CN116736363A - Portable conical single-sphere neutron spectrum measurement system and measurement method thereof - Google Patents
Portable conical single-sphere neutron spectrum measurement system and measurement method thereof Download PDFInfo
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- 238000001228 spectrum Methods 0.000 title claims abstract description 63
- 238000005259 measurement Methods 0.000 title claims abstract description 37
- 238000000691 measurement method Methods 0.000 title abstract description 6
- 239000000463 material Substances 0.000 claims abstract description 48
- 238000012545 processing Methods 0.000 claims abstract description 19
- 230000004044 response Effects 0.000 claims abstract description 16
- 238000007405 data analysis Methods 0.000 claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- 238000005316 response function Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 11
- 239000004698 Polyethylene Substances 0.000 claims description 9
- -1 polyethylene Polymers 0.000 claims description 9
- 229920000573 polyethylene Polymers 0.000 claims description 9
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 8
- 239000001257 hydrogen Substances 0.000 claims description 8
- 229910052739 hydrogen Inorganic materials 0.000 claims description 8
- 239000011133 lead Substances 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 6
- 239000012188 paraffin wax Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 3
- 229910052721 tungsten Inorganic materials 0.000 claims description 3
- 239000010937 tungsten Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 14
- 239000000523 sample Substances 0.000 description 11
- 230000005855 radiation Effects 0.000 description 7
- 230000008569 process Effects 0.000 description 6
- 238000005086 pumping Methods 0.000 description 5
- 238000013461 design Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000004364 calculation method Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 238000010606 normalization Methods 0.000 description 2
- 230000009257 reactivity Effects 0.000 description 2
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- G—PHYSICS
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- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention relates to the technical field of nuclear science, in particular to a portable conical single-sphere neutron spectrum measurement system and a measurement method thereof, wherein the system comprises a conical slowing body, cylindrical through holes, neutron detectors, a data analysis processing system, a controller, a motor and traction wires, wherein the cylindrical through holes are formed in the conical slowing body, 1 neutron detector is arranged in each cylindrical through hole, and the data analysis processing system, the controller, the motor, the traction wires and the neutron detectors are sequentially connected; the data analysis processing system is used for receiving and processing signals in the neutron detector and giving instructions as a controller, the controller drives the motor to rotate, the electrode controls the traction line to move the neutron detector up and down, and when auxiliary materials are not added, the electrode is arranged at 10 ‑9 The MeV-20 MeV has better response; at 10 when auxiliary material is added ‑9 The MeV-1000 MeV has better response, and solves the problem of influence of the slow-down sphere quantity limitation spectrum resolving effect of the multi-sphere neutron spectrometer.
Description
Technical Field
The invention relates to the technical field of nuclear science, in particular to a portable conical single-sphere neutron spectrum measuring system and a measuring method thereof.
Background
Neutron energy spectrum measurement is of great significance to many tasks in the fields of nuclear engineering and nuclear physics. The neutron energy spectrum can be accurately measured and rapidly analyzed in reactor design and application or under special environmental conditions, namely, the neutron source item can be determined as accurately and conveniently as possible, and the method is very important for reactor parameter design, radiation damage evaluation of special materials for nuclear and neutron shielding material design under special environments.
The multi-sphere neutron spectrometer system is firstly proposed by Bramblett in 1960 and consists of a series of polyethylene slowing balls with different diameters, a spherical proportional counter is adopted by a central detector, and the multi-sphere neutron spectrometer has the advantages of wide response range, isotropy, simplicity in operation and the like. However, with the development of nuclear technology, especially with the development of aerospace technology, a multi-sphere neutron spectrum measurement system is required to be portable and light in weight for space neutron spectrum measurement, so that the cost of aerospace transportation is reduced. In order to achieve the purpose of portable multi-sphere neutron spectrum measurement, a set of neutron spectrometer which is provided with four spheres and is arranged on a rotatable platform is designed abroad so as to achieve the purpose of multi-sphere measurement; the domestic multi-sphere neutron spectrometer is continuously researched and improved to form a plurality of types of multi-sphere neutron spectrometers, and domestic Li Taosheng develops a single-sphere multi-counter spectrometer which is essentially a multi-sphere neutron spectrometer, but a plurality of thermal neutron proportional counters are embedded in polyethylene slowing-down bodies in a pairwise orthogonal manner; a water pumping and injecting multilayer concentric sphere neutron spectrometer developed by the university of Chengdu university Yang Jianbo; the nested multi-sphere neutron spectrum measuring system designed by the university of Qinghua can achieve the aim of multi-sphere.
