rate is substituted into a formula for iterative calculation, and when the absolute value of the difference value of # imgabs1 # and # imgabs2 # is smaller than a preset first threshold value, # imgabs3 # is the neutron counting rate of the jth energy interval in the incident neutron beam; and calculating the neutron counting rates corresponding to the n energy intervals in the incident neutron beam corresponding to each detector in sequence to obtain the neutron energy spectrum of the incident neutron beam. The measuring method is simple in measuring process and high in accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of neutron spectrum measurement, and in particular to a neutron spectrum measurement method and a measurement system. Background Art

[0002] At present, the methods widely used to measure the neutron energy spectrum of BNCT (Boron Neutron Capture Therapy) radiation field are mainly multi-foil activation method and multi-sphere spectrometer method. However, these two methods have complicated operation procedures, and irradiation, measurement and analysis all take a long time. The measurement accuracy is generally low. The multi-sphere spectrometer needs to perform multiple measurements and is easily affected by external conditions. The above problems need to be solved urgently. Summary of the invention

[0003] The invention discloses a neutron spectrum measurement method and a measurement system, aiming to solve the technical problems existing in the prior art.

[0004] The present invention adopts the following technical solutions:

[0005] In a first aspect, the present invention provides a neutron spectrum measurement method, comprising:

[0006] Acquire a neutron signal obtained by detecting an incident neutron beam with a detector, wherein the detector comprises a plurality of detectors, and the plurality of detectors are sequentially arranged along a neutron movement direction and are numbered 1-S in sequence, and the incident neutron beam comprises n energy intervals, where n is a positive integer;

[0007] After the neutron signal is processed, a processed signal is obtained;

[0008] Obtaining a neutron counting rate of each detector based on the processed signal;

[0009] Set the initial neutron count rate in the jth energy interval of the incident neutron beam to

[0010] Substituting the initial neutron count rate into the formula Perform iterative calculations, when and When the absolute value of the difference is less than the preset first threshold, is the neutron count rate in the jth energy interval of the incident neutron beam, is the neutron count rate of the j-th neutron energy interval in the incident neutron beam at the k-th iteration, is the correction factor for the kth iteration;

[0011] The neutron counting rates corresponding to the n energy intervals in the incident neutron beam corresponding to each of the detectors are calculated in sequence to obtain the neutron energy spectrum of the incident neutron beam.

[0012] In the neutron spectrum measurement method of the present invention, the correction factor in, is the contribution weight, R sj is the response of the detector numbered S to the jth neutron energy interval in the incident neutron beam, δ S is the standard deviation of the neutron count rate of the n incident neutron beam energy intervals corresponding to the detector numbered S, N S is the counting rate of the detector numbered S for the j-th neutron energy interval in the incident neutron beam.

[0013] In the neutron spectrum measurement method of the present invention, the response can be obtained by the following formula:

[0014] R Sj =∫φ(E)nVσ(E)dE;

[0015] Among them, R Sj is the response of the detector numbered S when the energy of the energy interval of the incident neutron beam is E;

[0016] φ(E) is the neutron flux with energy E, in cm -2 ;

[0017] n is the number of LiO2·2SiO2(Ce) in the detector. 6 Li atomic number density, unit: cm -3 ;

[0018] V is the volume of LiO2·2SiO2(Ce), in cm 3 ;

[0019] σ(E) is 6 Li(n,α)T reaction cross-sectional area, unit: cm 2 .

[0020] In the neutron spectrum measurement method of the present invention, each of the neutron signals is processed to obtain a processed signal, the steps comprising: each of the neutron signals is shaped into a plurality of unipolar Gaussian waveforms; and each of the unipolar Gaussian waveforms is denoised to obtain a processed signal.

[0021] In the neutron energy spectrum measurement method of the present invention, the step of denoising each of the unipolar Gaussian waveforms to obtain a noise-reduced signal is performed by a comparator; the signals below the second threshold in the unipolar Gaussian waveform are eliminated by the comparator to obtain a noise-reduced signal.

