Well type gamma beam monitoring detector

Abstract

The invention discloses a well type gamma beam monitoring detector, which comprises a BGO scintillation crystal with a central axial through hole channel, a scattering layer arranged at the incident end of the through hole channel, and a photoelectric sensor which is optically coupled with the emergent end of the BGO scintillation crystal and is provided with a through hole channel with the same specification in the center, the fluorescent reflecting layer and the protective shell sequentially cover the outer side of the BGO scintillation crystal; wherein the BGO scintillation crystal is of a cylindrical structure, and the aperture of the central axial through hole channel is 5-10 mm. According to the well-type gamma beam monitoring detector provided by the invention, the problems of signal saturation and pulse accumulation during single-pulse high-flux gamma beam measurement can be effectively avoided, the authenticity of an original beam energy spectrum can be maintained, the detection efficiency can be simulated and calibrated, and the well-type gamma beam monitoring detector is compact in structure, easy to integrate and low in cost. A response function can be established through Monte Carlo simulation to realize beam energy spectrum reconstruction and improve the measurement precision, and online stable real-time measurement of the beam energy spectrum and flux is realized.

Description

Technical Field

[0001] This invention relates to the field of nuclear detector technology, and more specifically to a well-type gamma beam monitoring detector. Background Technology

[0002] Currently, in non-pulsed low-throughput (<10) 4 In high-energy (<20 MeV) gamma-ray beam measurement scenarios, large-size scintillator detectors (such as NaI(Tl), BGO, LaBr3) and high-energy-resolution semiconductor detectors (such as HPGe) can achieve reliable energy spectrum measurements under low to medium flux conditions. However, when the gamma-ray beam reaches single-pulse (pulse width less than 50 μs) high-intensity (>10 Hz) gamma-ray beams, reliable energy spectrum measurements can be achieved. 2 When operating at a rate of (per pulse), these detectors, due to their high detection efficiency and long decay time, may experience an excessive number of effective detection events per unit time. This can easily lead to signal saturation, pulse accumulation, and dead time effects, ultimately causing severe distortion of the energy spectrum shape and count rate.

[0003] In existing technologies, to address the aforementioned problems, methods often employ pre-positioned metal absorbers such as copper or lead to attenuate the incident gamma-ray flux, or reduce the count rate by shrinking the crystal volume or measuring the scattered gamma using Compton scattering. However, existing gamma beam monitoring methods struggle to simultaneously meet the requirements of high-throughput, real-time, and low-interference online monitoring, and they cannot measure the original energy spectrum distribution, significantly increasing the uncertainty in gamma beam reconstruction and hindering accurate measurement of the gamma-ray beam. Summary of the Invention

[0004] The purpose of this invention is to provide a well-type gamma beam monitoring detector, thereby solving the problems in the prior art where traditional scintillators and semiconductor detectors are prone to signal saturation, pulse accumulation, and dead time effects in single-pulse high-throughput high-energy gamma beam measurements. Furthermore, existing count rate reduction methods result in the inability to measure the original energy spectrum distribution, increase beam reconstruction uncertainty, and fail to achieve accurate measurements.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A well-type gamma beam monitoring detector is provided, comprising: a BGO scintillation crystal with a central axial through-hole, a scattering layer disposed at the incident end of the through-hole, a photoelectric sensor optically coupled to the exit end of the BGO scintillation crystal and having a central through-hole of the same specification, and a fluorescent reflective layer and a protective shell sequentially covering the outside of the BGO scintillation crystal; wherein, the BGO scintillation crystal has a cylindrical structure, and the aperture of the central axial through-hole is 5-10 mm; when measuring in a vacuum channel, most of the incident gamma beam passes directly through the vacuum channel, and only a small portion undergoes Compton scattering in the scattering layer before entering the BGO crystal and being detected, thereby realizing real-time measurement of a single-pulse high-throughput gamma beam.

