Underwater array radiation detector

Abstract

The invention relates to the technical field of underwater detectors, and discloses an underwater array radiation detector, which comprises a metal bracket, at least one NaI (T1) crystal detector and at least one CeBr3 crystal detector, the NaI crystal detector and the CeBr3 crystal detector are fixed in the first metal support. A metal protective net is arranged on the outer side of the NaI (T1) crystal detector and the outer side of the CeBr3 crystal detector. According to the invention, the detection efficiency and the detection speed are improved, the energy resolution is improved, the anti-interference capability is enhanced, the adaptability of the detector is enhanced, mobile radiation monitoring can be carried out, and the method can be suitable for radiation monitoring tasks in various complex environments.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater detectors, and in particular to an underwater array radiation detector. Background Art

[0002] Underwater detectors are devices specially designed to work in underwater environments and are used to detect, monitor and record underwater information. Underwater detectors play an important role in the fields of marine scientific research, environmental monitoring, resource exploration, etc., especially in radiation detection.

[0003] In the prior art, NaI(Tl) (sodium iodide doped thallium) crystal detectors or CeBr3 (cerium bromide) crystal detectors are usually used as underwater detectors. However, current underwater detectors only use NaI(Tl) crystal detectors or CeBr3 crystal detectors alone. The energy resolution of NaI(Tl) crystal detectors is relatively poor, and its detection effect is poor in applications requiring high resolution. The detection efficiency of CeBr3 crystal detectors is low, and using only CeBr3 crystal detectors will reduce the detection efficiency and affect the radiation monitoring task. In addition, NaI(Tl) crystals and CeBr3 crystals are relatively fragile and are easily broken during underwater movement. Existing NaI(Tl) crystal detectors or CeBr3 crystal detectors can only perform fixed-point monitoring.

[0004] Therefore, there is an urgent need for an underwater array radiation detector that can improve detection efficiency, detection speed, improve energy resolution, enhance anti-interference capability, enhance the adaptability of the detector, and be able to perform mobile radiation monitoring, which can be suitable for radiation monitoring tasks in a variety of complex environments. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an underwater array radiation detector, which can improve the detection efficiency, detection speed, improve the energy resolution, enhance the anti-interference ability, enhance the adaptability of the detector, and can also perform mobile radiation monitoring, which can be applicable to radiation monitoring tasks in a variety of complex environments.

[0006] The present invention provides an underwater array radiation detector, comprising: a first metal support, at least one NaI(Tl) crystal detector and at least one CeBr3 crystal detector; The NaI crystal detector and the CeBr3 crystal detector are fixed inside the first metal bracket.

[0007] Furthermore, the number of NaI (Tl) crystal detectors is 3, and the number of CeBr3 crystal detectors is 1.

[0008] Furthermore, the NaI (Tl) crystal detector is a cylinder with a diameter of 3 inches and a length of 6 inches, and the CeBr3 crystal detector is a cylinder with a diameter of 2 inches and a length of 2 inches.

[0009] Furthermore, the NaI (Tl) crystal detectors are arranged in a circumferential direction, and the interval between two adjacent NaI (Tl) crystal detectors in the circumferential direction is 30 cm.

[0010] Furthermore, the NaI (Tl) crystal detector is arranged around the periphery of the CeBr3 crystal detector.

[0011] Further, the crystal detector includes: spectrometer electronics, a GM counter tube, an aluminum alloy bracket and a detection crystal; The spectrometer electronics, GM counter tube and detection crystal are fixed on the aluminum alloy bracket in sequence; The detection crystal is NaI (Tl) crystal or CeBr3 crystal.

[0012] Furthermore, it also includes a metal protection net, which is arranged on the outside of the NaI (Tl) crystal detector and the CeBr3 crystal detector to protect the NaI (Tl) crystal detector and the CeBr3 crystal detector.

[0013] Furthermore, it also includes a second metal bracket and a triangle plate; The second metal bracket is fixed on the upper side of the triangle plate and is used to fix the underwater array radiation detector to the monitoring platform; The first metal bracket is fixed on the lower side of the triangle plate, and the first metal bracket is used to fix the NaI (Tl) crystal detector and the CeBr3 crystal detector on the triangle plate.

