A portable low-background α and β radiation detection device

Abstract

The present invention discloses a portable low-background α and β radiation detection device, which relates to the technical field of detection devices, and includes: a housing, a time projection chamber, an anti-coincidence detector and a readout electronics system. The time projection chamber is arranged in the housing; an incident window is arranged at the bottom of the time projection chamber, and a film window assembly is arranged at the incident window; a sample tray is arranged below the incident window, and in the detection state, the tray will hold samples to be detected; the time projection chamber is used to detect the three-dimensional track and deposited energy information of charged particles entering the time projection chamber; the anti-coincidence detector is arranged in the housing; the anti-coincidence detector is located above the time projection chamber; the readout electronics system is electrically connected to the time projection chamber and the anti-coincidence detector; the readout electronics system is used to collect the current signals generated by the time projection chamber and the anti-coincidence detector and perform digital processing. The present invention has portability to facilitate wide popularization, thereby meeting the radiation monitoring needs of the public.

Description

Technical Field

[0001] The invention relates to the technical field of detection devices, and in particular to a portable low-background alpha and beta radiation detection device. Background Art

[0002] α and β radiation detection devices are widely used in environmental radiation monitoring, including: indoor and outdoor atmospheric radiation monitoring, food and water pollution detection, and material radioactivity research. For example, α and β detection devices based on gas flow proportional counters are used to detect drinking water, food and radioactive pollutants. With the progress of society, people have a higher and higher pursuit of environmental safety. In the foreseeable future, the demand for radiation detection in various fields will continue to grow.

[0003] In most application scenarios of ionizing radiation detection, the radioactivity of the samples to be tested is relatively weak, and the α and β measurement devices need to have the characteristics of high sensitivity and low background. Existing measurement equipment can only perform single-channel measurements of particle counts, energy or waveforms, which results in its poor ability to exclude various backgrounds, especially β and γ radiation in the environment. Current commercial equipment requires the use of heavy shielding to reduce the environmental background. The presence of the shielding body greatly increases the weight, volume and complexity of the device, making the equipment unportable and unpopular, and unable to meet the growing radiation monitoring needs of the public. Summary of the invention

[0004] The purpose of the present invention is to provide a portable low-background α and β radiation detection device to solve the problems existing in the above-mentioned prior art, and to be portable so as to be widely popularized, thereby meeting the people's growing demand for radiation monitoring.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a portable low-background α and β radiation detection device, comprising: a housing, a time projection chamber, an anti-coincidence detector and a readout electronics system. The length, width and height of the housing are in the range of 300mm to 400mm, 230mm to 300mm and 150mm to 175mm respectively, and the weight of the portable low-background α and β radiation detection device is 15 to 18kg; the time projection chamber is arranged in the housing; an incident window is arranged at the bottom of the time projection chamber, and a film window assembly is arranged at the incident window; in the detection state, a sample tray is arranged below the incident window; samples are placed on the sample tray, and the time projection chamber is used for three-dimensional trajectory and deposition energy information of charged particles entering the time projection chamber The invention relates to a method for detecting a sample through a sample tray. The method comprises the following steps: performing detection; a push-pull opening is provided on one side of the shell; the sample tray can be pushed into the shell or pulled out from the shell through the push-pull opening; the anti-coincidence detector is provided in the shell; the anti-coincidence detector is located above the time projection chamber; the anti-coincidence detector is used to detect background particles from the environment; the readout electronics system is connected to the time projection chamber and the anti-coincidence detector, and the readout electronics system is used to collect the current signals generated by the anode of the time projection chamber and the anode of the anti-coincidence detector and transmit the current signals to the computer after digital processing.

[0007] Preferably, a shielding layer is provided under the sample tray and above the anti-coincidence detector; the shielding layer is made of lead or copper. When lead is used, a low-background metal layer needs to be provided on the inner side of the shielding layer.