[0022] In the neutron spectrum measurement method of the present invention, the step of obtaining a plurality of neutron count rates based on the processed signal comprises:

[0023] Each of the processed signals is converted into a unidirectional square wave signal recognizable by the FPGA, and each of the square wave signals is counted separately by a parallel pulse counting module of the FPGA to obtain the neutron counting rate.

[0024] In a second aspect, the present invention also provides a neutron energy spectrum measurement system, which includes a moderator, multiple detectors, multiple preamplifiers, a signal processing module and a host computer; the detectors and the preamplifiers are arranged in a one-to-one correspondence, and the detectors are electrically connected to the preamplifiers; multiple preamplifiers are electrically connected to the signal processing module; the signal processing module is used to process the neutron signals detected by the detectors to obtain a neutron counting rate; the host computer is electrically connected to the signal processing module, and is used to receive the neutron counting rate data, and execute any of the above-mentioned measurement methods to obtain the neutron energy spectrum.

[0025] In the measurement system of the present invention, the moderator includes a shell and a columnar moderator; the columnar moderator is arranged in the shell and includes a plurality of column segments; except for the end face of the column segment adjacent to the neutron inlet on the shell, the end face of each of the other column segments has a receiving recess for receiving the detector, and the thickness of each of the column segments is the same or different; the receiving recesses are arranged in sequence from close to to far from the neutron inlet; the inlet is arranged at a position directly opposite to the receiving recess.

[0026] In the measurement system of the present invention, the columnar moderator is a cylindrical structure with a length of 30-40 cm and a diameter of 10-20 cm.

[0027] In the measurement system of the present invention, the length of the columnar moderator is 35 cm and the diameter is 20 cm.

[0028] In the measurement system of the present invention, along the direction from close to the inlet to away from the inlet, the distance between each of the accommodating recesses and the end surface of the columnar moderator is 0.2 cm to 24 cm; or, 0.2 cm to 20 cm.

[0029] In the measurement system of the present invention, the detector and the preamplifier are an integrated structure.

[0030] In the measurement system of the present invention, the signal processing module includes a plurality of amplifying and shaping modules and a multi-channel counting module; the amplifying and shaping modules are arranged in a one-to-one correspondence with the preamplifier and are electrically connected to the preamplifier; the multi-channel counting module includes a plurality of counting channels, and the counting channels are arranged in a one-to-one correspondence with the amplifying and shaping modules, and are used to process the shaped signals of the amplifying and shaping modules to obtain the neutron counting rate.

[0031] The measurement system of the present invention further comprises an analysis module; the analysis module is electrically connected to the amplification and shaping module and is used to observe the waveform of the signal output by the detector.

[0032] The technical solution adopted by the present invention can achieve the following beneficial effects:

[0033] The present invention mainly provides a neutron energy spectrum measurement method, which is based on detecting an incident neutron beam with multiple detectors at the same time, and can simultaneously obtain neutron energy spectra of different energy ranges of the incident neutron beam, thereby increasing the energy range of detection, simplifying the measurement process, avoiding harm to operators caused by replacing a moderator, and based on the larger detection energy range, making the detection accuracy higher, and obtaining the neutron energy spectrum with a counting contribution weight function, which can avoid the problem that when calculating the neutron energy spectrum with a response matrix, it is impossible to accurately solve it through an analytical method, so that the obtained neutron energy spectrum is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions explain the present invention and do not constitute improper limitations on the present invention. In the drawings:

[0035] Figure 1 It is a structural schematic diagram of a neutron spectrum measurement method of the present invention;

[0036] Figure 2 It is a schematic diagram of the structure of the measurement system of the present invention;

[0037] Figure 3 is a schematic diagram of the structure of the moderator of the present invention;

[0038] Figure 4 It is a cross-sectional view of the moderator of the present invention.

[0039] Description of reference numerals:

[0040] 1. Moderator; 11. Shell; 111. Neutron inlet; 12. Columnar moderator; 121. Column section; 1211. Accommodating recess; 2. Detector; 3. Preamplifier; 4. Signal processing module; 41. Amplification and shaping module; 42. Multi-channel counting module; 5. Host computer; 6. Analysis module. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. In the description of the present invention, it should be noted that the term "or" is usually used in the sense of including "and / or", unless the content clearly indicates otherwise.

