SiPM readout-based double-beta plastic scintillator detector

Abstract

The invention relates to a double-beta plastic scintillator detector based on SiPM readout. The double-beta plastic scintillator detector comprises two hollow plastic scintillators, a SiPM array, a corresponding signal readout circuit, an inflation pipeline, a valve, a reflecting film and a light shielding layer. The two hollow plastic scintillators are stacked away from light; the SiPM array is coupled to the side surface of the hollow plastic scintillator, and the signal-to-noise ratio of the detector is improved by using the SiPM array partition according with the noise reduction technology; the two hollow plastic scintillators pasted with the reflecting films and the light shielding layers are packaged in a stainless steel shell to form a dual-channel beta plastic scintillator detector so as to realize synchronous high-sensitivity measurement of different radioactive gases. According to the invention, the two hollow plastic scintillators are packaged into the double-beta detector, so that synchronous high-sensitivity measurement of different radioactive gases can be realized. The SiPM is assembled on the side wall of the scintillator, and two oppositely arranged gamma detectors can be adopted for measurement, so that the gamma ray detection efficiency is improved, and the detection sensitivity is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of atmospheric radiation environment monitoring and nuclear facility safe operation monitoring, and in particular relates to a double-β plastic scintillator detector based on SiPM readout, which is used for measuring radioactive gas activity. Background Art

[0002] Monitoring of radioactive gases in the atmosphere is an important part of nuclear test ban verification and environmental radioactive radiation monitoring. Due to the production and release of multiple radioactive gas isotopes by reactor operation emissions, production and use of medical and industrial isotopes, and nuclear accident leaks, the sources of radioactive gases in the atmosphere are complex, and the types and concentrations of nuclides are superimposed in time and space, that is, the representativeness of single component samples has time and space differences. Research on simultaneous measurement technology of different radioactive gases can not only enrich monitoring methods, but also make up for the problem of insufficient time coverage of single component monitoring.

[0003] The various existing measurement methods and corresponding detectors for the noble gas xenon, as well as the measurement methods and detection equipment, have advantages in improving detection sensitivity, but do not involve detectors for measuring multiple radioactive gases simultaneously.

[0004] Compared with the measurement of single-component radioactive gas nuclides, simultaneous measurement of different radioactive nuclides will produce background interference with each other and reduce detection sensitivity. Summary of the invention

[0005] The present invention provides a dual-β plastic scintillator detector based on SiPM readout, and the technical problem to be solved is: solving the problem that simultaneous measurement of different radioactive nuclides will generate background interference with each other and reduce detection sensitivity.

[0006] In order to solve the above technical problems, the present invention provides a dual-β plastic scintillator detector based on SiPM readout, which is characterized by: comprising two hollow plastic scintillators, a SiPM array and an inflation pipeline; the two hollow plastic scintillators are stacked and packaged as a whole in a light-proof manner; the exteriors of the two hollow plastic scintillators 1 are both composed of scintillator materials, and the interior of the scintillator is a hollow sealed space; the two hollow plastic scintillators are provided with a through hole on a side wall connected to the inflation pipeline, and the three sides of the hollow plastic scintillator except the side where the inflation tube is located are coupled to the SiPM array.

[0007] Furthermore, the scintillator is in the shape of a cuboid.

[0008] Furthermore, the SiPM array is divided into N units, N is greater than or equal to 2, and the signal of each unit is added separately; when the SiPMs of N units have signals at the same time, the signals of the N units are added again and output as one signal as the output signal of the detector.

[0009] Furthermore, except for the area coupled to the SiPM array, the rest of the outer area of ​​the hollow plastic scintillator is covered with a reflective film.

[0010] Furthermore, a heat insulation layer is placed on the side where the two hollow plastic scintillators are led out of the inflation pipeline.

[0011] Furthermore, an anti-twist clamp is installed at the inflation pipeline.

[0012] Furthermore, two light-shielded stacked hollow plastic scintillators have carbon fiber windows attached to both end surfaces except the plane where the SiPM array and the inflation pipeline are located; the whole is encapsulated in a shell.

[0013] Furthermore, the center of the hollow plastic scintillator is a cylindrical cavity.

[0014] Furthermore, two hollow plastic scintillators are filled with different gases.

[0015] Furthermore, a PCB circuit board is provided above the side where the inflation pipeline is located.

[0016] Beneficial effects: The present invention eliminates the mutual interference between cosmic rays and radioactive gases through detector design and multiple coincidence / anti-coincidence technical means, and can achieve simultaneous measurement of different radioactive gas nuclides. At the same time, it can greatly improve the sensitivity of radioactive gas nuclide detection and obtain richer monitoring information.

