Imaging system and method based on high-power laser muon source

Abstract

The invention belongs to the field of particle physics and imaging, and relates to an imaging system and method based on a high-power laser muon source, and the system comprises a laser and tail field acceleration system, a muon generation system, and a particle detection and imaging system. The laser and tail field acceleration system is used for generating high-energy electron beams; a conversion target is placed in the muon generation system; the conversion target generates muons under the action of the high-energy electron beam; the particle detection and imaging system is used for detecting and collecting muons and carrying out position measurement and energy analysis; the particle detection and imaging system comprises a shielding attenuation layer, a detector array and an imaging processing system; the detector array adopts a stack type structure, comprises a plurality of detector layers and spacing layers, and is used for measuring the number and positions of muons at different depths; the imaging system and method have the advantages of compact equipment, low cost, high imaging speed and the like, and are suitable for the fields of super-thick material detection, industrial nondestructive detection and the like.

Description

Technical Field

[0001] This invention relates to the field of imaging, and specifically discloses an imaging system and method based on a high-power laser muon source. Background Technology

[0002] With the rapid development of infrastructure and the advancement of engineering technology in my country, the demand for non-destructive testing and imaging of large structures such as bridges, tunnels, and roads for long-term operational safety is increasing. For objects with low surface density and thinness, X-ray imaging can be used for scanning and analysis. However, for objects with high surface density and overall thickness, X-rays cannot penetrate and are therefore difficult to apply. Muons are charged elementary particles with stronger penetrating power than protons, electrons, gamma photons, and other particles, making them suitable for imaging high surface density objects. Traditional muon imaging techniques mainly rely on cosmic ray muon sources or muon beams generated by accelerators. However, the flux of cosmic ray muons is too low, approximately [missing information - likely a number] near sea level. The limitations imposed by accelerators on imaging efficiency are significant. Accelerator-generated muon beams typically require complex accelerator facilities for production and control, resulting in extremely high equipment costs, operational difficulties, substantial maintenance expenses, and immobility. The development of laser technology has provided a new avenue for generating high-energy electrons. The interaction of high-energy electrons with matter can generate muons, offering new possibilities for muon imaging technology. Compared to traditional muon sources, laser-generated muon sources offer advantages such as high flux and good directionality, enabling non-destructive detection of ultra-thick targets in a short time.

[0003] In view of this, the present invention proposes an imaging system and method based on a high-power laser muon source, which uses a high-power laser to generate muons and uses a detector array to detect the muons, thereby achieving imaging of the target object. Summary of the Invention

[0004] The purpose of this invention is to provide an imaging system based on a high-power laser muon source, specifically comprising a laser and wakefield acceleration system, a muon generation system, and a particle detection and imaging system. The laser and wakefield acceleration system generates a high-energy electron beam. A conversion target is placed inside the muon generation system. The conversion target generates muons under the influence of the high-energy electron beam. The particle detection and imaging system detects, collects, measures, and analyzes the muons. The particle detection and imaging system includes a shielding attenuation layer, a detector array, and an imaging processing system. The detector array adopts a stacked structure, including multiple detector layers and spacer layers, for measuring the number and position of muons at different depths.

[0005] Furthermore, the laser and wake field acceleration system includes a laser, a focusing device, and a gas target; the laser is used to output laser pulses; the focusing device is used to focus the laser pulses; the gas target is ionized into plasma by the passing laser, and free electrons are accelerated under the action of the laser wake field to generate a high-energy electron beam.

[0006] Furthermore, the conversion target is made of metal, semiconductor or insulator.

[0007] Furthermore, the detector array employs a scintillation detector and / or a position-resolved gas detector; the shielding attenuation layer is used to block secondary particle signals and reduce muon energy. The imaging system is used to acquire and store the signals output by the detector array, and to process and analyze the collected data to reconstruct a structural image of the target object.

[0008] Furthermore, the detector layer adopts a planar detector array; the spacer layer is made of metal material; the detector array is formed by stacking multiple detector layers and spacer layers in an interleaved manner.

[0009] Furthermore, it also includes a signal acquisition system, which includes a gating system; the gating system triggers the detector after the conversion target is hit and makes the detector work within a 20μs acquisition time window.

