阅读说明：本技术 一种中子能谱测量装置及其测量方法 (Neutron energy spectrum measuring device and measuring method thereof ) 是由 孙爱赟 黑大千 求梦程 赵冬 于 2020-10-26 设计创作，主要内容包括：本发明公开了一种中子能谱测量装置及其测量方法,该中子能谱测量装置的中子-伽马射线信息转换装置包括同心球体结构的热中子俘获材料、快中子慢化体、快中子非弹性散射材料和高能中子倍增材料,中心伽马探测器设置于同心球体中心处,多层热中子俘获材料、单层快中子慢化体、多层快中子非弹性散射材料和单层高能中子倍增材料由内至外依次包设在中心伽马探测器外部,数据采集处理系统电性连接中心伽马探测器。本发明通过中心伽马探测器探测中子与中子反应截面不同的各种核素反应产生的瞬发伽马射线,并通过数据采集处理系统及利用特征伽马射线的能量和强度及各种核素材料信息反推出中子能谱,有效提高系统探测效率,实现宽能区中子能谱的在线测量。(The invention discloses a neutron energy spectrum measuring device and a measuring method thereof, wherein a neutron-gamma ray information conversion device of the neutron energy spectrum measuring device comprises a thermal neutron capturing material, a fast neutron moderator, a fast neutron inelastic scattering material and a high-energy neutron multiplying material which are of concentric sphere structures, a central gamma detector is arranged at the center of a concentric sphere, a plurality of layers of thermal neutron capturing materials, a single-layer fast neutron moderator, a plurality of layers of fast neutron inelastic scattering materials and a single-layer high-energy neutron multiplying material are sequentially wrapped outside the central gamma detector from inside to outside, and a data acquisition and processing system is electrically connected with the central gamma detector. The invention detects the prompt gamma ray generated by the reaction of the neutron and various nuclides with different neutron reaction cross sections through the central gamma detector, and reversely deduces the neutron energy spectrum by the data acquisition and processing system and by utilizing the energy and the intensity of the characteristic gamma ray and the information of various nuclide materials, thereby effectively improving the detection efficiency of the system and realizing the on-line measurement of the neutron energy spectrum in the wide energy region.)

1. A neutron energy spectrum measuring device is characterized by comprising a neutron-gamma ray information conversion device, a central gamma detector (1) and a data acquisition and processing system (2), the neutron-gamma ray information conversion device comprises a thermal neutron capture material (3) with a concentric sphere structure, a fast neutron moderator (4), a fast neutron inelastic scattering material (5) and a high-energy neutron multiplication material (6), the central gamma detector (1) is arranged at the center of the concentric sphere, the multilayer thermal neutron capturing material (3), the single-layer fast neutron moderating body (4), the multilayer fast neutron inelastic scattering material (5) and the single-layer high-energy neutron multiplying material (6) are sequentially coated outside the central gamma detector (1) from inside to outside, the data acquisition and processing system (2) is electrically connected with the central gamma detector (1).

2. The neutron spectrum measurement device of claim 1, wherein: the central gamma detector (1) is a lanthanum bromide detector or a bismuth germanate detector or a sodium iodide detector or a high-purity germanium detector.

3. The neutron spectrum measurement device of claim 2, wherein: the thermal neutron capture material (3) is provided with 2-5 layers, each layer of thermal neutron capture material (3) is concentrically coated outside the central gamma detector (1) from inside to outside, and the materials of each layer of thermal neutron capture material (3) are different.

4. The neutron spectrum measurement device of claim 3, wherein: the thermal neutron capture material (3) is cadmium-containing polyethylene or boron carbide or gadolinium oxide or sodium chloride.

5. The neutron spectrum measurement device of claim 4, wherein: the fast neutron moderating body (4) concentrically wraps the thermal neutron capturing material (3) on the outermost layer, and the fast neutron moderating body (4) is a hydrogen-rich material.