[0017] The hollow plastic scintillator is laterally coupled to the SiPM array, and the SiPM array partitioning and noise reduction technology is used to improve the detector signal-to-noise ratio; two hollow plastic scintillators with a reflective film and a light-shielding layer are encapsulated in a stainless steel casing to form a dual-channel β detector to achieve synchronous and highly sensitive measurement of different radioactive gases.

[0018] 1. The present invention uses two hollow plastic scintillators to encapsulate a dual-β detector, which can achieve synchronous and highly sensitive measurement of different radioactive gases.

[0019] 2.SiPM is mounted on the side wall of the scintillator and can be measured using two oppositely placed γ detectors to improve the γ-ray detection efficiency and thus the detection sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the dual-β plastic scintillator detector structure based on SiPM readout;

[0021] Figure 2 Assembly diagram for dual-beta plastic scintillator detector based on SiPM readout;

[0022] Figure 3 It is a dual-β plastic scintillator detector based on SiPM readout;

[0023] Figure 4 Schematic diagram of the β-γ coincidence system constructed using a dual β plastic scintillator detector and a HPGe detector;

[0024] Figure 5 for 133 Two-dimensional coincidence spectrum of Xe 81keV gamma rays and beta rays with a maximum energy of 346keV;

[0025] Figure 6 for 85 The two-dimensional coincidence spectrum of Kr 514keV gamma rays and beta rays with a maximum energy of 178keV;

[0026] Among them: 1—hollow plastic scintillator; 2—SiPM array (silicon photomultiplier tube); 3—inflation pipeline; 4—PCB circuit board; 5—thermal insulation layer; 6—anti-twist clamp; 7—signal interface; 8—housing; 9—carbon fiber window; 10—power interface; 11—dual beta plastic scintillator detector; 12—2 sets of HPGe detectors; 13—2 preamplifiers; 14—2 main amplifiers; 15—2 high voltages; 16—"OR" logic circuit; 17—anti-cosmic ray detector output signal; 18—digital coincidence instrument; 19—computer; 20—liquid nitrogen condensation refrigeration device; 21—valve. DETAILED DESCRIPTION

[0027] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below.

[0028] The present invention proposes a dual-β plastic scintillator detector based on SiPM readout, comprising two hollow plastic scintillators 1, a SiPM array 2, an air filling pipeline 3, a valve 21, a reflective film and a light-proof layer; the two hollow plastic scintillators are stacked in a light-proof manner;

[0029] The exteriors of the two hollow plastic scintillators 1 are both made of scintillator material. The scintillators are in the shape of rectangular parallelepipeds with a hollow sealed space inside.

[0030] The two hollow plastic scintillators are provided with a through hole on a side wall to be connected with the gas filling pipeline as required.

[0031] The three sides of the hollow plastic scintillator except the side where the gas-filled tube is located are coupled to the SiPM array, and the SiPM array partitioning and noise reduction technology is used to improve the signal-to-noise ratio of the detector.

[0032] A signal readout circuit is provided on the PCB circuit board, which is used to process and output the SiPM array signals of the two hollow plastic scintillators. The SiPM array is divided into N units (N is greater than or equal to 2), and the signal of each unit is added separately; when the SiPMs of N units have signals at the same time, the signals of the N units are added again and output as one signal as the output signal of the detector.

[0033] Except for the area coupled to the SiPM array, the remaining outer area of ​​the hollow plastic scintillator is covered with a reflective film.

[0034] An insulation layer is placed on the side of the two hollow plastic scintillators leading out of the inflation pipeline to reduce the temperature change caused by the heating of the circuit board; an anti-twist clamp is installed on the inflation pipeline to avoid debonding and leakage caused by the torsion of the inflation tube.

[0035] Two hollow plastic scintillators, SiPM array and corresponding signal readout circuit and reflective film are all packaged in a light-proof layer to protect against light. The light-proof layer is provided with a through hole through which an air-filling pipeline passes. The air-filling pipeline is connected to a valve.

[0036] Two light-proof stacked hollow plastic scintillators have carbon fiber windows on both sides except the plane where the SiPM array and the inflation pipeline are located; power, signal and inflation interfaces are left after packaging.