Although the improved multi-sphere neutron spectrometer increases the portability of the spectrometer to a certain extent and reduces the quality of the spectrometer, the nested multi-sphere neutron spectrometer increases the risk of personnel being radiated because of manual operation; at the same time, adding a moderating layer per layer increases the complexity of the operating time. The water pumping and injecting multilayer concentric sphere neutron spectrometer adopts water as a slowing material, and changes the thickness of the slowing material by changing a water layer, so that the operation complexity of the spectrometer is increased under the condition of space neutron measurement, and the spectrometer is not applicable to the measurement of space neutrons; domestic Li Taosheng developed a single-sphere multi-counter spectrometer which adopts a thermal neutron proportional counter with three probes, the number of the probes is too small, and the risk of measuring neutron spectrum accuracy is increased.
In order to simplify a neutron spectrometer measurement system and enable the neutron spectrometer measurement system to be more portable and convenient, the invention provides a single-sphere multi-neutron energy spectrum counting system and a measurement method thereof. There are two measurement modes for this system: (1) a plurality of thermal neutron detectors are needed, and are embedded in a central through hole for placing thermal neutron detection at the central shaft of the cone, so that the purpose of realizing multi-sphere measurement is achieved through different slowing thicknesses of different heights at the cone; (2) the requirements of energy spectrum measurement can be met by only one detector and one set of electronic equipment, the thermal neutron probe is pulled by a motor to move up and down at the central through hole at the central axis of the cone, the purpose of multi-ball measurement is achieved by different slowing thicknesses at different heights at the cone, and the purpose of N slowing structures can be achieved by the scheme. The single-sphere multi-neutron energy spectrum counting system solves the problems that a conventional multi-sphere neutron spectrometer is large in size and inconvenient to carry. Meanwhile, the purpose of multiple slowing bodies of multiple balls is achieved through one slowing structure, and the weight of the spectrometer is greatly reduced.
The improved multi-sphere neutron spectrometer at home and abroad increases portability of the spectrometer to a certain extent, reduces quality of the spectrometer, but increases risk of personnel being radiated because of manual operation of the nested multi-sphere neutron spectrometer; at the same time, adding a moderating layer per layer increases the complexity of the operating time. The water pumping and injecting multilayer concentric sphere neutron spectrometer adopts water as a slowing material, and changes the thickness of the slowing material by changing a water layer, so that the operation complexity of the spectrometer is increased under the condition of space neutron measurement, and the spectrometer is not applicable to the measurement of space neutrons; domestic Li Taosheng developed a single-sphere multi-counter spectrometer which adopts a thermal neutron proportional counter with three probes, the number of the probes is too small, and the risk of measuring neutron spectrum accuracy is increased.
The invention aims to solve the problems of complex operation, large quantity and large volume of the conventional multi-sphere neutron spectrometer, and provides a portable conical single-sphere neutron energy spectrum measuring system which can well solve the problems of complex operation, poor spectrum resolving effect due to small quantity of response functions, large quantity and large volume of the conventional portable multi-sphere neutron spectrometer.
Reference to the literature
1.BRAMBLETT R L,EWING R I,BONNER T W.1960.A new type of neutron spectrometer.Nuclear Instruments andMethods[J],9:1-12.
2. Li Taosheng, le Zhixi, gong Cunkui, etc. binary moderated high energy neutron dosimeters, CN101419290A [ P ].2009.
3. Hong Bing, li Taosheng, zhang Zhiyong, et al. Electronics systems for single sphere multiple counter neutron dosimeters developed [ J ]. Nuclear technology, 2014 (011): 037.
4.Dubeau J,Witharana S,YonkeuA,et al.ANEWTYPE OF NEUTRON SPECTROMETERUSING NESTED MODERATOR.
5.WIEGEL B,ALEVRAA V.2002.NEMUS-the PTB Neutron Multisphere Spectrometer:Bonner spheres and more.Nuclear Instruments&Methods in Physics Research Section a-Accelerators Spectrometers Detectors and AssociatedEquipment[J],476:36-41.
