High-sensitivity radioactive gas activity measuring device

Abstract

The utility model relates to a high-sensitivity radioactive gas activity measuring device which comprises a set of double-beta plastic scintillator detector, two sets of gamma detectors, an anti-cosmic ray detector group and a digital coincidence circuit. The double-beta plastic scintillator detector and the gamma detectors are arranged in the lead shielding chamber, the double-beta plastic scintillator detector is arranged between the two gamma detectors, and mutual interference among radioactive gases in the double-beta plastic scintillator detector can be eliminated through coincidence and anticoincidence among four paths of signals; and the anti-cosmic ray detector group is used for shielding coincidence signals generated by cosmic rays in the double-beta plastic scintillator detector and the gamma detector. According to the utility model, a gamma detector original spectrum, an anti-cosmic ray gamma spectrum, a beta-gamma coincidence spectrum and an anti-cosmic ray beta-gamma coincidence spectrum, wherein the beta-gamma coincidence spectrum and the anti-cosmic ray beta-gamma coincidence spectrum are used for eliminating mutual influence among different radioactive gases. According to the utility model, synchronous measurement of different radioactive gases can be realized, and the detection sensitivity of the radioactive gases can be greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to atmospheric environment radiation monitoring technical field relates to a high sensitivity radioactive gas activity measuring device especially relates to a high sensitivity radioactive gas activity measuring device and method based on multiple coincidence / anti -coincidence technique. BACKGROUND

[0002] Atmospheric radioactive gas monitoring has important significance for nuclear test ban environmental radioactive radiation monitoring, and the key of the monitoring technology lies in the high sensitivity atmospheric radioactive activity measurement method.

[0003] Since the reactor operation discharge, medical and industrial isotope production and use, nuclear accident leakage, etc. can produce and release various inert gas isotopes, resulting in complex sources of atmospheric radioactive gas, multiple complex superposition of nuclide types and concentration in space and time, i.e. the existence of space-time difference of representative of single component sample, the research on simultaneous measurement technology of different radioactive gases not only can enrich the monitoring means of nuclear activities, but also can make up for the problem of insufficient time coverage of single component monitoring.

[0004] The existing literature introduces various measurement methods of inert gas xenon and corresponding detectors, and the advantages of measurement methods and detection equipment in improving detection sensitivity. Compared with single component radioactive gas nuclide measurement, simultaneous measurement of different radioactive nuclides will interfere with each other, reducing the detection sensitivity. UTILITY MODEL CONTENT

[0005] The utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0006] In order to solve the above technical problems, the utility model provides a kind of high sensitivity radioactive gas activity measuring device, and the technical problems to be solved are: solve the problem of mutual influence of simultaneous measurement of different radioactive gas nuclides, and can greatly improve the detection sensitivity of radioactive gas nuclide, and obtain more abundant monitoring information.

[0007] The double beta plastic scintillator detector comprises two hollow plastic scintillators, a silicon photomultiplier array; the two hollow plastic scintillators are stacked with light shielding on the end faces, and a gas charging pipeline is arranged on the side wall of the hollow plastic scintillator; the hollow plastic scintillator is coupled with the silicon photomultiplier array on the three side walls except the side wall where the gas charging pipeline is arranged; and the whole hollow plastic scintillator is packaged in a shell.

[0008] The digital coincidence circuit comprises four branches arranged in parallel, and specifically as follows:

[0009] The first route preamplifier, the single-channel analyzer, the OR logic adding circuit 6 and the digital signal collector are sequentially connected in series; the original signals of the anti-cosmic ray detector enter the OR logic adding circuit after passing through the respective preamplifiers and single-channel analyzers, and the output signals of the OR logic adding circuit enter the digital coincidence instrument and are marked as CH0;

[0010] The second route preamplifier, the main amplifier, the OR logic adding circuit and the digital signal collector are sequentially connected in series; the detection signals of the two sets of gamma detectors enter the OR logic adding circuit after passing through the preamplifiers and the main amplifiers in turn, and the output signals of the OR logic adding circuit enter the digital coincidence instrument and are marked as CH1;

[0011] The detection signal of the first hollow plastic scintillator 1-1 of the third route double beta plastic scintillator detector directly enters the digital coincidence instrument and is marked as CH2;

[0012] The detection signal of the second hollow plastic scintillator 1-2 of the fourth route double beta plastic scintillator detector directly enters the digital coincidence instrument and is marked as CH3.

