PGAI-NT analysis device and method based on accelerator cone-shaped thermal neutron beam

Abstract

The application discloses a PGAI-NT analysis device and method based on an accelerator cone-shaped thermal neutron beam, which comprises an accelerator D-Be double-target-point graphite-moderated body neutron source adopting a semicircular Be target design, wherein a D ion beam generated by the accelerator bombards two semicircular Be targets to form two wide-energy-spectrum neutron sources, and the two wide-energy-spectrum neutron sources are subjected to graphite moderation to form parallel beam thermal neutrons; a neutron beam focusing device for converging the parallel beam thermal neutrons into cone-shaped beam thermal neutrons; a sample table for placing a sample to be measured, so that the cone-shaped beam thermal neutrons irradiate the sample; a line collimator for collimating γ rays generated after the cone-shaped beam thermal neutrons irradiate the sample; a LaBr3 array detector for detecting the collimated γ signals; and an imaging device for detecting and imaging the cone-shaped beam thermal neutrons after passing through the sample.

Description

Technical Field

[0001] This invention relates to the field of transient gamma activation imaging technology, specifically to a PGAI-NT analysis device and method based on an accelerator cone thermal neutron beam. Background Technology

[0002] Immediately emitted gamma-ray activation imaging (PGAI-NT) is a non-destructive, highly sensitive 3D elemental imaging technique that has played a significant role in materials science, archaeology, and nuclear security. The precise measurement of three-dimensional elemental distribution information is of great importance in the field of archaeology, providing support for the identification, restoration, and preservation of cultural relics.

[0003] The earliest PGAI (Precision Proton Algorithm) was built on reactors, with Hungary's BRR and France's FRMII having established PGAI test sites. They employed a single neutron beam and single gamma beam collimation mapping mode. Chen et al. used a dual-layer CZT Compton camera to achieve the localization and detection of elements such as H, Cl, and Ti. Lee et al. used a gamma coincidence detector composed of high-purity germanium and a position-sensitive detector to achieve PGAI of elements such as Ni and Fe, reducing the imaging time of bulk samples to some extent. Traditional PGAI-NT is mostly based on reactor neutron sources, with some based on DD / DT neutron sources. DD / DT-based neutron sources have limited intensity, with neutron flux at the sample level around 10⁻⁶. 3 n / cm 2 / s~10 4 n / cm 2 Between / s, compared to traditional reactor neutron sources, the neutron flux is relatively low, and the measurement accuracy and measurement time are still unsatisfactory. Furthermore, the reactor neutron sources used in traditional methods have the disadvantages of being large in size, expensive, and complex to operate and maintain. Summary of the Invention

[0004] To achieve the above and other related objectives, this invention discloses a PGAI-NT analysis device based on an accelerator cone thermal neutron beam, comprising:

[0005] The accelerator D-Be dual-target graphite moderator neutron source adopts a semi-circular Be target design. The D ion beam generated by the accelerator bombards two semi-circular Be targets to form two broadband neutron sources, which are then converted into parallel beam thermal neutrons through the graphite moderator.

[0006] Neutron beam focusing equipment is used to focus parallel thermal neutron beams into a cone-shaped thermal neutron beam;

[0007] The sample stage is used to place the sample to be tested, so that the sample is irradiated by the cone beam of thermal neutrons;

[0008] Line collimator is used to collimate the gamma rays generated after a sample is irradiated by a cone beam of thermal neutrons.

[0009] LaBr3 array detectors are used to detect the aligned gamma signal;

[0010] Imaging equipment used to detect and image thermal neutrons in a cone-shaped beam after they have passed through a sample.

[0011] Preferably, the neutron beam focusing device is a capillary glass focusing tube.

[0012] Preferably, the neutron beam focusing device is a neutron focusing lens.

[0013] Preferably, the imaging device is a neutron imaging detector.

[0014] Preferably, the imaging device is a neutron semiconductor array detector.

[0015] Preferably, the imaging device is located in the magnification region of the focused neutrons, thus creating a magnified imaging effect.

[0016] Preferably, when the LaBr3 array detector performs detection, it uses the LaBr3 pixel below the collimator as the main detector and the LaBr3 pixel detectors around it as anti-cannon detectors to perform gamma spectrum analysis.