[0042] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or a magnetic connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three or more, etc., unless otherwise clearly and specifically limited.

[0043] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In order to solve the problems existing in the prior art, the embodiments of the present application provide a neutron energy spectrum measurement method and a measurement system.

[0045] like Figure 1 As shown, a neutron spectrum measurement method comprises:

[0046] Acquire a neutron signal by detecting an incident neutron beam with a detector, wherein the detector comprises a plurality of detectors, and the plurality of detectors are sequentially arranged along a neutron movement direction and are numbered 1-S in sequence, and the incident neutron beam comprises n energy intervals, that is, the incident neutron beam is divided into a plurality of energy intervals;

[0047] After the neutron signal is processed, a processed signal is obtained;

[0048] The neutron count rate of each detector is obtained based on the processed signal. When measured according to a single energy interval, the neutron count rate obtained at this time is the neutron count rate corresponding to the single interval. When measured in all intervals, the response function of the corresponding detector is obtained. The response functions of multiple detectors constitute a response spectrum. The detection of the incident neutron beam by each single detector is no different from that of existing detectors.

[0049] Assume that the initial neutron count rate in the jth energy interval of the incident neutron beam is

[0050] Substituting the initial neutron count rate into the formula Perform iterative calculations, when and When the absolute value of the difference is less than the preset first threshold, is the neutron count rate in the jth energy interval of the incident neutron beam, is the neutron count rate in the jth neutron energy interval in the incident neutron beam of the kth iteration, is the correction factor for the kth iteration;

[0051] The neutron counting rates corresponding to the n energy intervals in the incident neutron beam corresponding to each detector are calculated in turn to obtain the neutron energy spectrum of the incident neutron beam.

[0052] A neutron energy spectrum measurement method of the present invention is based on detecting an incident neutron beam with multiple detectors at the same time, and can simultaneously obtain neutron energy spectra of different energy ranges of the incident neutron beam, thereby increasing the energy range of detection, simplifying the measurement process, avoiding damage to operators caused by replacing a moderator, and based on a larger detection energy range, making the detection accuracy higher, and obtaining the neutron energy spectrum with a counting contribution weight function, which can avoid the problem that when calculating the neutron energy spectrum with a response matrix, it is impossible to accurately solve it through an analytical method, so that the obtained neutron energy spectrum is more accurate.

[0053] In some preferred embodiments, the correction factor in, is the contribution weight, R sj is the response of the detector numbered S to the jth neutron energy interval in the incident neutron beam (this value is calculated in advance), δ S is the standard deviation of the neutron count rate in the n incident neutron beam energy intervals corresponding to the detector numbered S, N S is the counting rate of the detector numbered S for the jth neutron energy interval in the incident neutron beam; the counting rates of the n neutron energy intervals detected by the detector numbered S is the response function; the response functions obtained by the S detectors form a response spectrum.

[0054] In some preferred embodiments, the response can be obtained by the following formula:

[0055] R Sj =∫φ(E)nVσ(E)dE;

[0056] Among them, R Sj is the response of the detector numbered S when the energy of the incident neutron beam is E;

[0057] φ(E) is the neutron flux with energy E, in cm -2 ;

[0058] n is the number of LiO2·2SiO2(Ce) in the detector. 6 Li atomic number density, unit: cm -3 ;

[0059] V is the volume of LiO2·2SiO2(Ce), in cm 3 ;

[0060] σ(E) is 6 Li(n,α)T reaction cross-sectional area, unit: cm 2 .

[0061] In some preferred embodiments, each neutron signal is processed to obtain a processed signal, and the steps include: shaping each neutron signal into a plurality of unipolar Gaussian waveforms; denoising each unipolar Gaussian waveform to obtain a processed signal; thereby further improving the signal-to-noise ratio.

[0062] In some preferred embodiments, the step of denoising each unipolar Gaussian waveform to obtain a noise-reduced signal is performed by a comparator; and the signal below the second threshold in the unipolar Gaussian waveform is removed by the comparator to obtain a noise-reduced signal.

