SiPM-based radioactive gas beta ray measuring device

Abstract

The utility model relates to a radioactive gas beta ray measuring device based on SiPM. The radioactive gas beta ray measuring device comprises an inflation pipeline, a SiPM array, a source box, a light shielding layer and an external packaging structure. The source box is of a hollow sealed structure, a through hole is reserved in a certain side wall of the source box, the source box is connected with the inflation pipeline, and the SiPM array is formed by splicing small-area SiPM units according to the surface shape of the source box and is coupled with the upper surface of the source box; except the surface, coupled with the SiPM array, of the source box, the other outer surface area is covered with a light shielding layer; and the source box is integrally packaged in the external packaging structure. According to the utility model, the miniaturization of the measuring device is realized; the influence of SiPM array dark counting is eliminated, the signal-to-noise ratio of the system is improved, the lower threshold of detection ray energy is reduced, and the detection efficiency of beta rays with continuous energy can be improved. The device is high in gamma ray transmittance, the SiPM array can be assembled on the side wall of the scintillator, the upper surface and the lower surface of the scintillator can be matched with two gamma detectors for detection at the same time, the gamma ray detection efficiency is improved, and the detection sensitivity of the system is further improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to nuclear detection technical field and atmospheric radiation environmental monitoring technical field, concretely relates to a radioactive gas beta ray measuring device based on SiPM. BACKGROUND

[0002] The reactor operation can discharge gas radionuclide, and carrying out the high sensitivity monitoring of gas radionuclide has important significance for the safe operation of nuclear facilities, radiation environmental monitoring.

[0003] Beta-gamma coincidence is a kind of gas radionuclide measuring method with higher detection sensitivity, and the existing method for measuring xenon isotope activity by adopting plastic scintillator as beta detector coincidence measurement, and the beta detector reads out signal by photomultiplier tube.But the detector based on photomultiplier tube is larger in size and is interfered by electromagnetic interference. UTILITY MODEL CONTENT

[0004] The utility model provides a kind of radioactive gas beta ray measuring device based on SiPM, and the technical problems to be solved are: the miniaturization problem of measuring device is solved, and the signal-to-noise ratio of system is also improved.

[0005] To solve the above technical problems, the utility model provides a kind of radioactive gas beta ray measuring device based on SiPM, characterized by: including inflation pipeline 1, SiPM array 4, source box 5, light-proof layer 6 and external packaging structure;The source box is hollow sealed structure, and the source box is connected with inflation pipeline and has through-hole in certain side wall, and SiPM array is spliced according to the shape of source box surface by small-area SiPM unit and is coupled with the upper surface of source box;Except the surface coupled with SiPM array, the rest of the surface area of source box is covered with light-proof layer;The whole source box is packaged in external packaging structure.

[0006] Beneficial effect: the utility model realizes the miniaturization of measuring device;

[0007] By multiple coincidence, the influence of SiPM array dark count is eliminated, the signal-to-noise ratio of system is improved, the lower threshold of detection ray energy is reduced, and the detection efficiency of energy continuous beta ray can be improved.

[0008] The device has high gamma ray transmittance, and SiPM array can be assembled on the side wall of scintillator, so that two gamma detectors can detect the upper and lower surfaces of scintillator simultaneously, improve the gamma ray detection efficiency and further improve the detection sensitivity of system. DRAWINGS

[0009] Figure 1 It is structure schematic diagram of radioactive gas beta ray measuring device based on SiPM;

[0010] Figure 2The utility model provides a kind of appearance of radioactive gas beta ray measurement device based on SiPM;

[0011] Figure 3 For the noise contrast of using multiple coincidence and not using multiple coincidence;

[0012] Figure 4 For the schematic diagram of beta-gamma coincidence system using radioactive gas beta ray measurement device based on SiPM and HPGe detector;

[0013] Figure 5 For the spectrum measured using beta-gamma coincidence system 131m Xe 129keV inner conversion electron spectrum;

[0014] Figure 6 For the spectrum measured using beta-gamma coincidence system 131m Xe 129keV inner conversion electron open 30keV X-ray spectrum. DETAILED DESCRIPTION

[0015] To make the purpose, content and advantages of the utility model more clear, the specific embodiment of the utility model is described in further detail below.