[0007] Preferably, the BGO scintillation crystal has an outer diameter of 50-100 mm and a length of 80-150 mm, and is formed by splicing two separate BGO scintillation crystals along the axial direction after end face polishing. It should be understood that when the length is small, the BGO scintillation crystal can also be composed of a single piece without splicing.

[0008] Preferably, the scattering layer is an aluminum foil or plastic film structure, the thickness of the scattering layer is 5-50 μm, and the scattering layer is fixed to the incident end of the through-hole by adhesive bonding, for Compton scattering of incident gamma rays.

[0009] Preferably, the photoelectric sensor is a silicon photomultiplier tube, and the silicon photomultiplier tube is connected to the emission end of the BGO scintillation crystal via an optical coupler.

[0010] Preferably, the fluorescent reflective layer is made of polytetrafluoroethylene, the thickness of the fluorescent reflective layer is 0.2 mm or more, and the fluorescent reflective layer is wrapped around the outer surface of the BGO scintillation crystal to improve light collection efficiency.

[0011] Preferably, it also includes a plumb collimator, which is disposed on the incident side of the detector. The diameter of the through-hole of the plumb collimator is smaller than the diameter of the central axial through-hole of the BGO scintillation crystal, but larger than the diameter of the gamma beam spot.

[0012] Preferably, the detector is designed to operate in a vacuum environment, wherein the vacuum level of the operating environment is not higher than 10. -2 Pa.

[0013] Preferably, the detector is equipped with a vacuum tube, both ends of which are sealed with aluminum or beryllium windows with a thickness of no more than 0.1 mm; the distance between the vertical collimator and the incident end of the vacuum tube is no less than 60 cm, and the distance between the detector and the exit end of the vacuum tube is no less than 10 cm.

[0014] Preferably, it also includes a flexible light guide, which is a sheet-like structure with a through hole in the center, and is fitted between the emitting end of the BGO scintillation crystal and the photoelectric sensor to realize the transmission of light signals; the inner diameter of the protective shell is adapted to the outer diameter of the BGO scintillation crystal, and the core components of the detector are completely covered to achieve protection and fixation.

[0015] Preferably, it also includes a power supply and signal output component, which is electrically connected to the photoelectric sensor to provide the photoelectric sensor with a working voltage and output the detection signal collected by the photoelectric sensor.

[0016] The key innovation of this invention lies in its breakthrough from the traditional detector design approach of increasing detection efficiency by making the cylindrical scintillator crystal larger and longer. Addressing the new, previously unexplored need for reduced detection efficiency in single-pulse high-throughput gamma detection, this invention innovatively creates a 5-10mm axial through-hole at the center of the cylindrical BGO scintillator crystal. This allows the majority of the incident gamma beam to pass directly through the vacuum channel, with only a small portion entering the crystal after Compton scattering by the front-end scattering layer. This structural design avoids signal saturation and pulse accumulation problems under high throughput. Simultaneously, with a suitable scattering layer, photoelectric sensing components, protective shell structure, and a specific vertical collimator layout and vacuum operating environment, a complete well-type detection structure is formed. This ensures energy measurement of the original beam spectrum, enables simulation and calibration of detection efficiency, and allows for beam spectrum reconstruction through Monte Carlo simulation to establish a response function. This balances the practicality and measurement accuracy of online monitoring of single-pulse high-throughput gamma beams.

[0017] It should be understood that the core of the detector is a cylindrical BGO scintillation crystal with a cylindrical through-hole in the center along the axis, forming a physical structure with an outer cylinder as the wall and a hollow core as the well. This hollow core serves as the flow channel during detection, allowing most of the incident gamma-ray beam to pass directly through it, with only a small portion being scattered and detected by the crystal. This structural design fundamentally avoids the problems of signal saturation and pulse accumulation under high throughput.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] Excellent anti-signal distortion performance: The detector of this invention can be effectively adapted to the single-pulse high-throughput gamma-ray beam measurement scenario. From the structural design, it avoids the problems of signal saturation, pulse accumulation and dead time effect that are easy to occur in traditional detectors. According to the well-type BGO detection efficiency experimental and simulated distribution data of this invention, it can be verified that this detector can stably realize the effective measurement of single-pulse high-throughput gamma-ray beams, and has a significant anti-distortion advantage compared with traditional detectors.