[0010] An imaging method based on a high-power laser muon source according to any one of the preceding claims, comprising: generating a laser pulse using a laser and a wake field acceleration system; the laser pulse passing through a gas to generate a wake field-accelerated high-energy electron beam; the high-energy electron beam acting on a conversion target within a muon generation system to generate muons; a particle detection and imaging system processing the muons passing through the target object to reconstruct a structural image of the target object; and determining whether there are internal defects in the target object based on the structural image.

[0011] Furthermore, the particle detection and imaging system processes muons passing through the target object to reconstruct a structural image of the target object, including: acquiring electrical signals generated by muons or muon decay particles from multiple detector layers in the detector array; analyzing the electrical signals in the multiple detector layers to obtain the energy spectrum distribution of muons after passing through the object; reconstructing the positions of the multiple detector layers and determining the muon density distribution in the grid at multiple depths by combining the energy spectrum distribution; comparing the muon density distribution with the initial muon density distribution without the target object to obtain the change values ​​of muon density distribution at different energies; and reconstructing the surface density distribution map of the target object structure based on the change values ​​of muon density distribution.

[0012] Furthermore, the target object is an ultra-thick object; an ultra-thick object has a surface density exceeding 500 g / cm³. 2.

[0013] The present invention has the following advantages and beneficial effects:

[0014] This invention proposes an imaging system and method based on a high-power laser muon source. It utilizes a laser tail field to accelerate a high-energy electron beam, generating a high-throughput, highly collimated muon beam for imaging ultra-thick objects. The imaging system incorporates a shielding attenuation layer and a stacked detector array layout. Furthermore, a gated delay system is added during signal collection to avoid interference from numerous secondary particle signals generated during the interaction between high-energy electrons and the target, significantly improving muon detection efficiency. In this stacked detector array, each layer of two-dimensional detectors can resolve the XY coordinates of different particle signals, providing high lateral spatial resolution. The design of multiple vertical detectors and spacer layers allows the system to measure the number of muons deposited at different depths and obtain the muon energy spectrum distribution. Moreover, by analyzing the changes in muon number density distribution across different layers, it is possible to infer the structure and thickness of the object, which is crucial for reconstructing three-dimensional structures. This helps identify structural defects within the object, thereby achieving accurate detection of the object's internal structure.

[0015] The stacked detector array design enhances the system's adaptability and flexibility, expanding its application range. The number of detector layers and the thickness of the spacer layers can be adjusted to meet different application requirements. For example, in applications requiring finer muon energy spectrum resolution, the thickness of the spacer layers can be reduced to obtain information from smaller energy intervals; in applications requiring deeper information, the number of detector layers can be increased to obtain high-energy spectrum information. This flexibility allows the system to adapt to various complex inspection tasks. In the field of industrial non-destructive testing, stacked detector arrays can also inspect the internal structures and defects of industrial equipment, such as pipes and pressure vessels. Through muon imaging technology, non-destructive testing of the equipment's interior can be achieved, ensuring the safe operation of the equipment. This high-precision imaging technology provides a new solution for industrial inspection, helping to improve inspection efficiency and accuracy while reducing maintenance costs. Attached Figure Description

[0016] Figure 1 This is an exemplary schematic diagram of an imaging system based on a high-power laser muon source provided by the present invention; Figure 2 An exemplary modeling diagram of the detector array provided by the present invention; Figure 3 This is an exemplary schematic diagram illustrating the relative positional relationship between the object and the detector array in this invention; Figure 4 This is an example diagram of the muon number density distribution of the single-layer detector of the present invention; Figure 5This is an example diagram showing the number of muon number signals collected by multiple detector layers at different depths in this invention; Figure 6 This is an example of comparing the number densities of muons on both sides of the single-layer detector of the present invention; Figure 7 This is an example of comparing the muon number density distribution on the Y=0 line of a single-layer detector with the thickness of the path through the object by a point light source, as shown in the figure. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0018] Figure 1 This is an exemplary schematic diagram of an imaging system based on a high-power laser muon source provided by the present invention. Figure 1 As shown, the imaging system based on a high-power laser muon source provided by this invention includes a laser and wakefield acceleration system, a muon generation system, and a particle detection and imaging system. The laser and wakefield acceleration system is used to generate a high-energy electron beam. The pulse energy, pulse width, wavelength, and other parameters of the high-power laser can be adjusted as needed to adapt to the plasma density within the gas target and optimize the generation efficiency of high-energy electrons. A conversion target is placed inside the muon generation system. The material and structure of the conversion target are designed to efficiently generate muons under the action of the high-energy electron beam generated by the laser wakefield acceleration, ensuring the quality of the generated muon beam. The particle detection and imaging system is used to detect, collect, measure, and analyze muons. The particle detection and imaging system includes a shielding attenuation layer, a detector array, and an imaging processing system. The detector array uses a stacked structure, including multiple high-sensitivity detector layers and spacer layers, which can accurately measure the number and location of muons deposited at different depths to obtain the muon number density distribution.

