Muon imaging detection system and method based on scintillation fiber and SiPM readout

Abstract

The invention discloses a muon imaging detection system and method based on scintillation fiber and SiPM reading. Comprising at least one detection unit, the detection unit comprises a scintillation optical fiber array and SiPM array support plates, the scintillation optical fiber array is formed by arranging a plurality of scintillation optical fibers in parallel, the two ends of the scintillation optical fiber array are each provided with one SiPM array support plate, SiPM arrays are integrated on the SiPM array support plates, the number of the SiPM units is the same as that of the scintillation optical fibers, and the SiPM units and the scintillation optical fibers are in one-to-one correspondence; the SiPM unit is optically coupled with one end of a corresponding scintillation optical fiber signal, receives a scintillation optical signal transmitted in the corresponding scintillation optical fiber and generates an electric signal; the signal processing unit is used for preprocessing the electric signal output by the SiPM to obtain a processed signal; and the positioning reconstruction unit is used for reconstructing the space motion trail of the muon according to the processed signal. The system can realize three-dimensional high-precision positioning and track reconstruction of muons, and has the advantages of high integration level, modular design and the like.

Description

Technical Field

[0001] This invention belongs to the field of cosmic ray muon detection and underground geological imaging technology, and relates to a three-dimensional detection system and signal processing method combining scintillation fiber and SiPM. Background Technology

[0002] Cosmic ray muon imaging technology is an advanced method for non-destructive detection of large targets or underground media using the penetrating power of high-energy muons. In recent years, it has received widespread attention in fields such as mineral resource exploration, spatial distribution identification of ore bodies, underground cavity detection, tunnel safety assessment, and volcanic structure imaging. Existing muon detection systems mostly use gas detectors as the core sensing unit, such as GEMs (Gas Electron Multipliers), MWPCs, and drift chambers. These detectors generate and amplify signals from ionized gas to measure muon trajectories. However, gas detectors generally suffer from complex structures, require continuous gas supply, operate at high pressures, and have stringent requirements for sealing and environmental stability. Especially when used in underground mines or harsh environments, system maintenance is difficult, and long-term operational reliability is insufficient, severely hindering their engineering application and promotion.

[0003] To address the aforementioned issues, some patents and research have attempted to combine scintillators with photomultipliers for muon detection. For example, plastic scintillators can be used in conjunction with vacuum photomultiplier tubes (PMTs) or silicon photomultiplier tubes (SiPMs) for muon detection. However, these solutions typically have limited spatial resolution and large detection unit volumes, making them unsuitable for constructing high-precision, modular three-dimensional imaging systems. Meanwhile, solutions employing strip scintillators or fiber optic structures are primarily used in particle physics experiments or medical imaging. In underground muon imaging applications, these solutions still suffer from complex signal readout channels, insufficient timing accuracy, and significant temperature drift effects.

[0004] Therefore, there is an urgent need for a new muon detection technology that is simple in structure, requires no gas system, is highly stable, and is suitable for complex underground environments, in order to improve the reliability, maintainability, and spatial imaging accuracy of muon imaging systems, and provide more efficient and practical technical means for mineral exploration and underground structure detection. Summary of the Invention

[0005] To address the problems of existing gas detector-based muon imaging systems, such as complex structure, requirement for ventilation and high pressure, poor adaptability to underground environments, and high stability and maintenance costs, this invention provides a muon imaging detection system and method based on scintillation fiber and SiPM readout. This invention achieves high-precision three-dimensional muon tracking detection system and its data processing method based on a scintillation fiber array and SiPM array, enabling high-precision three-dimensional imaging of muons without the need for a gas medium, with a compact structure and stable reliability, suitable for underground mineral exploration and geological structure reconstruction.

