Composite proliferation target system for BNCT

Abstract

The invention relates to the technical field of composite targets, and discloses a composite proliferation target system for BNCT, the composite proliferation target system comprises a Be-Li composite target and a primary proliferation system, the primary proliferation system is located right behind the Be-Li composite target, the primary proliferation system and the Be-Li composite target form a composite target structure, the primary proliferation system comprises a uranium layer and an aluminum substrate layer, the uranium layer is attached to the aluminum substrate layer, and the uranium layer is attached to the aluminum substrate layer. By optimizing the neutron generation and proliferation process, the output efficiency and quality of neutrons can be effectively improved, so that a more efficient neutron source is provided for the BNCT, the invention provides the composite proliferation target system for the BNCT, the neutron yield after proton targeting can be improved, and meanwhile, the neutron energy generated by the Li layer tends to be consistent with the neutron energy generated by the Be layer.

Description

Technical Field

[0001] The present invention relates to the technical field of composite targets, and particularly relates to a composite breeding target system for BNCT. Background Art

[0002] Cancer seriously threatens human health and is the most important issue in the medical field in the world today. Radiotherapy uses the energy released by ionizing radiation to kill cancer cells and has become one of the effective means for treating cancer. Boron Neutron Capture Therapy (BNCT) is a binary, targeted, and cell-level precise radiotherapy method. Its principle is that a boron-containing drug specifically accumulates at the tumor site, and a neutron is used to trigger the boron-10 nuclear fission reaction to release high-energy particles to selectively destroy cancer cells. Compared with traditional radiotherapy, BNCT has the advantage of cell-level targeted killing and is particularly suitable for invasive and recurrent tumors.

[0003] As the core of treatment, the current mainstream solution for the neutron source is to shift from a nuclear reactor to an accelerator (AB-BNCT). According to the latest report of the IAEA, the fluence rate of epithermal neutrons (0.5 eV to 40 keV) for treatment needs to exceed 5×108 cm -2 ·s -2 , which is difficult to achieve for AB-BNCT. Therefore, it is necessary to increase the neutron yield after proton bombardment to increase the fluence rate of epithermal neutrons at the exit beam port. The most commonly used target materials are Li targets or 9 Be targets. 7 Li has an extremely high neutron resonance cross-section (580 mb) at 2.25 MeV. 9 For Be targets, the neutron yield continuously increases as the incident proton energy increases. For 9 Be targets, as the incident proton energy becomes deeper with the depth of the incident target, the proton energy will continuously decrease. When the proton energy is 2.5 MeV, the neutron yield per unit proton current is much lower than that of 7 Li at this energy. Currently, common composite target systems include Be-Li composite targets and the beam shaping apparatus for BNCT. Since the proton energy continuously decreases from the 9 Be target to the Li target, if it is only a Be-Li composite target, the neutron energy from the 9 Be target is much higher than the neutron energy from the Li target. After the two parts of neutrons pass through the beam shaping apparatus (BSA) of BNCT, the neutrons from the Li target will all be absorbed, and there is almost no improvement effect on the neutron fluence rate at the final exit window. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a composite breeding target system for BNCT, which can improve the neutron yield after proton bombardment and make the neutron energies generated in the Li layer and the Be layer tend to be consistent.

[0005] The present invention provides a composite breeding target system for BNCT, comprising: a Be-Li composite target and a primary breeding system. The primary breeding system is located directly behind the Be-Li composite target, and the two form a composite target structure. Among them, the primary breeding system includes a uranium layer and an aluminum substrate layer. The uranium layer is attached to the aluminum substrate layer. By optimizing the neutron generation and breeding process, the output efficiency and quality of neutrons can be effectively improved, thereby providing a more efficient neutron source for BNCT.

[0006] Optionally, the uranium layer and the aluminum substrate layer form a uranium breeding layer, and the primary breeding system includes multiple layers of uranium breeding layers.