[0063] In some preferred embodiments, the neutron signal is amplified and divided into two paths, one of which is processed to obtain multiple neutron counting rate steps, and the other is analyzed by the original signal waveform of the analyzer. This signal is uploaded to the host computer, and the waveform can be observed in real time on the host computer to determine the signal accumulation state and the working state of the detector, ensuring that the working state of the entire detection system is normal.

[0064] In some preferred embodiments, the step of obtaining multiple neutron counting rates based on the processed signals includes: converting each processed signal into a unidirectional square wave signal recognizable by an FPGA (Field Programmable Gate Array Programmable Array Logic), and counting each square wave signal separately through a parallel pulse counting module of the FPGA to obtain the neutron counting rate.

[0065] Example 2

[0066] This embodiment provides a neutron spectrum measurement system, such as Figure 2 As shown, it includes a moderator 1, multiple detectors 2, multiple preamplifiers 3, a signal processing module 4 and a host computer 5; the detectors 2 and the preamplifiers 3 are arranged in a one-to-one correspondence, and the detectors 2 are electrically connected to the preamplifiers 3; the multiple preamplifiers 3 are all electrically connected to the signal processing module 4; the signal processing module 4 is used to process the neutron signal detected by the detector 2 to obtain the neutron counting rate; the host computer 5 is electrically connected to the signal processing module 4, and is used to receive the neutron counting rate data, and execute the measurement method of the above embodiment 1 to obtain the neutron energy spectrum.

[0067] A neutron energy spectrum measurement system of the present invention is based on using multiple detectors 2 to simultaneously detect an incident neutron beam, and can simultaneously obtain neutron energy spectra of different energy ranges of the incident neutron beam, thereby increasing the energy range of detection, simplifying the measurement process, avoiding harm to operators caused by replacing a moderator, and based on the larger detection energy range, the detection accuracy is higher, and online measurement can be performed.

[0068] In some preferred embodiments, Figure 3 and 4 As shown, the moderator 1 includes a shell 11 and a columnar moderator 12; the columnar moderator 12 is arranged in the shell 11, and includes a plurality of column segments 121, that is, the columnar moderator 12 is divided along a cross section perpendicular to the axis; except for the end face of the column segment 121 adjacent to the neutron inlet 111 on the shell 11, the end faces of the other column segments 121 are provided with a receiving recess 1211 for receiving the detector, that is, the end face close to the neutron inlet 111 is not provided with the receiving recess 1211; and the thickness of each column segment 121 is the same or different; the receiving recesses 1211 are arranged in sequence from close to to far from the neutron inlet 111; the inlet 111 is arranged at a position directly opposite to the receiving recess 1211. Based on the columnar structure as the moderator, and the columnar moderator 12 includes a plurality of column sections 121, a receiving recess 1211 for receiving the detector is provided on the column section 121, that is, a plurality of detectors can be provided at the same time, and the receiving recess 1211 is arranged in sequence from close to far from the neutron inlet 111, then when the detector is installed, each detector has a different installation depth, and can detect neutron energy spectra of different energies, based on measuring the neutron energy spectra of different energies at one time, the measurement time is reduced, and the measurement process is simpler; and based on the ability to obtain neutron energy spectra of different energies at one time, the response function coverage range of the neutron detector is larger, and the measurement result is more accurate; and, by forming the columnar moderator 12 with a plurality of column sections 121 of the same or different thicknesses, the position of each receiving recess 1211 in the columnar moderator 12 can be adjusted, so that different use requirements (such as different neutron radiation fields) can be applied, and disassembly is convenient.

