阅读说明：本技术 一种基于碲锌镉探测器阵列的中子源位置测量装置及测量方法 (Neutron source position measuring device and method based on cadmium zinc telluride detector array ) 是由 黑大千 孙爱赟 求梦程 赵冬 于 2020-10-26 设计创作，主要内容包括：本发明提供一种基于碲锌镉探测器阵列的中子源位置测量装置,包括探测器本体,探测器本体最外层为中子非弹散射材料层,探测器本体几何中心处设置伽马射线探测器；伽马射线探测器与中子非弹散射材料层之间设置有若干层中子慢化体和若干层中子俘获材料,中子慢化体与中子俘获材料隔层交错；中子慢化体内设置有若干个呈阵列分布的碲锌镉探测器；碲锌镉探测器与信号放大器、模数转换器、多道分析器和电脑依次连接；本发明还提供一种基于碲锌镉探测器阵列的中子源位置测量装置的测量方法。本发明利用不同入射方向的中子在不同位置的碲锌镉探测器能谱响应函数不同,根据能谱解析之后的差异判断中子入射方向,实现了4π方向中子入射测量的一致性与准确性。(The invention provides a neutron source position measuring device based on a cadmium zinc telluride detector array, which comprises a detector body, wherein the outermost layer of the detector body is a neutron non-elastic scattering material layer, and a gamma ray detector is arranged at the geometric center of the detector body; a plurality of layers of neutron moderators and a plurality of layers of neutron capture materials are arranged between the gamma ray detector and the neutron non-elastic scattering material layer, and the neutron moderators and the neutron capture material layers are staggered; a plurality of cadmium zinc telluride detectors distributed in an array are arranged in the neutron moderating body; the cadmium zinc telluride detector is sequentially connected with the signal amplifier, the analog-to-digital converter, the multichannel analyzer and the computer; the invention also provides a measuring method of the neutron source position measuring device based on the cadmium zinc telluride detector array. The invention judges the neutron incidence direction according to the difference after energy spectrum analysis by utilizing the difference of energy spectrum response functions of the tellurium-zinc-cadmium detectors at different positions of neutrons in different incidence directions, thereby realizing the consistency and the accuracy of the neutron incidence measurement in the 4 pi direction.)

1. A neutron source position measuring device based on a cadmium zinc telluride detector array is characterized by comprising a detector body, wherein a neutron non-elastic scattering material layer (5) is arranged on the outermost layer of the detector body, and a gamma ray detector (2) is arranged at the geometric center of the detector body; a plurality of layers of neutron moderators (3) and a plurality of layers of neutron capture materials (4) are arranged between the gamma ray detector (2) and the neutron non-elastic scattering material layer (5), and the neutron moderators (3) and the neutron capture materials (4) are arranged in a staggered mode through interlayer layers; a plurality of cadmium zinc telluride detectors (1) are arranged in the neutron moderating body (3), and the plurality of cadmium zinc telluride detectors (1) are distributed in an array on the same neutron moderating body (3) layer; the cadmium zinc telluride detector (1) is sequentially connected with a signal amplifier (6), an analog-to-digital converter (7), a multichannel analyzer (8) and a computer (9).

2. The device for measuring the position of a neutron source based on a cadmium zinc telluride detector array according to claim 1, wherein the detector body is in an axially symmetric shape, particularly a sphere or a cylinder, and the response of the gamma ray detector (2) is independent of the direction of incident neutrons.

3. The device for measuring the position of a neutron source based on a cadmium zinc telluride detector array according to claim 1, wherein the neutron moderators (3) and the neutron capture materials (4) are concentrically arranged in a staggered mode by taking the gamma ray detectors (2) as centers; the neutron moderating body (3) is used for moderating fast neutrons into thermal neutrons, and the neutron capturing material (4) reacts with the thermal neutrons after being moderated by the neutron moderating body (3) to generate prompt gamma rays.

4. The device for measuring the position of a neutron source based on a cadmium zinc telluride detector array as claimed in claim 1, wherein the neutron non-elastic scattering material layer (5) is made of heavy metal material, and prompt gamma rays with energy characteristics are generated through inelastic scattering with fast neutrons.