[0013] The signal acquisition logic for measuring the activity of the radioactive gas in the first hollow plastic scintillator 1-1 of the double beta plastic scintillator detector is as follows: CH1 is not processed, and the original spectrum of the gamma detector is obtained; CH1 and CH0 are anti-coincided, and the anti-cosmic ray gamma spectrum is obtained; the signals after the coincidence of CH1 and CH2 are anti-coincided with CH3, and the beta-gamma coincidence spectrum of the first hollow plastic scintillator 1-1 after eliminating the influence of the second hollow plastic scintillator 1-2 of the double beta plastic scintillator detector is obtained; the signals after the coincidence of CH2 and the anti-cosmic ray gamma spectrum are anti-coincided with CH3, and the anti-cosmic ray beta-gamma coincidence spectrum of the first hollow plastic scintillator 1-1 after eliminating the influence of the cosmic rays and the second hollow plastic scintillator 1-2 is obtained.

[0014] Beneficial effects: through the multiple coincidence / anti-coincidence technical means, the cosmic rays and the radioactive gas are eliminated from mutual interference, so that different radioactive gas nuclides can be measured at the same time, and the sensitivity of the radioactive gas nuclide detection can be greatly improved.

[0015] The utility model discloses two sets of gamma detector are placed oppositely, and product price management system software.

[0016] The utility model can measure different radioactive gas activity simultaneously, to obtain abundant monitoring information. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is schematic diagram of the utility model device;

[0018] Figure 2 It is electronic schematic diagram of the utility model device;

[0019] Figure 3 It is measured by the utility model 85 Two-dimensional coincidence spectrum obtained by Kr gas sample;

[0020] Figure 4 It is measured by the utility model 133 Two-dimensional coincidence spectrum obtained by Xe gas sample;

[0021] Figure 5 It is double beta plastic scintillator detector structure schematic diagram

[0022] Figure 6 It is double beta plastic scintillator detector appearance diagram.

[0023] 1-double beta plastic scintillator detector (1-1, 1-2 are hollow plastic scintillator in double beta plastic scintillator detector);2-1, 2-2-γ detector;3-1~3-14-Preamplifier;4-1, 4-2-main amplifier;5-1, 5-2-high voltage;6, 6-1, 6-2-OR logic circuit;7-anti cosmic ray detector output signal;8-digital coincidence instrument;9-computer;10-1, 10-2-liquid nitrogen back condensation refrigeration device;11-1, 11-2-gas line;12-lead shield room;13-anti cosmic ray detector;14, 14-1~14-14-PMT;15-1~15-12-single channel analyzer;16-delay gate;

[0024] 1-1-hollow plastic scintillator;22-SiPM array (silicon photomultiplier);23-gas line;24-PCB circuit board;25-thermal insulation layer;26-anti-twist holder;27-signal interface;28-housing;29-carbon fiber window. DETAILED DESCRIPTION

[0025] In order to make the purpose, content and advantage of the utility model more clearly, the specific embodiment of the utility model is described in further detail below.

[0026] The utility model provides a kind of high sensitivity radioactive gas activity measuring device, including double beta plastic scintillator detector 1, gamma detector, anti cosmic ray detector 13 and digital coincidence circuit;Double beta plastic scintillator detector 1 and gamma detector 2 measure beta signal and gamma signal respectively;

[0027] Double beta plastic scintillator detector 1, gamma detector 2 are arranged in lead shield room, and double beta plastic scintillator detector is placed in the middle of two sets of gamma detectors, and the mutual interference between radioactive gases in double beta plastic scintillator detector can be eliminated by coincidence and anti-coincidence between four-way signals;Anti cosmic ray detector 13 is used to shield coincidence signal generated by cosmic rays in double beta plastic scintillator detector 1 and gamma detector 2.