[0069] In some preferred embodiments, the columnar moderator 12 is a cylindrical structure with a length of 30-40 cm and a diameter of 10-20 cm. Within this range, the structure of the moderator 1 is more compact, and the total range covered by the response function of the detector is maximized. Taking 10 detectors as an example (the specific number of detectors is determined according to demand), the installation depths of the detectors are distributed at 0.2 cm, 0.5 cm, 1 cm, 2 cm, 4 cm, 8 cm, 12 cm, 16 cm, 20 cm and 24 cm. For a beam spot radius of 5 cm, when the diameter of the columnar moderator 12 is 10 cm and the lengths are respectively set to 30 cm, 35 cm, 40 cm and 45 cm, the total range covered by the response functions of the 10 detectors is not much different. Considering the overall size of the equipment, the selection of A length of 30-40 cm is selected as the preferred length, at which the equipment is more compact and easy to operate; when 10 detectors are also set, the installation depths of the detectors are distributed in sequence at 0.2 cm, 0.5 cm, 1 cm, 2 cm, 4 cm, 8 cm, 12 cm, 16 cm, 20 cm and 24 cm, the beam spot radius is 5 cm, the length of the columnar moderator 12 is 45 cm, and the diameters are 10 cm, 12 cm, 15 cm, 18 cm, 20 cm and 25 cm respectively. As the diameter of the columnar moderator 12 increases, the maximum response values ​​of the deeper detectors (i.e., the maximum value of the vertical axis of the response matrix) are significantly improved starting from the third thermal neutron detector; and the energy coverage range between the energy region of 1×10-3MeV and 10MeV is greatly improved. When the diameter of the columnar moderator 12 increases from 20 cm to 25 cm, this trend is already negligible; therefore, when the length of the columnar moderator 12 is 30-40 cm and the diameter is 10-20 cm, it can have a larger energy coverage range and a maximum response value, and the structure of the moderator 1 is more compact; based on the thermal neutrons used in the implementation of ~2×10 10 eV, therefore, the corresponding optimal size can be adjusted in the neutron radiation field with different energy spectrum characteristics.

[0070] Preferably, the length of the columnar moderator 12 is 35 cm and the diameter is 20 cm; in this case, the response function covers the largest total range, and the shielding of backscattered neutrons and the compactness are better.

[0071] In some preferred embodiments, along the direction from the inlet 111 to the direction from the inlet 111 away from the inlet 111, the distances of each accommodating recess 1211 (or the end face of each column section 121 close to the neutron inlet 111) from the end face of the columnar moderator 12 close to the neutron inlet 111 are distributed in the range of 0.2 cm to 24 cm (for example, the depths are 0.2 cm, 0.5 cm, 1 cm, 2 cm, 4 cm, 8 cm, 12 cm, 16 cm, 20 cm and 24 cm, Example 1); or 0.2 cm m~20cm range (such as the depth is 0.2cm, 0.5cm, 1cm, 2cm, 3cm, 5cm, 8cm, 12cm, 16cm and 20cm, Example 2); preferably, the distance between each accommodating recess 1211 and the end surface of the columnar moderator 12 is 0.2cm, 0.5cm, 1cm, 2cm, 4cm, 8cm, 12cm, 16cm, 20cm and 24cm respectively; at this time, the total range of the detector energy spectrum coverage is larger; especially in 1×10 -3 MeV~1×10 -1 MeV energy region (epitothermal neutron to fast neutron energy region).

[0072] In some preferred embodiments, the detector 2 and the preamplifier 3 are an integrated structure; based on one detector 2 corresponding to one preamplifier 3, since the signal amplitude generated by the thermal neutron detector 2 itself is weak, if the detector 2 is only placed in the moderator 1, and the detector 2 is connected to the amplifier outside the moderator 1 through a signal line, the signal amplitude will be further lost during the transmission process in the signal line, so that the amplitude ratio of the neutron signal to the electronic noise is reduced, and finally the signal-to-noise ratio of the neutron signal and the electronic noise after being amplified by the preamplifier 3 is small. After the detector 2 and the preamplifier 3 are welded together, the reduction in the signal transmission process is avoided, and the amplification is directly performed, thereby improving the signal-to-noise ratio.