[0006] The technical solution adopted in this invention includes the following: I. A Muon Imaging and Detection System Based on Scintillation Fiber and SiPM Readout The muon imaging detection system includes: At least one detection unit, the detection unit comprising a scintillation fiber array and a SiPM array carrier, the scintillation fiber array being composed of multiple scintillation fibers arranged in parallel, and a SiPM array carrier being disposed at each end of the scintillation fiber array, each SiPM array carrier integrating a SiPM array, wherein the number of SiPM units in the SiPM array is the same as the number of scintillation fibers and they correspond one-to-one, and the SiPM unit is optically coupled to one end of the corresponding scintillation fiber signal, receiving the scintillation light signal transmitted in the corresponding scintillation fiber and generating an electrical signal. The signal processing unit is used to preprocess the electrical signal output by the SiPM to obtain the processed signal. The positioning and reconstruction unit is used to reconstruct the spatial motion trajectory of the muon based on the processed signal.

[0007] In the scintillation fiber array of the detection unit, the scintillation fibers are arranged in concentric multiple layers.

[0008] The scintillation fibers are arranged in a concentric ring array, with the radius of adjacent rings increasing by a fixed multiple.

[0009] The signal processing unit includes a front-end signal processing module; each SiPM unit is connected to an independent input terminal of the front-end signal processing module; the front-end signal processing module is used to amplify, shape and / or time-discriminate the electrical signal output by the SiPM unit, and simultaneously measure time information and charge information.

[0010] The front-end signal processing module includes a front-end signal processing chip; the positioning and reconstruction unit includes an FPGA control module; the processed signal output by the front-end signal processing chip is transmitted to the FPGA control module via a high-speed differential interface for data caching, trigger selection and timestamp marking.

[0011] For each hit, with the axis of the scintillation fiber as the longitudinal direction and the radial direction as the transverse direction, the positioning and reconstruction unit determines the hit position of the muon in the transverse direction by detecting the number of the triggered scintillation fiber; at the same time, it uses the time difference and light intensity difference of the SiPM output signals at both ends of the scintillation fiber to invert and calculate the hit coordinates of the muon in the longitudinal direction, thus obtaining the three-dimensional hit coordinates corresponding to the triggered scintillation fiber.

[0012] For each crossing event, the positioning and reconstruction unit fits the three-dimensional hit coordinates of all triggered scintillation fibers and then reconstructs the spatial motion trajectory of the muon.

[0013] In the positioning and reconstruction unit, based on the spatial motion trajectory of the muon in at least one crossing event, the density distribution of the underground medium and / or the geological structure are reconstructed using the muon imaging inversion algorithm to obtain the reconstruction result.

[0014] II. A muon imaging detection method using the above-mentioned muon imaging detection system The muon imaging detection method includes the following steps: The signal processing unit reads and processes the electrical signals output by the SiPM units at both ends of each scintillation fiber in real time to generate a processed signal containing timestamps. Using the coupled time window method, based on the time-domain processed signal corresponding to each SiPM unit, we can identify individual hits and triggered scintillation fibers, and then mark each hit that is related in time as the same crossing event. For each hit, the corresponding three-dimensional hit coordinates are obtained based on the number of the triggered scintillation fiber, the time difference and light intensity difference of the SiPM output signals at both ends; For each crossing event, the positioning and reconstruction unit fits the three-dimensional hit coordinates of all triggered scintillation fibers and then reconstructs the spatial motion trajectory of the muon.

[0015] Furthermore, the muon imaging detection method also includes the following steps: based on the spatial motion trajectory of the muon in at least one crossing event, the density distribution of the underground medium and / or the geological structure are reconstructed using a muon imaging inversion algorithm to obtain the reconstruction result.

[0016] The beneficial effects of this invention are: 1) No gas system or high-pressure device is required, which significantly reduces system complexity and improves reliability and safety in underground environments; 2) High-precision three-dimensional positioning and track reconstruction of muons are achieved by using scintillation fiber and dual-ended SiPM measurement method; 3) The system has a high degree of integration, and its modular design facilitates expansion and on-site deployment; 4) Introduce a temperature compensation mechanism to improve the working stability and long-term measurement consistency of SiPM; 5) It is suitable for continuous mineral exploration and underground structure imaging in complex geological environments, and has good engineering application value and promotion prospects. Attached Figure Description

[0017] Figure 1 This is a three-dimensional schematic diagram of the detector structure of the present invention; Figure 2 This is a schematic diagram of the SiPM carrier plate structure; Figure 3 This is a block diagram of the system of the present invention. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

[0019] This invention provides a muon imaging detection system based on scintillation fiber and SiPM readout.