[0007] Optionally, there are gaps between the multiple layers of uranium breeding layers.

[0008] Optionally, it further includes a secondary breeding system, and the secondary breeding system includes 9 Be balls, 9 The Be balls are wrapped around the periphery of the composite target structure. The design of the secondary breeding system enables the system to adapt to proton beams and neutron sources of different energies, with high flexibility and applicability.

[0009] Optionally, 9 the diameter of the Be balls is obtained by simulating the incident proton energy using the Monte Carlo algorithm.

[0010] Optionally, the secondary breeding system further includes a Pb layer wrapped around the 9 periphery of the Be balls.

[0011] Optionally, the thickness of the Pb layer is obtained by simulating the incident proton energy using the Monte Carlo algorithm.

[0012] Optionally, the Be-Li composite target is fixed to the surfaces of a copper substrate and a vanadium substrate by coating, and the copper substrate is closely attached to the Be-Li composite target.

[0013] Optionally, in the Be-Li composite target, the Be layer is located directly in front of the Li layer.

[0014] The technical solutions provided by the embodiments of the present invention have the following advantages compared with the prior art: The composite multiplication target system for BNCT provided by the embodiments of the present invention fully combines the advantageous energy regions of the reactions of Be targets and Li targets with protons to increase the neutron yield. When the proton energy is relatively high, the reaction of Be with protons can produce a relatively high neutron yield. As the proton penetration depth increases deeper and deeper, the proton energy becomes lower and lower. When the protons enter the Li target, a relatively large neutron yield is generated by utilizing the resonance cross-section of Li. A primary multiplication system is placed directly behind the Be-Li composite target so that more neutrons generated after protons bombard the target can undergo fission reactions with uranium to multiply the neutron yield. Since the reaction of protons with Be usually requires a relatively high proton energy, according to the law of conservation of energy, the released neutrons have a relatively high energy, and a relatively thick BSA is required to slow them down to the epithermal neutron energy region for treatment. However, the neutrons released by the reaction of protons with Li near the resonance energy region have a relatively low energy and will be absorbed after entering the BSA, greatly reducing the effect of the composite target in increasing the yield. The uranium in the primary multiplication system has a relatively high fission reaction cross-section for reactions with low-energy neutrons and will release neutrons with a relatively high energy. After being slowed down and shaped by the BSA, there will still be more neutrons reserved for treatment. Therefore, the primary multiplication system can make the neutron energy generated by the Li layer tend to be consistent with the neutron energy generated by the Be layer while increasing the neutron yield. Description of the Drawings

[0015] Figure 1 It is a flowchart of a composite multiplication target system for BNCT provided by the embodiments of the present invention; Figure 2 Provided by the embodiments of the present invention 9 (N, 2N) reaction cross-section of Be; Figure 3 Provided by the embodiments of the present invention 206 (N, 2N) reaction cross-section of Pb; Figure 4 Provided by the embodiments of the present invention 207 (N, 2N) reaction cross-section of Pb; Figure 5 Provided by the embodiments of the present invention 208 (N, 2N) reaction cross-section of Pb; Figure 6 It is a schematic structural diagram of the composite target structure provided by the embodiments of the present invention; Figure 7 It is a schematic structural diagram of a composite multiplication target system for BNCT provided by the embodiments of the present invention; Figure 8 It is a comparison of the neutron fluence of the composite multiplication target system (A) for BNCT provided by the embodiments of the present invention with that of the non-composite target system (B) and the pure Be target without the multiplication system, where the proton energy is 14 MeV.

[0016] Description of the reference numerals: 1. Be-Li composite target; 10. Be layer; 11. Li layer; 2. Primary multiplication system; 20. Uranium layer; 21. Aluminum substrate layer; 3. Secondary multiplication system; 30. 9 Be sphere; 31. Pb layer; 4. Copper substrate; 5. Vanadium substrate. Specific embodiments

[0017] The following combines the accompanying drawings to describe in detail a specific embodiment of the present invention. However, it should be understood that the protection scope of the present invention is not limited by the specific embodiment.