[0019] In some embodiments, the laser and wake field acceleration system includes a laser, a focusing device, and a gas target. The laser is used to output laser pulses, and the laser may be a high-power solid-state laser, a fiber laser, or a free-electron laser, etc. The laser pulses output by the laser are focused by the focusing device to obtain suitable beam quality and energy distribution. The laser ionizes into plasma when it passes through the gas target, and the free electrons are accelerated under the action of the laser wake field, thereby generating a high-energy electron beam.

[0020] In some embodiments, the conversion target may be made of materials such as metal, semiconductor, or insulator, and the high-energy electron beam interacts with the conversion target to generate muons. The shape and size of the conversion target can also be designed as needed, including but not limited to cuboids, hemispheres, cylinders, and combinations thereof, to optimize laser muon generation efficiency and improve muon beam quality.

[0021] In some embodiments, the particle detector array and the detector array in the imaging system may employ position-resolved detectors such as scintillation detectors and / or gas detectors, which feature high sensitivity, high resolution, and fast response, enabling precise detection of muon signals. The detector array adopts a stacked structure, comprising detector layers and spacer layers. The imaging system can rapidly acquire and store the signals output by the detectors, further processing and analyzing the collected data to help reconstruct a structural image of the target object. The target object refers to the object to be inspected, such as materials and industrial equipment.

[0022] Figure 2 An exemplary modeling diagram of the detector array provided by the present invention. For example... Figure 2 As shown, the stacked detector array provided by this invention can be designed according to factors such as the shape and size of the target object and the required imaging resolution. It includes a detector layer and a spacer layer. The detector layer uses a planar detector array, which can distinguish signals at different locations, acquire the XY coordinates of the signals, and has a certain spatial resolution. Its typical thickness is [missing information]. The spacer layer is typically made of metal to attenuate muon energy and provide an energy gradient. The thicker the spacer layer, the greater the energy difference between muons collected by adjacent detector layers. Taking Pb as an example, the energy loss of muons in Pb is approximately 20-300 MeV / cm, and the typical thickness of the spacer layer is... The energy difference of muons measured between adjacent detector layers Multiple detector layers and spacer layers are stacked together to form a detector array, which can provide partial energy spectrum information for measuring muons. Each detector layer is connected to the data acquisition system via electrical cables or optical fibers to transmit detection signals.

[0023] Figure 3 This is an exemplary schematic diagram illustrating the relative positional relationship between the object and the detector array in this invention. Figure 3 As shown, the object in front of the detector array is composed of a relatively thick metallic material.

[0024] In some embodiments, a signal acquisition system is also included, which includes a gating system with a time delay function. Adding a gating system to the signal acquisition system can ensure that only signals from muons or electrons generated by muon decay are collected. It is generally believed that the particle generation from the interaction of the laser with the target is instantaneous, with particle transport approximately at the speed of light, and the transport time is negligible. Taking a liquid scintillation detector as an example, the liquid scintillation detector is equipped with a microchannel plate (MCP) photomultiplier tube (MCP-PMT). Because the electron beam generates an instantaneous and strong secondary particle signal when it hits the conversion target, the microchannel plate may saturate. To avoid signal saturation, the MCP-PMT is delayed in triggering after the target is hit, and... The system operates within a specific acquisition window. During this window, secondary particle signals are either blocked by the shielding layer or have already passed the detector array and therefore will not be collected. Muons, on the other hand, will deposit into the detector array and begin to decay. At this time, the signals collected by the detector are mostly electron signals generated by muon decay. This method can effectively distinguish between background signals and actual signals, improving the collection efficiency of muon decay signals.

[0025] Since the muon decay signals acquired by the detector array require further processing and analysis, this invention also provides an imaging method based on a high-power laser muon source, comprising: generating a laser pulse using a laser and tail field acceleration system; the laser pulse being accelerated into a high-energy electron beam by a tail field through a gas stream; the high-energy electron beam acting on a conversion target within the muon generation system to generate muons; and a particle detection and imaging system processing the muons passing through the target object to reconstruct a structural image of the target object. The target object can refer to any target requiring non-destructive testing, specifically an ultra-thick object. For example, the target object can be a bridge, tunnel, or container truck with a surface density greater than 500 g / cm³. 2 The target object. A structural image can refer to the surface density distribution map of the target object's structure. Based on the structural image, it is determined whether there are internal defects in the target object. Internal defects include, but are not limited to, structural problems such as defects, cracks, and holes.