[0020] High accuracy of energy spectrum measurement: The detector has a high degree of reproduction of the original gamma-ray beam energy spectrum with no obvious energy spectrum distribution distortion. Moreover, the detection efficiency has the characteristics of being simulable and calibrable. The relevant quantitative data of detection efficiency can be directly reflected in Figure 3, providing data support for the accuracy of the measurement results.

[0021] Excellent practicality and integration: The detector has a compact overall structure with no complex redundant parts, making it easy to integrate and adapt with gamma beam measurement-related equipment. It can meet the online real-time monitoring requirements of single-pulse high-throughput gamma beams, and its adaptability and ease of operation are outstanding.

[0022] High measurement accuracy and optimizability: A dedicated response function can be established for the detector through Monte Carlo simulation. Based on this function, the gamma beam energy spectrum can be accurately reconstructed, effectively reducing the uncertainty of beam reconstruction and significantly improving the measurement accuracy of single-pulse high-throughput gamma beams.

[0023] In summary, the well-type gamma beam monitoring detector provided by this invention can effectively avoid signal saturation and pulse accumulation problems during single-pulse high-flux gamma beam measurement, maintain the authenticity of the original beam energy spectrum, and the detection efficiency can be simulated and calibrated. It has a compact structure and is easy to integrate. The response function can be established through Monte Carlo simulation to reconstruct the beam energy spectrum and improve the measurement accuracy, thus realizing online stable real-time measurement of the energy spectrum and flux of single-pulse high-flux gamma beams. Attached Figure Description

[0024] Figure 1 This is a perspective view of a well-type gamma beam monitoring detector according to a preferred embodiment of the present invention;

[0025] Figure 2 This is a cross-sectional view of the well-type gamma beam monitoring detector;

[0026] Figure 3 This is a layout diagram of the well-type gamma beam monitoring detector within the vacuum channel;

[0027] Figure 4 The experimental and simulated distribution of the detector's detection efficiency is shown in the figure.

[0028] Figure 5 Comparison of online measured energy spectra and simulations at different laser-electron collision angles;

[0029] The meanings of the reference numerals in the attached figures are as follows:

[0030] 1. BGO scintillation crystal; 2. Scattering layer; 3. Photoelectric sensor; 4. Fluorescent reflective layer; 6. Flexible light guide; 7. Protective housing; 8. DB9 male connector; 9. Through-hole; 10. Printed circuit board; 11. Through-channel; 12. Aluminum or beryllium window; 13. Plumb line collimator; 14. Vacuum tube; 71. Top cover; 72. Housing; 100. Well-shaped gamma beam monitoring detector. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified, the techniques used in the embodiments are conventional practices in the art, or experimental methods recommended by the instrument manufacturer. Unless otherwise specified, the reagents and materials used in the embodiments are commercially available.

[0032] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0033] Example 1

[0034] Combination Figure 1 , Figure 2 The image shows a well-type gamma beam monitoring detector 100 according to a preferred embodiment of the present invention. The core design of this well-type gamma beam monitoring detector involves creating an axial vacuum through-hole at the center of a cylindrical BGO scintillation crystal. Combined with a scattering layer, photoelectric sensing components, a protective housing structure, and a corresponding vacuum environment and collimator layout, it enables online real-time monitoring of a single-pulse high-throughput gamma-ray beam, solving problems such as signal saturation and pulse accumulation in traditional detectors.

[0035] The well-type gamma beam monitoring detector 100 mainly includes: BGO scintillation crystal 1, scattering layer 2, photoelectric sensor 3, fluorescent reflective layer 4, flexible light guide 6, and protective shell 7.