[0016] The utility model provides a kind of radioactive gas beta ray measurement device based on SiPM, including aeration pipeline 1, PCB circuit board 2, heat insulation layer 3, silicon photomultiplier (SiPM) array 4, plastic scintillator source box 5, light-proof layer 6, carbon fiber plate 7 and external packaging structure;

[0017] Plastic scintillator source box is the core component of the present beta ray measurement device, its external shape is cylindrical body, and the sealed structure with hollow chamber in the inside, the chamber is used to store radioactive gas to be measured.

[0018] Plastic scintillator source box material is plastic scintillator, main part is integrally formed by injection molding, then and lid are bonded by optical silicon glue.

[0019] Plastic scintillator source box has through-hole in certain side wall, it is connected with aeration pipeline and valve, is used to carry out the injection and extraction of radioactive gas to be measured.

[0020] Aeration pipeline adopts 1 / 16 inch stainless steel pipe, minimizes to reduce the influence on light transmission in scintillator.

[0021] SiPM array is spliced according to the surface shape of plastic scintillator source box by small area SiPM unit, and air coupling is used on the upper surface of plastic scintillator source box;

[0022] SiPM unit adopts 6mm x6mm size, and a total of 36 SiPM units are used.

[0023] The plastic scintillator source box covers a light-proof layer on the rest of the outer surface area except the upper surface coupled with the SiPM array.

[0024] The light-proof layer adopts an ESR reflective film for reflecting the scintillation fluorescence generated by the scintillator, thereby improving the light detection efficiency of the SiPM array.

[0025] The PCB circuit board is used for collecting and outputting the signals of the SiPM array, and can adopt the prior art.

[0026] Preferably, the PCB circuit board comprises a SiPM array analog signal processing module, an FPGA logic processing module, and a SiPM array power supply module.

[0027] The SiPM array analog signal processing module divides the SiPM array into multiple groups, and the analog signals of each group of SiPMs are merged and led out, and are outputted after being amplified and converted into digital signals.

[0028] The FPGA logic processing module processes the multiple groups of digitized signals, divides each group of digital signals into two paths, and respectively performs signal addition and AND gate judgment, when the AND gate is valid, the system outputs the summed SiPM array signal, and when the AND gate is invalid, the system outputs the current electronic noise.

[0029] The SiPM array power supply module reads the working environment temperature of the SiPM array in real time, and adjusts the power supply voltage of the SiPM array based on the preset temperature-voltage relationship in the FPGA.

[0030] Specifically, the FPGA logic processing module comprises a signal acquisition module, a signal processing module, and a signal triggering module.

[0031] The signal acquisition module performs peak searching or integration on the converted SiPM digital signals, and adds and sums the multiple groups of SiPM signals.

[0032] The signal processing module is used for comparing the peak searching or integration results of each group of SiPM signals with the set threshold value parameters, and outputting the comparison results in binary, with "1" outputted when greater than the threshold value and "0" outputted when less than the threshold value.

[0033] The signal triggering module is used for determining whether to output the added and summed SiPM signals according to the results of the logic processing module.

[0034] The heat insulation layer adopts silica gel material, is installed between the SiPM array and the PCB circuit board, and is used for absorbing the heat generated by the PCB circuit to reduce the influence of temperature rise on the SiPM array.

[0035] The carbon fiber plate is installed at the bottom of the plastic scintillator source box, which can protect the plastic scintillator source box in use and reduce the influence on the gamma rays.

[0036] The side wall of the packaging structure is made of stainless steel material, and the top is made of polyethylene material, which, together with the carbon fiber plate at the bottom, packages the whole device as a whole, improving the reliability of the device.