6.WIEGEL B,ALEVRAAV,SIEBERT B R L.1994.Calculations ofthe response functions ofBonner Spheres with a spheriacl He-3proportional counter using a realistic detector model[M].Physikalisch Technische Bundesanstalt.
7.ING H,CLIFFORD T,MCLEAN T,et al.1997.ROSPEC-A simple reliable high resolution neutron spectrometer.Radiation Protection Dosimetry[J],70:273-278.
Disclosure of Invention
The invention provides a portable conical single-sphere neutron spectrum measurement system, which comprises a conical slowing body 1, cylindrical through holes 4, neutron detectors 2, a data analysis processing system, a controller, a motor and traction wires, wherein the cylindrical through holes 4 are arranged in the conical slowing body 1, the neutron detectors 2 are arranged in the cylindrical through holes 4, 1 neutron detector 2 is arranged, and the data analysis processing system, the controller, the motor, the traction wires and the neutron detectors 2 are sequentially connected; the data analysis processing system is used for receiving and processing signals in the sub-detector 2 and giving instructions to the controller, the controller drives the motor to rotate, and the electrodes control the traction line to move the sub-detector up and down.
Preferably, the auxiliary material 3 is arranged in the conical slowing body 1 near the cylindrical through hole 4.
Preferably, the cone-shaped slowing body 1 is prepared from a hydrogen-rich material.
Preferably, the hydrogen-rich material is polyethylene, paraffin or water.
Preferably, the hydrogen-rich material is water, the water can be injected when the spectrometer is used, and the water is discharged when the spectrometer is not used, so that the quality of the spectrometer is reduced to the greatest extent.
Preferably, the cylindrical through hole 4 is located at the central axis of the conical slowing body 1.
Preferably, the neutron detector 2 is a spherical neutron detector.
Preferably, the auxiliary material 3 is lead, iron or tungsten.
The second object of the invention is to provide a measuring method of the portable conical single-sphere neutron spectrum measuring system, which comprises the following steps: forms m different moderated thickness structures, at 10 -9 Selecting n discrete energy values in each energy level of the neutron energy range from MeV to 20MeV, obtaining response function values under m different slowing thicknesses by using Monte Carlo simulation software, and finally forming a response function matrix in the following formula;
wherein 1-m represent m different moderation thicknesses, i represents a selected energy discrete number;
if the energy of the incident neutron is at most E max The minimum energy of the incident neutron is E min Then the fluence can be defined as follows:
wherein N is d Is the count of the detector, R φ (E) The response function of the detector, namely the response number of unit neutron fluence caused in the detector, and the neutron energy spectrum calculated by phi (E);
discretizing the formula to obtain the following formula:
the matrix of m rows and one column measured by the neutron detector is as follows:
bringing equations (1) and (4) into equation (3) yields:
obtained by deconvolutionThe neutron spectrum is obtained.
The beneficial effects of the invention are as follows: (1) The portable conical single-sphere neutron spectrum measuring system is provided, and the thickness of different positions of a conical slowing body is different, so that different slowing effects on neutrons are obtained. The taper slowing body is made of polyethylene, paraffin, water and other materials, and can further reduce the weight of the spectrometer by adopting a water injection pumping mode. (2) To improve the response of the spectrometer to high-energy neutrons, an auxiliary material with a certain thickness is added into the conical slowing bodyThe portable conical single-sphere neutron spectrum measurement system avoids the sphere interference problem of the conventional multi-sphere neutron spectrometer; (3) The portable conical single-sphere neutron spectrum measuring system of the invention has the advantages that the neutron energy of the conical slowing body without auxiliary materials is 10 -9 The MeV-20 MeV neutrons have a good response effect; the tapered moderator added with auxiliary material has neutron energy of 10 -9 The MeV-1000 MeV neutrons have a good response effect; (4) The portable conical single-sphere neutron spectrum measuring system avoids the purpose that the measuring process repeatedly enters a radiation place to replace a slowing sphere. (5) The portable single-cone multi-sphere neutron spectrum measuring system is simple to operate, and the number of the slowing spheres replaces the whole conventional multi-sphere neutron spectrum measuring system, so that the weight of the spectrometer is greatly reduced, and the portability of the spectrometer is improved. (6) The system adopts a neutron detector, and the neutron detector is pulled by a motor to move up and down at a cylindrical hole, so that the purpose of multi-ball measurement is realized. The system avoids the ball interference problem of the conventional multi-ball neutron spectrometer; the purpose of repeatedly entering the radiation place to replace the slowing ball in the measuring process is avoided. The portable single-cone multi-sphere neutron spectrum measuring system is simple to operate, the whole conventional multi-sphere neutron spectrum measuring system is replaced by one moderated sphere number, the weight of the spectrometer is greatly reduced, and the portability of the spectrometer is improved.