[0028] The output signals of anti cosmic ray detector, the output signals of double beta plastic scintillator detector and the output signals of two sets of gamma detector 2 are input into digital coincidence circuit through OR logic addition circuit, to obtain gamma detector original spectrum, anti cosmic ray gamma spectrum, beta-gamma coincidence spectrum eliminating mutual influence between different radioactive gases and anti cosmic ray beta-gamma coincidence spectrum.

[0029] The above-mentioned gamma detector is HPGe detector, and two sets of HPGe detectors are placed oppositely.

[0030] The double beta plastic scintillator detector includes two hollow plastic scintillators, a silicon photomultiplier (SiPM) array, a corresponding signal readout circuit, a gas charging pipeline, a valve, a reflective film and a light-proof layer.

[0031] The reflective film is an ESR (Enhanced Specular Reflector) film, and the light-proof layer is a black tape, which separately wraps the two hollow plastic scintillators; the two hollow plastic scintillators are stacked with light-proof end faces, and the gas charging pipeline is arranged on the side wall of the hollow plastic scintillator; the valve is arranged on the gas charging pipeline; the hollow plastic scintillator is coupled with the SiPM array by optical silicone grease except the side face where the gas charging pipeline is located; carbon fiber windows are attached to the other two end faces except the plane where the SiPM array and the gas charging pipeline are located; the whole is packaged in a shell, and power supply, signal and gas charging interfaces are left after packaging. The packaged double beta plastic scintillator detector is placed in the middle of the two sets of gamma detectors.

[0032] The PCB circuit board processes and outputs the SiPM array signals of the two hollow plastic scintillators respectively, the SiPM array is divided into N units, N is greater than or equal to 2, and each unit signal is added separately; when the N units of SiPM have signals at the same time, the signals of the N units are added again to output as one-way signal as the output signal of the detector.

[0033] The hollow scintillator is in the shape of a cuboid, with a cylindrical cavity in the middle, and different gases can be filled into the two hollow scintillators.

[0034] The hollow plastic scintillator side-coupling SiPM array uses SiPM array partition coincidence noise reduction technology to improve the signal-to-noise ratio of the detector; two hollow plastic scintillators with reflective films and light-proof layers are packaged into a stainless steel shell to form a double-channel beta detector, so as to realize synchronous high-sensitivity measurement of different radioactive gases.

[0035] The digital coincidence circuit includes four branches arranged in parallel;

[0036] The first routing preamplifier, single-channel analyzer group, OR logic addition circuit 6 and digital signal collector are connected in series; the preamplifier group and the single-channel analyzer group are respectively composed of 12 parallelly arranged preamplifiers and 12 parallelly arranged single-channel analyzers; the original signal of the anti-cosmic ray detector enters the OR logic addition circuit after passing through the respective preamplifier and single-channel analyzer, and the output signal of the OR logic addition circuit enters the digital coincidence instrument and is marked as CH0;

[0037] The second routing preamplifier, main amplifier, OR logic addition circuit and digital signal collector are connected in series; the detection signals of the two sets of gamma detectors enter the OR logic addition circuit after passing through the preamplifier and the main amplifier in turn, and the output signal of the OR logic addition circuit enters the digital coincidence instrument and is marked as CH1.

[0038] The detection signal of the first hollow plastic scintillator 1-1 of the third route double beta plastic scintillator detector directly enters the digital coincidence instrument and is marked as CH2.

[0039] The detection signal of the second hollow plastic scintillator 1-2 of the fourth route double beta plastic scintillator detector directly enters the digital coincidence instrument and is marked as CH3.

[0040] When measuring the activity of the radioactive gas in the first hollow plastic scintillator 1-1 of the double beta plastic scintillator detector, the signal acquisition is as follows: CH1 is not processed, and the original spectrum of the gamma detector is obtained; CH1 and CH0 are anticoincided to obtain the anti-cosmic ray gamma spectrum; the signal after CH1 and CH2 are coincided is anticoincided with CH3, so that the beta-gamma coincidence spectrum of the first hollow plastic scintillator 1-1 is obtained by eliminating the influence of the second hollow plastic scintillator 1-2 of the double beta plastic scintillator detector; the signal after CH2 and the anti-cosmic ray gamma spectrum are coincided is anticoincided with CH3, so that the anti-cosmic ray beta-gamma coincidence spectrum of the first hollow plastic scintillator 1-1 is obtained by eliminating the influence of the cosmic ray and the second hollow plastic scintillator 1-2.