[0018] In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the technical solution of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be construed as a limitation of the present invention.

[0019] Currently, common composite target systems include Be-Li composite targets and beam shaping devices for BNCT. Since the energy of protons continuously decreases from 9 the Be target to the Li target, if it is only a Be-Li composite target, the neutrons from 9 the Be target have much higher energy than the neutrons from the Li target. After the two parts of neutrons pass through the beam shaping device (BSA) of BNCT, the neutrons from the Li target will all be absorbed, and there is almost no improvement effect on the neutron fluence rate of the final exit window.

[0020] Therefore, the embodiments of the present invention provide a composite multiplication target system for BNCT, which can improve the neutron yield after proton bombardment of the target, and at the same time make the neutron energies generated by the Li layer and the Be layer tend to be consistent.

[0021] At least one embodiment of the present invention provides a composite multiplication target system for BNCT, including: a Be-Li composite target and a primary multiplication system. The primary multiplication system is located directly behind the Be-Li composite target, and the two form a composite target structure. Among them, the primary multiplication system includes a uranium layer and an aluminum substrate layer, and the uranium layer is attached to the aluminum substrate layer.

[0022] In the composite multiplication target system for BNCT provided by the above embodiments of the present invention, the advantageous energy regions of the reactions of the Be target and the Li target with protons are fully combined to increase the neutron yield. Through the primary multiplication system, on the basis of increasing the neutron yield, the neutron energies generated in the Li layer can be made to approach those generated in the Be layer.

[0023] The present invention will be described below through several specific embodiments. To keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of known functions and known components may be omitted. When any component of an embodiment of the present invention appears in more than one drawing, the component may be denoted by the same reference numeral in each drawing.

[0024] Reference Figure 1 、 Figure 6 and Figure 7 , Figure 1 is a flowchart of a composite multiplication target system for BNCT provided by an embodiment of the present invention, Figure 6 is a schematic structural diagram of the composite target structure provided by an embodiment of the present invention, Figure 7 is a schematic structural diagram of a composite multiplication target system for BNCT provided by an embodiment of the present invention. As shown in Figure 1 、 Figure 6 and Figure 7 show, an embodiment of the present invention provides a composite multiplication target system for BNCT, including: a Be-Li composite target 1 and a primary multiplication system 2. The Be-Li composite target 1 is one of the core components of this system, and its main function is to generate neutrons through the nuclear reaction of protons with the target material. The Be-Li composite target 1 is usually composed of two materials, beryllium (Be) and lithium (Li). These two materials have excellent performance in neutron generation. Beryllium has a high neutron yield when the proton energy is relatively high, while lithium has a high neutron resonance cross-section and a high neutron yield when the proton energy is about 2.25 MeV. By using these two materials in combination, the neutron generation efficiency can be significantly improved. The primary multiplication system 2 is located directly behind the Be-Li composite target 1, and its main function is to further multiply and optimize the neutrons generated by the Be-Li composite target 1, forming a composite target structure. Among them, the primary multiplication system 2 includes a uranium layer 20 and an aluminum substrate layer 21. The uranium layer 20 is attached to the aluminum substrate layer 21. The uranium layer 20 is a key material for multiplying neutrons, and usually enriched uranium is used (such as 235U) As a multiplication material, the uranium layer 20 generates more secondary neutrons through the fission reaction of neutrons with uranium nuclei, thus achieving neutron multiplication. The thickness and distribution of the uranium layer 20 are carefully designed to ensure the maximization of neutron multiplication efficiency while avoiding excessive neutron loss. The aluminum substrate layer 21, as the support structure of the uranium layer 20, not only has good mechanical strength but also can effectively reduce neutron absorption. The design of the aluminum substrate layer 21 takes into account heat conduction and heat dissipation issues to ensure the stability of the system during high-power operation.