6. The neutron spectrum measurement device of claim 5, wherein: the fast neutron moderating body (4) is one of polyethylene and organic glass.

7. The neutron spectrum measurement device of claim 6, wherein: the fast neutron inelastic scattering material (5) is provided with 2-4 layers, each layer of fast neutron inelastic scattering material (5) is concentrically coated outside the fast neutron moderating body (4) from inside to outside, and materials of each layer of fast neutron inelastic scattering material (5) are different.

8. The neutron spectrum measurement device of claim 7, wherein: the fast neutron inelastic scattering material (5) is organic glass or iron-containing organic glass or lead-containing organic glass or aluminum-containing organic glass.

9. The neutron spectrum measurement device of claim 8, wherein: the high-energy neutron multiplication material (6) is concentrically coated outside the fast-neutron inelastic scattering material (5) on the outermost layer and is located on the outermost layer of the neutron-gamma ray information conversion device with the concentric sphere structure, and the high-energy neutron multiplication material (6) is one of lead, tungsten and copper.

10. The method for measuring a neutron spectrum measuring device according to any one of claims 1 to 9, comprising the steps of:

s1, placing a neutron energy spectrum measuring device in a mixed neutron field of fast neutrons and high-energy neutrons, wherein the neutrons enter a central gamma detector (1) from a certain direction, inelastic scattering reaction is carried out between the fast neutrons and a fast neutron inelastic scattering material (5) on the outermost layer to generate prompt characteristic gamma rays, reaction threshold values are different, fast neutron energy differentiation is achieved, and the central gamma detector (1) measures the prompt characteristic gamma rays;

s2, performing multiplication reaction on high-energy neutrons and the high-energy neutron multiplication material (6) in the mixed neutron field to generate fast neutrons with energy of 1-6 MeV;

s3, the fast neutrons generated in the step S2 further generate inelastic scattering reaction with the fast neutron inelastic scattering material (5) to generate prompt characteristic gamma rays so as to realize high-energy neutron response;

s4, moderating fast neutrons generated by the multiplication reaction of the fast neutrons and the high-energy neutrons in the mixed neutron field into thermal neutrons through a fast neutron moderating body (4);

s5, the thermal neutrons in the mixed neutron field and the thermal neutrons moderated by the fast neutrons further generate capture reaction with a thermal neutron capture material (3) to generate prompt characteristic gamma rays, and the central gamma detector (1) measures the prompt characteristic gamma rays;

s6, the central gamma detector (1) transmits the detected prompt characteristic gamma rays to the data acquisition and processing system (2), and the gamma ray energy spectrum is obtained through data acquisition and processing, so that the energy and the intensity of the characteristic gamma rays and the information of various nuclide materials can be used for reversely deducing the energy spectrum information of the neutron field to be detected.

Technical Field

The invention belongs to the technical field of radiation detection, and particularly relates to a neutron energy spectrum measuring device and a measuring method thereof.

Background

Neutron spectrum measurement is a fundamental research in neutron physics and has great significance for nuclear physics research work. The measurement result accuracy of the traditional common neutron energy spectrum measurement method is generally not high and has limitations, such as an active slice measurement method, which has low cost and excellent n/gamma discrimination capability, but most of the measurement results have the defects of dependence on an initial spectrum, low energy resolution and the like. The measurement method based on the plastic scintillator or the liquid scintillator is convenient to use, but the problems of n/gamma discrimination and accurate response function acquisition need to be solved. The development of commonly used gas detectors is also limited by the problems of shortage of raw materials and the like.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a neutron energy spectrum measuring device and a measuring method thereof, wherein the neutron energy spectrum measuring device emits gamma rays through a neutron multiplication reaction, an inelastic scattering reaction and a capture reaction with uncharged neutrons, and obtains neutron energy spectrum information by performing a gamma ray spectrum decomposition analysis, and when the structure and the element content of the neutron energy spectrum measuring device are determined, the energy and the intensity of the gamma rays emitted by the neutron energy spectrum measuring device are only related to the energy spectrum of incident neutrons.