[0017] Preferably, when the neutron beam focusing device focuses parallel thermal neutrons into a conical thermal neutron beam, the focal point of the conical thermal neutron beam is focused on the side of the sample away from the neutron beam focusing device.

[0018] Preferably, the line collimator has multiple collimation holes arranged in a row.

[0019] Secondly, the present invention provides a PGAI-NT analysis method based on an accelerator cone thermal neutron beam, wherein the device described above is used to perform the following steps:

[0020] The accelerator generates a D-ion beam that bombards two semi-circular Be targets, producing broad-spectrum neutrons and achieving a thermal neutron fluence of 10-1. 6 n / cm 2 / s, after being moderated by graphite, parallel beam thermal neutrons are extracted;

[0021] Neutron beam focusing equipment focuses parallel thermal neutron beams to form a cone-shaped thermal neutron beam;

[0022] Adjust the neutron beam focusing device so that the focal point of the cone-shaped neutron beam is located behind the sample;

[0023] Adjust the position of the imaging device so that it is positioned within the focused neutron amplification region to create a magnified imaging effect;

[0024] The sample is irradiated with a cone-shaped thermal neutron beam, and the γ signal generated by the neutron is collimated using a linear collimator.

[0025] The LaBr3 array detector detects the gamma signal, using the LaBr3 pixel below the collimator aperture as the main detector and the surrounding LaBr3 pixel detectors as anti-cannon detectors for gamma spectrum analysis.

[0026] By adopting the above technical solution, a thermal neutron beam is generated using an accelerator-based D-Be dual-target graphite moderator neutron source. Compared with traditional reactor-based neutron beam generation methods, this approach offers higher flexibility, greater adjustability, and easier control. The equipment is also relatively smaller and less expensive. Furthermore, the neutron flux is higher than that of DD / DT neutron sources, meeting detection requirements. A neutron beam focusing device is then used to focus the parallel beam of thermal neutrons, forming a conical beam. This conical beam effectively reduces the scattering effect of thermal neutrons in the bulk sample, thereby improving measurement accuracy. A combination design of a linear array collimator and a LaBr3 array detector expands the traditional single-point imaging mode to multi-point imaging, improving imaging efficiency and time. Utilizing the LaBr3 array's "Compton-photoelectric" coincidence technology, the full-energy peak count rate is increased while suppressing the Compton effect, further optimizing imaging efficiency. Attached Figure Description

[0027] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. The drawings are provided for a better understanding of the invention and are not intended to limit the scope of this disclosure. In the drawings, the same or similar reference numerals denote the same or similar elements, wherein:

[0028] Figure 1 This is a schematic diagram of the structure of the present invention.

[0029] Figure reference numerals: 1. Accelerator D-Be dual-target graphite moderator neutron source; 2. Neutron beam focusing device; 3. Sample stage; 4. Linear collimator; 5. LaBr3 array detector; 6. Imaging device. Detailed Implementation

[0030] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Reference Figure 1 This invention provides a PGAI-NT analysis device based on an accelerator cone thermal neutron beam, comprising:

[0032] The accelerator D-Be dual-target graphite moderator neutron source 1 adopts a semi-circular Be target design. The D ion beam generated by the accelerator preferably has a D ion beam specification of 10MeV 50μA. Half of the D ion beam bombards the first Be target and the other half bombards the second Be target, forming two broad-spectrum neutron sources. After passing through the graphite moderator, parallel beam thermal neutrons are formed.

[0033] Neutron beam focusing device 2 is located at the exit of the D-Be dual-target graphite moderator neutron source 1 of the accelerator and is used to focus parallel thermal neutron beams into conical thermal neutron beams.

[0034] Sample stage 3 is used to place the sample to be tested, so that the sample is irradiated by the cone beam of thermal neutrons;

[0035] Line collimator 4 is used to collimate the γ-rays generated after the sample is irradiated by a cone beam of thermal neutrons.

[0036] The LaBr3 array detector 5 is used to detect the aligned gamma signal;

[0037] Imaging device 6 is used to detect and image the cone-shaped thermal neutrons after they pass through the sample.

[0038] The aforementioned D-Be dual-target graphite moderator neutron source 1 of the accelerator is used to generate parallel beam thermal neutrons, and the neutrons generated by this neutron source can reach 10 6 n / cm 2 / s, which can meet the requirements of PGAI-NT, is lower in cost, more flexible, more adjustable and easier to control than traditional reactor neutron sources, making it more suitable for laboratory use.