[0025] Uranium (especially 235 U) has a relatively high fission reaction cross-section. Especially when bombarded by low-energy neutrons, uranium can release more secondary neutrons through fission reactions. These secondary neutrons have relatively high energies and can still retain a relatively large number of neutrons for treatment after moderation. Therefore, the introduction of the uranium layer not only increases the neutron yield but also makes the neutron energies generated by the Li target tend to be consistent with those generated by the Be target, thereby optimizing the neutron energy distribution. The neutrons generated by the Li target have relatively low energies and are easily absorbed after entering the moderation layer, resulting in a decrease in neutron yield. By introducing a primary multiplication system, the uranium layer can undergo fission reactions with low-energy neutrons and release secondary neutrons with relatively high energies. After moderation, these secondary neutrons can still retain a relatively large number of neutrons for treatment, thus improving the overall efficiency of the system.

[0026] The composite multiplication target system for BNCT provided by the embodiments of the present invention fully combines the advantageous energy regions of the Be target and the Li target in the reaction with protons to increase the neutron yield. When the proton energy is relatively high, Be can produce a relatively high neutron yield in the reaction with protons. As the proton penetration depth increases, the proton energy becomes lower. When the protons enter the Li target, a relatively large neutron yield is generated by utilizing the resonance cross-section of Li. A primary multiplication system is placed directly behind the Be-Li composite target so that more neutrons generated after proton bombardment can undergo fission reactions with uranium to multiply the neutron yield. Since the proton energy usually required for the reaction between protons and Be is relatively high, according to the law of conservation of energy, the released neutrons have relatively high energies and thus require a relatively thick BSA to be moderated to the epithermal neutron energy region suitable for treatment. However, the neutrons released by the reaction of protons with energies near the resonance energy region and Li have relatively low energies and will be absorbed after entering the BSA, greatly reducing the effect of the composite target in increasing the yield. The uranium in the primary multiplication system has a relatively high fission reaction cross-section in the reaction with low-energy neutrons and will release neutrons with relatively high energies. After being moderated and shaped by the BSA, a relatively large number of neutrons will still be retained for treatment. Therefore, the primary multiplication system can make the neutron energies generated by the Li layer tend to be consistent with those generated by the Be layer while increasing the neutron yield.

[0027] Since uranium is attached to the aluminum substrate layer, the thicker the uranium layer, 235The higher the U concentration, the better the proliferation effect. Due to the relatively high density of uranium, if a relatively thick uranium layer is considered, there will be the following problems, such as relatively high mechanical property requirements for the aluminum lining layer, and the uranium layer is prone to dripping, etc.

[0028] Therefore, in a composite proliferation target system for BNCT provided in an embodiment of the present invention, the uranium layer 20 and the aluminum lining layer 21 form a uranium proliferation layer, and the primary proliferation system 2 includes multiple layers of uranium proliferation layers. In this way, the thickness of the uranium layer 20 in each layer of uranium proliferation layer does not need to be too thick, so the mechanical property of the aluminum lining layer does not need to be too high, and it will not cause the uranium layer to drip. The primary proliferation system 2 includes multiple layers of uranium proliferation layers. This design further improves the neutron yield and the uniformity of energy distribution. The design of multiple layers of uranium proliferation layers has the following characteristics and advantages: Multiple layers of uranium proliferation layers can make full use of the energy of incident neutrons, generate more secondary neutrons through multiple fission reactions, and each layer of uranium proliferation layer can proliferate the incident neutrons, thereby significantly increasing the overall neutron yield of the system; Through layer-by-layer fission reactions, multiple layers of uranium proliferation layers make the energy distribution of neutrons more uniform, and each layer of uranium proliferation layer can adjust the neutron energy, so that the finally output neutron energy is more suitable for the requirements of BNCT treatment; The design of multiple layers of uranium proliferation layers enables the system to achieve efficient neutron proliferation in a limited space. This compact design not only reduces the volume of the system, but also reduces the complexity and cost of the equipment; The aluminum lining layer 21 in multiple layers of uranium proliferation layers not only provides structural support, but also can effectively conduct and dissipate heat. This design ensures the thermal stability of the system during high-power operation and avoids performance degradation or equipment damage caused by overheating.