5. The apparatus for measuring the position of a neutron source based on a cadmium zinc telluride detector array as claimed in claim 1, wherein the cadmium zinc telluride detector (1) layers are distributed in an array at different positions of the neutron moderator (3) where neutrons have been sufficiently moderated by the neutron moderator (3).

6. The device for measuring the position of a neutron source based on the cadmium zinc telluride detector array as claimed in claim 1, wherein the cadmium zinc telluride detector (1) is used for detecting prompt gamma rays generated by inelastic scattering of a neutron nonelastic scattering material layer (5) and fast neutrons, prompt gamma rays generated by reaction of a neutron capturing material (4) and thermal neutrons after moderation by a neutron moderator (3), and 558keV characteristic gamma rays generated by reaction of the thermal neutrons and cadmium in the cadmium zinc telluride detector (1), forming a response energy spectrum, and then performing spectrum decomposition by a gamma spectrum decomposition technology to realize separation of a capture spectrum, a nonelastic scattering spectrum and a background spectrum.

7. The device for measuring the position of a neutron source based on a cadmium zinc telluride detector array according to claim 1, wherein the adjacent layer of the neutron non-elastic scattering material layer (5) is a neutron moderator (3), and the adjacent layer of the gamma ray detector (2) is the neutron moderator (3).

8. The measurement method of the device for measuring the position of the neutron source based on the cadmium zinc telluride detector array as claimed in any one of claims 1 to 6, characterized by comprising the following steps:

s1, enabling neutrons to enter the detector from a certain direction;

s2, when the fast neutrons pass through the neutron non-elastic scattering material layer (5), non-elastic scattering occurs, and prompt gamma rays with characteristic energy are generated;

s3, after the fast neutrons are fully moderated by the neutron moderating body (3), prompt gamma rays are generated by the thermal neutrons and the neutron capture material (4), and react with cadmium in the cadmium zinc telluride detector (1) to generate 558keV characteristic gamma rays;

s4, detecting gamma rays at corresponding positions by a cadmium zinc telluride detector (1) array arranged in the neutron moderating body (3) to obtain a superposition energy spectrum;

s5, performing energy spectrum analysis on the gamma ray superposition energy spectrum detected by the cadmium zinc telluride detector (1) through a gamma spectrum resolving technology to realize separation of the gamma ray superposition energy spectrum;

s6, constructing a response function spectrum library in different neutron incidence directions according to different response functions of the cadmium zinc telluride detectors (1) placed at different positions to different neutron incidence directions, thereby realizing judgment of the neutron incidence directions.

Technical Field

The invention belongs to the technical field of radiation detection, and particularly relates to a neutron source position measuring device and a neutron source position measuring method based on a cadmium zinc telluride detector array.

Background

The special nuclear material and nuclear waste contain a large amount of different radioactive nuclides, and the gamma rays of partial key nuclides have low energy (such as gamma rays)²³⁵185.7keV for U, and 57.2% branch ratio), there is also often a certain thickness of shielding protection structure outside the detected object. The penetration depth of gamma rays in the shielding structure is limited, and it is difficult to obtain enough information from the outside, so that it is difficult to realize the purpose of utilizing gamma rays to shield inside the shielding structure²³⁵U and other elements. High-energy neutrons are released by spontaneous or induced fission from a large amount of uranium and heavy uranium elements contained in special nuclear materials and nuclear wastes. Since neutrons are of high energy and a single fission releases multiple neutrons, it can be a characteristic indicator of special nuclear materials, nuclear waste. Neutrons are electrically neutral, have deep penetrability in materials, are difficult to shield with heavy metal materials, and therefore, the detection of a management object in a deep place can be realized by utilizing neutron signals. With the continuous development of nuclear technology, neutron application technology is increasingly applied to various fields, and the position of a neutron source needs to be determined in some cases. Aiming at complex detection environment, the positioning of the neutron source is difficult to realize by using the signal acquired by a single detector.

