Preparation method and application of boron target for generating high-energy photon radiation field

Abstract

The invention provides a preparation method and application of a boron target for generating a high-energy photon radiation field, and the preparation method comprises the following steps: mixing filtered boron elementary substance with mineral oil, and stirring until the mixture is uniformly mixed; standing for a certain time until the boron elementary substance is uniformly suspended, dipping the boron elementary substance on the upper layer of the mineral oil by using a brush, and uniformly coating on the surface of the substrate; the substrate is placed in a drying box to be baked under flowing air till the mineral oil is completely evaporated, and the boron target coated with the boron elementary substance layer is obtained. The preparation method of the boron target is easy and convenient to operate, professional equipment is not needed, and the prepared boron target is durable and not prone to damage. A proton beam with incident energy greater than or equal to 240keV and beam intensity greater than or equal to 15mu A is used for bombarding the boron target, and a stable high-energy photon radiation field with a dose rate greater than 100mu Sv / h can be generated.

Description

Technical Field

[0001] This invention relates to the field of high-energy photon radiation, and more particularly to a method for preparing a boron target for generating a high-energy photon radiation field and its application. Background Technology

[0002] The construction of a high-energy photon reference radiation field has significant social implications. It provides crucial testing conditions for radiation protection-grade monitoring instruments and human radiation protection equipment. Furthermore, a series of fundamental studies conducted based on the high-energy photon field serve as important bases for the formulation of radiation protection-related standards and specifications. In addition, the high-energy photon radiation field of the accelerator can be used to conduct scientific research on the interaction between photons and particles, verifying and refining theoretical research in particle physics, and providing crucial data support for basic scientific research and even astrophysical theories.

[0003] The energy range of RF and RC radiation sources is limited to 4 MeV to 7 MeV. To expand the number of energy points and the energy range, other types of target materials are typically used to generate specific high-energy photon radiation. Among them, boron targets have great application potential due to their unique (p,γ) reaction characteristics. However, the fragility and difficulty in fabrication of boron targets severely restrict their widespread application. Therefore, there is an urgent need to develop a boron target fabrication method that is simple in process and durable, thereby enabling the widespread application of boron targets in the generation of high-energy photon radiation fields. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing a boron target for generating a high-energy photon radiation field and its application. The preparation method is simple and convenient, and the boron target prepared in this way is durable and not easily damaged.

[0005] In a first aspect, the present invention discloses a method for preparing a boron target for generating a high-energy photon radiation field, the method comprising the following steps: The boron element filtered through a filter screen is mixed and stirred with mineral oil until it is evenly mixed. Let it stand for a certain period of time until the boron element is evenly suspended. Use a brush to dip the boron element in the mineral oil and coat it evenly on the dry substrate surface. The boron-coated substrate is placed in a drying oven and baked under flowing air until the mineral oil is completely evaporated, resulting in a boron target coated with a boron layer.

[0006] Preferably, the boron is analytical grade B-11 amorphous boron.

[0007] Preferably, the particle size of the filter screen is 200 mesh or larger.

[0008] Preferably, the weight ratio of boron to mineral oil is 1:3 to 5.

[0009] Preferably, the substrate is 0.2 mm thick tantalum metal.

[0010] Preferably, before coating with boron, the substrate is ultrasonically cleaned using anhydrous ethanol.

[0011] Preferably, the baking temperature is 600~900℃ and the baking time is ≥10h.

[0012] Preferably, the thickness of the boron elemental layer is 0.005~0.015 μm.

[0013] In a second aspect, the present invention also provides a method for generating a high-energy photon radiation field, the method comprising: bombarding a boron target with protons from an accelerator, the boron target being prepared by the boron target preparation method described in the first aspect of the present invention; performing circulating water cooling on the back side of the boron target substrate, controlling the maximum temperature at the center of the target material to be lower than the melting point of the substrate and elemental boron, and the temperature difference between the maximum temperature at the center of the target material and the melting point of the substrate or elemental boron being greater than 500°C.

[0014] Preferably, the incident energy of the protons is ≥240keV, and the proton beam intensity is ≥15μA.

[0015] Compared with the prior art, this application has at least the following beneficial effects: (1) The boron target preparation method proposed in this application is simple and convenient to operate. The preparation process does not require expensive professional equipment such as physical vapor deposition or chemical vapor deposition. Using B-11 amorphous boron as raw material, a stable and durable boron target can be prepared by simple steps such as filtration through a filter screen, mixing with ordinary mineral oil, static suspension, brush coating, and baking in a drying oven.

[0016] (2) Compared with existing general-purpose RF and RC accelerator radiation materials, this application relies on boron targets to obtain higher high-energy photon radiation fields at lower accelerator proton energies and beam intensities. Moreover, the target material is easier to prepare and cheaper.