[0026] In some embodiments, the particle detection and imaging system processes muons passing through a target object to reconstruct a structural image of the target object, including: processing the electronic signals generated by muon decay collected from each detector layer in the detector array to obtain their XY coordinates in each layer; analyzing the electrical signals in multiple detector layers to obtain the energy spectrum distribution of the muons after passing through the object; and processing the multiple detector layers according to... Location reconstruction is performed, and combined with energy spectrum distribution, the muon density distribution in each grid at multiple depths is determined; the muon density distribution is compared with the initial muon density distribution without a target object to obtain the variation values ​​of muon density distribution at different energies; based on the variation values ​​of muon density distribution, the surface density distribution map of the target object structure is reconstructed. Figure 4 As shown, X represents the horizontal axis coordinate, and Y represents the vertical axis coordinate. The total number of signals collected by each detector layer is summarized, and the penetration depth is determined based on the number of interlayers in front of it, thus reconstructing the depth spectrum of muons behind the target. For example... Figure 5 As shown, ① represents the first detector layer, ② represents the second detector layer, ③ represents the third detector layer, ④ represents the fourth detector layer, and ⑤ represents the fifth detector layer. Z represents the vertical axis coordinate, and Count represents the number of muons. The corresponding energy spectrum distribution is obtained based on the thickness of the shielding attenuation layer and the spacer layer, as well as the energy loss rate of the material. Comparing the results without an imaging object, the surface density of muons collected at different deposition depths also changes. Taking the absolute value of the difference between the two results yields a two-dimensional distribution map of the surface density change. For ease of comparison, a left-right comparison method is used in one experiment, as shown below. Figure 6 and Figure 7 As shown, Number represents quantity and Length represents length. According to the distribution image of surface density variation, if the target imaging object has internal defects or is mixed with other materials, it will be reflected in the surface density distribution image as a certain position being darker or brighter than other places, which can further help to judge the structural defects of the imaging object.

[0027] Example 1 In this embodiment, the laser and wake field acceleration system employs a high-power solid-state laser with an output laser pulse energy of 10 J, a pulse width of 100 fs, and a wavelength of 1053 nm. A beam focusing device is used to focus the laser pulse, resulting in a spot diameter of 100 μm and a laser power density reaching [value missing]. The laser is used. Nitrogen is chosen as the gas target due to its simple atomic structure, high ionization energy, and ability to generate stable plasma under laser pulses. The conversion target is made of Pb metal with a thickness of 5 cm. The imaged object is a cube with sides of 10 cm.

[0028] The detector array employs scintillation fiber optic detectors, which offer high sensitivity and fast response, enabling precise detection of muon signals. A typical stacked detector array contains... Each detector is layered, and selection is made within each layer. Planar detector; the spacer layer material is Pb, with a typical thickness of [missing information]. The gate control system delay is as designed. The system is then activated to collect the electronic signals generated by muon decay. The imaging processing system uses a high-speed data acquisition card and data analysis software to quickly acquire and process the signals output by the detector, obtain the signals of muon deposition in different detector layers, and further obtain part of the muon energy spectrum and the two-dimensional muon number density distribution of different layers according to the working principle.

[0029] In this embodiment, during the operation of the laser muon source imaging system, a high-power laser pulse passes through a gas plasma, generating a high-energy electron beam using the laser tail field. These high-energy electrons act on a conversion target, producing a large number of secondary particles, including neutrons, secondary electrons, gamma photons, and muons. After passing through a shielding attenuation layer, the number of these secondary particles decreases dramatically, with the majority remaining as muons. These muons are transmitted to a detector array and deposited at different depths. A gating system collects the quantity and location of electron signals generated by muon decay, and an imaging processing system processes and analyzes the detected data.

[0030] Example 2 In this embodiment, the laser and wakefield acceleration system uses a free-electron laser with an output laser pulse energy of 50, a pulse width of 50 fs, and a wavelength of 800 nm. A beam focusing device is used to focus the laser pulse, with a spot diameter of 50 μm and a laser power density reaching [value missing]. Nitrogen is chosen as the gas target due to its simple atomic structure, high ionization energy, and ability to generate stable plasma under laser pulses. The conversion target material is carbon (C), and the target shape is cylindrical.