[0029] The working principle of multiple layers of uranium proliferation layers: Neutron incidence and fission reaction: Incident neutrons first enter the first layer of uranium proliferation layer, undergo fission reactions with the uranium layer 20, generate secondary neutrons, and these secondary neutrons then enter the next layer of uranium proliferation layer to continue fission reactions, thereby generating more neutrons; Neutron energy is adjusted layer by layer: Each layer of uranium proliferation layer can adjust the neutron energy. Through layer-by-layer fission reactions, the energy distribution of neutrons gradually becomes uniform, so that the finally output neutron energy is more suitable for the requirements of BNCT treatment; The neutron yield is increased layer by layer: Multiple layers of uranium proliferation layers significantly increase the neutron yield through layer-by-layer fission reactions. Each layer of uranium proliferation layer can proliferate the incident neutrons, thereby greatly increasing the overall neutron yield of the system.

[0030] Refer again to Figure 6 , Figure 6 which shows the case of 3 layers of uranium proliferation layers. There are gaps between multiple layers of uranium proliferation layers, and the layer spacing of multiple layers of uranium proliferation layers is as small as possible to ensure that more neutrons from the target interact with uranium and are proliferated.

[0031] A composite multiplication target system for BNCT provided by an embodiment of the present invention, in addition to including a Be-Li composite target 1 and a primary multiplication system 2, further includes a secondary multiplication system 3, and the secondary multiplication system 3 includes 9 Be balls 30, 9 The Be balls 30 are wrapped around the periphery of the composite target structure, further optimizing the neutron moderation and multiplication processes, thereby significantly increasing the neutron yield of the system and the uniformity of the energy distribution. 9 The design of the Be balls 30 makes full use of the (N, 2N) reaction characteristics of beryllium (Be) when the neutron energy is higher than 3 MeV, as well as its advantage as a epithermal neutron moderation material. It can moderate high-energy neutrons to the epithermal neutron energy range suitable for BNCT treatment (usually between 0.5 eV and 10 keV), thereby improving the utilization efficiency of neutrons. The secondary multiplication system 3 can increase the neutron yield: through the (N, 2N) reaction and neutron reflection, 9 The Be balls 30 significantly increase the neutron yield of the system; 9 The moderation function of the Be balls 30 makes the energy distribution of neutrons more uniform, thus better meeting the requirements of BNCT treatment; 9 The low neutron absorption cross-section and neutron reflection function of the Be balls 30 reduce neutron losses, thereby improving the overall efficiency of the system.

[0032] Reference Figure 2 , Figure 2 is provided by an embodiment of the present invention 9 The (N, 2N) reaction cross-section of Be, as Figure 2 shown, the overall composite target structure is placed in a sphere containing 9 Be balls, 9 Be has a relatively high (N, 2N) reaction cross-section when the neutron energy is higher than 3 MeV. At the same time 9 Be is an epithermal neutron moderation material. Generally, the proton energy used to bombard the Be target exceeds 8 MeV, the reaction threshold is 2.057 MeV, and the highest neutron energy is higher than 6 MeV. It can moderate and multiply the neutrons generated after primary multiplication.

[0033] Specifically, 9 The diameter of the Be balls 30 is obtained by substituting the incident proton energy into the Monte Carlo algorithm for simulation, 9 The diameter of the Be balls depends on the incident proton energy. Based on the simulation calculation results of Monte Carlo software, the total number of neutrons emitted from the sphere surface is the highest, which is the optimal diameter.