In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows: a neutron energy spectrum measuring device comprises a neutron-gamma ray information conversion device, a central gamma detector and a data acquisition and processing system, wherein the neutron-gamma ray information conversion device comprises a thermal neutron capturing material, a fast neutron moderator, a fast neutron inelastic scattering material and a high-energy neutron multiplying material which are of a concentric sphere structure, the central gamma detector is arranged at the center of the concentric sphere, multiple layers of thermal neutron capturing materials, a single-layer fast neutron moderator, multiple layers of fast neutron inelastic scattering materials and a single-layer high-energy neutron multiplying material are sequentially wrapped outside the central gamma detector from inside to outside, and the data acquisition and processing system is electrically connected with the central gamma detector.

Furthermore, the central gamma detector is a lanthanum bromide detector or a BGO bismuth germanate detector or a NaI sodium iodide detector or a high-purity germanium detector.

Furthermore, the thermal neutron capture material is provided with 2-5 layers, each layer of thermal neutron capture material is concentrically coated outside the central gamma detector from inside to outside, and the materials of each layer of thermal neutron capture material are different.

Further, the thermal neutron capture material is cadmium-containing polyethylene or boron carbide or gadolinium oxide or sodium chloride.

Further, the fast neutron moderators are concentrically wrapped outside the thermal neutron capture material on the outermost layer, and the fast neutron moderators are hydrogen-rich materials.

Further, the fast neutron moderating body is one of polyethylene and organic glass.

Furthermore, the fast neutron inelastic scattering materials are provided with 2-4 layers, each layer of fast neutron inelastic scattering materials is concentrically coated outside the fast neutron moderator from inside to outside, and the fast neutron inelastic scattering materials of each layer are different in material.

Further, the fast neutron inelastic scattering material is organic glass or iron-containing organic glass or lead-containing organic glass or aluminum-containing organic glass.

Further, the high-energy neutron multiplication material is concentrically coated outside the fast neutron inelastic scattering material on the outermost layer and is located on the outermost layer of the neutron-gamma ray information conversion device with the concentric sphere structure, and the high-energy neutron multiplication material is one of lead, tungsten and copper.

Furthermore, the data acquisition processing system is a signal analyzer composed of a preamplifier, an amplifier, a multichannel analyzer and other devices, wherein the preamplifier, the amplifier and the multichannel analyzer are respectively used for filtering and shaping, signal amplification and amplitude analysis.

The invention also provides a measuring method of the neutron energy spectrum measuring device, which comprises the following steps:

s1, placing a neutron energy spectrum measuring device in a mixed neutron field of fast neutrons and high-energy neutrons, wherein the neutrons enter a central gamma detector from a certain direction, inelastic scattering reaction is carried out between the fast neutrons and a fast neutron inelastic scattering material on the outermost layer to generate prompt characteristic gamma rays, the reaction thresholds are different, the fast neutron energy is distinguished, and the central gamma detector measures the prompt characteristic gamma rays;

s2, performing multiplication reaction on high-energy neutrons and a high-energy neutron multiplication material in the mixed neutron field to generate fast neutrons with energy of 1-6 MeV;

s3, the fast neutrons generated in the step S2 further generate inelastic scattering reaction with the fast neutron inelastic scattering material to generate prompt characteristic gamma rays so as to realize high-energy neutron response;

s4, moderating fast neutrons generated by the fast neutron multiplication reaction and the high-energy neutron multiplication reaction in the mixed neutron field into thermal neutrons through a fast neutron moderator;

s5, the thermal neutrons in the mixed neutron field and the thermal neutrons moderated by the fast neutrons further generate capture reaction with a thermal neutron capture material to generate prompt characteristic gamma rays, and the central gamma detector measures the prompt characteristic gamma rays;

s6, the central gamma detector transmits the detected prompt characteristic gamma ray to a data acquisition and processing system, and a gamma ray energy spectrum is obtained through data acquisition and processing, and the energy and the intensity of the characteristic gamma ray and the information of various nuclide materials are used for reversely deducing the energy spectrum information of the neutron field to be detected.