[0008] Preferably, the length, width and height of the shell are 358 mm, 270 mm and 168 mm respectively, and the weight of the portable low-background α, β radiation detection device is 17 kg.

[0009] Preferably, the time projection chamber serves as the main detector, and the time projection chamber includes a main detector gas box, a field cage and a two-dimensional readout MPGD. The incident window is arranged at the bottom of the main detector gas box, the field cage is arranged around the main detector gas box, the two-dimensional readout MPGD is arranged in the main detector gas box and located at the top of the detection sensitive area, and the detection sensitive area is formed between the incident window, the field cage and the two-dimensional readout MPGD; the main detector gas box, the field cage, the two-dimensional readout MPGD, the membrane window assembly and the sample tray are all made of low-background materials.

[0010] Preferably, the anode of the two-dimensional readout MPGD and the anode of the anti-coincidence detector are respectively arranged on the front and back sides of the same PCB board.

[0011] Preferably, the two-dimensional readout MPGD uses a microgrid gas detector.

[0012] Preferably, the membrane window assembly includes a film and a membrane window body; the membrane window body is detachably arranged at the incident window of the main detector gas box, the membrane window body is ring-shaped, and the inner hole of the membrane window body is opposite to the incident window, the film is arranged on the membrane window body and closes the inner hole of the membrane window body, and the overall structure formed by the film and the membrane window body can close the incident window.

[0013] Preferably, the film window assembly also includes a pressure ring and a fixing ring, both of which are annular, the circumferential edge of the film is bonded to one side of the pressure ring and completely closes the inner hole of the pressure ring, the film window body, the pressure ring and the fixing ring are parallel and arranged in sequence, the fixing ring is connected to one side of the film window body by bolts, and the fixing ring presses the pressure ring against one side of the film window body; the overall structure formed by the pressure ring and the film closes the inner hole of the film window body.

[0014] Preferably, a wrench is also included; the outer wall of the membrane window body is a cylindrical surface, the outer wall of the membrane window body is provided with a thread, the membrane window body is threadedly connected to the main detector gas box, and when the membrane window assembly is installed on the main detector gas box, the membrane window body and the fixing ring do not protrude from the outer surface of the main detector gas box, and the front of the membrane window body or the fixing ring is provided with a plurality of holes extending along the thickness direction, and the plurality of holes are sequentially arranged along the circumference of the membrane window body or the fixing ring; the wrench includes a supporting part and a force transmission column, the force transmission column is fixed on the supporting part, the number of the force transmission columns is the same as the number of the holes, the force transmission column is used to be inserted into the hole, and the supporting part is used to transmit external torque to the force transmission column and enable the force transmission column to drive the membrane window assembly to rotate.

[0015] Preferably, the membrane window assembly also includes three sealing rings, one sealing ring is provided between the membrane window body and the main detector gas box, one sealing ring is provided between the pressure ring and the membrane window body, and one sealing ring is provided between the fixing ring and the membrane window body, and the incident window is located in the cylindrical surface where each sealing ring is located.

[0016] Compared with the prior art, the present invention has achieved the following technical effects:

[0017] First, the detection device provided by the present invention uses a time projection chamber to obtain more abundant particle characteristic information. Based on this, according to the characteristics of different particles, particles can be effectively identified and background can be eliminated. Without adding too many shielding layers, the device can achieve low-background α and β measurement levels, thus having portability.

[0018] Second, the length, width and height of the detection device range from 300mm to 400mm, 230mm to 300mm and 150mm to 175mm respectively, and the weight is 15 to 18kg, thus achieving the purpose of portability, facilitating wide popularization and meeting the people's growing demand for radiation monitoring.