[0014] The embodiments of the present invention have the following technical effects: The present invention combines NaI (Tl) crystal detectors and CeBr3 crystal detectors to form an underwater array radiation detector, combines the advantages of high detection efficiency of NaI (Tl) crystal detectors and good energy resolution of CeBr3 crystal detectors, and designs the number, size, spacing, arrangement and other parameters of NaI (Tl) crystal detectors and CeBr3 crystal detectors, so as to cover a wider energy range, improve the detection sensitivity to different types of radiation, and improve the detection efficiency and energy resolution of the entire system. Mobile radiation detection also requires higher detection efficiency to meet the requirements. The present invention can provide data redundancy by combining multiple detectors to work simultaneously. Even if a detector fails, other detectors can still continue to work to ensure data continuity and reliability. Among them, CeBr3 crystal has a faster scintillation decay time and can respond to radiation events more quickly. Combined with NaI (Tl) crystal, it can improve the detection speed while maintaining high sensitivity. Different detectors have different responses to different types of background noise. By combining them, interference signals from other sources can be better identified and eliminated, and multiple parameter information can be obtained at the same time to improve the accuracy of radiation detection. In addition, the present invention also arranges a metal protective net in the underwater array radiation detector to protect the NaI (Tl) crystal detector and the CeBr3 crystal detector, thereby preventing the NaI (Tl) crystal detector and the CeBr3 crystal detector from breaking during the underwater movement, thereby enabling the underwater array radiation detector of the present invention to perform mobile radiation detection and be applicable to radiation monitoring tasks in a variety of complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 is a schematic structural diagram of an underwater array radiation detector provided by an embodiment of the present invention; Figure 2 It is a curve schematic diagram of the detection efficiency of NaI (Tl) crystals of different sizes for gamma rays provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of a marine environment model detection efficiency curve provided by an embodiment of the present invention.

[0017] In the figure: 1-first metal support; 2-NaI (Tl) crystal detector; 3-CeBr3 crystal detector; 4-second metal support; 5-triangle plate. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0019] The present invention proposes an underwater array radiation detector. Figure 1 : is a schematic diagram of the structure of an underwater array radiation detector provided by an embodiment of the present invention, the underwater array radiation detector comprises: A first metal support 1 , at least one NaI (Tl) crystal detector 2 and at least one CeBr3 crystal detector 3 ; the NaI crystal detector 2 and the CeBr3 crystal detector 3 are fixed inside the first metal support 1 .

[0020] Furthermore, the underwater array radiation detector further includes a second metal bracket 4 and a triangular plate 5; The second metal bracket 4 is fixed to the upper side of the triangular plate 5 and is used to fix the underwater array radiation detector to the monitoring platform; The first metal bracket 1 is fixed to the lower side of the triangular plate 5 , and the first metal bracket 1 is used to fix the NaI (Tl) crystal detector 2 and the CeBr 3 crystal detector 3 on the triangular plate 5 .

[0021] Among them, the monitoring platform can be but is not limited to large monitoring ships, various types of unmanned ships and other offshore mobile platforms.

[0022] Specifically, NaI crystal is a commonly used γ detection material, which is easy to prepare and has high detection efficiency, and can achieve a low nuclide detection limit; at the same time, CeBr3 crystal has high energy resolution, which can better distinguish the types of seawater nuclides. By combining the two detection materials, more accurate seawater radioactivity monitoring can be achieved. By combining the two crystals, a wider energy range can be covered, and the detection sensitivity of different types of radiation can be improved.

[0023] Preferably, the number of NaI (Tl) crystal detectors 2 is 3, and the number of CeBr3 crystal detectors 3 is 1. Preferably, the NaI (Tl) crystal detector 2 is a cylinder with a diameter of 3 inches and a length of 6 inches, and the CeBr3 crystal detector 3 is a cylinder with a diameter of 2 inches and a length of 2 inches.

