Electric charge particle trajectory detection device, and electric charge particle trajectory detection method
The charged particle trajectory detection device uses a system of detectors and circuits to filter noise, ensuring stable muon trajectory detection in high-radiation environments by identifying simultaneous coincident signals, thereby improving detection accuracy.
Patent Information
- Application Number
- JP2023112407
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-07-07
- Publication Date
- 2025-01-20
AI Technical Summary
In high-radiation environments, the detection of muon trajectories becomes unstable due to increased gamma ray interactions, leading to excessive data and noise that interfere with the detection process.
A charged particle trajectory detection device employing a planar arrangement of detectors with a reading circuit, coincidence circuit, verification circuit, and selection circuit to filter out noise signals, allowing stable detection of muon trajectories by identifying simultaneous coincident signals from adjacent detectors.
The device effectively filters out noise signals from gamma rays and neutrons, enabling stable detection and analysis of muon trajectories even in high-radiation environments.
Smart Images
Figure 2025009412000001_ABST
Abstract
Description
[Technical field]
[0001] An embodiment of the present invention relates to a charged particle trajectory detection technique capable of observing cosmic ray muons reaching the earth's surface. [Background technology]
[0002] As a method for understanding the inside of a structure, a technique for observing the cosmic ray muons that reach the ground surface and seeing through the inside of the structure is known. Specifically, the transmission method measures the attenuation of the muon particle flux, and the scattering method observes the flight trajectory of the muons in front of and behind the structure to be measured and images the Coulomb multiple scattering angle.
[0003] It has been proposed to apply this muon observation technology for observing inside structures even in high radiation environments (e.g., Non-Patent Document 1).In addition, observation of radioactive structures has also been proposed (e.g., Non-Patent Document 2). [Prior art documents] [Non-patent literature]
[0004] [Non-Patent Document 1] H. Miyadera,etal.,AIP Advances 3,052133(2013). [Non-Patent Document 2] H. Miyadera,etal.,Applied Optics 61,C154(2022). Summary of the Invention [Problem to be solved by the invention]
[0005] In muon imaging, a charged particle tracking detector is installed on the outside of the structure to be observed. The flight trajectory of the detected muons is then detected and analyzed to image the object. As a charged particle tracking detector for detecting the trajectory of such muons, a device with a stack of drift tube detectors using ionized gas or a stack of multi-channel scintillation detectors is used.
[0006] However, when the amount of gamma rays in an environment is high, the number of occurrences of Compton scattering of gamma rays also increases, and detections due to gamma rays, apart from muons, increase in the charged particle trajectory detector. Therefore, in a high radiation environment, detections due to gamma rays increase the amount of data to be analyzed, which causes a problem of making the detection of muon trajectories in the charged particle trajectory detector unstable.
[0007] The embodiments of the present invention have been made in consideration of the above circumstances, and an object of the present invention is to provide a charged particle trajectory detection technology that can stably detect the trajectory of muons in a high radiation environment. [Means for solving the problem]
[0008] In the charged particle trajectory detection device of the embodiment, the device includes a reading circuit that reads detection signals output when a charged particle is incident on a detection layer consisting of a plurality of detectors arranged in a planar shape, a coincidence circuit that outputs a coincidence signal when adjacent detectors along the direction of travel of the charged particle simultaneously output electrical signals, a testing circuit that outputs a trigger signal when at least two or more of the coincidence signals are output from different detection layers within a certain period of time, and a selection circuit that stores data of event information of the detection signals selected by the trigger signal. Effect of the Invention
[0009] According to an embodiment of the present invention, a charged particle trajectory detection technique is provided that stably detects the trajectory of a muon in a high radiation environment. [Brief description of the drawings]
[0010] [Figure 1] FIG. 1 is a configuration diagram of a charged particle trajectory detection device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view of a stack of detection layers of a drift tube type detector. [Diagram 3] (A) is a diagram showing a detector that outputs a detection signal when a charged particle is incident on the detection layer, and (B) is a diagram showing a detector that outputs a detection signal when a gamma ray is incident on the detection layer. [Figure 4] FIG. 1 is an explanatory diagram of the operation of a drift tube type detector. [Diagram 5] 4 is a flowchart illustrating a charged particle trajectory detection method according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a configuration diagram of a charged particle trajectory detection device 10 according to the embodiment. Fig. 2 is a perspective view of a laminate 20 formed by a detection layer 22 of a drift tube type detector 21. Fig. 3(A) is a diagram showing a detector 21a that outputs a detection signal 12 when a charged particle 11 is incident on the detection layer 22. Fig. 3(B) is a diagram showing a detector 21b that outputs a detection signal 12 when a gamma ray is incident on the detection layer 22.