[0073] In some preferred embodiments, the signal processing module 4 includes a plurality of amplifying and shaping modules 41 and a multi-channel counting module 42; the amplifying and shaping modules 41 are arranged one-to-one with the preamplifier 3 and are electrically connected to the preamplifier 3, and are used to amplify and shape the output signal of the preamplifier 3; the multi-channel counting module 42 includes a plurality of counting channels, and the counting channels are arranged one-to-one with the amplifying and shaping modules 41, and are used to process the shaped signals of the amplifying and shaping modules 41 to obtain the neutron counting rate; the multi-channel counting module 42 is an FPGA multi-channel counting module (existing components for realizing multi-channel technology can be adopted, such as model XC7A100T-FGG484-2); specifically, the amplifying and shaping modules 41 and the preamplifier 3 can both be selected as existing equipment, wherein the amplifying and shaping module 41 is used to shape the amplified signal output by the preamplifier 3 into multiple unipolar Gaussian waveforms; each unipolar Gaussian waveform is denoised to obtain a processed signal; thereby, the signal-to-noise ratio is further improved. Among them, the step of denoising each unipolar Gaussian waveform to obtain a noise-reduced signal is performed by a comparator; the signals below a second threshold (the specific value can be selected according to working conditions) in the unipolar Gaussian waveform are eliminated by the comparator to obtain a noise-reduced signal.

[0074] Preferably, a plurality of amplifying and shaping modules 41 and a multi-channel counting module 42 are integrated on a signal processing circuit board and protected and shielded by a metal casing to simultaneously process multi-channel (all detectors) neutron signals.

[0075] In some preferred embodiments, an analysis module 6 is also included; the analysis module 6 is electrically connected to the amplification and shaping module 41, and is used to observe the waveform of the signal output by the detector, and can also observe the signal accumulation; specifically, the optional model of the analysis module 6 is ad9235.

[0076] In some preferred embodiments, each preamplifier 3 is connected to a signal line and a power line and a ground line in series, that is, 2S+1 lines, which are used to power the detector 2 and transmit the signal output by the preamplifier 3 to each amplification and shaping module 41 of the signal processing part. In order to avoid external noise interference during the transmission process, all power lines and ground lines are welded to a multi-core plug, all signal lines are welded to another multi-core plug, and the two plugs are fixed to the metal shell of the moderator 1. Similarly, the signal lines of each amplification and shaping module 41 are welded to the same multi-core plug, and the lines of the power supply system of the signal processing module 4 are welded to another multi-core plug. The two plugs are fixed to the metal shell of the signal processing module 4. Finally, two well-shielded cables are used to connect to the corresponding plugs of the probe and the signal processing part respectively to realize the communication between the probe and the signal processing module.

[0077] In some preferred embodiments, the spectrum decomposition software in the host computer 5 can be developed in C language and support the Windows operating environment. The data of the signal processing module 4 is read through the interface as the data file of the software, and the response matrix calculated in advance using the simulation software is built in, that is, the response matrix composed of multiple responses; and the preset spectrum obtained through various channels, and then the spectrum decomposition calculation is performed using the iterative algorithm based on maximum entropy. The spectrum decomposition software supports changing the measurement cycle; the measurement method of the above embodiment 1 is executed when the spectrum decomposition software is running; and other existing spectrum decomposition software can also be used.

[0078] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A neutron spectrum measurement method, characterized in that: include: Acquire a neutron signal obtained by detecting an incident neutron beam with a detector, wherein the detector comprises a plurality of detectors, and the plurality of detectors are sequentially arranged along a neutron movement direction and are numbered 1-S in sequence, and the incident neutron beam comprises n energy intervals, where n is a positive integer; After the neutron signal is processed, a processed signal is obtained; Obtaining a neutron counting rate of each detector based on the processed signal; Set the initial neutron count rate in the jth energy interval of the incident neutron beam to Substituting the initial neutron count rate into the formula Perform iterative calculations, when and When the absolute value of the difference is less than the preset first threshold, is the neutron count rate in the jth energy interval of the incident neutron beam, is the neutron count rate of the j-th neutron energy interval in the incident neutron beam at the k-th iteration, is the correction factor for the kth iteration; The neutron counting rates corresponding to the n energy intervals in the incident neutron beam corresponding to each of the detectors are calculated in sequence to obtain the neutron energy spectrum of the incident neutron beam.

