A surface contamination detector based on SiPM array

Abstract

This utility model relates to the field of nuclear radiation detector technology, specifically a surface contamination detector based on a SiPM array. Its features include a housing and a SiPM array signal acquisition unit mounted on the housing. The housing forms a conical open cavity, with a plastic scintillator at the bottom. The SiPM array signal acquisition unit includes a SiPM readout circuit board and a light guide structure. Multiple SiPM arrays are integrated on one side of the SiPM readout circuit board, and the light guide structure faces the interior of the cavity. This utility model uses two SiPM array signal acquisition units instead of existing photomultiplier tubes. SiPMs are inexpensive and can withstand strong impacts, operating without an additional high-voltage power supply, significantly reducing the detector's size. Furthermore, the SiPM array signal acquisition unit can collect light from different directions, increasing the light-gathering area and greatly increasing the effective detection area. It also provides excellent detection for edge areas, improving detection efficiency.

Description

Technical Field

[0001] This utility model relates to the field of nuclear radiation detector technology, specifically a surface contamination detector based on a SiPM array. Background Technology

[0002] During the use of radioactive materials, lack of protection or violation of operating procedures by operators can lead to contamination of human bodies and other object surfaces, affecting not only the operator's health but also polluting the surrounding environment. Surface contamination detectors are instruments used to detect alpha, beta radioactive contamination and gamma dose rates on object surfaces, primarily used in nuclear facilities, medical fields, and environmental protection.

[0003] Existing surface contamination detectors generally consist of electronic components such as a housing, a photomultiplier tube, a voltage divider circuit, and a high-voltage circuit. Due to the large size of the photomultiplier tube and its need to be installed in the center of the detector, existing surface contamination detectors are generally bulky. When the detection area of ​​the detector is large, the detection efficiency for edge areas is low. Furthermore, photomultiplier tubes are expensive and, being constructed entirely of glass, are easily broken by impact. Additionally, photomultiplier tubes require a kilovolt-level DC high voltage to operate, necessitating a high-voltage circuit, further increasing the cost. Utility Model Content

[0004] The technical problem to be solved by this invention is to provide a surface contamination detector based on a SiPM (silicon photomultiplier tube) array, which can effectively solve the problems mentioned in the background art.

[0005] To solve the above problems, the technical solution adopted by this utility model is: a surface contamination detector based on a SiPM array, characterized in that it includes a housing and a SiPM array signal acquisition unit disposed on the housing; the housing forms a conical open cavity, and a plastic scintillator is disposed at the bottom of the cavity, the plastic scintillator being used to emit fluorescence when receiving α and β rays; The SiPM array signal acquisition unit is located above the plastic scintillator. The SiPM array signal acquisition unit includes a SiPM readout circuit board and a light guide structure. The SiPM readout circuit board is connected to the light guide structure. Multiple SiPM arrays are integrated on one side of the SiPM readout circuit board. The light guide structure faces the interior of the cavity. The light guide structure is used to collect the fluorescence generated by the plastic scintillator. The SiPM readout circuit board is used to convert the optical signal into an electrical signal and output a current signal.

[0006] Preferably, the side of the light guide structure is composed of multiple uniformly distributed rectangles, and the top surface of the light guide structure is provided with a groove corresponding to the SiPM array. The SiPM array is fixedly installed in the groove by optical adhesive.

[0007] Preferably, the light guide structure is made of acrylic.

[0008] Preferably, the inner surface of the housing is coated with a reflective coating of uniform thickness, and the reflective coating is a titanium dioxide coating.

[0009] Preferably, the surface roughness of the reflective coating is Ra12-Ra13, and the thickness of the titanium dioxide coating is 16μm-24μm.

[0010] Preferably, the side of the plastic scintillator facing away from the cavity is coated with a light-emitting coating of uniform thickness, and a light-shielding film is attached to the outside of the light-emitting coating.

[0011] Preferably, the luminescent coating is ZnS (Ag), and the light-shielding film is a Mylar film.

[0012] Preferably, a protective net assembly is installed on the outside of the light-shielding film, and the protective net assembly is fixedly installed on the housing by screws.

[0013] Preferably, the housing is integrally molded using injection molding, and the top of the housing is provided with a mounting hole for mounting the SiPM array signal acquisition unit; a circuit box cover is provided above the SiPM array signal acquisition unit.