[0034] Refer to again Figure 6 , the secondary multiplication system 3 further includes being wrapped around 9The Pb layer 31 outside the Be sphere 30. A variety of stable isotopes of Pb also have relatively high (N, 2N) reaction cross-sections, and the resonance energy is 300 keV. It can not only quickly reduce the neutron energy to about 1 MeV, but also increase the neutron yield.

[0035] Reference Figure 3 、 Figure 4 and Figure 5 , Figure 3 provided for the embodiments of the present invention 206 the (N, 2N) reaction cross-section of Pb, Figure 4 provided for the embodiments of the present invention 207 the (N, 2N) reaction cross-section of Pb, Figure 5 provided for the embodiments of the present invention 208 the (N, 2N) reaction cross-section of Pb, as Figure 3 、 Figure 4 and Figure 5 shown, the secondary multiplication system 3 utilizes 9 the resonance cross-section and (N, 2N) reaction cross-section of Be and Pb reacting with neutrons to further increase the neutron yield and reduce the neutron energy, so as to reduce the design difficulty, cost and size of the backend BSA. A composite multiplication target system for BNCT provided by the present invention, by calculating the appropriate thicknesses of Be and Li, is designed into a Be-Li composite target, and the neutron yield after proton bombardment is increased through a variety of multiplication nuclides in the primary multiplication system 2 and the secondary multiplication system 3, ultimately enhancing the neutron fluence rate at the exit window. For the Be target: (1) increase the incident proton energy and the thickness of the Be target; (2) increase the incident proton beam intensity. For the Li target: increase the incident proton beam intensity. The composite multiplication target system for BNCT provided by the present invention is compatible with existing methods for increasing the neutron yield, such as increasing the proton beam intensity, etc.

[0036] Specifically, the thickness of the Pb layer 31 is obtained by simulating with the Monte Carlo algorithm (such as MCNP, Geant4, etc.) by bringing in the incident proton energy. The Monte Carlo algorithm can accurately simulate the transport process of protons and neutrons in materials, thereby providing a scientific basis for the thickness design of the Pb layer 31. The thickness of the Pb layer also depends on the incident proton energy. Based on the simulation calculation results of the Monte Carlo software, the total number of neutrons emitted from the Pb surface is the highest, which is the optimal thickness. The thickness of the Pb layer 31 depends on the incident proton energy. Protons with different energies interact with the Pb layer 31 in different ways. Therefore, it is necessary to optimize the design according to the specific proton energy range. For example:

[0037] For high-energy protons (such as dozens of MeV), the Pb layer 31 needs to be designed thicker to fully absorb the proton energy and reflect neutrons; for low-energy protons (such as a few MeV), the thickness of the Pb layer 31 can be appropriately reduced to avoid excessive neutron loss.

[0038] Optionally, the Be-Li composite target 1 is fixed to the surfaces of the copper substrate 4 and the vanadium substrate 5 by coating. The copper substrate 4 is in close contact with the Be-Li composite target 1. Adopting a composite structure of a Be-Li target with Be in the first layer and Li in the second layer, and coating it on the surfaces of copper (Cu) and vanadium (V) substrates can dissipate heat and prevent the Li layer from blistering.

[0039] The copper substrate 4 is in close contact with the Be-Li composite target 1. Its main functions are to provide efficient heat dissipation and structural support: copper has excellent thermal conductivity and can quickly conduct the heat generated by the Be-Li composite target 1 during high-power operation, thereby avoiding performance degradation or damage caused by overheating of the target material; the copper substrate 4 provides stable mechanical support for the Be-Li composite target 1, ensuring the structural integrity of the target material under high-power operating conditions. The vanadium substrate 5 is located behind the copper substrate 4. Its main functions are to further dissipate heat and prevent the Li layer from blistering; vanadium has good thermal conductivity and high-temperature stability and can work together with the copper substrate 4 to further improve the heat dissipation efficiency of the system; the vanadium substrate 5 can effectively suppress the blistering phenomenon that may occur in the Li layer under high-temperature and high-power operating conditions, thereby ensuring the long-term stable operation of the Be-Li composite target 1.

