High-precision transmission imaging method of cosmic ray muons based on virtual space point constraints

Abstract

The present invention relates to the field of imaging technology, and in particular to a high-precision transmission imaging method for cosmic ray muons based on virtual space point constraints. Assuming a quasi-virtual space point, the cosmic ray muon track is constrained by the virtual space point, and the cosmic ray muon track data passing through the virtual space point is screened; the screened cosmic ray muon track is projected onto a fixed plane, and a two-dimensional scatter plot is drawn according to the focus of these tracks; the data of the two-dimensional scatter plot is converted into a counting two-dimensional map within a fixed voxel area, and after careful background subtraction processing, a high-precision imaging effect is finally presented. Compared with the prior art, the high-precision transmission imaging method for cosmic ray muons based on virtual space point constraints of the present invention can greatly improve the accuracy of muon transmission imaging results by realizing a constraint effect similar to a physical pinhole; the imaging result can be directly compared with the actual scene, without the need for simulation data comparison and analysis, thereby improving the accuracy and intuitiveness of the result.

Description

[Technical field]

[0001] The invention relates to the field of imaging technology, and in particular to a cosmic ray muon high-precision transmission imaging method based on virtual space point constraints. [Background technology]

[0002] With the development of cosmic ray muon transmission imaging, due to the improvement of the position accuracy of muon detectors, transmission imaging can be achieved by measuring muon tracks. The current main method is to perform transmission imaging through the angular classification of muon three-dimensional tracks.

[0003] In the specific implementation process, first, a multi-layer muon detector is used to accurately determine the three-dimensional tracks of muons. Then, based on a reference point, the directions of these detected three-dimensional muon tracks are classified. Specifically, the two parameters of direction angle and rotation angle are used as measurement standards to construct a two-dimensional scatter plot.

[0004] In order to further refine the imaging effect, the data of the scatter plot needs to be converted into a two-dimensional counting map within a fixed voxel area, and finally the background needs to be subtracted to finally achieve imaging.

[0005] The existing cosmic ray muon transmission imaging method has the following shortcomings:

[0006] 1. The three-dimensional geometric space of the entire muon detection system is simplified into a reference point when analyzing the imaging, which introduces a large system error, which is not conducive to improving the imaging accuracy;

[0007] 2. Imaging is measured using two parameters, the direction angle and the rotation angle of the muon direction, which is not conducive to comparison with the actual measured object. The analysis of experimental data imaging results strongly depends on the comparison of simulation data results. [Summary of the invention]

[0008] In order to overcome the above problems, the present invention proposes a cosmic ray muon high-precision transmission imaging method based on virtual space point constraints, which can effectively solve the above problems.

[0009] The present invention provides a technical solution to solve the above technical problems: providing a cosmic ray muon high-precision transmission imaging method based on virtual space point constraints, comprising the following steps:

[0010] Step S1, assuming a virtual space point, constraining the cosmic ray muon track through the virtual space point, and screening out the cosmic ray muon track data that pass through the virtual space point;

[0011] Step S2, projecting the screened cosmic ray muon tracks onto a fixed plane, and drawing a two-dimensional scatter plot based on the foci of these tracks;

[0012] Step S3, converting the data of the two-dimensional scatter plot into a two-dimensional counting plot within a fixed voxel area, and undergoing a meticulous background subtraction process, ultimately presenting a high-precision imaging effect;

[0013] Step S4, combining multiple images based on multiple similar virtual space point constraint imaging to form a final muon transmission imaging image.

[0014] Preferably, in step S1, the virtual space point is a set of space points, which is used to be equivalent to a small hole.

[0015] Preferably, in step S1, assuming a virtual space point includes the following steps:

[0016] Step S11, unifying all measured cosmic ray muon tracks into a focus and a three-dimensional direction vector on a first plane, and virtualizing a second plane on one side of the first plane;

[0017] Step S12, making a constrained circular surface on the second plane with the center point of the second plane as the center of the circle;

[0018] Step S13, making a central axis passing through the center point of the first plane and the center point of the second plane, and the cosmic ray muon tracks passing through the edge of the constrained circular surface converge on the central axis to form a first focus;

[0019] Step S14, making a first cone with the constrained circular surface as the base and the first focus as the vertex, and making a second cone with the second plane as the symmetry plane, wherein the vertex of the second cone intersects the central axis at the second focus;

[0020] Step S15, a first cone and a second cone with the constrained circular surface as the bottom surface and the constrained circular surface as the symmetry surface form a virtual space point.

[0021] Preferably, in the step S11, the first plane and the second plane are parallel, and a line connecting a center point of the first plane and a center point of the second plane is perpendicular to the first plane and the second plane respectively.