The invention has the following beneficial effects:

1) different from the traditional neutron measurement method which utilizes the pulse amplitude or the pulse shape to perform n/gamma discrimination in a complex way, the method can provide a new solution for the difficult problem of n/gamma discrimination by an effective nuclear information extraction method of a gamma energy spectrum;

2) the measurement process is simplified: compared with an active sheet method and a Bonner sphere spectrometer which needs to measure the activity of different active sheets or the count of different Bonner spheres, the measurement process is complex; the neutron energy spectrum measuring device can simultaneously obtain the characteristic peak information of all selected nuclides in a single measuring process in the measuring process, thereby simplifying the neutron energy spectrum measuring process and improving the detection efficiency;

3) wide energy response range and better energy resolution: the neutron energy spectrum measuring device comprises a neutron-gamma ray information conversion device with a concentric sphere structure, wherein a central gamma detector is positioned at the center of the neutron-gamma ray information conversion device with the concentric sphere structure, the neutron-gamma ray information conversion device comprises a plurality of fast neutron inelastic scattering materials with different reaction thresholds, a plurality of high-energy neutron multiplication materials capable of performing multiplication reaction with high-energy neutrons, a plurality of thermal neutron capturing materials with higher thermal neutron capturing cross sections and a fast neutron moderator with a better fast neutron moderating material, the selection of nuclides in the neutron energy spectrum measuring device determines that the nuclides can react with neutrons in a very wide energy range, the incident high-energy neutrons firstly perform multiplication reaction with the high-energy neutron multiplication materials to generate fast neutrons with the energy of several MeV to further react with the measuring device, realizing the response of the material to high-energy neutrons; fast neutron inelastic scattering material and fast neutron generate inelastic scattering reaction to generate characteristic gamma rays, then the fast neutron is moderated into thermal neutrons through a fast neutron moderating body, the thermal neutrons further react with nuclides of a thermal neutron capturing material to emit more characteristic gamma rays, a central gamma detector is used for measuring and resolving the gamma energy spectrum, the detection device (a neutron-gamma ray information conversion device and the central gamma detector are integrally spherical and are not influenced by neutron incidence directions (the central gamma detector has response consistency to neutrons incident in different directions), the gamma rays emitted by the neutron energy spectrum measurement device when neutrons with different energies are incident are large in difference, the conversion efficiency of the neutrons and the gamma rays is high, data acquisition and processing are carried out through a data acquisition processing system to obtain the gamma ray energy spectrum, and the energy and intensity of the characteristic gamma rays and the information of various material nuclides in the to-be-detected are used for reversely deducing the energy nuclides in the neutron-to-be-detected neutron field The spectrum information effectively improves the system detection efficiency, realizes the on-line measurement of the neutron energy spectrum in the wide energy region with the energy response range covering the thermal neutron region to hundreds of megaelectron volts, provides a brand-new and effective solution for the neutron energy spectrum measurement, and has wide application prospect in the neutron flux and energy spectrum measurement.

Drawings

FIG. 1 is a schematic half-section view of the present invention;

fig. 2 is a graph of the response function of a central gamma detector to neutrons of different energies.

Wherein the reference numerals are: the device comprises a central gamma detector 1, a data acquisition and processing system 2, a thermal neutron capturing material 3, an inner layer thermal neutron capturing material 3-1, an outer layer thermal neutron capturing material 3-2, a fast neutron moderator 4, a fast neutron inelastic scattering material 5, an inner layer fast neutron inelastic scattering material 5-1, an outer layer fast neutron inelastic scattering material 5-2 and a high-energy neutron multiplier material 6.