[0041] The signal acquisition logic when measuring the activity of the radioactive gas in the second hollow plastic scintillator 1-2 is the same as above.

[0042] There are six anti-cosmic ray detectors, which are installed on the top, bottom and four sides of the lead shield room, and the rest of the detectors are placed in the lead shield room, and the bottom of the lead shield room is provided with a track to facilitate sample replacement.

[0043] Figure 1 The utility model discloses a high sensitivity radioactive gas activity measurement device based on multiple coincidence / anticoincidence technology schematic diagram. Radioactive gas sample is filled into two hollow plastic scintillators 1-1 and 1-2 of the packaged SiPM readout double beta plastic scintillator detector 1, and double beta plastic scintillator detector 1 and gamma detector 2 measure beta signal and gamma signal respectively. Gamma signal is input into digital coincidence instrument 8 through preamplifier 3-1 or 3-2, main amplifier 4 and logic OR circuit 6. High voltage 5-1 and 5-2 are used to provide working high voltage for gamma detector 2-1 and 2-2 respectively. Beta signal is input into digital coincidence instrument 8. Anti-cosmic ray signal 7 is also input into digital coincidence instrument 8. Data acquisition and offline processing are carried out at computer 9 end. Liquid nitrogen recondensation refrigeration device 10 is used to provide low-temperature working environment for gamma detector. The inflation pipeline 11 provided with valve is used to fill radioactive gas. Lead shield room 12 is used to shield environmental radioactivity background.

[0044] Figure 2 It is the electronic circuit schematic diagram. The signal electronic circuit of double beta plastic scintillator detector 1 and gamma detector 2 has been described in the foregoing description. Figure 1 The 12-way anti-cosmic ray detector 13 is read out by photomultiplier tube PMT group 14-1 to 14-12, is input into OR logic circuit 6 through preamplifier group 3-3 to 3-14 and single-channel analyzer group 15-1 to 15-12 respectively, and is then input into digital coincidence instrument through delay gate 16.

[0045] The high sensitivity radioactive gas activity measurement method is as follows:

[0046] 1) radioactive gas I is filled into the first hollow plastic scintillator 1-1 of double beta plastic scintillator detector, radioactive gas II is filled into the second hollow plastic scintillator 1-2 of double beta plastic scintillator detector, beta rays emitted by the sample are detected by double beta plastic scintillator detector, gamma rays emitted by the sample are detected by HPGe gamma detector, and cosmic rays are detected by anti-cosmic ray detector.

[0047] 2) the parameters of digital coincidence circuit are adjusted, noise is removed to ensure that the signal is normal, and the cosmic ray signal, beta signal and gamma signal are consistent in time.

[0048] 3) cosmic ray signal, two-way beta signal and gamma signal are simultaneously input into digital coincidence circuit, to obtain gamma detector original spectrum, anti-cosmic ray gamma spectrum, beta-gamma coincidence spectrum eliminating mutual influence between different radioactive gases and anti-cosmic ray beta-gamma coincidence spectrum.

[0049] 4) Calculate the activity of radioactive gas A using anti-cosmic ray β-γ coincidence spectrum:

[0050] (1)

[0051] In the above formula (1),

[0052] N γC Count the γ peaks in the anti-cosmic ray β-γ coincidence spectrum of the radioactive gas sample;

[0053] P βγ For β-γ ray coincidence emission probability;

[0054] ε β and ε γ These represent the detection efficiencies for β and γ rays, respectively.

[0055] t l and t r These are the live time and real time of the energy spectrum acquisition, respectively;

[0056] λ The decay constant of the radioactive gas nuclide;

[0057] k V This is the sample count loss factor caused by accidental coincidences with the anti-cosmic ray detector.