[0012] As shown in FIG. 1, the charged particle trajectory detector 10 includes a detection layer 22 (22 x1 ,twenty two y1 ,twenty two x2 ,twenty two y2 A read circuit 15 reads and digitizes the detection signal 12 output when a charged particle 11 (FIG. 3(A)) is incident on the detector 21 (...), a coincidence circuit 23 outputs a coincidence signal when adjacent detectors 21 along the traveling direction of the charged particle 11 simultaneously output electric signals, a test circuit 16 outputs a trigger signal 14 when at least two coincidence signals are output from separate detection layers 22 within a certain period of time, and a detection signal 12 (12 x,12 y and a selection circuit 17 for storing the event information 26 of the event information 26 as data.
[0013] The reading circuit 15 , the testing circuit 16 , the selection circuit 17 and the transmission circuit 18 are provided on a common substrate 19 .
[0014] As shown in FIG. x1 ,twenty two y1 ,twenty two x2 ,twenty two y2 Each of the detectors 21 (21 ...) is aligned in a direction perpendicular to each other. x ,twenty one y ) are arranged in a planar fashion and are stacked alternately. Each detector 21 outputs one pulse signal when one charged particle 11 is incident on it, regardless of the incident position in the longitudinal direction. When pulse signals are simultaneously output from two detectors 21 adjacent to each other in the traveling direction of the charged particle 11, a coincidence circuit 23 determines that the signal is likely to be a charged particle 11 and not noise such as gamma rays.
[0015] 3(A), when the incident particles on the detection layer 22 are charged particles 11 such as positive muons, negative muons, electrons, or positrons, the detection layer 22 exhibits high penetration. On the other hand, when the incident particles on the detection layer 22 are electromagnetic waves such as X-rays and gamma rays, or neutrons, the energy of the charged particles 11 generated by Compton scattering or the like is low and cannot penetrate multiple detectors, as shown in FIG.
[0016] Therefore, whether the incident on the detection layer 22 is a charged particle 11 or an event caused by electromagnetic waves or neutrons can be identified by evaluating the penetration of each incident. However, since adjacent detector pairs along the traveling direction of the charged particle 11 may simultaneously output signals due to different gamma rays, the detection accuracy of the charged particle 11 can be improved by detecting the simultaneous occurrence of multiple coincidence signals.
[0017] In addition, the detectors 21 have a short insensitive period immediately after responding to the charged particle 11, electromagnetic wave, or neutron. Therefore, even if the charged particle 11 penetrates, some of the detectors 21 along the trajectory may not output the detection signal 12.
[0018] Although a drift tube type detector is shown as an example of the detector 21, any of a multi-wire type, a GEM type, and a scintillation type may also be used. For the scintillation type, a plastic scintillator or a fiber scintillator may be used.
[0019] In the drift tube, multi-wire and GEM detectors 21, the filler gas is preferably a gas mainly composed of a rare gas such as argon, since the commonly used hydrocarbon gases decompose in a high radiation environment.
[0020] Returning to FIG. 1, the description will be continued. The reading circuit 15 reads all of the detectors 21 (21 x ,twenty one y ) is output at any time from the detection signal 12 (12 x ,12 y ) is input, and a combination of the identification ID of the detector 21 that emitted it and the time of output is output.