Drawings
FIG. 1 is a schematic diagram of a portable single cone multi-sphere neutron spectrum measurement system
FIG. 2 is a flow chart of a portable single cone multi-sphere neutron spectrum measurement system
FIG. 3 schematic diagram of Monte Carlo model without auxiliary material
Left: a cross-sectional view; right: plan view of a computer
FIG. 4 response function of 8 probes without auxiliary material
FIG. 5 schematic of Monte Carlo model with auxiliary material
Left: a cross-sectional view; right: plan view of a computer
FIG. 6 response function of 8 probes with auxiliary material
Note that: lead thickness 1cm
FIG. 7 response function of 8 probes with auxiliary material
Note that: lead thickness 2cm
FIG. 8 response function of 8 probes with auxiliary material
Note that: lead thickness 3cm
Neutron spectrum resolved by the detector of FIG. 9
Detailed Description
The following describes the scope of the present invention in detail with reference to the accompanying drawings, and it should be noted that the scope of the present invention is not limited by the following examples.
Embodiment one, a portable conical single sphere neutron spectrum measurement system
As shown in fig. 1 and 2, the invention provides a portable conical single-sphere neutron spectrum measurement system, which comprises a conical slowing body 1, cylindrical through holes 4, neutron detectors 2, a data analysis processing system, a controller, a motor and traction wires, wherein the cylindrical through holes 4 are arranged in the conical slowing body 1, the neutron detectors 2 are arranged in the cylindrical through holes 4, 1 neutron detector 2 is arranged, and the data analysis processing system, the controller, the motor, the traction wires and the neutron detectors 2 are sequentially connected; the data analysis processing system is used for receiving and processing signals in the sub-detector 2 and giving instructions to the controller, the controller drives the motor to rotate, and the electrodes control the traction line to move the sub-detector up and down. An auxiliary material 3 is arranged in the conical slowing body 1 near the cylindrical through hole 4. The conical moderator 1 is prepared from a hydrogen-rich material. The hydrogen-rich material is polyethylene, paraffin or water. The cylindrical through hole 4 is positioned on the central axis of the conical slowing body 1. The neutron detector 2 is a spherical neutron detector. The auxiliary material 3 is composed of lead, iron or tungsten.
Embodiment two, neutron spectrum measuring method
Forms m different moderated thickness structures, at 10 -9 Selecting n discrete energy values in each energy level of the neutron energy range from MeV to 20MeV, obtaining response function values under m different slowing thicknesses by using Monte Carlo simulation software, and finally forming a response function matrix in the following formula;
wherein 1-m represent m different moderation thicknesses, and i represents a selected energy discrete number.
If the energy of the incident neutron is at most E max The minimum energy of the incident neutron is E min Then the fluence can be defined as follows:
wherein N is d Is the count of the detector, R φ (E) The response function of the detector, namely the response number of the unit neutron fluence caused in the detector, and the neutron energy spectrum calculated by phi (E).
Discretizing the formula to obtain the following formula:
the matrix of m rows and one column measured by the neutron detector is as follows:
bringing equations (1) and (4) into equation (3) yields:
obtained by deconvolutionThe neutron spectrum is obtained.
Embodiment three, measuring neutron spectrum with neutron spectrum measurement system
According to the structure of the detector shown in fig. 1, the controller starts the motor traction, the neutron detector is drawn to reach a designated position, the detector starts working, after the data analysis processing system obtains the neutron count N1, the controller continues to control the motor to draw the neutron detector to repeat the operation until the data analysis processing system obtains the neutron last count Nend, and the data analysis processing system analyzes the neutron count to obtain a neutron energy spectrum.