The neutron scattering camera composed of the detectors can simultaneously acquire the position and energy information of the neutron source, and therefore the neutron source can be accurately positioned. The neutron scattering camera determines the position of a neutron source by providing a scattering angle for each neutron effective signal, determining the scattering angle on a probability cone, wherein the intersection point of the probability cone and an image plane is an ellipse, and is called an event circle, and performing image reconstruction by overlapping a plurality of event circles of the neutron effective signals. And further establishing a corresponding neutron source distribution imaging reconstruction method, and determining the position of the neutron source through the limited effective neutron signal. However, the neutron scattering camera has low detection efficiency, high price and poor position resolution.

Therefore, there is a need to improve the conventional neutron source position measuring method, establish a novel neutron source position measuring device and a measuring method, and solve the defects of the conventional neutron source position measuring method and device.

Disclosure of Invention

The invention aims to provide a neutron source position measuring device and a neutron source position measuring method based on a cadmium zinc telluride detector array, aiming at the defects of the prior art.

The invention adopts the following technical scheme:

a neutron source position measuring device based on a cadmium zinc telluride detector array comprises a detector body, wherein a neutron non-elastic scattering material layer is arranged on the outermost layer of the detector body, and a gamma ray detector is arranged at the geometric center of the detector body; a plurality of layers of neutron moderators and a plurality of layers of neutron capture materials are arranged between the gamma ray detector and the neutron non-elastic scattering material layer, and the neutron moderators and the neutron capture material interlayers are arranged in a staggered mode; a plurality of cadmium zinc telluride detectors are arranged in the neutron moderator and are distributed in an array on the same neutron moderator layer; the cadmium zinc telluride detector is sequentially connected with the signal amplifier, the analog-to-digital converter, the multichannel analyzer and the computer.

Furthermore, the detector body is in an axial symmetry shape, specifically a sphere or a cylinder, and the response of the gamma ray detector is irrelevant to the direction of incident neutrons.

Further, the neutron moderators and the neutron capture materials are concentrically arranged in a staggered manner by taking the gamma ray detector as a center; the neutron moderating body is used for moderating fast neutrons into thermal neutrons, and the neutron capturing material reacts with the thermal neutrons after the neutron moderating body moderates to generate prompt gamma rays.

Furthermore, the neutron inelastic scattering material layer is made of a heavy metal material, and instantaneous gamma rays with energy characteristics are generated through inelastic scattering of the neutron inelastic scattering material layer and fast neutrons.

Furthermore, the cadmium zinc telluride detector layers are distributed at different positions of the neutron moderating body in an array mode, and neutrons are sufficiently moderated by the neutron moderating body at the positions.

Furthermore, the tellurium-zinc-cadmium detector is used for detecting prompt gamma rays generated by inelastic scattering of the neutron nonelastic scattering material layer and fast neutrons, prompt gamma rays generated by reaction of a neutron capture material and thermal neutrons after the neutron moderation body is moderated, and 558keV characteristic gamma rays generated by reaction of thermal neutrons and cadmium in the tellurium-zinc-cadmium detector, forming a response energy spectrum, and then performing spectrum decomposition through a gamma spectrum decomposition technology to realize separation of a capture spectrum, a nonelastic scattering spectrum and a background spectrum.

Furthermore, the adjacent layer of the neutron non-elastic scattering material layer is a neutron moderating body, and the adjacent layer of the gamma ray detector is the neutron moderating body.

The measuring method of the neutron source position measuring device based on the cadmium zinc telluride detector array comprises the following steps:

s1, enabling neutrons to enter the detector from a certain direction;

s2, when the fast neutrons pass through the neutron non-elastic scattering material layer, non-elastic scattering occurs, and prompt gamma rays with characteristic energy are generated;

s3, after the fast neutrons are fully moderated by the neutron moderator, prompt gamma rays are generated by the thermal neutrons and the neutron capture material, and the prompt gamma rays react with cadmium in the cadmium zinc telluride detector to generate 558keV characteristic gamma rays;

s4, detecting gamma rays at corresponding positions by the cadmium zinc telluride detector 1 array arranged in the neutron moderator 3 to obtain a superposition energy spectrum;

s5, performing energy spectrum analysis on the gamma ray superposition energy spectrum detected by the cadmium zinc telluride detector 1 through a gamma spectrum resolving technology to realize separation of the gamma ray superposition energy spectrum;

s6, constructing a response function spectrum library in different neutron incidence directions according to different response functions of the cadmium zinc telluride detectors placed at different positions in different neutron incidence directions, and accordingly judging the neutron incidence directions.