[0019] Third, the sample tray adopts a pull-out drawer mode, which improves the convenience of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of the structure of a portable low-background α and β radiation detection device provided in an embodiment of the present invention;

[0022] Figure 2 for Figure 1 A cross-sectional view of

[0023] Figure 3 for Figure 1 A schematic diagram of the structure of the medium-time projection room and the anti-coincidence detector;

[0024] Figure 4 This is a schematic diagram of the structure of the time projection room and the drawer structure;

[0025] Figure 5 This is a schematic diagram of the interior of the time projection room and the drawer structure;

[0026] Figure 6 It is a structural schematic diagram when the sample tray is arranged on the drawer structure;

[0027] Figure 7 is a schematic diagram of the structure of a membrane window assembly;

[0028] Figure 8 for Figure 7 Exploded diagram of the structure;

[0029] Fig. 9 It is a structural schematic diagram of the sealing ring;

[0030] Fig.10 is a schematic diagram of the structure of a wrench;

[0031] Fig.11 is a cross-sectional view of a membrane window assembly;

[0032] Fig.12 for Fig.11 A magnified view of the structure at center A;

[0033] In the figure: 1-time projection chamber; 2-detection sensitive area; 3-housing; 4-anti-coincidence detector; 5-readout electronics system; 6-sample tray; 7-incident window; 8-shielding layer; 9-main detector gas box; 10-field cage; 11-PCB board; 12-two-dimensional readout MPGD; 13-drawer handle; 14-gas cylinder; 15-intake pipe; 16-float flowmeter; 20-membrane window assembly; 21-membrane window body; 22-fixing ring; 23-film; 24-pressure ring; 25-sealing ring; 26-circular support; 27-cross rod; 28-force transmission column; 29-hole; 30-detector housing. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 are within the scope of protection of the present invention.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Combine the following Figures 1 to 12 , describing an embodiment of the present invention.

[0037] The present invention provides a portable low-background α and β radiation detection device, hereinafter referred to as the detection device, such as Figure 1 to Figure 3As shown, the detection device includes: a housing 3, a time projection chamber 1, an anti-coincidence detector 4 and a readout electronics system 5. The length, width and height of the housing 3 are respectively 300mm-400mm, 230mm-300mm and 150mm-175mm, and the weight of the portable low-background α and β radiation detection device is 15-18kg; the time projection chamber 1 is arranged in the housing 3; an incident window 7 is arranged at the bottom of the time projection chamber 1, and a film window assembly 20 is arranged at the incident window 7; in the detection state, a sample tray 6 is arranged below the incident window 7; the sample tray 6 is placed on the sample tray 6, and the time projection chamber 1 is used to detect the three-dimensional track and sedimentation of charged particles entering the time projection chamber 1. The accumulated energy information is detected; a push-pull port is provided on one side of the shell 3; the sample tray 6 can be pushed into the shell 3 or pulled out from the shell 3 through the push-pull port; the anti-coincidence detector 4 is arranged in the shell 3; the anti-coincidence detector 4 is located above the time projection chamber 1; the anti-coincidence detector 4 is used to detect background particles from the environment; the readout electronics system 5 is connected to the time projection chamber 1 and the anti-coincidence detector 4, and the readout electronics system 5 is used to collect the current signal generated by the anode of the time projection chamber 1 and the anode of the anti-coincidence detector 4 and transmit it to the computer after digital processing.

[0038] The detection device provided by the present invention utilizes the time projection chamber 1 to obtain richer particle characteristic information. Based on this, according to the characteristics of different particles, the particles can be effectively identified and the background can be eliminated. Under the condition that too many shielding layers 8 are not added, the device can achieve low-background α and β measurement levels, thereby having portability. Specifically, the length, width and height of the detection device range from 300mm to 400mm, 230mm to 300mm and 150mm to 175mm, respectively, and the weight is 15 to 18kg, thereby achieving the purpose of portability. In addition, in the embodiment of the present invention, the sample tray 6 adopts a pull-out drawer mode to improve the convenience of operation.

[0039] Specifically, Figures 4 to 6 As shown, the sample tray 6 is arranged on a drawer structure, and the drawer structure is slidably arranged in or on the housing 3 through a linear guide assembly. The drawer structure has a drawer handle 13.