[0037] The hollow plastic scintillator of the present invention is a 65mm×65mm×14mm rectangular parallelepiped on the outside, and a Φ60mm×10mm cylindrical cavity is located in the middle of the inside, which is used to fill the radioactive gas sample; except for the side where the inflation pipeline is located, the other three sides of the scintillator are coupled with 30 (2×10×3) 6mm×6mm SiPM arrays 2; the heat insulation layer 5 is used to prevent the SiPM amplification factor from changing due to heating of electronic devices such as a PCB circuit board 4; the anti-twist clamp 6 is used to prevent the detector from debonding and leaking due to the rotation of the stainless steel pipe; the inflation pipeline 3 and the scintillator 1 are bonded with epoxy glue to ensure that the gas filled into the scintillator cavity does not leak; the carbon fiber window 9 is placed on the two end faces of the double-β plastic scintillator detector to reduce the absorption of γ rays.

[0038] Will 85 Kr and 133 Xe is respectively filled into two hollow plastic scintillators 21-1 and 21-2 of the dual β plastic scintillator detector based on SiPM readout, and a β-γ coincidence system is established using the dual β plastic scintillator detector based on SiPM readout and the HPGe detector of the present invention (shown in FIG. Figure 4), wherein the dual-β plastic scintillator detector 11 is placed between the two sets of HPGe detectors 12-1 and 12-2, the signals of the two sets of HPGe detector preamplifiers 13-1 and 13-2 are respectively amplified by the main amplifiers 14-1 and 14-2 and then input into the digital coincidence instrument 18 through the "OR" logic circuit 16; the two high-voltage modules 15-1 and 15-2 are respectively used to provide high voltage to the two HPGe detectors; the output signal of the dual-β plastic scintillator detector 11 and the output 7 of the anti-cosmic ray detector are both connected to the digital coincidence instrument 18.

[0039] Two liquid nitrogen condensation refrigeration devices 20-1 and 20-2 provide low-temperature working environment for two sets of HPGe detectors respectively; the double-β plastic scintillator detector and the two sets of HPGe detectors are arranged in a lead shielding room 22 to shield the environmental radioactive background.

[0040] use 85 The correspondence between Kr's maximum energy 173.1keV β-ray and 514keV γ-ray and 133 The maximum energy of Xe is 346keV β-ray and 81keV γ-ray. The two gases are respectively filled into the two hollow plastic scintillators of the double β plastic scintillator detector. 133 Xe is eliminated by combining the output signal I of the double-β plastic scintillator detector with the HPGe signal after “OR” addition, and then anti-coinciding with the output signal II of the double-β plastic scintillator detector. 85 Kr Bremsstrahlung 133 Background effects of Xe measurements; 85 Kr is the result of the combination of the output signal II of the dual-β plastic scintillator detector and the HPGe signal after “OR” addition, and then anti-coincides with the output signal I of the dual-β plastic scintillator detector to reduce 133 Xe 85 The impact of cosmic rays on Kr measurement; the anti-cosmic ray device can further reduce the impact of cosmic rays and thus improve the detection sensitivity. Figure 5-Figure 6 They are 85 Kr and 133 The β-γ two-dimensional coincidence spectrum of Xe gas samples. Using this detector and coincidence measurement system, synchronous and highly sensitive measurements of different radioactive gases can be achieved.

[0041] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual-β plastic scintillator detector based on SiPM readout, characterized in that: It comprises two hollow plastic scintillators, a SiPM array and an air filling pipeline; the two hollow plastic scintillators are stacked and packaged as a whole in a light-proof manner; the exteriors of the two hollow plastic scintillators 1 are both composed of scintillator materials, and the interiors of the scintillators are hollow sealed spaces; a through hole is left on a side wall of the two hollow plastic scintillators to be connected to the air filling pipeline, and the other three sides of the hollow plastic scintillator except the side where the air filling tube is located are coupled to the SiPM array.

2. A dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: The scintillator is in the shape of a cuboid.

3. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: The SiPM array is divided into N units, N is greater than or equal to 2, and the signal of each unit is added separately; when the SiPMs of N units have signals at the same time, the signals of the N units are added again and output as one signal as the output signal of the detector.

4. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: Except for the area coupled to the SiPM array, the remaining outer area of ​​the hollow plastic scintillator is covered with a reflective film.

5. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: A heat-insulating layer is placed on the sides of the two hollow plastic scintillators leading out of the gas-filled pipeline.

6. A dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: An anti-twist clamp is installed on the inflation line.

7. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: Two light-proof and stacked hollow plastic scintillators have carbon fiber windows on both end surfaces except for the plane where the SiPM array and the inflation pipeline are located; the whole is encapsulated in a shell.

8. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: The center of the hollow plastic scintillator is a cylindrical cavity.

9. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: Two hollow plastic scintillators are filled with different gases.

10. The dual-β plastic scintillator detector based on SiPM readout according to claim 1, characterized in that: A PCB circuit board is provided above the side where the inflation pipeline is located, which is used for processing and outputting the SiPM array signals of the two hollow plastic scintillators.

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