Detailed Description

Embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

The design concept of the invention is as follows: the reaction cross sections of neutrons with different energies and nuclides are different, meanwhile, inelastic scattering reaction has an energy threshold, and when the material is determined, the type and the intensity of gamma rays measured by a detector are related to those of a neutron field; and selecting proper indicative nuclides for reflecting neutron energy information (for example, using Cl, B and other elements to reflect thermal neutron information, and Pb, C and other elements to reflect fast neutron information) aiming at different application fields (neutron fields), and simultaneously enabling different elements to be distributed at different positions of the sample through the structural design of the material. Incident neutrons are slowed down and subjected to (n, xn) equal-time-multiplication reaction through the sample, so that the energy response interval of the device is expanded, neutron energy reacting with different indicative nuclides is different, and response difference is increased so as to improve energy resolution of the incident neutrons.

The invention provides a neutron energy spectrum measuring device, which comprises a neutron-gamma ray information conversion device, a central gamma detector 1 and a data acquisition and processing system 2, wherein the neutron-gamma ray information conversion device comprises a thermal neutron capturing material 3 with a concentric sphere structure, a fast neutron moderator 4, a fast neutron inelastic scattering material 5 and a high-energy neutron multiplying material 6, the central gamma detector 1 is a lanthanum bromide detector or a BGO detector or a NaI detector or a high-purity germanium detector, the central gamma detector 1 is arranged at the center of the concentric sphere, the thermal neutron capturing material 3 is provided with 2-5 layers, each layer of thermal neutron capturing material 3 is concentrically coated outside the central gamma detector 1 from inside to outside, the thermal neutron capturing material 3 of each layer is different in material selection, the thermal neutron capturing material 3 is polyethylene containing cadmium or boron carbide or gadolinium oxide or sodium chloride, the single-layer fast neutron moderating body 4 is concentrically coated outside the outermost layer of thermal neutron capturing material 3, the fast neutron moderating body 4 is a hydrogen-rich material, 2-4 layers of fast neutron inelastic scattering materials 5 are arranged, each layer of fast neutron inelastic scattering material 5 is concentrically coated outside the fast neutron moderating body 4 from inside to outside, materials of the fast neutron inelastic scattering material 5 are different, the fast neutron inelastic scattering material 5 is organic glass or iron-containing organic glass or lead-containing organic glass or aluminum-containing organic glass, the single-layer high-energy neutron multiplying material 6 is concentrically coated outside the outermost layer of fast neutron inelastic scattering material 5 and is located on the outermost layer of the neutron-gamma ray information conversion device in the concentric sphere structure, the high-energy neutron multiplying material 6 is one of lead, tungsten and copper, and the data acquisition and processing system 2 is electrically connected with the center gamma detector 1.

Preferably, the fast neutron moderator 4 is polyethylene or plexiglass.