[0040] In some embodiments, the readout electronics system 5 can specifically use discrete devices such as field effect transistors, operational amplifiers, capacitors and resistors to complete the shaping and amplification of the current signal generated by the anode, preferably, such as ADA4896, 2SK932 and THS4561. The system digitizes analog signals based on programmable devices and commercial multi-channel high-speed digital-to-analog conversion chips, preferably, such as XC7K420T-3FFG901l and ADS52J90.

[0041] In some embodiments, a shielding layer 8 is provided under the sample tray 6 and above the anti-coincidence detector 4 ; the shielding layer 8 is made of lead or copper. When lead is used, a low-background metal layer needs to be provided on the inner side of the shielding layer 8 .

[0042] The upper and lower shielding layers 8 in this embodiment are used to shield the environmental γ-radioactive background from the upper and lower sides of the time projection chamber 1. The thickness of the shielding layer 8 can be selected to be 5-50 mm as required. If lead shielding is used, it is further preferred that an additional 2-5 mm thick low-background metal layer be provided between the shielding layer 8 and the detector chamber, preferably oxygen-free copper, or low-background aluminum alloy or stainless steel, to isolate the lead from the detection sensitive area to prevent the additional background introduced by the β-radioactivity of the lead material itself.

[0043] In some embodiments, the length, width and height of the housing 3 are 358 mm, 270 mm and 168 mm respectively, and the portable low-background α and β radiation detection device weighs 17 kg.

[0044] This embodiment provides detailed size and weight information of the detection device.

[0045] In some embodiments, the time projection chamber 1 includes a main detector gas box 9, a field cage 10 and a two-dimensional readout MPGD12, the incident window 7 is arranged at the bottom of the main detector gas box 9, the field cage 10 is arranged around the main detector gas box 9, the two-dimensional readout MPGD12 is arranged in the main detector gas box 9 and is located at the top of the detection sensitive area 2, and a detection sensitive area 2 is formed between the incident window 7, the field cage 10, and the two-dimensional readout MPGD12; the main detector gas box 9, the field cage 10, the two-dimensional readout MPGD12, the membrane window assembly 20 and the sample tray 6 are all made of low-background materials.

[0046] The test principle is as follows: During the test, the sample to be tested is placed in the sample tray 6, and the radioactive particles therein pass through the membrane window assembly 20 into the TPC (i.e., time projection chamber 1) cavity. The ionized electrons generated in the detection sensitive area 2 are collected by the two-dimensional readout MPGD12 after drift. According to the two-dimensional information of the signal position and the drift time information, the three-dimensional trajectory of the particles can be measured, and then the energy loss (dE / dx) information on the unit path of the particles is obtained in combination with the signal amplitude information. The type of particles can be judged and the α particles and β particles can be identified. The application of the anti-coincidence detector 4 can effectively exclude the cosmic ray muon background, and the upper and lower shielding layers 8 can largely remove the environmental γ background. For background particles entering the TPC from the side, the particle track and energy deposition information measured by the TPC can be used to judge and screen them out.

[0047] In some embodiments, the anti-coincidence detector 4 and the time projection chamber 1 are located within the detector housing 30 .

[0048] In some embodiments, the anode of the two-dimensional readout MPGD 12 and the anode of the anti-coincidence detector 4 are respectively disposed on the front and back sides of the same PCB board 11 .

[0049] This embodiment further improves the integration of the system, thereby reducing the volume and weight.

[0050] In some embodiments, the two-dimensional readout MPGD12 uses a micro-grid gas detector.

[0051] In some embodiments, such as Figure 7 to Figure 12 As shown, the membrane window assembly 20 includes a film 23 and a membrane window body 21; the membrane window body 21 is detachably arranged at the incident window 7 of the main detector gas box 9, the membrane window body 21 is annular, and the inner hole 29 of the membrane window body 21 is opposite to the incident window 7, the film 23 is arranged on the membrane window body 21 and closes the inner hole 29 of the membrane window body 21, and the overall structure formed by the film 23 and the membrane window body 21 can close the incident window 7.