[0024] Specifically, through the early Monte Carlo simulation, 2-6 crystal arrays with different numbers were compared. Different numbers of crystal arrays will have different degrees of influence on the detection range, radiation attenuation, etc. When the total volume of NaI (Tl) crystals is the same, the number and size of the crystals will affect the detection efficiency. Because large-volume crystals have their own shielding effect, they need to be split into small crystals to weaken the shielding effect. The more the number and the smaller the size, the higher the detection efficiency for the low-energy segment. It can be understood that its detection range becomes larger and more particles can be detected. However, its detection efficiency for the high-energy segment will decrease, because the product energy of high-energy particles in small crystals is small, so the detection efficiency will decrease instead. Specifically, Figure 2 is a curve diagram of the detection efficiency of NaI (Tl) crystals of different sizes for gamma rays provided by an embodiment of the present invention, see Figure 2 According to the simulation results, three large-volume NaI (Tl) crystals with a diameter of 3 inches and a length of 6 inches (i.e. Φ3×6 inches) have good detection efficiency in both high-energy and low-energy bands under the same volume and are easier to integrate. Therefore, the number and size of NaI (Tl) crystals are determined.

[0025] Since CeBr3 crystals are only used to identify nuclides in the environment, simulation tests show that only one probe with a diameter of 2 inches and a length of 2 inches (i.e. Φ2×2 inches) can meet the needs.

[0026] Furthermore, through actual calibration, it is known that the energy resolution of NaI(Tl) crystal is less than 7.5%@662 keV, the energy resolution of CeBr3 crystal is less than 4.5%@662 keV, and the lower limit of radionuclide detection is no higher than 0.01Bq / L( 137 Cs, 24h).

[0027] Among them, energy resolution is the material's own property. Through actual calibration, under the current size, the energy resolution of the gamma spectrometer of NaI#1 is 7%; the energy resolution of the gamma spectrometer of NaI#2 is 7.2%; the energy resolution of the gamma spectrometer of NaI#3 is 6.9%; the energy resolution of the gamma spectrometer of cerium bromide (CeBr3) is 4.44%; the smaller the energy resolution value, the better the detector performance, the easier it is to distinguish the types of radioactive nuclides in the gamma energy spectrum, and the higher the accuracy of the calculation of the activity concentration of nuclides. The lower the detection limit of radioactive nuclides, the higher the accuracy and sensitivity of the detection system. Through the previous comparative investigation of the existing seawater radioactivity monitoring system, the detection limit of the underwater detector currently in use is about 0.02Bq / L( 137 Cs, 24h), while the structure of the present invention can achieve a detection limit of no more than 0.01Bq / L ( 137 Cs, 24h), which is at the international advanced level; the minimum detectable activity of different radionuclides at different times is shown in Table 1.

[0028] Table 1 Minimum detectable activity of different radionuclides at different times;

[0029] Preferably, the NaI (Tl) crystal detectors 2 are arranged in a circumferential direction, and the interval between two circumferentially adjacent NaI (Tl) crystal detectors 2 is 30 cm.

[0030] Specifically, the particle transport process is simulated by modeling the underwater array radiation detector, and the detector detection efficiency under the model and the passive efficiency calibration method of the seawater measurement boundary are calculated for calibration.

[0031] Further, for the (Φ3×6)-inch NaI (Tl) crystal detector, the overall size is a cylinder with a height of 67.5 cm and a diameter of 9.52 cm, wherein the outer shell titanium alloy is 0.5 cm thick, the aluminum shell that wraps the crystal is 0.2 cm thick, the magnesium oxide reflective layer is 0.25 cm thick, and the crystal is covered with 0.5 cm thick silica glass to connect the photomultiplier tube. The outer shell of the NaI (Tl) crystal detector is set to air except for the crystal. In order to ensure that each detector needs to be greater than its detection distance from the seawater sphere boundary, it is placed in a spherical seawater source with a radius of 150 cm for simulation.

[0032] Furthermore, through modeling, the full energy peak detection efficiency of different energies can be obtained. The full energy peak efficiency and gamma energy are fitted by the following formula: ; In the formula, It represents the total absorption peak detection efficiency of NaI(Tl) crystal detector for γ-rays with energy E; represents the fitting constant; represents the energy corresponding to the gamma ray; k represents the highest order of the polynomial.

[0033] For example, k=6, the goodness of fit R 2 Reaching 0.9995, meeting the technical requirements, the ocean environment model detection efficiency curve is as follows Figure 3 As shown, the efficiency curve formula is as follows: .

[0034] The detection efficiencies of the three NaI (Tl) crystal detectors are superimposed to obtain the comprehensive detection efficiency. In order to achieve the maximum detection efficiency while taking into account the influence of the self-shielding effect, the interval between two circumferentially adjacent NaI (Tl) crystal detectors 2 is set to 30 cm.