The invention has the beneficial effects that:

the invention utilizes the difference of energy spectrum response functions of neutrons in different incidence directions at different tellurium-zinc-cadmium detector positions, thereby judging the neutron incidence direction according to the difference after energy spectrum analysis, and realizing the consistency and accuracy of neutron incidence measurement in the 4 pi direction; meanwhile, the judgment of the neutron incidence direction can be realized by assisting the built-in cadmium zinc telluride detector, the application field and the application scene of the method can be widened, and the method has great practical practicability.

Description of the drawings:

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a flow chart of a measurement method of the present invention;

FIG. 3 is a schematic structural view of embodiment 1 of the present invention;

FIG. 4 is a diagram of energy spectra of various elements in gamma energy spectrum analysis in example 1 of the present invention;

FIG. 5 is a distribution diagram of each secondary particle of a cadmium zinc telluride detector in six different directions according to example 1 of the present invention;

the reference numbers in the drawings are: 1. a cadmium zinc telluride detector; 2. a gamma ray detector; 3. a neutron moderator; 4. a neutron capture material; 5. a layer of neutron non-elastic scattering material; 6. a signal amplifier; 7. an analog-to-digital converter; 8. a multi-channel analyzer; 9. a computer.

The specific implementation mode is as follows:

in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Referring to the figures, the invention provides a neutron source position measuring device based on a cadmium zinc telluride detector array, which comprises a detector body, wherein the outermost layer of the detector body is a neutron non-elastic scattering material layer 5, and a gamma ray detector 2 is arranged at the geometric center of the detector body; a plurality of layers of neutron moderators 3 and a plurality of layers of neutron capture materials 4 are arranged between the gamma ray detector 2 and the neutron non-elastic scattering material layer 5, and the neutron moderators 3 and the neutron capture materials 4 are arranged in an interlayer staggered manner; a plurality of cadmium zinc telluride detectors 1 are arranged in the neutron moderating body 3, and the plurality of cadmium zinc telluride detectors 1 are distributed in an array on the same neutron moderating body 3 layer; the cadmium zinc telluride detector 1 is sequentially connected with a signal amplifier 6, an analog-to-digital converter 7, a multichannel analyzer 8 and a computer 9.

According to the invention, the detector body is in an axial symmetry shape, specifically a sphere or a cylinder, the response of the gamma ray detector 2 is irrelevant to the direction of incident neutrons, the gamma ray detector 2 is mainly used for collecting nonelastic gamma rays and capture gamma rays generated by the action of neutrons and surrounding coating materials, and the obtained energy spectrum is combined with a gamma energy spectrum obtained by the cadmium zinc telluride detector 1 to obtain the neutron response of the cadmium zinc telluride detector 1 through a gamma spectrum resolving technology; the response energy spectrum of each cadmium zinc telluride detector 1 has symmetry with the neutron incidence direction, and the relation between the incidence direction and the energy spectrum response can be effectively obtained.

If a component higher than the threshold value of the neutron non-elastic scattering material layer 5 on the outer layer of the measuring system exists in the incident neutron energy spectrum, the energy neutrons and the neutron non-elastic scattering material layer 5 on the outer layer are subjected to inelastic scattering to generate prompt gamma rays; if the incident neutron energy spectrum does not contain a component higher than the threshold value of a neutron non-elastic scattering material layer 5 on the outer layer of the measuring system, the thickness of a neutron moderating body 3, which is arranged between the cadmium zinc telluride detector 1 and the surface of the measuring system, can be set, so that the incident neutrons are sufficiently moderated before reaching the cadmium zinc telluride detector 1, the distribution of the thermal neutrons is in a monotonous descending trend along with the incident depth, and the moderated thermal neutrons in the system and a first layer of neutron capture material 4 generate prompt gamma rays; and the moderated thermal neutrons react with cadmium element in the cadmium zinc telluride detector 1 to generate characteristic gamma rays of 558 keV.