1. Neutron spectrum measurement method without adding auxiliary material
The Monte Carlo model shown in figure 3 is established by using Monte Carlo simulation program simulation software, and 8 spheres are designed in the conical moderator 3 He is proportional to the counter. A single-energy planar source is perpendicularly incident to the conical moderator, and the source is defined as a rectangular planar source, and the side length of the planar source is the same as the diameter and the height of the lower bottom surface of the conical moderator. Calculation of response functions at different water layer combinations using MCNPX Monte Carlo radiation transport codes with ENDF/B-VI-0 neutron cross section libraryRecording neutrons and using F4 card and FM4 card in MCNPX 3 He-generated (n, p) reactivity in the corresponding format FM 4C M R, where M represents the material of the cell to be recorded [ ] 3 He); r is a channel number, and the channel number of the (n, p) reaction is 103; c represents a normalization factor.
C＝-V He ·S。
After the FM4 card is used, the result obtained by the FM4 card is neutron fluence response. In addition, in the interaction process of neutrons and substances, the elastic scattering effect is accompanied with inelastic scattering effect with a certain probability. Thus, neutron thermalization in the MCNPX code takes into account the use of S (α, β) cross-section libraries (water: MTn lwtr.01, polyethylene: MTnpoly.01).
When no auxiliary material is added, the conical moderator has the following dimensions: the diameter of the lower bottom is 40cm, the diameter of the upper bottom is 7cm, the height is 40cm, and the density of the conical moderator material is 0.95g/cm 3 . The diameter of the cylindrical through hole is 5cm.Neutron detector using 3 He proportional counter, gas pressure is 10 atmospheres, 3 the density of He gas was 1.89427 ×10 -3 g/cm 3 The probe diameter was 5cm.
The response function without the addition of auxiliary material is shown in FIG. 4, and the tapered moderator without the addition of auxiliary material has a neutron energy of 10 -9 The MeV-20 MeV neutrons have a better response effect.
2. Auxiliary material is added to measure neutron spectrum by neutron spectrum measurement method
The Monte Carlo model shown in FIG. 5 was built using Monte Carlo simulation program simulation software, and 8 positions were designed in the cone-shaped moderator 3 He is proportional to the counter. A single-energy planar source is perpendicularly incident to the conical moderator, and the source is defined as a rectangular planar source, and the side length of the planar source is the same as the diameter and the height of the lower bottom surface of the conical moderator. Calculation of response functions at different water layer combinations using MCNPX Monte Carlo radiation transport codes with ENDF/B-VI-0 neutron cross section libraryRecording neutrons and using F4 card and FM4 card in MCNPX 3 He-generated (n, p) reactivity in the corresponding format FM 4C M R, where M represents the material of the cell to be recorded [ ] 3 He); r is a channel number, and the channel number of the (n, p) reaction is 103; c represents a normalization factor, c= -V He S. After the FM4 card is used, the result obtained by the FM4 card is neutron fluence response. In addition, in the interaction process of neutrons and substances, the elastic scattering effect is accompanied with inelastic scattering effect with a certain probability. Thus, neutron thermalization in the MCNPX code takes into account the use of S (α, β) cross-section libraries (water: MTn lwtr.01, polyethylene: MTnpoly.01).
The detector is mounted in the manner shown in fig. 5. The thickness of the added auxiliary material is 1cm, 2cm and 3cm of lead respectively, the height of the auxiliary material is 15cm, the distance from the bottom of the conical slowing body is 10cm, and the size of the conical slowing body is as follows: the diameter of the lower bottom is 40cm, the diameter of the upper bottom is 7cm, the height is 40cm, and the density of the conical moderator material is 0.95g/cm 3 . Round circleThe diameter of the cylindrical through hole is 5cm. The neutron detector adopts a 3He proportional counter, the air pressure is 10 atmospheres, 3 the density of He gas was 1.89427 ×10 -3 g/cm 3 The probe diameter was 5cm.
The response function of the neutron detector is shown in figures 6-9, and the tapered moderator added with auxiliary material has a neutron energy of 10 -9 The MeV-1000 MeV neutrons have a better response effect.