[0035] The obtained efficiency scale was verified by placing the NaI(Tl) crystal gamma spectrometer in the experimental environment. The large standard liquid source had a liquid level of 3m and a diameter of 2.5m. 137 Cs(0.85Bq / L), 133 Ba (0.36Bq / L). The measurement was carried out 15 times, each time for 1 hour, and the efficiency calibration curve was used for calculation. 137 Cs and 133 Activity concentration of Ba, measurement results 137 The deviation between Cs and the standard value is less than 12%. 133 The deviation between Ba and the standard value is less than 5%, as shown in Table 2: Table 2: The measured simulation environment 137 Cs, 133 Ba activity concentration.

[0036]

[0037] Preferably, the NaI (Tl) crystal detector 2 is arranged around the periphery of the CeBr 3 crystal detector 3 .

[0038] Specifically, the CeBr3 crystal detector 3 can be set at any position within the surrounding range of the NaI (Tl) crystal detector 2. Since the NaI (Tl) crystal detector 2 is a cylinder with a diameter of 3 inches and a length of 6 inches, and the CeBr3 crystal detector 3 is a cylinder with a diameter of 2 inches and a length of 2 inches, the CeBr3 crystal is shorter than the NaI (Tl) crystal, so it will not block or affect the NaI (Tl) crystal when set at any position. Placing the CeBr3 crystal detector 3 within the surrounding range of the NaI (Tl) crystal detector 2, rather than outside the surrounding range of the NaI (Tl) crystal detector 2, can avoid additionally increasing the overall volume of the underwater array radiation detector, resulting in an increase in the water-facing surface area during movement, thereby increasing resistance and affecting detection or movement.

[0039] Further, the crystal detector includes: spectrometer electronics, a GM counter tube, an aluminum alloy bracket and a detection crystal; The spectrometer electronics, GM counter tube and detection crystal are fixed on the aluminum alloy bracket in sequence; The detection crystal is NaI (Tl) crystal or CeBr3 crystal.

[0040] Specifically, spectrometer electronics is used to amplify the weak electrical signal generated by the detector to a measurable level, filter and shape the amplified signal to remove noise, determine the energy of the incident radiation by analyzing the amplitude of the signal, record and store signal information, and classify the signal according to different energies to form an energy spectrum. GM counter tubes (Geiger-Müller Counter Tubes) are used to detect charged particles (such as beta particles) or high-energy gamma rays. When radiation enters the GM counter tube, ionization occurs in the tube to form an electrical pulse. Each electrical pulse represents a detected radiation event, so the GM counter tube can be used to count radiation events. Aluminum alloy brackets are used to provide mechanical support, keep the position of various parts of the detector stable, and protect the detector from external physical damage. Aluminum alloy has good thermal conductivity, which helps to dissipate heat and keep the operating temperature of the detector within an appropriate range. In some designs, aluminum alloy brackets may also play a certain shielding role to reduce background noise. Detection crystals are used when gamma rays or X-rays enter the crystal, which generates electron-hole pairs inside the crystal. The generated electron-hole pairs cause the crystal to emit light (scintillation), a phenomenon called the scintillation effect. The light signal is then detected by a photomultiplier tube or other light sensor and converted into an electrical signal.

[0041] Preferably, the spectrometer electronics, GM counter tube and detection crystal are fixed on the aluminum alloy bracket from top to bottom. The spectrometer electronics are arranged at the top for communication and power supply, and the detection crystal is arranged at the bottom to avoid shielding and reduce detection efficiency and detection effect.

[0042] Preferably, the underwater array radiation detector also includes a metal protective net (not shown in the figure), which is arranged on the outside of the NaI (Tl) crystal detector 2 and the CeBr3 crystal detector 3 to protect the NaI (Tl) crystal detector 2 and the CeBr3 crystal detector 3.

[0043] Specifically, a metal protective net is arranged on the outside of the NaI (Tl) crystal detector 2 and the CeBr3 crystal detector 3 to prevent marine organisms, floating objects or other hard objects from directly hitting or scratching the detectors, causing damage to the fragile crystal parts; the metal protective net increases the structural strength of the entire detector device, making it more sturdy and durable; thereby, the underwater array radiation detector of the present invention can be suitable for mobile radiation detection.