Example 1

As shown in figure 1, the neutron energy spectrum measuring device comprises a neutron-gamma ray information conversion device, a central gamma detector 1 and a data acquisition and processing system 2, wherein the neutron-gamma ray information conversion device comprises a thermal neutron capturing material 3, a fast neutron moderating body 4, a fast neutron inelastic scattering material 5 and a high-energy neutron multiplying material 6 which are in concentric sphere structures, the central gamma detector 1 adopts a lanthanum bromide detector and is arranged at the center of a concentric sphere, the thermal neutron capturing material 3 is provided with two layers, the inner layer thermal neutron capturing material 3-1 is boron-containing polyethylene, the outer layer thermal neutron capturing material 3-2 is sodium chloride, the inner layer thermal neutron capturing material 3-1 is coated outside the central gamma detector 1, the outer layer thermal neutron capturing material 3-2 is coated outside the inner layer thermal neutron capturing material 3-1, the fast neutron moderating body 4 is made of polyethylene, a single-layer fast neutron moderating body 4 is concentrically coated outside an outer-layer thermal neutron capturing material 3-2, the fast neutron inelastic scattering material 5 is two layers, an inner-layer fast neutron inelastic scattering material 5-1 is organic glass containing carbon and oxygen, an outer-layer fast neutron inelastic scattering material 5-2 is iron-containing organic glass, an inner-layer fast neutron inelastic scattering material 5-1 is concentrically coated outside the fast neutron moderating material 4, a high-energy neutron multiplying material 6 is made of lead, a single-layer high-energy neutron multiplying material 6 is concentrically coated outside the outer-layer fast neutron scattering inelastic material 5-2 and is positioned on the outermost layer of a neutron-gamma ray information conversion device with a concentric sphere structure, and the data acquisition and processing system 2 is a signal analyzer composed of a preamplifier, an amplifier, a multi-channel analyzer and the like, and the gamma ray energy spectrum acquisition device is connected with the central gamma detector 1, and is used for performing filtering shaping, signal amplification and amplitude analysis on the gamma rays with instantaneous characteristics, and finally acquiring the gamma ray energy spectrum measured by the central gamma detector 1.

The measuring method of the neutron energy spectrum measuring device comprises the following steps:

s1, placing a neutron energy spectrum measuring device in a mixed neutron field of fast neutrons and high-energy neutrons, wherein the neutrons enter a central gamma detector 1 from a certain direction, inelastic scattering reaction is carried out on the fast neutrons and elements such as iron, carbon and oxygen in a fast neutron inelastic scattering material 5, prompt characteristic gamma rays with different energies are generated, and the central gamma detector 1 measures the prompt characteristic gamma rays;

s2, for high-energy neutrons in the mixed neutron field, the inelastic scattering and capturing reaction cross sections of the high-energy neutrons and the nuclides are small, and the high-energy neutrons and lead in the high-energy neutron multiplication material 6 are subjected to multiplication reaction to generate fast neutrons with energy of 1-6 MeV;

s3, the fast neutrons generated in the step S2 further generate inelastic scattering reaction with the fast neutron inelastic scattering material 5 to generate prompt characteristic gamma rays, and the central gamma detector 1 measures the prompt characteristic gamma rays to realize high-energy neutron response;

s4, moderating fast neutrons generated by the fast neutron multiplication reaction and the high-energy neutron multiplication reaction in the mixed neutron field into thermal neutrons through a fast neutron moderating body 4;

s5, the thermal neutrons in the mixed neutron field and the thermal neutrons moderated by the fast neutrons further generate capture reaction with boron and cadmium elements in the thermal neutron capture material 3 to release more prompt characteristic gamma rays, and the central gamma detector 1 measures the prompt characteristic gamma rays

S6, the central gamma detector 1 transmits the detected prompt characteristic gamma ray to the data acquisition and processing system 2, and the gamma ray energy spectrum is obtained through data acquisition and processing, and the energy and the intensity of the characteristic gamma ray and the information of various nuclide materials are used for reversely deducing the energy spectrum information of the neutron field to be detected.

The multi-gamma-ray energy spectrum detector mainly utilizes capture reaction of thermal neutrons and nuclides and inelastic scattering reaction of fast neutrons and nuclides to obtain prompt characteristic gamma rays, incident neutron information such as the number and energy distribution of incident neutrons can be obtained through further back-pushing of the gamma rays, and meanwhile, in the multi-gamma-ray energy spectrum detector with the concentric sphere structure, as the device is spherical (a neutron-gamma-ray information conversion device and a central gamma-ray detector are integrated at the center), the response of the central gamma-ray detector 1 is basically irrelevant to the direction of the incident neutrons, namely, the multi-gamma-ray energy spectrum detector has response consistency to the neutrons incident in different directions, the detection efficiency of the system is effectively improved, and the online measurement of the neutron energy spectrum in a wide energy region is realized.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may be made by those skilled in the art without departing from the principle of the invention.