[0039] After the parallel beam of thermal neutrons is generated by the D-Be dual-target graphite moderator neutron source 1 of the accelerator, it is extracted to the neutron beam focusing device 2 through the neutron extraction system. In this embodiment, the neutron conduit is used to guide the thermal neutron beam, which will not be described in detail here.

[0040] The neutron beam focusing device 2 is used to converge parallel beam thermal neutrons into a cone-shaped beam. Compared with the traditional method of irradiating the sample with parallel beam thermal neutrons, this reduces the scattering effect of thermal neutrons in the sample, thereby improving detection accuracy. In this embodiment, the neutron beam focusing device 2 can be a capillary glass focusing tube or other types of neutron focusing lenses, as long as they can achieve the function of focusing the parallel neutron beam. The specific choice can be made by those skilled in the art based on actual usage needs, and will not be elaborated here. When the neutron beam focusing device 2 converges the parallel beam thermal neutrons into a cone-shaped beam, the focal point of the cone-shaped beam is focused on the side of the sample away from the neutron beam focusing device 2, reducing thermal neutron scattering.

[0041] The linear collimator 4 is a cuboid composed of materials such as W and Pb, and is equipped with a row of collimation holes. The linear collimator 4 is used to collimate the gamma rays generated after the sample is irradiated by neutrons, so that the gamma rays enter the LaBr3 array detector 5 along a specific direction, reducing the interference of scattered gamma rays on the detection results. Through collimation, the source position of gamma rays can be determined more accurately, thereby improving the positioning accuracy of the elemental distribution of the sample.

[0042] The LaBr3 array detector 5 is made of LaBr3 crystal cut into cubes, with Al and other light-reflecting layers between each cube, and SiPM is used for readout at the readout end. When the LaBr3 array detector is performing detection, the LaBr3 pixel below the alignment collimator 4 is used as the main detector, and the LaBr3 pixel detectors around it are used as anti-cannon detectors for gamma spectrum analysis.

[0043] LaBr3 crystals possess high density and atomic number, exhibiting a strong photoelectric effect cross-section for gamma rays. This allows for efficient detection and absorption of gamma rays, converting them into visible light signals, thus enabling highly efficient gamma ray detection. LaBr3 crystals also provide good energy resolution, facilitating the differentiation of gamma rays with different energies. This allows for more accurate identification and analysis of characteristic gamma rays emitted by different elements in the sample, providing a more reliable data foundation for qualitative and quantitative elemental analysis. When used in conjunction with a linear collimator 4, spatial positioning and directional control of gamma rays can be achieved. By using the LaBr3 pixel below the collimator aperture as the main detector and the surrounding pixels as anti-Compton detectors, coincidence detection is performed, effectively suppressing the Compton scattering background signal and improving the signal-to-noise ratio and positioning accuracy of the gamma ray source. The LaBr3 array detector 5, composed of multiple pixel units, can simultaneously detect gamma rays emitted from different locations on the sample, achieving multi-point simultaneous imaging. Compared to traditional single-point detection methods, this significantly improves imaging speed and efficiency, enabling faster acquisition of three-dimensional elemental distribution information of the sample. The design employs a combination of a linear array collimator and a LaBr3 array detector 5, expanding from the traditional single-point imaging mode to multi-point imaging, thereby improving imaging efficiency and time. By utilizing the "Compton-photoelectric" composite technology of the LaBr3 array, the full-energy peak count rate is increased while suppressing the Compton effect, further optimizing imaging efficiency.

[0044] The imaging device 6 in this embodiment is a neutron imaging detector or a neutron semiconductor array detector. The imaging device 6 can also be replaced according to the actual needs of those skilled in the art, which will not be elaborated here.

[0045] Secondly, the present invention provides a PGAI-NT analysis method based on an accelerator cone thermal neutron beam, wherein the device described above is used to perform the following steps:

[0046] The accelerator generates a D-ion beam that bombards two semi-circular Be targets, producing broad-spectrum neutrons and achieving a thermal neutron fluence of 10-1. 6 n / cm 2 / s, after being moderated by graphite, parallel beam thermal neutrons are extracted;

[0047] Neutron beam focusing device 2 focuses parallel thermal neutron beams to form a cone-shaped thermal neutron beam;

[0048] Adjust the neutron beam focusing device 2 so that the focal point of the cone-shaped neutron beam is located behind the sample;

[0049] Adjust the position of imaging device 6 so that it is positioned in the focused neutron amplification region to create a magnified imaging effect;

[0050] The sample was irradiated with a cone-shaped thermal neutron beam, and the γ signal generated by the neutron was collimated using a linear collimator 4.