[0022] Preferably, in step S11, the distance between the first plane and the second plane is related to the distance between the multi-layer muon detectors. The distance between the first plane and the second plane can be the sum of the distances between the multi-layer muon detectors, which can be between 150 mm and 250 mm.

[0023] Preferably, in step S12, the radius of the constraining circular surface may be between one eighth and one fifth of the distance between the first plane and the second plane.

[0024] Preferably, the distance from the first focus to the center point of the second plane is equal to the radius of the constraining circular surface divided by the tangent value of the angle between the cosmic ray muon track passing through the edge of the constraining circular surface and the first focus and the central axis.

[0025] Preferably, in step S1, cosmic ray muon tracks that intersect with the virtual space point are screened out.

[0026] Preferably, in step S4, a plurality of similar virtual space points can be obtained by performing multiple translations on the second plane with the geometric center of the virtual space point as the moving center.

[0027] Preferably, the translation distance is not greater than the radius of the constraining circular surface.

[0028] Compared with the prior art, the high-precision transmission imaging method of cosmic ray muons based on virtual space point constraints of the present invention effectively improves the accuracy of data processing by realizing a constraint effect similar to that of a physical pinhole, thereby greatly improving the accuracy of muon transmission imaging results; the imaging results can be directly compared with the actual scene without the need for simulation data comparison and analysis, thereby greatly simplifying the application of the technology and improving the accuracy and intuitiveness of the results.

Brief Description of the Drawings

[0029] Figure 1 A schematic diagram of virtual space points of the cosmic ray muon high-precision transmission imaging method based on virtual space point constraints of the present invention;

[0030] Figure 2 This is a local muon transmission imaging diagram of a building achieved by using the cosmic ray muon high-precision transmission imaging method based on virtual space point constraints of the present invention. [Specific implementation method]

[0031] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0033] In addition, in the present invention, descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0034] See also Figure 1 and Figure 2 The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints of the present invention comprises the following steps:

[0035] Step S1, assuming a virtual space point, constraining the cosmic ray muon track through the virtual space point, and screening out the cosmic ray muon track data that pass through the virtual space point.

[0036] Step S2, projecting the screened cosmic ray muon tracks onto a fixed plane, and drawing a two-dimensional scatter plot based on the foci of these tracks.

[0037] Step S3, converting the data of the two-dimensional scatter plot into a two-dimensional counting plot within a fixed voxel area, and undergoing a meticulous background subtraction process, ultimately presenting a high-precision imaging effect.

[0038] Step S4, combining multiple images based on multiple similar virtual space point constraint imaging to form a final muon transmission imaging image.

[0039] In the step S1, the virtual space point is a set of space points, which is used to be equivalent to a small hole.

[0040] In step S1, assuming that the virtual space point includes the following steps:

[0041] Step S11, unifying all measured cosmic ray muon tracks into a focus and a three-dimensional direction vector on a first plane with a center point B, and virtualizing a second plane with a center point A on one side of the first plane.

[0042] In the step S11, the first plane and the second plane are parallel, and a line connecting a center point B of the first plane and a center point A of the second plane is perpendicular to the first plane and the second plane respectively.

[0043] In step S11, the distance between the first plane and the second plane is related to the distance between the multi-layer muon detectors. The distance between the first plane and the second plane can be the sum of the distances between the multi-layer muon detectors, which can be between 150 mm and 250 mm.

[0044] Step S12, making a constrained circular surface on the second plane with the center point A of the second plane as the center of the circle.

[0045] In step S12, the radius AC or AD of the constrained circular surface may be between one eighth and one fifth of the distance between the first plane and the second plane.

[0046] Step S13, making a central axis AB passing through the center point B of the first plane and the center point A of the second plane, and the cosmic ray muon tracks passing through the edge of the constrained circular surface converge on the central axis AB to form a first focus O'.

[0047] The distance between the first focus O' and the center point A of the second plane is equal to the radius of the constraining circular surface divided by the tangent value of the angle between the cosmic ray muon track passing through the edge of the constraining circular surface and the first focus O' and the central axis AB.

[0048] Step S14 , a first cone is constructed with the constrained circular surface as the base and the first focus O′ as the vertex, and a second cone is constructed with the second plane as the symmetry plane. The vertex of the second cone intersects the central axis AB at the second focus O.

[0049] Step S15, a first cone and a second cone with the constrained circular surface as the bottom surface and the constrained circular surface as the symmetry surface form a virtual space point.

[0050] In the step S1, cosmic ray muon tracks that intersect the virtual space point are screened out.

[0051] In step S1, the condition for screening the cosmic ray muon track is that the distance between the focus of the muon track on the virtual second plane and the center point A of the virtual second plane is less than the tangent value of the angle between the muon track and the central axis AB multiplied by a certain length ( Figure 1 where is the length of AO or AO').