[0020] The muon imaging detection system provided by this invention includes: At least one detection unit, the detection unit includes a scintillation fiber array and a SiPM array carrier plate. The scintillation fiber array is composed of multiple scintillation fibers arranged in parallel (side by side). A SiPM array carrier plate is set at each end of the scintillation fiber array. Each SiPM array carrier plate integrates a SiPM array. In the SiPM array, the number of SiPM units is the same as that of the scintillation fibers and they correspond one-to-one. The SiPM unit is optically coupled to one end of the corresponding scintillation fiber signal, receives the scintillation light signal transmitted in the corresponding scintillation fiber and generates an electrical signal. The signal processing unit is used to preprocess the electrical signal output by the SiPM to obtain the processed signal. The positioning and reconstruction unit is used to reconstruct the spatial motion trajectory of the muon based on the processed signal.

[0021] The optical coupling between the SiPM unit and the corresponding scintillation fiber signal means that the end of the scintillation fiber is fixedly connected to the SiPM array carrier at the same end, and the end face is optically coupled to the corresponding SiPM unit integrated on the SiPM array carrier.

[0022] Each detection unit is located in an underground environment, and the specific location can be determined according to the detection needs.

[0023] Preferably, in the scintillation fiber array of the detection unit, the scintillation fibers are arranged in concentric multiple layers.

[0024] More preferably, the scintillation fibers are arranged in a concentric ring array, with the radius of adjacent rings increasing by a fixed multiple.

[0025] Furthermore, the detection unit also includes a temperature sensor and a back-end control module; the temperature sensor is arranged on the SiPM array carrier to monitor the operating temperature in real time and feed the temperature signal back to the back-end control module to realize dynamic compensation of the SiPM bias voltage.

[0026] Each SiPM array carrier has at least one temperature sensor. In practice, the number, density, and placement of the temperature sensors can be adjusted according to the detection accuracy.

[0027] Alternatively, the SiPM array carrier can be a PCB board or similar structure.

[0028] Furthermore, the signal processing unit includes a front-end signal processing module; each SiPM unit is connected to an independent input signal corresponding to its own front-end signal processing module; the front-end signal processing module is used to amplify, shape and / or time-discriminate the electrical signal output by the SiPM unit, and synchronously measure time information and charge information.

[0029] In practice, the front-end signal processing module can be integrated onto the SiPM array carrier. If the underground environment is harsh, it can also be installed on the ground.

[0030] Preferably, the front-end signal processing module includes a front-end signal processing chip; the positioning and reconstruction unit includes an FPGA control module; the processed signal output by the front-end signal processing chip is transmitted to the FPGA control module via a high-speed differential interface for data buffering, trigger selection and timestamp marking.

[0031] Among them, trigger selection refers to identifying each hit and triggered flashing fiber during the crossing event and process.

[0032] Specifically, for each hit, with the axis of the scintillation fiber as the longitudinal direction and the radial direction as the transverse direction, the positioning and reconstruction unit determines the hit position of the muon in the transverse direction by detecting the number of the triggered scintillation fiber; at the same time, it uses the time difference and light intensity difference of the SiPM output signals at both ends of the scintillation fiber to invert and calculate the hit coordinates of the muon in the longitudinal direction, thereby realizing the three-dimensional spatial positioning of a single hit and obtaining the three-dimensional hit coordinates of this hit corresponding to the triggered scintillation fiber.

[0033] Specifically, for each crossing event, the localization and reconstruction unit fits the three-dimensional impact coordinates of each hit corresponding to all triggered scintillation fibers to reconstruct the spatial motion trajectory of the muon.

[0034] Preferably, the fitting process is a linear fitting.