In the invention, the neutron moderating body 3 and the neutron capturing material 4 are concentrically staggered by taking the gamma ray detector 2 as a center; the neutron moderating body 3 is used for moderating fast neutrons into thermal neutrons, and the neutron capturing material 4 reacts with the thermal neutrons moderated by the neutron moderating body 3 to generate prompt gamma rays; the neutron inelastic scattering material layer 5 is made of a heavy metal material and generates prompt gamma rays with energy characteristics through inelastic scattering with fast neutrons.

The cadmium zinc telluride detector 1 layers are distributed at different positions of the neutron moderator 3 in an array mode, and neutrons are fully moderated by the neutron moderator 3 at the positions; the cadmium zinc telluride detector 1 is used for detecting prompt gamma rays generated by inelastic scattering of a neutron non-elastic scattering material layer 5 and fast neutrons, prompt gamma rays generated by reaction of a neutron capture material 4 and thermal neutrons moderated by a neutron moderator 3, and 558keV characteristic gamma rays generated by reaction of thermal neutrons and cadmium in the cadmium zinc telluride detector 1, and forming a superposition energy spectrum; and then resolving the spectrum by a gamma spectrum resolving technology to realize the separation of the capture spectrum, the non-elastic scattering spectrum and the background spectrum. The adjacent layer of the neutron non-elastic scattering material layer 5 is a neutron moderating body 3, and the adjacent layer of the gamma ray detector 2 is the neutron moderating body 3.

The measuring method of the neutron source position measuring device based on the cadmium zinc telluride detector array comprises the following steps:

s1, enabling neutrons to enter the detector from a certain direction;

s2, when the fast neutrons pass through the neutron non-elastic scattering material layer 5, non-elastic scattering occurs, and prompt gamma rays with characteristic energy are generated;

s3, after the fast neutrons are fully moderated by the neutron moderating body 3, prompt gamma rays are generated by the thermal neutrons and the neutron capture material 4, and react with cadmium in the cadmium zinc telluride detector 1 to generate gamma rays with the characteristics of 558 keV;

s4, detecting gamma rays at corresponding positions by an array of cadmium zinc telluride detectors 1 arranged in a neutron moderator 3, wherein the gamma rays form analog signals in the cadmium zinc telluride detectors 1, the signals are amplified and filtered by a signal amplifier 6, converted into digital signals by an analog-to-digital converter 7, processed in a multichannel analyzer 8 for signal energy and amplitude, and finally the response energy spectrums of the cadmium zinc telluride detectors 1 are obtained in a computer 9; the obtained response energy spectrum of the gamma ray of the cadmium zinc telluride detector is a superposition energy spectrum of characteristic prompt gamma rays generated by inelastic scattering, characteristic prompt gamma rays generated by neutron capture, 558keV characteristic gamma rays generated by the reaction of thermal neutrons and cadmium elements and background gamma rays;

s5, performing energy spectrum analysis on the gamma ray response superposition energy spectrum detected by the cadmium zinc telluride detector 1 through a gamma spectrum resolving technology to realize the separation of the four gamma ray energy spectrums in the S4;

s6, constructing a response function spectrum library in different neutron incidence directions according to different response functions of the cadmium zinc telluride detectors 1 placed at different positions in different neutron incidence directions, and accordingly judging the neutron incidence directions. The response function includes a characteristic prompt gamma ray spectrum generated by inelastic scattering, a characteristic prompt gamma ray spectrum generated by neutron capture, and a characteristic gamma ray spectrum of 558keV generated by the reaction of thermal neutrons and cadmium elements.

