A dose calibration system and method for a wide energy spectrum neutron radiation detector

Abstract

The present invention discloses a dose calibration system and method for a wide-energy-spectrum neutron radiation detector. The system comprises a neutron target device, a deflection system, a beam waste bin, a neutron collimator, and a test bench, which are sequentially arranged. The neutron target device is used to generate high-yield neutrons; the deflection system is used to deflect the proton beam remaining after passing through the neutron target device; the beam waste bin is used to collect and shield the deflected proton beam and radiation field; the neutron collimator is used to shield the background neutron radiation field that needs to be eliminated; and the test bench is used to calibrate the high-energy, narrow-spectrum neutron dose after the background neutron radiation field is eliminated. This solution can improve the accuracy of high-energy neutron dose calibration for a wide-energy-spectrum neutron radiation detector.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation monitoring, and in particular to a dose calibration system and method for a wide energy spectrum neutron radiation detector. Background Art

[0002] A neutron radiation monitor is an instrument used to measure neutron radiation, capable of detecting neutrons across different energy ranges. During nuclear equipment construction and operation, as well as in neutron-related applications, neutron radiation is present in the surrounding environment. Neutron radiation dose equivalent monitoring is essential during these applications.

[0003] The traditional neutron radiation detector dose calibration method is: use a neutron source of known intensity and energy to perform response measurement; use the neutron source to perform energy spectrum measurement on the neutron number and energy distribution in each energy range; use the results of response measurement and energy spectrum measurement to perform dose calibration and establish a relationship curve between response and dose; after completing the dose calibration, verify and adjust the neutron radiation detector by comparing the neutron source of known intensity and energy with the calibrated results.

[0004] However, existing calibration methods and equipment suffer from inaccurate response and dose calibration, leading to misjudgment of neutron radiation exposure. This can prevent people from taking appropriate protective measures in a timely manner when exposed to radiation, increasing the potential risks of neutron radiation to people and the environment. In proton therapy applications, if neutron radiation dose cannot be accurately measured and monitored, it may not be possible to ensure that patients receive the intended treatment dose, affecting treatment effectiveness and safety. Summary of the Invention

[0005] To improve the accuracy of energy and dose response calibration of neutron radiation detectors, this paper proposes a dose calibration system and method for wide-energy-spectrum neutron radiation detectors. A high-purity lithium target is used to generate a high-yield of neutrons, and a Halbach array permanent magnet is used to achieve large-angle deflection of the proton beam in a small space. Background neutrons are minimized by using a beam trash can and collimator designed using an optimization algorithm, thereby improving the accuracy of monoenergetic neutron dose calibration.

[0006] According to a first aspect of the present invention, a dose calibration system for a wide energy spectrum neutron radiation detector is provided, comprising: a neutron target device, a deflection system, a beam waste bin, a neutron collimator, and a test bench.

[0007] Among them, the neutron target device is used to make the proton beam produce high-yield neutrons; the deflection system is used to deflect the proton beam remaining after passing through the neutron target device; the beam trash can is used to collect and shield the deflected proton beam and radiation field; the neutron collimator is used to shield the background neutron radiation field that needs to be eliminated; and the test bench is used to calibrate the high-energy narrow-spectrum neutron dose after eliminating the background neutron radiation field.

[0008] The system can perform real-time calibration testing and response performance testing on the dose response of a wide energy response neutron radiation detector, eliminate the radiation field of background neutrons to the maximum extent, and improve the accuracy of monoenergetic narrow spectrum neutron dose calibration.

[0009] Optionally, in the above-mentioned dose calibration system, the neutron target device adopts a lithium target, and the lithium target adopts a lithium target film of 2-167 mg / cm2, and the thickness of the lithium target film is proportional to the yield of monoenergetic neutrons.

[0010] Optionally, in the above-mentioned dose calibration system, the deflection system uses an annular Halbach permanent magnet array to deflect the proton beam remaining after passing through the neutron target device, and the magnetic field strength of the array permanent magnet is 1.5T.

[0011] Optionally, in the above-mentioned dose calibration system, the good field range of the annular Halbach permanent magnet array is 20 mm, which is used to make the deflection angle of the proton beam with energy of 70 MeV-235 MeV range from 10° to 5°.

[0012] Optionally, in the above-mentioned dose calibration system, the neutron collimator is used to eliminate background neutrons with a radiation intensity less than a preset intensity value and to shield the radiation field of reflected neutrons.

[0013] Optionally, in the above-mentioned dose calibration system, the material, size and shielding thickness of the beam trash can and the material, size and thickness of the neutron collimator are optimized by simulating the radiation field with Monte Carlo software.