[0031] The detector array employs multi-gap resistive plate chamber (MRPC) gas detectors in layers, which feature high temporal resolution and high count rate, enabling precise detection of muons. The imaging processing system utilizes a digitizer and data analysis software to rapidly acquire and process the signals output by the detectors.

[0032] In this embodiment, during the operation of the laser muon source imaging system, the high-power laser pulse generated by the laser passes through gas plasma to produce a high-energy electron beam. The electron beam interacts with the C-conversion target to generate a large number of secondary particles and muons to be measured. The muons are transmitted to the detector array, and the decay signals of muons deposited in different layers of detectors are collected using a gating system. The imaging processing system processes and analyzes the detected data.

[0033] This invention provides an imaging system and method based on a high-power laser muon source. It utilizes a high-power laser to generate muons and then detects these muons using a detector array to achieve imaging of a target object. Compared to traditional muon imaging methods, this method offers higher imaging efficiency and lower operating costs, providing new ideas and operational methods for materials testing, industrial non-destructive testing, and other fields.

[0034] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An imaging system based on a high-power laser muon source, characterized in that, This includes laser and wake field acceleration systems, muon generation systems, and particle detection and imaging systems; The laser and wake field acceleration system is used to generate high-energy electron beams; The muon generation system contains a conversion target; the conversion target generates muons under the action of a high-energy electron beam. The particle detection and imaging system is used to detect, collect, measure, and analyze muons. The particle detection and imaging system includes a shielding attenuation layer, a detector array, and an imaging processing system. The detector array adopts a stacked structure, including multiple detector layers and spacer layers, for measuring the number and position of muons at different depths. The detector layers are planar detector arrays. The spacer layers are made of metallic material. The detector array is formed by stacking multiple detector layers and spacer layers.

2. The imaging system based on a high-power laser muon source according to claim 1, characterized in that, The laser and wake field acceleration system includes a laser, a focusing device, and a gas target; The laser is used to output laser pulses; The focusing device is used to focus the laser pulse; The gas target is ionized into plasma by the passing laser, and free electrons are accelerated under the action of the laser tail field to generate a high-energy electron beam.

3. The imaging system based on a high-power laser muon source according to claim 1, characterized in that, The conversion target is made of metal, semiconductor or insulator.

4. The imaging system based on a high-power laser muon source according to claim 1, characterized in that, The detector array employs scintillation detectors and / or position-resolved gas detectors; The shielding attenuation layer is used to block secondary particle signals and reduce muon energy; The imaging system is used to collect and store the signals output by the detector array, process and analyze the collected data, and reconstruct the structural image of the target object.

5. The imaging system based on a high-power laser muon source according to claim 1, characterized in that, It also includes a signal acquisition system, which includes a gating system; the gating system triggers the detector after the conversion target is hit and makes the detector work within a 20μs acquisition time window.

6. An imaging method based on a high-power laser muon source for an imaging system according to any one of claims 1-5, characterized in that, include: Laser pulses are generated using a laser and a wake field acceleration system. These laser pulses are then accelerated into a high-energy electron beam by a wake field generated by the gas. A high-energy electron beam acts on a conversion target within a muon generation system to produce muons. The particle detection and imaging system processes muons passing through a target object to reconstruct a structural image of the target object; Determine whether there are internal defects in the target object based on structural images.

7. The imaging method based on a high-power laser muon source according to claim 6, characterized in that, The particle detection and imaging system processes muons passing through the target object to reconstruct a structural image of the target object, including: Collect electrical signals generated by muons or muon decay particles from multiple detector layers in the detector array; The energy spectrum distribution of muons after passing through the guest was obtained by analyzing the electrical signals in multiple detector layers. The positions of multiple detector layers were reconstructed, and the muon density distribution in grids at multiple depths was determined by combining the energy spectrum distribution. The muon density distribution is compared with the initial muon density distribution without a target object to obtain the changes in muon density distribution at different energies; Reconstruct the surface density distribution map of the target object structure based on the changes in muon density distribution.

8. The imaging method based on a high-power laser muon source according to claim 6, characterized in that, The target object is an ultra-thick object; an ultra-thick object has a surface density exceeding 500 g / cm³. 2 .

Images