[0036] This embodiment is applicable to single pulse throughput less than 10. 4 For a Hz gamma-ray beam monitoring scenario, the parameters, connection methods, and layout requirements of each component of the detector are described below:

[0037] like Figure 2As shown, the BGO scintillation crystal 1 has a cylindrical structure with an outer diameter of 76 mm and a length of 100 mm. A through-hole 11 with a diameter of 10 mm is opened in the center of the crystal along the axial direction. Because the BGO scintillation crystal is fragile, it is processed into two equal-length split BGO scintillation crystals, BGO1 and BGO2 (see...). Figure 2 Both BGO1 and BGO2 are φ76×50mm in size. The splicing ends of the two crystals are polished and then spliced ​​along the axial direction to ensure the overall structural integrity and light transmission effect of the crystal.

[0038] The scattering layer 2 is a 15μm thick aluminum foil, which is adhered to the incident end of the through-hole 11 (e.g., Figure 1 Bottom of BGO scintillation crystal 1 Figure 3 The left end of the BGO scintillation crystal 1), with the edge of the aluminum foil fixed by tape, is used for Compton scattering of incident gamma rays, allowing a small portion of the rays to enter the BGO scintillation crystal for detection.

[0039] According to this embodiment, the photoelectric sensor 3 is a silicon photomultiplier tube (SiPM), which is disposed at the emission end of the BGO scintillation crystal 1. Figure 1 Above BGO scintillation crystal 1 Figure 3 The photoelectric sensor 3 has a 10mm through hole of the same specification as the through-hole 11 at the center of the right end of the BGO scintillation crystal 1. The photoelectric sensor 3 and the emitting end of the BGO scintillation crystal 1 are optically connected by a 50μm thick optical coupling agent to ensure effective transmission of the light signal.

[0040] A flexible light guide 6 is attached between the output end of the BGO scintillation crystal 1 and the photoelectric sensor 3. This flexible light guide is a circular sheet structure with a 10mm through-hole in the center, which further improves the light signal transmission efficiency.

[0041] The outer surface of the BGO scintillation crystal 1 is covered with a 0.2 mm thick polytetrafluoroethylene (Teflon) fluorescent reflective layer 4 by wrapping, which is used to improve the collection efficiency of scintillation light inside the crystal.

[0042] The detector is also equipped with an aluminum alloy protective shell 7, including a top cover 71 and a housing 72. The entire shell is 3mm thick, and its inner diameter is adapted to the outer diameter of the BGO scintillation crystal 1. It covers the core components such as the BGO scintillation crystal 1, the fluorescent reflective layer 4, and the flexible light guide 6, achieving structural protection and fixation, while also serving to block light. The top cover 71 has a through hole 9. The top cover 71 and the housing 72 are connected by screws. A cavity is reserved between the top cover 71 and the printed circuit board 10 (PCB) corresponding to the photoelectric sensor 3 for placing power supply and signal transmission lines. The printed circuit board 10 and the photoelectric sensor 3 are connected by bolts to maintain spatial spacing.

[0043] According to this embodiment, a DB9 male connector 8 and a Remo ERA-OS single-core interface are also provided as power supply and signal output components. The DB9 male connector 8 provides the working voltage for the silicon photomultiplier tube, and the Remo ERA-OS single-core interface is used to output the detection signal collected by the silicon photomultiplier tube. Both are electrically connected to the printed circuit board 10.