2. The neutron spectrum measurement method according to claim 1, characterized in that: The correction factor in, is the contribution weight, R sj is the response of the detector numbered S to the jth neutron energy interval in the incident neutron beam, δ S is the standard deviation of the neutron count rate of the n incident neutron beam energy intervals corresponding to the detector numbered S, N S is the counting rate of the detector numbered S for the j-th neutron energy interval in the incident neutron beam.

3. The neutron spectrum measurement method according to claim 2, characterized in that: The response can be obtained as follows: R Sj =∫φ(E)nVσ(E)dE; Among them, R Sj is the response of the detector numbered S when the energy of the energy interval of the incident neutron beam is E; φ(E) is the neutron flux with energy E, in cm -2 ; n is the number of LiO2·2SiO2(Ce) in the detector. 6 Li atomic number density, unit: cm -3 ; V is the volume of LiO2·2SiO2(Ce), in cm 3 ; σ(E) is 6 Li(n,α)T reaction cross-sectional area, unit: cm 2 .

4. The neutron spectrum measurement method according to claim 1, characterized in that: The neutron signals are processed to obtain processed signals, comprising: Each of the neutron signals becomes a plurality of unipolar Gaussian waveforms after being shaped; Each of the unipolar Gaussian waveforms is denoised to obtain a processed signal.

5. The neutron spectrum measurement method according to claim 4, characterized in that: The step of denoising each of the unipolar Gaussian waveforms to obtain a noise-reduced signal is performed by a comparator; The comparator removes the signal below the second threshold in the unipolar Gaussian waveform to obtain a noise reduction signal.

6. The neutron spectrum measurement method according to claim 1, characterized in that: The step of obtaining a plurality of neutron count rates based on the processed signal comprises: Each of the processed signals is converted into a unidirectional square wave signal recognizable by the FPGA, and each of the square wave signals is counted separately by a parallel pulse counting module of the FPGA to obtain the neutron counting rate.

7. A neutron spectrum measurement system, characterized in that: It includes a moderator, multiple detectors, multiple preamplifiers, a signal processing module and a host computer; The detector and the preamplifier are arranged in a one-to-one correspondence, and the detector is electrically connected to the preamplifier; The plurality of preamplifiers are electrically connected to the signal processing module; The signal processing module is used to process the neutron signal detected by the detector to obtain a neutron counting rate; The host computer is electrically connected to the signal processing module and is used to receive the neutron count rate data and execute the measurement method described in any one of claims 1 to 6 to obtain the neutron energy spectrum.

8. The measuring system according to claim 7, characterized in that The moderator includes a shell and a columnar moderator; The columnar moderator is disposed in the shell and includes a plurality of column segments; Except for the column segment end face adjacent to the neutron inlet on the shell, the end faces of the remaining column segments are provided with a receiving recess for receiving the detector, and the thickness of each column segment is the same or different; The accommodating recesses are arranged in sequence from close to to far from the neutron inlet; The inlet is arranged opposite to the accommodating recess.

9. The measuring system according to claim 8, characterized in that The columnar moderator is a cylindrical structure with a length of 30-40 cm and a diameter of 10-20 cm.

10. The measuring system according to claim 9, characterized in that The columnar moderator has a length of 35 cm and a diameter of 20 cm.

11. The measuring system according to claim 8, characterized in that Along the direction from close to the inlet to away from the inlet, the distance between each of the accommodating recesses and the end surface of the columnar moderator is 0.2 cm to 24 cm; or, 0.2 cm to 20 cm.

12. The measuring system according to claim 11, characterized in that The detector and the preamplifier are an integrated structure.

13. The measuring system according to claim 11, characterized in that The signal processing module includes a plurality of amplification and shaping modules and a multi-channel counting module; The amplification and shaping modules are arranged in one-to-one correspondence with the preamplifiers and are electrically connected to the preamplifiers; The multi-channel counting module includes a plurality of counting channels, and the counting channels are arranged in a one-to-one correspondence with the amplifying and shaping modules, and are used to process the shaping signals of the amplifying and shaping modules to obtain the neutron counting rate.

14. The measuring system according to claim 13, characterized in that Also includes analysis modules; The analysis module is electrically connected to the amplification and shaping module and is used to observe the waveform of the signal output by the detector.

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