[0052] In this embodiment, the film window assembly 20 is independently provided from the main detector gas box 9, and can be installed at the incident window 7 or removed from the incident window 7, so that a plurality of additional film window assemblies 20 can be prepared as spare parts, and when the film 23 in the film window assembly 20 in use is damaged, the film window assembly 20 can be replaced as a whole. The purpose of quickly replacing the film 23 is achieved, thereby reducing the replacement time of the film 23, and reducing the loss of gas in the main detector gas box 9, thereby improving the detection efficiency.

[0053] It can be understood that one detection device includes a plurality of film window assemblies 20 .

[0054] In some embodiments, the film window assembly 20 also includes a pressure ring 24 and a fixing ring 22, both of which are annular, and the circumferential edge of the film 23 is bonded to one side of the pressure ring 24 and completely closes the inner hole 29 of the pressure ring 24, the film window body 21, the pressure ring 24 and the fixing ring 22 are parallel and arranged in sequence, the fixing ring 22 is connected to one side of the film window body 21 by bolts, and the fixing ring 22 presses the pressure ring 24 to one side of the film window body 21; the overall structure formed by the pressure ring 24 and the film 23 closes the inner hole 29 of the film window body 21.

[0055] This embodiment sets the film 23 and the pressure ring 24 as an independent component, so that several additional pressure rings 24 and films 23 can be prepared, and only a small number of film window bodies 21 are required, for example, three film window bodies 21, 10 pressure rings 24 and films 23 are prepared. In this way, when a damaged film window assembly 20 is replaced and replaced with a new film window assembly 20, the film 23 in the damaged film window assembly 20 can be quickly replaced, so there is no need to prepare too many film window assembly 20 overall structures, saving costs and the space occupied by idle film window assemblies 20.

[0056] In some embodiments, the embodiments of the present invention further include a wrench; the outer wall of the membrane window body 21 is a cylindrical surface, the outer wall of the membrane window body 21 is provided with a thread, and the membrane window body 21 is threadedly connected to the main detector gas box 9. It can be understood that the corresponding part of the main detector gas box 9 is provided with an internal thread. When the membrane window assembly 20 is installed on the main detector gas box 9, the membrane window body 21 and the fixing ring 22 do not protrude from the outer surface of the main detector gas box 9, and the front of the membrane window body 21 or the fixing ring 22 is provided with a plurality of holes 29 extending along the thickness direction, and the plurality of holes 29 are sequentially arranged along the circumference of the membrane window body 21 or the fixing ring 22; the wrench includes a support portion and a force transmission column 28, the force transmission column 28 is fixed on the support portion, the number of the force transmission column 28 is the same as the number of the holes 29, the force transmission column 28 is used to be inserted into the hole 29, and the support portion is used to transmit external torque to the force transmission column 28 and make the force transmission column 28 drive the membrane window assembly 20 to rotate.

[0057] The wrench provided in this embodiment is used for disassembling and installing the membrane window assembly 20. Specifically, when disassembling a damaged membrane window assembly 20, align each force transmission column 28 with each hole 29 and insert it into the hole 29, then hold the wrench by hand or mechanically clamp it and twist it, and the wrench drives the membrane window assembly 20 to rotate during the twisting process to achieve disassembly; when installing a new membrane window assembly 20, align each force transmission column 28 with each hole 29 and insert it into the hole 29, then hold the wrench by hand or mechanically clamp it and twist it in the opposite direction, and the wrench drives the membrane window assembly 20 to rotate during the twisting process to achieve installation.

[0058] It can be understood that the housing 3 of the detection device is a structure in which the top plate or the bottom plate can be opened to facilitate the inspection of the components in the housing 3, such as replacing the film window assembly 20, etc.