[0021] Coincidence circuit 23 (23 x1 ,twenty three y1 ,twenty three x2 ,twenty three y2 ...) are stacked detection layers 22 (22 x1 ,twenty two y1 ,twenty two x2 ,twenty two y2 1, the detection layer 22 is divided into a plurality of segments 25 (25 a ,twenty five b ) as a unit, the coincidence circuit 23 (23 x1a ,twenty three x1b ,twenty three y1a ,twenty three y1b ,twenty threex2a ,twenty three x2b ,twenty three y2a ,twenty three y2b ...) is provided.
[0022] When a pair of connected detectors 21, as shown in Figure 3 (A), simultaneously output detection signals 12, this coincidence circuit 23 outputs a coincidence signal indicating a test result that there is incidence on the detection layer 22.
[0023] The test circuit 16 detects all the coincidence circuits 23 (23 x1a ,twenty three x1b ,twenty three y1a ,twenty three y1b ,twenty three x2a ,twenty three x2b ,twenty three y2a ,twenty three y2b When a certain number or more (for example, four) of coincidence signals are simultaneously input from the plurality of inputs, a trigger signal 14 is output.
[0024] The time interval during which the coincidence occurs in the coincidence circuit 23 and the detection circuit 16 is the sum of the passing time of the charged particle and the time from when the charged particle passes until when the detector outputs a detection signal.
[0025] In this manner, the assay circuit 16 detects each of the detection layers 22 (22 x1 ,twenty two y1 ,twenty two x2 ,twenty two y2 …) or segment 25 (25 a ,twenty five b ) is divided into detection layer 22 (22 x1a ,twenty two x1b ,twenty two y1a ,twenty two y1b ,twenty two x2a ,twenty two x2b ,twenty two y2a ,twenty two y2b ...) is examined to see whether it is due to noise such as gamma rays or charged particles 11.
[0026] Only when the trigger signal 14 output by the test circuit 16 is input, the selection circuit 17 outputs a series of combinations of detector identification IDs and output times output by the reading circuit 15 to the transmission circuit 18. If the trigger signal 14 is not input, the information on the detector identification IDs and output times is discarded.
[0027] The transmission circuit 18 transmits event information 26 including a series of combinations of detector identification IDs and output times to the data storage unit 27. As a result, a series of combinations of detector IDs and output times are stored in the data storage unit 27 as event information 26 of the charged particle 11. Most noise events caused by electromagnetic waves such as gamma rays and neutrons are eliminated.
[0028] Then, the trajectory analysis unit 28 analyzes the trajectory of the charged particle 11 from the event information 26 of the charged particle 11 including a series of combinations of detector IDs and output times in the data storage unit 27 .
[0029] 4 is an explanatory diagram of the operation of drift tube type detector 21. Drift tube detector 21 has a core wire 29 to which a positive high voltage is applied stretched at the center position inside a metallic cylindrical tube as a cylinder. A gas mainly composed of a rare gas such as argon is sealed inside the cylindrical tube of detector 21.
[0030] When a charged particle 11 such as a cosmic ray muon passes through the drift tube detector 21, the gas is ionized and separated into ions and electrons. When the separated electrons move and reach the core wire 29, the drift tube detector 21 outputs a detection signal 12.
[0031] 4, the passing position of the charged particle 11 in the detector 21 can be detected based on the drift time it takes for an electron generated in the drift tube detector 21 to travel to the core wire 29. In other words, the travel time (drift time) from when the electron is generated until it travels to the core wire 29 is determined from the time when the charged particle 11 passes and an electron is generated, and the time when the electron reaches the core wire 29 (the time when the detection signal is generated). By calculating the travel distance (drift radius r) of the electron to the core wire 29 based on this drift time, the detection resolution of the passing position of the charged particle 11 in the drift tube detector 21 can be improved.
[0032] A charged particle trajectory detection method according to an embodiment will be described with reference to the flowchart of FIG. 5 (see FIG. 1 as appropriate). First, the detection layer 22 (22 x1 ,twenty two y1 ,twenty two x2 ,twenty two y2 When a charged particle 11 (FIG. 3A) is incident on the detector 21 (...) (S11), a detection signal 12 is output from the detector 21 (S12).
[0033] Next, the pair of detectors 21 is identified from the combination of the pair of detection signals 12 output simultaneously (S13). Then, a coincidence signal is transmitted as the occurrence of an event likely to be a muon passing (S14).