[0058] This invention utilizes an established β-γ coincidence system to measure... 85 Kr and 133 Xe gas sample, Figures 3-4 They are respectively 85 Kr and 133 The β-γ two-dimensional coincidence spectrum of the Xe gas sample shows that, without removing the radioactive gas... 85 Kr and 133 Interactions between Xe 85 The coincidence of Kr bremsstrahlung photons and beta rays will superimpose. 133 Xe coincidence region, thereby reducing the system's dependence on 133 The detection sensitivity of Xe, and the degree of influence with 85 It is related to Kr activity.

[0059] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A highly sensitive radioactive gas activity measuring device, characterized in that: It includes a dual-β plastic scintillator detector, a gamma detector, an anti-cosmic ray detector, and a digital coincidence circuit. The dual-β plastic scintillator detector and the gamma detector are housed in a lead-shielded room. The dual-β plastic scintillator detector is placed between two gamma detectors. The mutual interference between radioactive gases in the dual-β plastic scintillator detector can be eliminated by the coincidence and anti-coincidence of four signals. The anti-cosmic ray detector is used to shield the coincidence signal generated by cosmic rays in the dual-β plastic scintillator detector and the gamma detector. The output signal of the anti-cosmic ray detector, the output signal of the dual-β plastic scintillator detector, and the output signal of the two gamma detectors are respectively input into the digital coincidence circuit to obtain the original gamma detector spectrum, the anti-cosmic ray gamma spectrum, the β-γ coincidence spectrum after eliminating the mutual influence between different radioactive gases, and the anti-cosmic ray β-γ coincidence spectrum.

2. The highly sensitive radioactive gas activity measuring device according to claim 1, characterized in that: The gamma detector is an HPGe detector.

3. The highly sensitive radioactive gas activity measuring device according to claim 2, characterized in that: Two HPGe detectors are placed opposite each other.

4. The highly sensitive radioactive gas activity measuring device according to claim 1, characterized in that: The dual-β plastic scintillator detector includes two hollow plastic scintillators and a silicon photomultiplier tube array; the two hollow plastic scintillators are stacked together with their end faces shielded from light, and an inflation line is set on the side wall of the hollow plastic scintillator; the three sides of the hollow plastic scintillator, except for the side where the inflation line is located, are coupled to the silicon photomultiplier tube array; the hollow plastic scintillator is entirely encapsulated in a housing.

5. The highly sensitive radioactive gas activity measuring device according to claim 4, characterized in that: The digital composite circuit includes four branches connected in parallel, as follows: The first circuit consists of a preamplifier, a single-channel analyzer, an "OR" logic adder circuit, and a digital signal acquisition unit connected in series. The raw signal from the anti-cosmic ray detector enters the "OR" logic adder circuit after passing through its respective preamplifier and single-channel analyzer. The output signal of the "OR" logic adder circuit enters the digital coincidence analyzer. The second circuit consists of a preamplifier, a main amplifier, an "OR" logic adder circuit, and a digital signal acquisition unit connected in series. The detection signals from the two sets of gamma detectors pass through the preamplifier and the main amplifier in sequence before entering the "OR" logic adder circuit. The output signal of the "OR" logic adder circuit enters the digital coincidence analyzer. The detection signal from the first hollow plastic scintillator of the third-channel dual-β plastic scintillator detector is directly fed into the digital coincidence analyzer. The detection signal from the second hollow plastic scintillator of the fourth-channel dual-β plastic scintillator detector is directly fed into the digital coincidence analyzer.

6. The highly sensitive radioactive gas activity measuring device according to claim 5, characterized in that: In the first channel, multiple preamplifiers and multiple single-channel analyzers are connected in parallel.

7. The highly sensitive radioactive gas activity measuring device according to claim 4, characterized in that: Except for the plane containing the photomultiplier tube array and the inflation pipeline, the other two ends of the two hollow plastic scintillators are covered with carbon fiber windows.

8. The highly sensitive radioactive gas activity measuring device according to claim 4, characterized in that: Both hollow plastic scintillators are covered with a reflective film and a light-shielding layer.

9. A highly sensitive radioactive gas activity measuring device according to any one of claims 4-8, characterized in that: A valve is installed on the inflation line.

10. A highly sensitive radioactive gas activity measuring device according to any one of claims 4-8, characterized in that: The hollow scintillator is rectangular in shape with a cylindrical cavity in the center.

Images