[0014] Compared with the prior art, this utility model provides a surface contamination detector based on a SiPM array, which has the following advantages: The surface contamination detector based on SiPM array provided by this utility model uses two SiPM array signal acquisition units to replace the photomultiplier tubes in the prior art. Compared with photomultiplier tubes, SiPM is less expensive and can withstand strong impact. Its operating voltage is only tens of volts, so it can work without an additional high-voltage power supply. Therefore, the size of the surface contamination detector is greatly reduced in structure. In addition, by setting these two SiPM array signal acquisition units, light from different directions can be collected, increasing the light-collecting area and thus greatly increasing the effective detection area of ​​the detector. It can also play a good detection role in edge areas and improve detection efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a schematic diagram of the disassembly structure of this utility model; Figure 3 This is a cross-sectional view of the present invention; Figure 4 This is a schematic diagram of the structure of the SiPM array signal acquisition unit of this utility model; Figure 5 This is a schematic diagram of the structure of this utility model; Figure 6 This is a schematic diagram illustrating the effect of the surface roughness of the reflective coating on the efficiency of this invention. Figure 7 This is a schematic diagram illustrating the effect of the reflective coating material and thickness on the efficiency of this utility model.

[0016] The components include: 1. Housing; 11. Mounting hole; 20. SiPM array signal acquisition unit; 2. SiPM readout circuit board; 3. Light guide structure; 4. Reflective coating; 5. Plastic scintillator; 6. Protective mesh assembly; 7. Circuit box cover. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0018] Reference Figure 1-7 This invention provides a surface contamination detector based on a SiPM array, comprising a housing 1 and a SiPM array signal acquisition unit 20. The SiPM array signal acquisition unit 20 includes a SiPM readout circuit board 2 and a light guide structure 3 in the shape of a frustum. One side of the SiPM readout circuit board 2 integrates a 2*2 SiPM array. The large surface (top surface) of the light guide structure 3 is provided with a groove corresponding to the SiPM array, and the SiPM array is fixedly installed in the groove. In this embodiment of the invention, the SiPM array is installed in the groove of the light guide structure 3 with optical adhesive, which can achieve a good coupling effect and increase the light guiding performance.

[0019] The housing 1 forms a conical open cavity. A plastic scintillator 5 is installed on the large surface (bottom) of the cavity to emit fluorescence when receiving α and β rays. The small surface (top) of the cavity has two mounting holes for mounting the SiPM array signal acquisition unit 20. The light guide structure 3 of the SiPM array signal acquisition unit 20 faces the inside of the cavity to collect the fluorescence generated by the plastic scintillator 5. The SiPM readout circuit board 2 is used to convert the optical signal into an electrical signal and output a current signal.

[0020] Specifically, the side of the light guide structure 3 in this invention is composed of multiple uniformly distributed rectangles.

[0021] In a preferred embodiment of this invention, the side of the light guide structure 3 is composed of 10 evenly distributed rectangles, and the chamfer of the side is 60 degrees. This allows the SiPM to be fixed at the focal point of the light guide structure 3, thereby maximizing the light-gathering area and improving detection efficiency. It should be noted that in this embodiment, the degree of the chamfer and the number of rectangles on the side of the light guide structure 3 are not specifically limited and can be adjusted according to the actual size of the surface contamination detector.

[0022] In order to achieve better light guiding and light receiving effects, the light guiding structure 3 is made of acrylic in this embodiment of the invention.

[0023] Specifically, in order to achieve a good light-gathering effect, a reflective coating 4 of uniform thickness is sprayed onto the inner surface of the housing 1. In this utility model, a titanium dioxide (also commonly called titanium oxide) coating is used because the titanium dioxide coating can diffusely reflect the fluorescence emitted by the plastic scintillator 5, reflecting the light onto the light guide structure 3, thus achieving a better light-gathering effect.

[0024] To achieve better reflection results, the applicant also conducted experiments on the influence of the surface roughness (Ra) of the reflective coating 4 on the reflection efficiency, as well as the influence of the coating material and thickness on the reflection efficiency. Figure 6-7 As shown in the figure, experiments demonstrate that the maximum reflection efficiency is achieved when the surface roughness is Ra12.5, and the maximum reflection efficiency is also achieved when the titanium dioxide coating is 20 μm thick. Compared with conventional specular reflection (Ra3), the reflection efficiency is improved by 25% when the surface roughness is Ra12.5; and the reflection efficiency is improved by 23% when the titanium dioxide coating is 20 μm thick, compared with the conventional thickness (15 μm).