[0051] The LaBr3 array detector 5 detects the γ signal. The LaBr3 pixel below the collimator 4 hole is used as the main detector, and the surrounding LaBr3 pixel detectors are used as anti-cannon detectors for γ spectrum analysis.

[0052] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0053] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the embodiments of the present invention are not limited to the described order of actions, because according to the embodiments of the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions involved are not necessarily essential to the embodiments of the present invention.

[0054] As can be seen from the above description of the embodiments, those skilled in the art can clearly understand that this application can be implemented by means of software plus necessary general-purpose hardware platforms. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of this application.

[0055] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A PGAI-NT analysis device based on an accelerator cone-shaped thermal neutron beam, characterized in that, include: An accelerator-D-Be dual-target graphite moderator neutron source includes an accelerator, two semi-circular Be targets, and a graphite moderator. The D-ion beam generated by the accelerator can bombard the two semi-circular Be targets respectively to form two broad-spectrum neutron sources, and then form parallel beam thermal neutrons through the graphite moderator. A neutron beam focusing device, wherein the neutron beam focusing device is a capillary glass focusing tube or a neutron focusing lens, is used to focus the parallel thermal neutron beam into a cone-shaped thermal neutron beam; The sample stage is used to place the sample to be tested, so that the cone-shaped thermal neutron beam irradiates the sample; A linear collimator, which is cuboid in shape and has multiple collimation holes arranged in a row, is used to collimate the gamma rays generated after the sample is irradiated by the thermal neutrons of the cone beam. The LaBr3 array detector includes multiple cubic pixels formed by LaBr3 crystals, with an Al light-reflecting layer between each cubic pixel. The readout end of the LaBr3 array detector is read out using SiPM. The LaBr3 pixel aligned with the collimation aperture of the linear collimator serves as the main detector, and the LaBr3 pixels located around the main detector serve as anti-cannon detectors for gamma-ray spectral analysis. Imaging equipment used to detect and image thermal neutrons in a cone-shaped beam after they have passed through a sample.

2. The PGAI-NT analysis device based on an accelerator cone-shaped thermal neutron beam according to claim 1, characterized in that, The imaging device is a neutron imaging detector.

3. The PGAI-NT analysis device based on an accelerator cone-shaped thermal neutron beam according to claim 1, characterized in that, The imaging device is a neutron semiconductor array detector.

4. The PGAI-NT analysis device based on an accelerator cone-shaped thermal neutron beam according to claim 1, characterized in that, The imaging device is located in the magnification region of the focused neutrons, thus creating a magnified imaging effect.

5. The PGAI-NT analysis device based on an accelerator cone-shaped thermal neutron beam according to claim 1, characterized in that, When the neutron beam focusing device focuses parallel thermal neutrons into a conical thermal neutron beam, the focal point of the conical thermal neutron beam is focused on the side of the sample away from the neutron beam focusing device.

6. A PGAI-NT analysis method based on an accelerator cone-shaped thermal neutron beam, characterized in that, The following steps are performed using the apparatus according to any one of claims 1 to 5: The accelerator generates a D-ion beam that bombards two semi-circular Be targets, producing broad-spectrum neutrons, resulting in a thermal neutron fluence of [missing information]. Neutrons are slowed down by graphite and then extracted into parallel beams of thermal neutrons. Neutron beam focusing equipment focuses parallel thermal neutron beams to form a cone-shaped thermal neutron beam; Adjust the neutron beam focusing device so that the focal point of the cone-shaped neutron beam is located behind the sample; Adjust the position of the imaging device so that it is positioned within the focused neutron amplification region to create a magnified imaging effect; The sample is irradiated with a cone-shaped thermal neutron beam, and the γ signal generated by the neutron is collimated using a linear collimator. The LaBr3 array detector detects the gamma signal, using the LaBr3 pixel below the collimator aperture as the main detector and the surrounding LaBr3 pixel detectors as anti-cannon detectors for gamma spectrum analysis.

Images