[0052] Such constraints restrict the muon track on the virtual second plane, which depends on the angle between the muon track and the central axis AB. Because the muon transmission imaging system itself has a solid angle acceptance limit, this limit can ultimately limit the range of the muon track on the virtual second plane; in addition, the muon track can be restricted between point O' and point O in the direction of the central axis AB. Therefore, the plane restriction on the virtual second plane described above plus the line restriction on the central coaxial line AB constitute the core virtual space point constraint of the present invention.

[0053] In step S4, a plurality of similar virtual space points can be obtained by performing multiple translations on the second plane with the geometric center of the virtual space point as the moving center, and the translation distance is not greater than the radius of the constrained circular surface.

[0054] like Figure 2 The figure shows a local muon transmission imaging diagram of a building achieved by the high-precision transmission imaging method of cosmic ray muons based on virtual space point constraints of the present invention. This imaging result looks like a directly captured real-life photo of muon transmission. The analysis of the imaging result can be directly compared with the real object without relying on any simulation data, thereby improving the accuracy and intuitiveness of the imaging result.

[0055] Compared with the prior art, the high-precision transmission imaging method of cosmic ray muons based on virtual space point constraints of the present invention effectively improves the accuracy of data processing by realizing a constraint effect similar to that of a physical pinhole, thereby greatly improving the accuracy of muon transmission imaging results; the imaging results can be directly compared with the actual scene without the need for simulation data comparison and analysis, thereby greatly simplifying the application of the technology and improving the accuracy and intuitiveness of the results.

[0056] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included in the patent protection scope of the present invention.

Claims

1. A high-precision transmission imaging method for cosmic ray muons based on virtual space point constraints, characterized in that: The steps include: Step S1, assuming a virtual space point, constraining the cosmic ray muon track through the virtual space point, and screening out the cosmic ray muon track data that pass through the virtual space point; Step S2, projecting the screened cosmic ray muon tracks onto a fixed plane, and drawing a two-dimensional scatter plot based on the foci of these tracks; Step S3, converting the data of the two-dimensional scatter plot into a two-dimensional counting plot within a fixed voxel area, and undergoing a meticulous background subtraction process, ultimately presenting a high-precision imaging effect; Step S4, combining multiple images based on multiple similar virtual space point constraint imaging to form a final muon transmission imaging image; In step S1, assuming that the virtual space point includes the following steps: Step S11, unifying all measured cosmic ray muon tracks into a focus and a three-dimensional direction vector on a first plane, and virtualizing a second plane on one side of the first plane; Step S12, making a constrained circular surface on the second plane with the center point of the second plane as the center of the circle; Step S13, making a central axis passing through the center point of the first plane and the center point of the second plane, and the cosmic ray muon tracks passing through the edge of the constrained circular surface converge on the central axis to form a first focus; Step S14, making a first cone with the constrained circular surface as the base and the first focus as the vertex, and making a second cone with the second plane as the symmetry plane, wherein the vertex of the second cone intersects the central axis at the second focus; Step S15, a first cone and a second cone with the constrained circular surface as the bottom surface and the constrained circular surface as the symmetry surface form a virtual space point.

2. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints according to claim 1, characterized in that: In the step S1, the virtual space point is a set of space points, which is used to be equivalent to a small hole.

3. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints according to claim 1, characterized in that: In the step S11, the first plane and the second plane are parallel, and a line connecting a center point of the first plane and a center point of the second plane is perpendicular to the first plane and the second plane respectively.

4. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints according to claim 1, characterized in that: In step S11, the distance between the first plane and the second plane is related to the distance between the multi-layer muon detectors. The distance between the first plane and the second plane can be the sum of the distances between the multi-layer muon detectors, which can be between 150 mm and 250 mm.

5. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints according to claim 4, characterized in that: In step S12, the radius of the constrained circular surface may be between one eighth and one fifth of the distance between the first plane and the second plane.

6. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints as claimed in claim 5, characterized in that: The distance from the first focus to the center point of the second plane is equal to the radius of the constraining circular surface divided by the tangent value of the angle between the cosmic ray muon track passing through the edge of the constraining circular surface and the first focus and the central axis.

7. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints according to claim 1, characterized in that: In the step S1, cosmic ray muon tracks that intersect the virtual space point are screened out.

8. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints according to claim 1, characterized in that: In step S4, a plurality of similar virtual space points can be obtained by performing multiple translations on the second plane with the geometric center of the virtual space point as the moving center.

9. The method for high-precision transmission imaging of cosmic ray muons based on virtual space point constraints as claimed in claim 8, characterized in that: The translation distance is no greater than the radius of the constraining circular surface.

Images