[0035] In the localization and reconstruction unit, based on the spatial motion trajectory of the muon in at least one crossing event, the density distribution of the underground medium and / or the geological structure are reconstructed using the muon imaging inversion algorithm to obtain the reconstruction results.

[0036] The present invention also provides a muon imaging detection method using the above-described muon imaging detection system.

[0037] The muon imaging detection method used in this invention includes the following steps: The signal processing unit reads and processes the electrical signals output by the SiPM units at both ends of each scintillation fiber in real time to generate a processed signal containing timestamps. Using the coupled time window method, based on the time-domain processed signal corresponding to each SiPM unit, we can identify individual hits and triggered scintillation fibers, and then mark each hit that is related in time as the same crossing event. For each hit, the corresponding three-dimensional hit coordinates are obtained based on the number of the triggered scintillation fiber, the time difference and light intensity difference of the SiPM output signals at both ends; For each crossing event, the localization and reconstruction unit fits the three-dimensional hit coordinates of all triggered scintillation fibers and then reconstructs the spatial motion trajectory of the muon.

[0038] Temporal correlation refers to being within the same global time window. The global time window can be determined based on parameters such as the mound velocity and the detector size.

[0039] Based on the spatial trajectory of the muon during at least one crossing event, the density distribution and / or geological structure of the subsurface medium are reconstructed using a muon imaging inversion algorithm to obtain the reconstruction results.

[0040] Furthermore, in an imaging system comprising multiple detection units, conventional data fusion methods can be used to integrate the data from each detection unit at different stages of the data processing flow.

[0041] Specific embodiments of the present invention are as follows: Example like Figure 1 As shown, the specific implementation process of the cosmic ray muon three-dimensional track detection system based on scintillation fiber and SiPM array in this embodiment is as follows: Step 1: Construction and Installation of the Detection Unit A detection layer consisting of multiple parallel scintillation fibers was constructed. Commercially available Kuraray SCSF-78 fibers were selected, each with a diameter of 1 mm and a length of 200 mm, totaling 128 fibers with a spacing of 1.2 mm to form an effective detection area. Each fiber was fixed at both ends to a mechanical support and end-face coupled to a SiPM array using optical coupling adhesive to ensure efficient optical signal transmission.

[0042] Step 2: SiPM Array and Carrier Configuration like Figure 2 As shown, SiPM array carriers are installed at both ends of the scintillation fiber. Each carrier integrates 128 SiPM detector units (Hamamatsu S13360-1325PE), corresponding to one pair of SiPMs for each scintillation fiber, enabling dual-end readout. Temperature sensors are also integrated on the carriers for real-time acquisition of operating temperature data.

[0043] Step 3: Electronic System Connection and Signal Acquisition The SiPM output signal is input to the front-end signal processing chip MPT2321 through four 40-pin connectors, where it is amplified, shaped, and timed, and time and charge information is measured simultaneously. The processed signal is then transmitted to the FPGA control module via a high-speed differential interface for data buffering, trigger selection, and timestamp marking.

[0044] Step 4: Temperature Compensation and Bias Control The FPGA adjusts the SiPM bias voltage in real time based on the temperature information collected by the temperature sensor to keep its operating gain stable, thereby reducing the impact of temperature fluctuations on time resolution and signal amplitude.

[0045] Step 5: 3D localization and trajectory reconstruction When a cosmic ray muon passes through the detection unit and excites a scintillation fiber to generate an optical signal, the lateral impact position of the muon is determined by detecting the number of the triggered fiber. At the same time, the time difference and intensity difference of the output signals of the SiPM at both ends of the fiber are used to calculate the impact coordinates of the muon along the fiber axis, thereby achieving three-dimensional spatial positioning of a single impact.

[0046] Based on the spatial positioning results of multiple hits during the same time travel, the spatial trajectory of the muon is reconstructed using a straight-line fitting algorithm, such as... Figure 3 As shown.

[0047] Step Six: Imaging and Data Processing The reconstructed muon trajectories are input into the imaging inversion algorithm. Combined with the muon scattering angle distribution and penetration, the density distribution of the target area is inverted to obtain the underground structure profile map, which is used for mineral exploration and geological structure analysis.