[0044] like Figure 3 As shown, in the test scenario, the detector 100 is placed entirely inside the vacuum pipe 14 (target chamber), and the vacuum level inside the vacuum pipe is maintained at no higher than 10 by a molecular pump. -2 Pa; The incident end (left side in the figure) and the exit end (right side in the figure) of the vacuum pipe 14 are both sealed with 0.1mm thick aluminum or beryllium windows 12 to reduce the obstruction of gamma rays; A plumb line 13 is set on the incident side of the detector. The plumb line 13 has an outer diameter of 80mm, a length of 100mm, and a central through hole diameter of 6mm (smaller than the diameter of the vacuum through-hole of the BGO scintillation crystal and larger than the diameter of the gamma beam spot); The distance L1 between the front end of the plumb line 13 and the incident end of the vacuum pipe 14 is 60cm, and the distance L2 between the rear end of the detector 100 and the exit end of the vacuum pipe 14 is 10cm, so as to realize the directional guidance and stable detection of gamma rays.

[0045] The detector in this embodiment was used in an online measurement experiment on a laser gamma source. Figure 4 shows the experimental and simulated distribution of the detector's detection efficiency, and Figure 5 shows the comparison between the online measured energy spectrum and the simulation at different laser electron collision angles. The experimental results show that the detection efficiency distribution and energy spectrum shape are highly consistent with the Monte Carlo simulation results, which can effectively realize the energy spectrum and flux measurement of a single-pulse high-throughput gamma beam without signal saturation or pulse accumulation. Furthermore, the original beam energy spectrum can be further accurately restored through energy spectrum reconstruction.

[0046] Example 2

[0047] This embodiment applies to a single pulse flux of 10. 2 -10 5For monitoring scenarios with higher flux gamma-ray beams at Hz, the overall structure, component connection methods, external layout, and vacuum environment requirements are the same as in Example 1, with adjustments only made to the material and thickness of the scattering layer. Specifically:

[0048] The 15μm thick aluminum foil scattering layer 2 in Example 1 is replaced with a 5μm thick plastic film scattering layer. By reducing the thickness of the scattering layer, it can be adapted to the detection requirements of higher flux gamma-ray beams and avoid the distortion of detection signals caused by excessive scattered rays.

[0049] In this embodiment, the diameter of the BGO scintillation crystal through-hole 11 and the thickness of the plastic film scattering layer 2 are optimized through Monte Carlo simulation, which further improves the energy measurement range and energy spectrum reconstruction accuracy of the detector. In the monitoring of higher flux gamma beams, it can still effectively avoid signal saturation and pulse accumulation problems, maintain a high degree of restoration of the original beam energy spectrum, and the detection efficiency can be simulated and calibrated.

[0050] Example 3

[0051] This embodiment is a conventional variation of the BGO scintillation crystal parameters, applicable to monitoring scenarios with different installation spaces and different energy gamma rays. The only difference between this embodiment and Embodiment 1 is the external shape parameters of the BGO scintillation crystal, specifically:

[0052] A cylindrical BGO scintillation crystal with an outer diameter of 50 mm and a length of 80 mm is used. A 5 mm vacuum through-hole is opened in the center of the crystal along the axial direction. The crystal is composed of a single piece. The parameters and connection methods of the remaining scattering layer, photoelectric sensing components, protective shell, as well as the layout requirements of the external collimator and vacuum pipe are the same as in Example 1.

[0053] The detector in this embodiment is better suited to the installation requirements of confined spaces due to the reduced outer diameter and length of the crystal. It also has good accuracy in detecting low-energy gamma rays and can still achieve stable monitoring of single-pulse high-throughput gamma beams, thus possessing all the beneficial effects of Embodiment 1.

[0054] Example 4

[0055] This embodiment is another example with modified crystal parameters, suitable for monitoring high-energy gamma rays. Its difference from Embodiment 1 is as follows:

[0056] A cylindrical BGO scintillation crystal with an outer diameter of 100 mm and a length of 150 mm is used. An 8 mm vacuum through-hole is opened in the center of the crystal along the axial direction. Due to the increased crystal size, the proportion of full-energy deposition peaks of high-energy gamma rays in the crystal is improved, which is more conducive to the energy spectrum measurement of high-energy gamma beams. The other component parameters, connection methods and external layout are the same as in Example 1, which can effectively realize the online monitoring of high-energy, high-flux gamma beams.