[0034] Next, if a certain number of coincidence signals or more are transmitted at the same time (S15, Yes), a trigger signal 14 is output as a muon event, and a detection signal 12 (12 x ,12 y A combination of the identification IDs of the series of detectors that emitted the signal and information on the output time is transmitted to the data storage unit 27 (S16), and the data is stored as event information 26 (S17).
[0035] On the other hand, the detection signal 12 (12) that was not identified at the same time as the emission of the trigger signal 14 x ,12 y) (S15, No) is regarded as detection of noise components such as gamma rays and is discarded. Then, the flow from (S11) to (S17) is repeated until the measurement is completed (S18, No, Yes, END).
[0036] The charged particle trajectory detection technology described in the embodiment can be used to measure any of a nuclear reactor, a dry cask, fuel debris, a container, a vehicle, a train, and a ship using charged particles such as cosmic ray muons that reach the earth's surface. In particular, the technology is suitable for detecting the trajectories of charged particles in high radiation environments such as gamma rays or neutrons, such as when targeting a nuclear reactor, a nuclear reactor structure, nuclear fuel, spent fuel, fuel debris, radioactive waste, special nuclear material, and the like.
[0037] According to at least one of the embodiments of the charged particle trajectory detection device 10 described above, by selecting a combination of a series of detection signals 12 identified simultaneously with a trigger signal 14 indicating a test result of incidence between detection layers 22 of different hierarchical levels, it is possible to stably detect the trajectory of a charged particle 11 even in a high radiation environment.
[0038] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]
[0039] 10...Charged particle trajectory detection device, 11...Charged particle, 12(12 x ,12 y 1) detection signal, 14 trigger signal, 15 reading circuit, 16 testing circuit, 17 selection circuit, 18 transmission circuit, 19 substrate, 20 laminate, 21 (21 x ,twenty one y , 21a, 21b) ... detector, 22 (22 x1,twenty two y1 ,twenty two x2 ,twenty two y2 …)…detection layer, 23(23 x1a ,twenty three x1b ,twenty three y1a ,twenty three y1b ,twenty three x2a ,twenty three x2b ,twenty three y2a ,twenty three y2b ...)...coincidence circuit, 25...segment, 26...event information, 27...data storage unit, 28...trajectory analysis unit, 29...core wire.
Claims
1. a read circuit for reading a detection signal outputted when a charged particle is incident on a detection layer formed by a planar array of a plurality of detectors; a coincidence circuit that outputs a coincidence signal when the detectors adjacent to each other in the traveling direction of the charged particle simultaneously output electric signals; a test circuit that outputs a trigger signal when at least two or more of the coincidence signals are output from different detection layers within a certain period of time; A selection circuit for storing data of event information of the detection signal selected by the trigger signal.
2. 2. The charged particle trajectory detection device according to claim 1, The detector is a charged particle trajectory detection device that is any one of a drift tube type, a multi-wire type, a GEM type, and a scintillation type.
3. 3. The charged particle trajectory detector according to claim 2, The gas sealed in the drift tube type, multi-wire type and GEM type detectors is a charged particle trajectory detection device that contains a rare gas as a main component and does not contain hydrocarbons.
4. 3. The charged particle trajectory detection device according to claim 1, The event information includes an identification ID of the detector that outputs the selected detection signal and an output time, The charged particle trajectory detection device includes a transmission circuit for transmitting the identification IDs of the detectors and the output times to a data storage unit.
5. 5. The charged particle trajectory detector according to claim 4, A charged particle trajectory detection device, wherein the reading circuit, the testing circuit, the selection circuit and the transmission circuit are provided on a common substrate.
6. a step of reading a detection signal outputted when a charged particle is incident on a detection layer formed by a planar array of a plurality of detectors; outputting a coincidence signal when the detectors adjacent to each other in a traveling direction of the charged particle simultaneously output electric signals; outputting a trigger signal when at least two or more of the coincidence signals are output from different detection layers within a certain period of time; and storing event information of the detection signal selected by the trigger signal as data.