[0048] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A muon imaging detection system based on scintillation fiber and SiPM readout, characterized in that, include: At least one detection unit, the detection unit comprising a scintillation fiber array and a SiPM array carrier, the scintillation fiber array being composed of multiple scintillation fibers arranged in parallel, and a SiPM array carrier being disposed at each end of the scintillation fiber array, each SiPM array carrier integrating a SiPM array, wherein the number of SiPM units in the SiPM array is the same as the number of scintillation fibers and they correspond one-to-one, and the SiPM unit is optically coupled to one end of the corresponding scintillation fiber signal, receiving the scintillation light signal transmitted in the corresponding scintillation fiber and generating an electrical signal. The signal processing unit is used to preprocess the electrical signal output by the SiPM to obtain the processed signal. The positioning and reconstruction unit is used to reconstruct the spatial motion trajectory of the muon based on the processed signal.

2. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 1, characterized in that: In the scintillation fiber array of the detection unit, the scintillation fibers are arranged in concentric multiple layers.

3. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 2, characterized in that: The scintillation fibers are arranged in a concentric ring array, with the radius of adjacent rings increasing by a fixed multiple.

4. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 1, characterized in that: The signal processing unit includes a front-end signal processing module; each SiPM unit is connected to an independent input terminal of the front-end signal processing module; the front-end signal processing module is used to amplify, shape and / or time-discriminate the electrical signal output by the SiPM unit, and simultaneously measure time information and charge information.

5. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 4, characterized in that: The front-end signal processing module includes a front-end signal processing chip; the positioning and reconstruction unit includes an FPGA control module; the processed signal output by the front-end signal processing chip is transmitted to the FPGA control module via a high-speed differential interface for data caching, trigger selection and timestamp marking.

6. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 1, characterized in that: For each hit, with the axis of the scintillation fiber as the longitudinal direction and the radial direction as the transverse direction, the positioning and reconstruction unit determines the hit position of the muon in the transverse direction by detecting the number of the triggered scintillation fiber; at the same time, it uses the time difference and light intensity difference of the SiPM output signals at both ends of the scintillation fiber to invert and calculate the hit coordinates of the muon in the longitudinal direction, thus obtaining the three-dimensional hit coordinates corresponding to the triggered scintillation fiber.

7. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 6, characterized in that: For each crossing event, the positioning and reconstruction unit performs fitting processing on the three-dimensional hit coordinates corresponding to all triggered scintillation fibers to reconstruct the spatial motion trajectory of the muon.

8. The muon imaging detection system based on scintillation fiber and SiPM readout according to claim 1 or 7, characterized in that: In the positioning and reconstruction unit, based on the spatial motion trajectory of the muon in at least one crossing event, the density distribution of the underground medium and / or the geological structure are reconstructed using the muon imaging inversion algorithm to obtain the reconstruction result.

9. A muon imaging detection method employing the muon imaging detection system as described in any one of claims 1 to 8, characterized in that, Includes the following steps: The signal processing unit reads and processes the electrical signals output by the SiPM units at both ends of each scintillation fiber to generate the processed signal. Using the coupled time window method, based on the time-domain processed signal corresponding to each SiPM unit, we can identify individual hits and triggered scintillation fibers, and then mark each hit that is related in time as the same crossing event. For each hit, the corresponding three-dimensional hit coordinates are obtained based on the number of the triggered scintillation fiber, the time difference and light intensity difference of the SiPM output signals at both ends; For each crossing event, the positioning and reconstruction unit performs fitting processing on the three-dimensional hit coordinates corresponding to all triggered scintillation fibers to reconstruct the spatial motion trajectory of the muon.

10. The muon imaging detection method according to claim 9, characterized in that, It also includes the following steps: Based on the spatial trajectory of the muon during at least one crossing event, the density distribution and / or geological structure of the subsurface medium are reconstructed using a muon imaging inversion algorithm to obtain the reconstruction results.

Images