[0059] In some embodiments, the support portion includes a circular ring support member 26 and a cross rod 27 disposed in the circular ring support member 26 , and four ends of the cross rod 27 are fixedly connected to the inner wall of the circular ring support member 26 .

[0060] The cross bars 27 in this embodiment are convenient for manual holding.

[0061] In some embodiments, the membrane window assembly 20 also includes three sealing rings 25. A sealing ring 25 is provided between the membrane window body 21 and the main detector gas box 9, between the pressure ring 24 and the membrane window body 21, and between the fixing ring 22 and the membrane window body 21. The incident window 7 is located in the cylindrical surface where each sealing ring 25 is located.

[0062] This embodiment ensures the air tightness of the main detector gas box 9 and avoids the reduction of the air tightness of the main detector gas box 9 due to the independent arrangement of the film window assembly 20.

[0063] In some embodiments, in order to ensure the purity of the working gas in the time projection chamber 1 and the anti-coincidence detector 4, the embodiments of the present invention adopt a gas flow detection. Therefore, in order to realize the gas flow detection, it also includes a gas cylinder 14 and a float flowmeter 16; the gas cylinder 14 is connected to the air inlet of the time projection chamber 1 and the anti-coincidence detector 4; the air inlet of the float flowmeter 16 is connected to the air outlet of the time projection chamber 1 and the anti-coincidence detector 4, and the air outlet of the float flowmeter 16 is connected to the external space to discharge the gas to the outside; during the working process, the gas cylinder 14 continuously provides working gas to the time projection chamber 1 and the anti-coincidence detector 4, and the working gas is a mixed gas of different proportions of inert gas (such as helium, neon, argon, krypton and xenon) and polyatomic molecules (such as isobutane, carbon dioxide, carbon tetrafluoride, methane, etc.).

[0064] In addition, a mass flow meter is also provided on the air intake pipe 15 of the gas cylinder 14 to detect the air intake flow rate. The gas cylinder 14 contains high-pressure gas, while the time projection chamber 1 and the anti-coincidence detector 4 contain normal-pressure gas, so a gas pressure reducing valve is also provided on the air intake pipe 15.

[0065] The anti-coincidence detector 4 and the time projection chamber 1 are connected by an air pipe, so that the purpose of inflating the two components can be achieved by only filling the working gas into one of the anti-coincidence detector 4 and the time projection chamber 1. The staff can also judge whether there is a leak in the time projection chamber 1 and the anti-coincidence detector 4 through the readings of the mass flow meter and the float flowmeter 16. If there is a leak, the components need to be repaired, such as replacing the membrane window component 20.

[0066] In some embodiments, the gas cylinder 14 is detachably arranged on one side outside the outer shell 3, a support plate is arranged at the bottom of one side of the outer shell 3, and a clamp is arranged on the outer wall of the outer shell 3 above the support plate. The support plate is used to support the bottom of the gas cylinder 14, and the clamp is used to clamp the middle part of the gas cylinder 14.

[0067] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A portable low-background α and β radiation detection device, characterized in that: include: A shell, wherein the length, width and height of the shell are in the range of 300 mm to 400 mm, 230 mm to 300 mm and 150 mm to 175 mm respectively, and the weight of the portable low-background α and β radiation detection device is 15 to 18 kg; A time projection chamber, the time projection chamber is arranged in the shell; an incident window is arranged at the bottom of the time projection chamber, and a film window assembly is arranged at the incident window; a sample tray is arranged below the incident window; in a detection state, a sample to be detected is placed on the sample tray; the time projection chamber is used to detect the three-dimensional track and deposition energy information of the charged particles entering the time projection chamber; a push-pull opening is arranged on one side of the shell; the sample tray can be pushed into the shell or pulled out from the shell through the push-pull opening; An anti-coincidence detector, the anti-coincidence detector is arranged in the housing; the anti-coincidence detector is located above the time projection chamber; the anti-coincidence detector is used to detect background particles from the environment; A readout electronics system is electrically connected to the time projection chamber and the anti-coincidence detector; the readout electronics system is used to collect the current signals generated by the anode of the time projection chamber and the anode of the anti-coincidence detector and transmit them to the computer after digital processing.