[0014] According to a second aspect of the present invention, a dose calibration method for a wide-energy-response neutron radiation detector is provided, comprising: increasing the neutron yield by increasing the target film thickness of a lithium target; deflecting the discarded proton beam by adjusting the magnetic field strength of an annular Halbach permanent magnet array; optimizing the material, size, and thickness of a beam trash can and a neutron collimator based on a Monte Carlo method to maximize the elimination of background neutron radiation fields; and calibrating the high-energy narrow-spectrum neutron dose after the background neutron radiation fields have been eliminated.

[0015] Optionally, in the above dose calibration method, the magnetic field strength of the annular Halbach permanent magnet array is adjusted so that the permanent magnet good field range is 20 mm, and the deflection angle of the waste proton beam with an energy of 70 MeV-235 MeV is in the range of 10° to 5°.

[0016] According to the dose calibration scheme provided by the present invention, a high-purity lithium target is used to generate a high-yield neutron in a proton beam, an annular Halbach permanent magnet array is used to achieve large-angle deflection of the proton beam within a wide energy spectrum within a small space, and a Monte Carlo simulation method is used to optimize the material, size, and thickness of the beam trash can and collimator. This can minimize the background neutron radiation field and improve the accuracy of high-energy narrow-spectrum neutron dose calibration.

[0017] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0019] Figure 1 A schematic structural diagram of a dose calibration system for a wide energy spectrum neutron radiation detector according to an embodiment of the present invention is shown;

[0020] Figure 2 shows a relationship curve between neutron yields of different energies and target film thickness according to one embodiment of the present invention;

[0021] Figure 3 FIG2 shows a schematic diagram of a magnetic field distribution curve of an annular Halbach permanent magnet array according to an embodiment of the present invention;

[0022] Figure 4 shows a schematic diagram of proton beam deflection according to one embodiment of the present invention;

[0023] Figure 5 shows a schematic diagram of a neutron radiation energy spectrum curve according to an embodiment of the present invention;

[0024] Figure 6 A schematic flow chart of a dose calibration method 600 for a wide energy spectrum neutron radiation detector according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0026] Figure 1 FIG. 1 shows a schematic structural diagram of a dose calibration system for a wide energy spectrum neutron radiation detector according to an embodiment of the present invention. Figure 1 As shown, the calibration system includes: a neutron target device, a deflection system, a beam trash can, a neutron collimator and a test bench.

[0027] The proton beam generated by the proton therapy device bombards the neutron target device (lithium target) to produce neutrons with different wide energy spectra. The remaining proton beam is deflected by the deflection magnet and then collected and shielded by the beam trash can. The background neutrons in the wide energy spectrum neutrons are eliminated by the neutron collimator. Finally, the high-energy narrow-spectrum neutron dose is calibrated in real time on the test bench.

[0028] Among them, the neutron target device is used to make the proton beam produce high-yield neutrons. The proton beam accelerated by the accelerator bombards the lithium target to produce neutrons of different energies. In order to produce high-yield neutrons, this scheme uses a high-purity lithium target, which is prepared by the rolling method with a yield of 2-167 mg / cm 2 of lithium target film.

[0029] By studying the relationship between target film thickness and monoenergetic neutron yield, it can be seen that the thickness of the lithium target film is proportional to the monoenergetic neutron yield. Figure 2 FIG. 4 shows a relationship curve between neutron yield of different energies and Li target film thickness according to an embodiment of the present invention. Figure 2 As shown in Figure 2, the relationship between neutron yield and lithium target film thickness at energies of 70MeV, 150MeV, and 235MeV was studied, indicating that the thicker the target film, the greater the neutron yield. The thickness of the lithium target film can be appropriately increased to obtain a high neutron yield.

[0030] The deflection system is used to deflect the proton beam remaining after passing through the neutron target assembly. It uses a Halbach array of permanent magnets to deflect the proton beam. The array's magnetic field strength is 1.5 Tesla, allowing it to generate the strongest magnetic field with a minimal number of magnets.

[0031] Figure 3 FIG. 1 shows a schematic diagram of a magnetic field distribution curve of an annular Halbach permanent magnet array according to an embodiment of the present invention. Figure 3 As shown, by arranging magnets with different magnetization directions in sequence, the magnetic field strength on one side of the Halbach permanent magnet array is enhanced, while the magnetic field strength on the other side is weakened.

[0032] In one embodiment of the present invention, the good field range of the annular Halbach permanent magnet array is 20 mm, which is used to make the deflection angle of the proton beam with energy of 70 MeV-235 MeV range from 10° to 5°.