[0044] In addition, the metal protective net can also play a certain electromagnetic shielding role, reducing the impact of external electromagnetic interference on the electronic equipment inside the detector.

[0045] The present invention combines NaI (Tl) crystal detectors and CeBr3 crystal detectors to form an underwater array radiation detector, combines the advantages of high detection efficiency of NaI (Tl) crystal detectors and good energy resolution of CeBr3 crystal detectors, and designs the number, size, spacing, arrangement and other parameters of NaI (Tl) crystal detectors and CeBr3 crystal detectors, so as to cover a wider energy range, improve the detection sensitivity to different types of radiation, and improve the detection efficiency and energy resolution of the entire system. Mobile radiation detection also requires higher detection efficiency to meet the requirements. The present invention can provide data redundancy by combining multiple detectors to work simultaneously. Even if a detector fails, other detectors can still continue to work to ensure data continuity and reliability. Among them, CeBr3 crystal has a faster scintillation decay time and can respond to radiation events more quickly. Combined with NaI (Tl) crystal, it can improve the detection speed while maintaining high sensitivity. Different detectors have different responses to different types of background noise. By combining them, interference signals from other sources can be better identified and eliminated, and multiple parameter information can be obtained at the same time to improve the accuracy of radiation detection. In addition, the present invention also arranges a metal protective net in the underwater array radiation detector to protect the NaI (Tl) crystal detector and the CeBr3 crystal detector, thereby preventing the NaI (Tl) crystal detector and the CeBr3 crystal detector from breaking during the underwater movement, thereby enabling the underwater array radiation detector of the present invention to perform mobile radiation detection and be applicable to radiation monitoring tasks in a variety of complex environments.

[0046] It should be noted that the terms used in the present invention are only for describing specific embodiments, rather than limiting the scope of the present application. As shown in the present specification, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of more restrictions, the elements defined by the sentence "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0047] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. 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 an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.

Claims

1. An underwater array radiation detector, characterized in that: include: A first metal support (1), at least one NaI (Tl) crystal detector (2) and at least one CeBr3 crystal detector (3); The NaI crystal detector (2) and the CeBr3 crystal detector (3) are fixed inside the first metal bracket (1).

2. The underwater array radiation detector according to claim 1, characterized in that: The number of the NaI (Tl) crystal detectors (2) is 3, and the number of the CeBr3 crystal detector (3) is 1.

3. The underwater array radiation detector according to claim 2, characterized in that: The NaI (Tl) crystal detector (2) is a cylinder with a diameter of 3 inches and a length of 6 inches, and the CeBr3 crystal detector (3) is a cylinder with a diameter of 2 inches and a length of 2 inches.

4. The underwater array radiation detector according to claim 3, characterized in that: The NaI (Tl) crystal detectors (2) are arranged in a circumferential direction, and the distance between two adjacent NaI (Tl) crystal detectors (2) in the circumferential direction is 30 cm.

5. The underwater array radiation detector according to claim 4, characterized in that: The NaI (Tl) crystal detector (2) is arranged around the periphery of the CeBr3 crystal detector (3).

6. The underwater array radiation detector according to claim 5, characterized in that: The crystal detector comprises: spectrometer electronics, GM counter tube, aluminum alloy bracket and detection crystal; The spectrometer electronics, the GM counter tube and the detection crystal are fixed on the aluminum alloy bracket in sequence; The detection crystal is a NaI (Tl) crystal or a CeBr3 crystal.

7. The underwater array radiation detector according to claim 1, characterized in that: It also comprises a metal protection net, which is arranged outside the NaI (Tl) crystal detector (2) and the CeBr3 crystal detector (3) and is used to protect the NaI (Tl) crystal detector (2) and the CeBr3 crystal detector (3).

8. The underwater array radiation detector according to claim 1, characterized in that: It also includes a second metal bracket (4) and a triangular plate (5); The second metal bracket (4) is fixed to the upper side of the triangular plate (5) and is used to fixedly connect the underwater array radiation detector to the monitoring platform; The first metal bracket (1) is fixed to the lower side of the triangular plate (5), and the first metal bracket (1) is used to fix the NaI (Tl) crystal detector (2) and the CeBr3 crystal detector (3) on the triangular plate (5).

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