[0025] To simultaneously detect alpha and beta rays, a uniformly thick luminescent coating is sprayed onto the side of the plastic scintillator 5 facing away from the cavity. Specifically, in this embodiment, the luminescent coating is ZnS(Ag), i.e., silver-doped zinc sulfide. To achieve good light-shielding effect, a light-shielding film is attached to the outside of the luminescent coating. In this embodiment, the light-shielding film is a Mylar film. Specifically, three 2μm Mylar films or two 3μm Mylar films can be attached, both providing good light-shielding effect. Because the Mylar film is very thin, alpha rays can penetrate the Mylar film and strike the ZnS(Ag) coating, exciting the ZnS(Ag) coating to emit fluorescence, while beta rays can penetrate the Mylar film and the ZnS(Ag) coating, striking the plastic scintillator 5 and exciting the plastic scintillator 5 to emit fluorescence, thereby achieving simultaneous detection of alpha and beta rays.

[0026] Because the Mylar membrane is extremely thin, a protective mesh assembly 6 is installed on the outside of the Mylar membrane to prevent damage. This protective mesh assembly 6 can be installed on the housing 1 by means of a threaded connection.

[0027] In this invention, the housing 1 of the surface contamination detector is integrally molded using injection molding. Compared with aluminum housing 1, it is not only cheaper and simpler to process, but also reduces the weight of the surface contamination detector.

[0028] As an embodiment of this utility model, the housing 1 is made into a square pyramid with an external dimension of 399*199*50mm and an effective detection surface of 370*170*2mm. Through simulation calculation, when the four vertical sides of the housing 1 are 30° and the internal cavity height of the housing 1 is 33mm, two SiPM array signal acquisition units 20 can be installed on the focal point of the cavity of the housing 1. That is, when the SiPM focal point is 80mm away from the central axis of the housing 1, the light guide structure 3 has the highest light collection efficiency, which improves the light collection efficiency by about 55%. Therefore, even if the detection area of ​​the detector is large, the edge area can be detected, thus improving the detection efficiency of the entire detector.

[0029] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A surface contamination detector based on a SiPM array, characterized in that, It includes a housing (1) and a SiPM array signal acquisition unit (20) disposed on the housing (1); the housing (1) forms a cone-shaped open cavity, and a plastic scintillator (5) is provided at the bottom of the cavity. The plastic scintillator (5) is used to emit fluorescence when receiving α and β rays; The SiPM array signal acquisition unit (20) is located above the plastic scintillator (5). The SiPM array signal acquisition unit (20) includes a SiPM readout circuit board (2) and a light guide structure (3). The SiPM readout circuit board (2) is connected to the light guide structure (3). Multiple SiPM arrays are integrated on one side of the SiPM readout circuit board (2). The light guide structure (3) faces the cavity. The light guide structure (3) is used to collect the fluorescence generated by the plastic scintillator (5). The SiPM readout circuit board (2) is used to convert the optical signal into an electrical signal and output a current signal.

2. The surface contamination detector based on SiPM array according to claim 1, characterized in that, The side of the light guide structure (3) is composed of multiple uniformly distributed rectangles, and the top surface of the light guide structure (3) is provided with a groove corresponding to the SiPM array. The SiPM array is fixedly installed in the groove by optical adhesive.

3. A surface contamination detector based on SiPM array according to claim 2, characterized in that, The light guide structure (3) is made of acrylic.

4. The surface contamination detector based on SiPM array according to claim 1, wherein, The inner surface of the housing (1) is coated with a reflective coating (4) of uniform thickness, which is a titanium dioxide coating.

5. A surface contamination detector based on a SiPM array according to claim 4, characterized in that, The surface roughness of the reflective coating is Ra12-Ra13, and the thickness of the titanium dioxide coating is 16μm-24μm.

6. The surface contamination detector based on SiPM array according to claim 1, wherein, The plastic scintillator (5) has a uniformly thick luminescent coating sprayed on the side facing away from the cavity, and a light-shielding film is attached to the outside of the luminescent coating.

7. A surface contamination detector based on a SiPM array according to claim 6, characterized in that, The luminescent coating is ZnS(Ag), and the light-shielding film is Mylar film.

8. The surface contamination detector based on SiPM array according to claim 6, wherein, A protective net assembly (6) is installed on the outside of the light-shielding film, and the protective net assembly (6) is fixedly installed on the housing (1) by screws.

9. The surface contamination detector based on SiPM array according to claim 1, wherein, The housing (1) is integrally formed by injection molding. The top of the housing (1) is provided with a mounting hole for mounting the SiPM array signal acquisition unit (20). The SiPM array signal acquisition unit (20) is provided with a circuit box cover (7) above it.

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