[0033] Figure 4 FIG. 1 shows a schematic diagram of proton beam deflection according to an embodiment of the present invention. Figure 4 As shown in the figure, after deflection by the annular Halbach permanent magnet array, the deflection angle of a proton beam with an energy of 235MeV is 5°, the deflection angle of a proton beam with an energy of 70MeV is 10°, and the deflection angles of proton beams with other energies are between 10° and 5°. The greater the energy, the smaller the deflection angle.

[0034] The beam trash can is used to collect and shield the deflected proton beam and radiation field. It is placed within the deflection angle range of the proton beam by the deflection system and is filled with water. The neutron collimator is used to shield the radiation field of background neutrons that need to be eliminated and reflected neutrons.

[0035] Radiation shielding can be systematically analyzed, and the material, size and shielding thickness of the beam trash can and the material, size and thickness of the neutron collimator can be optimized by simulating the radiation field using Monte Carlo software.

[0036] Among them, the use of Monte Carlo software calculations can comprehensively consider the attenuation effects of various reaction cross-sections and shielding bodies, and then optimize the shielding design to obtain the optimal shielding material and corresponding thickness to minimize background neutrons.

[0037] Figure 5 FIG. 1 shows a schematic diagram of a neutron radiation energy spectrum curve according to an embodiment of the present invention. Figure 5 As shown in the figure, the neutron energy spectrum curves for energies of 70MeV, 100MeV, 125MeV, 150MeV, 175MeV, 200MeV, and 235MeV contain a large number of low-intensity background neutrons that need to be eliminated. The test bench is used to calibrate the high-energy narrow-spectrum neutron dose after eliminating the background neutron radiation field.

[0038] Figure 6 FIG. 6 is a flow chart showing a dose calibration method 600 for a wide energy spectrum neutron radiation detector according to an embodiment of the present invention. Figure 6 As shown, the method 600 is executed by the dose calibration system of the wide energy spectrum neutron radiation detector as described above. The method 600 begins at step S610 , where the neutron yield is increased by increasing the target film thickness of the lithium target.

[0039] Research into neutron target physics design has revealed that neutron yield is proportional to the thickness of the lithium target film. Based on this relationship between target thickness and monoenergetic neutron yield, the target film thickness can be determined to produce a high neutron yield.

[0040] Then, step S620 is performed to deflect the wasted proton beam by adjusting the magnetic field strength of the annular Halbach permanent magnet array.

[0041] By adjusting the magnetic field strength of the annular Halbach permanent magnet array to a good field range of 20 mm, the deflection angle of the waste proton beam with energies of 70 MeV to 235 MeV can be adjusted to a range of 10° to 5°. This allows for large-angle beam deflection within a small space, preventing the waste proton beam from entering the subsequent calibration platform.

[0042] Then, step S630 is performed to optimize and adjust the material, size, and thickness of the beam trash can and the neutron collimator based on the Monte Carlo method to maximize the elimination of the background neutron radiation field.

[0043] Among them, background neutrons are neutrons with low radiation intensity in a wide energy response. Background neutrons will affect the accuracy of subsequent monoenergetic neutron dose calibration. Therefore, the radiation field of background neutrons needs to be shielded. Through the optimized design of beam trash cans and neutron collimators, the radiation field of background neutrons can be eliminated to the maximum extent.

[0044] Finally, step S640 is executed to calibrate the high-energy narrow-spectrum neutron dose after eliminating the background neutron radiation field.

[0045] Since wide-spectrum neutron radiation detectors have a wider energy response range than conventional neutron radiation detectors, when performing high-energy neutron dose calibration, the accuracy of dose calibration can be improved by eliminating unnecessary background neutrons and only detecting the single-energy peak radiation intensity.

[0046] According to the dose calibration system and method provided by the present invention, a high-purity lithium target is used to generate a high-yield neutron in a proton beam, an annular Halbach permanent magnet array is used to achieve large-angle deflection of the proton beam within a wide energy spectrum within a small space, and a Monte Carlo simulation method is used to optimize the material, size, and thickness of the beam trash can and collimator. This can minimize background neutrons and improve the accuracy of high-energy narrow-spectrum neutron dose calibration.

[0047] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures, and techniques are not shown in detail so as not to obscure the understanding of this description.

[0048] Similarly, it should be understood that in order to streamline the present disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, this disclosed method should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims below, inventive aspects lie in less than all the features of the individual embodiments disclosed above. Accordingly, the claims that follow the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the invention.