[0040] Optionally, in the Be-Li composite target 1, the Be layer 10 is located directly in front of the Li layer 11.

[0041] Specific implementation examples: Taking 14 MeV protons as an example to illustrate the design of the composite breeding target system: (1) Use Monte Carlo calculation software to calculate the combination of the thicknesses of the Be target and the Li target in the composite target when the neutron yield is the largest. The thickness of the Be target is 0.89 mm, and the thickness of Li is 2 mm ( 6 Li accounts for 7.5%, 7 Li accounts for 92.5%); (2) The composite target is plated with Be in the front and Li in the back on the surface of a 0.6 mm copper (Cu) substrate. 2 mm vanadium (V) is placed closely behind the copper. The use of Cu and V is to prevent the Li layer from blistering and for heat dissipation. Three U breeding layers are added behind the composite target and attached to the Al substrate. The thickness of each U layer is 0.5 mm (as Figure 6 shown);

[0042] (3) Place the above target structure in a 9 Be with a radius of 15 cm, which has a high neutron multiplication rate and can reduce the neutron energy; (4) Place the outer layer of the 9 Be sphere in a 5 cm thick Pb shell, which has a high neutron multiplication rate and can reduce the neutron energy (as Figure 7 shown).

[0043] According to Figure 8 It can be seen that the neutron energy spectra of the Be-Li composite target system (A) and the non-composite target system (B) are relatively close, but the neutron yield is increased by 12.8%. Compared with the non-breeding system with a pure Be target, the neutron yield is increased by 11.2%, but the average neutron energy is greatly decreased, which can greatly reduce the design difficulty and cost of the backend BSA.

[0044] The above are only several specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A composite breeding target system for BNCT, characterized in that, Including: A Be-Li composite target (1) and a primary breeding system (2), the primary breeding system (2) being located directly behind the Be-Li composite target (1), and the two forming a composite target structure; wherein, the primary breeding system (2) includes a uranium layer (20) and an aluminum substrate layer (21), and the uranium layer (20) is attached to the aluminum substrate layer (21).

2. The composite breeding target system for BNCT according to claim 1, characterized in that, The uranium layer (20) and the aluminum substrate layer (21) form a uranium breeding layer, and the primary breeding system (2) includes multiple layers of uranium breeding layers.

3. The compound breeding target system for BNCT according to claim 2, wherein There are gaps between multiple layers of the uranium breeding layers.

4. The composite multiplication target system for BNCT according to claim 1, characterized in that, It further includes a secondary multiplication system (3), and the secondary multiplication system (3) includes 9 Be balls (30), and the 9 Be balls (30) are wrapped around the periphery of the composite target structure.

5. The composite multiplication target system for BNCT according to claim 4, characterized in that, The 9 diameter of the Be sphere (30) is obtained by bringing the incident proton energy into a Monte Carlo algorithm simulation.

6. The compound breeding target system for BNCT according to claim 4, characterized in that, The secondary multiplication system (3) further includes a Pb layer (31) wrapped around the 9 Be sphere (30).

7. The composite breeding target system for BNCT according to claim 6, characterized in that, The thickness of the Pb layer (31) is obtained by bringing the incident proton energy into Monte Carlo algorithm simulation.

8. The compound breeding target system for BNCT according to claim 1, characterized in that, The Be-Li composite target (1) is fixed to the surfaces of a copper substrate (4) and a vanadium substrate (5) by coating, and the copper substrate (4) is in close contact with the Be-Li composite target (1).

9. The composite multiplication target system for BNCT according to claim 1, characterized in that, In the Be-Li composite target (1), the Be layer (10) is located directly in front of the Li layer (11).

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