2. The portable low-background α and β radiation detection device according to claim 1, characterized in that: A shielding layer is provided below the sample tray and above the anti-coincidence detector; the shielding layer is made of lead or copper. When lead is used, a low-background metal layer needs to be provided inside the shielding layer.

3. The portable low-background α and β radiation detection device according to claim 1, characterized in that: The length, width and height of the shell are 358 mm, 270 mm and 168 mm respectively, and the weight of the portable low-background α and β radiation detection device is 17 kg.

4. The portable low-background α and β radiation detection device according to claim 1, characterized in that: The time projection chamber serves as a main detector, and the time projection chamber includes a main detector gas box, a field cage, and a two-dimensional readout MPGD. The incident window is arranged at the bottom of the main detector gas box, the field cage is arranged around the main detector gas box, the two-dimensional readout MPGD is arranged in the main detector gas box and located at the top of the detection sensitive area, and the incident window, the field cage, and the two-dimensional readout MPGD form the detection sensitive area. The main detector gas box, the field cage, the two-dimensional readout MPGD, the membrane window assembly and the sample tray are all made of low-background materials.

5. The portable low-background α and β radiation detection device according to claim 4, characterized in that: The anode of the two-dimensional readout MPGD and the anode of the anti-coincidence detector are respectively arranged on the front and back sides of the same PCB board.

6. The portable low-background α and β radiation detection device according to claim 4, characterized in that: The two-dimensional readout MPGD uses a microgrid gas detector.

7. The portable low-background α and β radiation detection device according to claim 4, characterized in that: The membrane window assembly includes a film and a membrane window body; the membrane window body is detachably arranged at the incident window of the main detector gas box, the membrane window body is ring-shaped, and the inner hole of the membrane window body faces the incident window. The film is arranged on the membrane window body and closes the inner hole of the membrane window body. The integral structure formed by the film and the membrane window body can close the incident window.

8. The portable low-background α and β radiation detection device according to claim 7, characterized in that: The film window assembly also includes a pressure ring and a fixing ring, both of which are annular, the circumferential edge of the film is bonded to one side of the pressure ring and completely closes the inner hole of the pressure ring, the film window body, the pressure ring and the fixing ring are parallel and arranged in sequence, the fixing ring is connected to one side of the film window body by bolts, and the fixing ring presses the pressure ring against one side of the film window body; the overall structure formed by the pressure ring and the film closes the inner hole of the film window body.

9. The portable low-background α and β radiation detection device according to claim 8, characterized in that: It also includes a wrench; the outer wall of the membrane window body is a cylindrical surface, and the outer wall of the membrane window body is provided with a thread, and the membrane window body is threadedly connected to the main detector gas box, and when the membrane window assembly is installed on the main detector gas box, the membrane window body and the fixing ring do not protrude from the outer surface of the main detector gas box, and the front of the membrane window body or the fixing ring is provided with a plurality of holes extending along the thickness direction, and the plurality of holes are sequentially arranged along the circumference of the membrane window body or the fixing ring; the wrench includes a supporting part and a force transmission column, the force transmission column is fixed on the supporting part, the number of the force transmission columns is the same as the number of the holes, the force transmission column is used to be inserted into the hole, and the supporting part is used to transmit external torque to the force transmission column and enable the force transmission column to drive the membrane window assembly to rotate.

10. The portable low-background α and β radiation detection device according to claim 8, characterized in that: The membrane window assembly also includes three sealing rings, one of which is provided between the membrane window body and the main detector gas box, between the pressure ring and the membrane window body, and between the fixing ring and the membrane window body. The incident window is located in the cylindrical surface where each sealing ring is located.

Images