[0049] Those skilled in the art will appreciate that the modules, units, or components of the devices in the examples disclosed herein may be arranged in the device described in the embodiment, or alternatively may be located in one or more devices different from the devices in the examples. The modules in the foregoing examples may be combined into one module or further divided into multiple submodules.

[0050] Those skilled in the art will appreciate that the modules in the devices of the embodiments can be adaptively modified and installed in one or more devices different from the embodiments. The modules, units, or components in the embodiments can be combined into a single module, unit, or component, and furthermore, they can be divided into multiple sub-modules, sub-units, or sub-components. All features disclosed in this specification (including the accompanying claims, abstract, and drawings), and all processes or units of any method or device disclosed therein, can be combined in any combination, unless at least some of such features and / or processes or units are mutually exclusive. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0051] Furthermore, those skilled in the art will appreciate that although some embodiments described herein include certain features included in other embodiments but not other features, combinations of features from different embodiments are intended to be within the scope of the present invention and to form different embodiments. For example, in the claims below, any of the claimed embodiments may be used in any combination.

[0052] In addition, some of the embodiments are described herein as methods or combinations of method elements that can be implemented by a processor of a computer system or by other devices that perform the functions. Thus, a processor having the necessary instructions for implementing a method or method element forms a device for implementing the method or method element. In addition, the elements described herein of the device embodiments are examples of devices for implementing the functions performed by the elements for the purpose of implementing the invention.

[0053] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved and are not intended to imply that the objects so described must have a given order in time, space, ranking, or in any other manner.

[0054] Although the present invention has been described with respect to a limited number of embodiments, it will be apparent to those skilled in the art, having benefit of the foregoing description, that other embodiments are contemplated within the scope of the invention thus described. Furthermore, it should be noted that the language used in this specification has been selected primarily for readability and didactic purposes, rather than for the purpose of explaining or limiting the subject matter of the present invention. Consequently, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is intended to be illustrative and not restrictive of the scope of the invention, which is defined by the appended claims.

Claims

1. A dose calibration system for a wide energy spectrum neutron radiation detector, characterized in that: It includes a neutron target device, a deflection system, a beam waste bin, a neutron collimator and a test bench placed in sequence. The neutron target device is used to make the proton beam produce high-yield neutrons; the deflection system is used to deflect the proton beam remaining after passing through the neutron target device; the beam trash can is used to collect and shield the deflected proton beam and radiation field; the neutron collimator is used to shield the background neutron radiation field that needs to be eliminated; the test bench is used to calibrate the high-energy narrow-spectrum neutron dose after eliminating the background neutron radiation field, wherein the neutron target device uses a lithium target, and the lithium target uses 2-167 mg / cm 2 The invention relates to a lithium target film, wherein the thickness of the lithium target film is proportional to the yield of monoenergetic neutrons; the deflection system uses an annular Halbach permanent magnet array to deflect the proton beam remaining after passing through the neutron target device, and the magnetic field strength of the annular Halbach permanent magnet array is 1.5 T; the good field range of the annular Halbach permanent magnet array is 20 mm, and is used to make the deflection angle of the proton beam with an energy of 70 MeV-235 MeV within the range of 10° to 5°; the beam waste bin is placed within the deflection angle range of the proton beam by the deflection system, and the beam waste bin is filled with water.

2. The dose calibration system for a wide energy spectrum neutron radiation detector according to claim 1, characterized in that: The neutron collimator is used to eliminate background neutrons whose radiation intensity is less than a preset intensity value and to shield the radiation field of reflected neutrons.

3. The dose calibration system for a wide energy spectrum neutron radiation detector according to claim 1, characterized in that: The material, size and shielding thickness of the beam trash can and the material, size and thickness of the neutron collimator are optimized by simulating the radiation field with Monte Carlo software.

4. A dose calibration method for a wide energy spectrum neutron radiation detector, characterized in that: The method is implemented by a dose calibration system for a wide energy spectrum neutron radiation detector according to any one of claims 1 to 3, and the method comprises: The neutron yield is increased by increasing the target film thickness of the lithium target; By adjusting the magnetic field strength of the annular Halbach permanent magnet array so that the good field range of the permanent magnet is 20 mm, the deflection angle of the waste proton beam with an energy of 70 MeV-235 MeV is within the range of 10° to 5°; The materials, sizes, and thicknesses of the beam trash can and neutron collimator are optimized based on the Monte Carlo method to maximize the elimination of background neutron radiation fields. The high-energy narrow-spectrum neutron dose is calibrated after eliminating the background neutron radiation field.

Images