In summary, the invention provides a portable conical single-sphere neutron spectrum measurement system, which adopts the conical slowing-down bodies with different thicknesses at different positions so as to obtain different slowing-down effects on neutrons. The taper slowing body is made of polyethylene, paraffin, water and other materials, and can further reduce the weight of the spectrometer by adopting a water injection pumping mode. In order to improve the response of the spectrometer to high-energy neutrons, an auxiliary material with a certain thickness is added into the conical slowing body, and the portable conical single-sphere neutron energy spectrum measuring system avoids the problem of sphere interference of the conventional multi-sphere neutron spectrometer; the portable conical single-sphere neutron spectrum measuring system of the invention has the advantages that the neutron energy of the conical slowing body without auxiliary materials is 10 -9 The MeV-20 MeV neutrons have a good response effect; the tapered moderator added with auxiliary material has neutron energy of 10 -9 The MeV-1000 MeV neutrons have a good response effect; the portable conical single-sphere neutron spectrum measuring system avoids the purpose that the measuring process repeatedly enters a radiation place to replace a slowing sphere. The portable single-cone multi-sphere neutron spectrum measuring system is simple to operate, and the number of the slowing spheres replaces the whole conventional multi-sphere neutron spectrum measuring system, so that the weight of the spectrometer is greatly reduced, and the portability of the spectrometer is improved. The system adopts a neutron detector, and the neutron detector is pulled by a motor to move up and down at a cylindrical hole, so that the purpose of multi-ball measurement is realized. The system avoids the ball interference problem of the conventional multi-ball neutron spectrometer; the purpose of repeatedly entering the radiation place to replace the slowing ball in the measuring process is avoided. The portable single-cone multi-sphere neutron spectrum measuring system is simple to operate, the whole conventional multi-sphere neutron spectrum measuring system is replaced by one moderated sphere number, the weight of the spectrometer is greatly reduced, and the portability of the spectrometer is improved.
Claims (9)
1. The portable conical single-sphere neutron spectrum measurement system is characterized by comprising a conical slowing body, cylindrical through holes, neutron detectors, a data analysis processing system, a controller, a motor and traction wires, wherein the cylindrical through holes are formed in the conical slowing body, 1 neutron detector is arranged in each cylindrical through hole, and the data analysis processing system, the controller, the motor, the traction wires and the neutron detectors are sequentially connected; the data analysis processing system is used for receiving and processing signals in the neutron detector and giving instructions to the controller, the controller drives the motor to rotate, and the electrodes control the traction line to move the neutron detector up and down.
2. The portable conical single-sphere neutron spectrum measurement system according to claim 1, wherein the conical slowing body is provided with an auxiliary material 3 near the cylindrical through hole 4.
3. The portable conical single sphere neutron spectrum measurement system of claim 1, wherein the conical moderator is made of a hydrogen rich material.
4. The portable conical single sphere neutron spectrum measurement system of claim 2, wherein the hydrogen-rich material is polyethylene, paraffin or water.
5. The portable conical single sphere neutron spectrum measurement system of claim 2, wherein the hydrogen-rich material is water.
6. The portable conical single sphere neutron spectrum measurement system of claim 1, wherein the cylindrical through hole is located at a central axis of the conical moderator.
7. The portable conical single sphere neutron spectrum measurement system of claim 1, wherein the neutron detector is a spherical neutron detector.
8. The portable conical single sphere neutron spectrum measurement system of claim 1, wherein the auxiliary material is comprised of lead, iron or tungsten.
9. The method of measuring a portable conical single sphere neutron spectrum measurement system according to claim 1, comprising the steps of: forms m different moderated thickness structures, at 10 -9 Selecting n discrete energy values in each energy level of the neutron energy range from MeV to 20MeV, obtaining response function values under m different slowing thicknesses by using Monte Carlo simulation software, and finally forming a response function matrix in the following formula;
wherein 1-m represent m different moderation thicknesses, i represents a selected energy discrete number;
if the energy of the incident neutron is at most E max The minimum energy of the incident neutron is E min Then the fluence can be defined as follows:
wherein N is d Is the count of the detector, R φ (E) The response function of the detector, namely the response number of unit neutron fluence caused in the detector, and the neutron energy spectrum calculated by phi (E);
discretizing the formula to obtain the following formula:
the matrix of m rows and one column measured by the neutron detector is as follows:
bringing equations (1) and (4) into equation (3) yields:
obtained by deconvolutionThe neutron spectrum is obtained.
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