[0057] In all the above embodiments, the aperture of the vacuum through-hole of the BGO scintillation crystal 1 can be adjusted within the range of 5-10 mm, the thickness of the scattering layer 2 can be adapted within the range of 5-20 μm according to the actual flux requirements, and the thickness of the polytetrafluoroethylene fluorescent reflective layer 4 is not less than 0.2 mm to achieve effective light collection. The adjustment of each parameter does not deviate from the core technical solution of the present invention, and all of them can achieve stable detection of single-pulse high-flux gamma beam, thus achieving the design goal of the present invention.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. All simple and equivalent changes and modifications made in accordance with the claims and description of this application fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A well-type gamma beam monitoring detector, characterized in that, include: The device comprises a BGO scintillation crystal with a central axial through-hole, a scattering layer disposed at the incident end of the through-hole, a photoelectric sensor optically coupled to the emitting end of the BGO scintillation crystal and having a through-hole of the same specification in the center, and a fluorescent reflective layer and a protective shell sequentially covering the outside of the BGO scintillation crystal; wherein the BGO scintillation crystal has a cylindrical structure, and the aperture of the central axial through-hole is 5-10 mm.

2. The well-type gamma beam monitoring detector according to claim 1, characterized in that, The BGO scintillation crystal has an outer diameter of 50-100 mm and a length of 80-150 mm. It is formed by splicing two separate BGO scintillation crystals along the axial direction after the end faces are polished.

3. The well-type gamma beam monitoring detector according to claim 1, characterized in that, The scattering layer is an aluminum foil or plastic film structure with a thickness of 5-50 μm. The scattering layer is fixed to the incident end of the through-hole by adhesive bonding and is used for Compton scattering of incident gamma rays.

4. The well-type gamma beam monitoring detector according to claim 1, characterized in that, The photoelectric sensor is a silicon photomultiplier tube, and the silicon photomultiplier tube is connected to the emission end of the BGO scintillation crystal through an optical coupler.

5. The well-type gamma beam monitoring detector according to claim 1, characterized in that, The fluorescent reflective layer is made of polytetrafluoroethylene and has a thickness of 0.2 mm or more. The fluorescent reflective layer is wrapped around the outer surface of the BGO scintillation crystal to improve light collection efficiency.

6. The well-type gamma beam monitoring detector according to claim 1, characterized in that, It also includes a plumb line collimator, which is located on the incident side of the detector. The diameter of the through-hole of the plumb line collimator is smaller than the diameter of the central axial through-hole of the BGO scintillation crystal, but larger than the diameter of the gamma beam spot.

7. The well-type gamma beam monitoring detector according to claim 6, characterized in that, The detector is designed to operate in a vacuum environment, where the vacuum level is no higher than 10. -2 Pa.

8. The well-type gamma beam monitoring detector according to claim 7, characterized in that, The detector is equipped with a vacuum tube, both ends of which are sealed with aluminum or beryllium windows with a thickness of no more than 0.1 mm; the distance between the vertical collimator and the incident end of the vacuum tube is no less than 60 cm, and the distance between the detector and the exit end of the vacuum tube is no less than 10 cm.

9. The well-type gamma beam monitoring detector according to claim 1, characterized in that, It also includes a flexible light guide, which is a sheet-like structure with a through hole in the center, and is fitted between the emitting end of the BGO scintillation crystal and the photoelectric sensor to realize the transmission of light signals; the inner diameter of the protective shell is adapted to the outer diameter of the BGO scintillation crystal, and the core components of the detector are completely covered to achieve protection and fixation.

10. The well-type gamma beam monitoring detector according to any one of claims 1-9, characterized in that, It also includes a power supply and signal output component, which is electrically connected to the photoelectric sensor to provide the working voltage to the photoelectric sensor and output the detection signal collected by the photoelectric sensor.

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