[0037] Embodiment:

[0038] The plastic scintillator source box 5 is a cylinder with a diameter of 50 mm and a height of 12 mm, and the inner chamber is a cylindrical cavity with a diameter of 40 mm and a height of 10 mm. The radioactive gas sample is filled into the scintillator chamber, which has a high detection efficiency. The SiPM array is composed of 32 SiPM units with a size of 6 mm x 6 mm, which is coupled to the top of the scintillator. A heat insulation layer and a PCB circuit board are sequentially arranged above the SiPM array. The readout circuit is integrated on the PCB circuit board. The heat insulation layer 3 is used to prevent the heating of the electronic devices from increasing the SiPM noise. The light-proof layer 6 adopts ESR reflective film. The inflation pipeline 1 is adhered to the scintillator 5 by epoxy glue to ensure the sealing, and the gas filled into the scintillator cavity does not leak. The carbon fiber plate 7 is placed at the bottom to reduce the absorption of gamma rays.

[0039] The β-γ coincidence system is established by using the SiPM radioactive gas β ray measurement device and the HPGe detector. Figure 3 , 131m Xe is filled into the SiPM radioactive gas β ray measurement device. The 29.7 keV X-ray generated by the decay of Xe is used as the opening signal, which has a coincidence relationship with the 129 keV internal conversion electron. 131m The 29.7 keV X-ray peak count in the 129 keV internal conversion electron energy spectrum is measured. 131m The energy resolution of the 29.7 keV X-ray peak count in the 129 keV internal conversion electron energy spectrum is less than 22.5%. The γ coincidence energy spectrum is obtained by using the 129 keV internal conversion electron energy region as the opening signal. Figure 5 The detection efficiency of the 129 keV internal conversion electron is 97.1%, which has a very high detection efficiency.

[0040]

[0041] In the formula, ε β (129) is the detection efficiency of the 129 keV internal conversion electron; N γC (30) is the 129 keV internal conversion electron energy region as the opening signal. The 29.7 keV X-ray peak count in the γ coincidence energy spectrum is N γ (30); and N (30) is the 29.7 keV X-ray peak count in the original γ spectrum.

[0042] The above merely describes preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as falling within the protection scope of the present application.

Claims

1. A SiPM-based radioactive gas beta-ray measurement device, characterized by: The application relates to a radioactive gas detection device, which comprises a gas filling pipeline, a SiPM array, a source box, a light-proof layer and an external packaging structure; the source box is a hollow sealed structure, a through hole is left on one side wall of the source box, the through hole is connected with the gas filling pipeline, the SiPM array is spliced according to the surface shape of the source box by small-area SiPM units and is coupled with the upper surface of the source box; the remaining outer surface area of the source box is covered with the light-proof layer except the surface coupled with the SiPM array. The source box is integrally packaged in the external packaging structure.

2. The SiPM-based radioactive gas beta-ray measurement device of claim 1, wherein: The hollow chamber of the source box stores radioactive gas to be detected.

3. The SiPM-based radioactive gas beta-ray measurement device of claim 1, wherein: The source box is made of plastic scintillator.

4. The SiPM-based radioactive gas beta measurement device of claim 1, wherein: The gas filling pipeline is made of stainless steel pipe.

5. The SiPM-based radioactive gas beta measurement device of claim 1, wherein: The SiPM unit adopts a size of 6mm*6mm.

6. The SiPM-based radioactive gas beta measurement device of claim 1, wherein: The light-proof layer adopts an ESR reflective film.

7. The SiPM-based radioactive gas beta measurement device of claim 1, wherein: The external packaging structure is further provided with a PCB circuit board for collecting and outputting the signals of the SiPM array.

8. The SiPM-based radioactive gas beta measurement device of claim 7, wherein: A heat insulation layer is arranged between the SiPM array and the PCB circuit board.

9. The SiPM-based radioactive gas beta measurement device of claim 8, wherein: The heat insulation layer is made of silica gel material.

10. A SiPM-based radioactive gas beta measurement device according to any one of claims 1-9, characterized in that: The side wall of the external packaging structure is made of stainless steel material, the top is made of polyethylene material, and the bottom is made of carbon fiber plate.

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