After the neutrons enter the detector system, no matter the energy or the quantity of the neutrons is obviously reduced, the tellurium-zinc-cadmium detector closest to the neutron incidence direction has the maximum response, so that a response function of the neutron incidence direction can be constructed according to the difference of the positions of the tellurium-zinc-cadmium detector in the system, and the neutron incidence direction is judged.

Example 1

As shown in fig. 3 to 5, a neutron source position measuring device based on a cadmium zinc telluride detector array comprises a spherical detector body, wherein a gamma ray detector is arranged at the spherical center of the spherical detector body, and a neutron non-elastic scattering material layer 5 is arranged on the outermost layer of the spherical detector body and is specifically made of lead; two layers of neutron moderators 3 and one layer of neutron capture material 4 are arranged between the neutron non-elastic scattering material layer 5 and the gamma ray detector, the neutron moderators 3 are made of polyethylene, and the neutron capture material 4 is made of sodium chloride; six cadmium zinc telluride detectors 6 are arranged in the neutron moderating body 3, and the six cadmium zinc telluride detectors 6 form an array and surround the front direction, the rear direction, the left direction, the right direction, the upper direction and the lower direction of the central gamma ray detector.

The neutron source position measuring method comprises the following steps:

s1, Am-Be neutron source is incident to the measuring device in the direction of 0 degrees;

s2, when the fast neutrons pass through the neutron non-elastic scattering material layer 5, non-elastic scattering occurs, and prompt gamma rays with characteristic energy are generated;

s3, after the fast neutrons are fully moderated by the neutron moderating body 3, prompt gamma rays are generated by the thermal neutrons and the neutron capture material 4, and react with cadmium in the cadmium zinc telluride detector 1 to generate gamma rays with the characteristics of 558 keV;

s4, detecting gamma rays at corresponding positions by the cadmium zinc telluride detector 1 array arranged in the neutron moderator 3 to obtain a superposition energy spectrum;

s5, performing energy spectrum analysis on a gamma ray response energy spectrum detected by the cadmium zinc telluride detector 1 closest to the neutron incidence direction through a gamma spectrum resolving technology to obtain a lead non-elastic scattering characteristic gamma ray energy spectrum, a characteristic gamma ray energy spectrum generated by the reaction of the slowed thermal neutrons and cadmium elements in the cadmium zinc telluride detector, a chlorine element characteristic gamma ray response energy spectrum, a hydrogen element characteristic gamma ray response energy spectrum and a background energy spectrum; the response energy spectrums of the cadmium zinc telluride detectors at other positions are subjected to gamma energy spectrum analysis, and the response energy spectrums of the cadmium zinc telluride detectors at different positions are obviously different by comparison;

s6, constructing a response function spectrum library in different neutron incidence directions according to different response functions of the cadmium zinc telluride detectors 1 placed at different positions in different neutron incidence directions, and accordingly judging the neutron incidence directions. Fig. 5 shows the distribution of secondary particles of cadmium zinc telluride detectors in six different directions, and it is apparent that the response (especially Pb non-elastic scattering count) of each detector is significantly different. The method can be used as a judgment basis for the incident direction of neutrons and can be used for constructing a direction response function. Therefore, the neutron responses of the upper and lower tellurium-zinc-cadmium detectors are almost consistent, the neutron direction can be judged to be at the vertical bisector of the two detectors, the neutron response of the left tellurium-zinc-cadmium detector is larger than the neutron response of the right tellurium-cadmium detector, and the neutron direction can be judged to be from left to right and to pass through the center of the system.

According to the invention, the cadmium zinc telluride detectors at different positions carry out energy spectrum response detection on characteristic gamma rays and capture gamma rays through different incident directions of neutrons, and the incident directions of the neutrons are judged through response differences of the cadmium zinc telluride detectors at different positions obtained through gamma energy spectrum analysis, so that the effect is good, and the method can be used as a measuring method for judging the positions of the neutron sources with excellent performance.

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 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, for those skilled in the art, several modifications and decorations without departing from the principle of the present invention should be regarded as the protection scope of the present invention.