[0017] (3) According to the method for generating a high-energy photon radiation field proposed in this application, the boron target obtained by the boron target preparation method of this application is bombarded with protons from an accelerator, which can form a stable high-energy photon radiation field with a dose rate greater than 100 μSv / h. It can be used for testing radiation protection level monitoring instruments and human radiation protection equipment, formulating radiation protection standards and specifications, and related scientific research. Detailed Implementation

[0018] The technical solution to be protected by this application will be clearly and completely described below with reference to the embodiments. Obviously, the embodiments described in the specific embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] Unless otherwise stated, all temperatures are in degrees Celsius and all percentages are by weight. Unless otherwise specified, preferred embodiments can be freely combined as needed. Those skilled in the art will understand that the data and parameters described in the examples are merely exemplary and do not constitute a limitation of the invention. All components used in the following examples and comparative examples are monomers or compounds known in the art, and all equipment used is well-known in the art and can be obtained commercially or prepared using known techniques.

[0020] Example 1 A method for preparing a boron target for generating a high-energy photon radiation field in an accelerator, the method comprising the following steps: Analytical grade B-11 amorphous boron was filtered through a 200-mesh sieve and mixed with saturated hydrocarbon mineral oil (MOSH) at a boron-oil weight ratio of 1:5, and stirred until homogeneous. It should be noted that any mineral oil capable of dissolving and dispersing boron powder can be used in this invention.

[0021] Let it stand until the boron is evenly suspended. Use a brush to apply the upper layer of boron in mineral oil evenly to the surface of the dry substrate. The substrate is made of high-temperature resistant tantalum metal with a thickness of 0.2 mm. The size of the substrate is selected according to actual needs, and is 5 cm × 5 cm. Before coating with boron, the substrate is ultrasonically cleaned with anhydrous ethanol.

[0022] The boron-coated substrate was placed in a drying oven and baked in flowing air at 900°C for 10 hours until the mineral oil was completely evaporated, resulting in a boron target coated with a boron layer with a thickness of 0.005 μm.

[0023] Example 2 A method for preparing a boron target for generating a high-energy photon radiation field in an accelerator, the method comprising the following steps: Analytical grade B-11 amorphous boron was filtered through a 300-mesh sieve and mixed with aromatic mineral oil (MOAH) at a boron-oil weight ratio of 1:4. The mixture was stirred until homogeneous. Let it stand until the boron is uniformly suspended. Use a brush to apply the boron from the mineral oil layer evenly to the dry substrate surface. The substrate is a 0.2mm thick high-temperature resistant tantalum metal. The size of the substrate is selected according to actual needs, and is 5cm×5cm. Before coating the boron, the substrate is ultrasonically cleaned with anhydrous ethanol. The boron-coated substrate was placed in a drying oven and baked in flowing air at 800°C for 12 hours until the mineral oil was completely evaporated, resulting in a boron target coated with a boron layer with a thickness of 0.01 μm.

[0024] Example 3 A method for preparing a boron target for generating a high-energy photon radiation field in an accelerator, the method comprising the following steps: Analytical grade B-11 amorphous boron was filtered through a 500-mesh sieve and mixed with saturated hydrocarbon mineral oil (MOSH) at a boron-oil weight ratio of 1:3 and stirred until homogeneous. Let it stand until the boron is uniformly suspended. Use a brush to apply the boron from the mineral oil layer evenly to the dry substrate surface. The substrate is a 0.2mm thick high-temperature resistant tantalum metal. The size of the substrate is selected according to actual needs, and is 5cm×5cm. Before coating the boron, the substrate is ultrasonically cleaned with anhydrous ethanol. The boron-coated substrate was placed in a drying oven and baked in flowing air at 600°C for 14 hours until the mineral oil was completely evaporated, resulting in a boron target coated with a boron layer with a thickness of 0.015 μm.

[0025] Application Example 1 A method for generating a high-energy photon radiation field, the method comprising: bombarding a boron target with protons from an accelerator, the boron target being the boron target prepared in Example 1.

[0026] High-energy photon radiation based on a boron target is... 11 B(p,γ) 12 C-nuclear reactions produce this, considering the low photon yield (approximately 10). 7 ( / s), to ensure a sufficient photon count, place the object to be irradiated close to the target.

[0027] A proton incidence of 240 keV was selected. Since the high-energy photon radiation dose rate of the boron target is linearly positively correlated with the incident proton beam intensity, a proton beam intensity of 15 μA was chosen. Considering the melting point of the boron target (B-11) is 2076℃, the energy deposited during accelerator proton incidence will be entirely deposited on the target material as heat power. Failure to dissipate the heat in time will lead to the melting of the target material. When the incident proton energy is 240 keV, the penetration depth in the boron target is 2 μm, and the Bragg peak is mainly deposited on the tantalum substrate, allowing for timely heat conduction. At a high beam intensity of 15 μA, the heat power is 3.6 W. Circulating water cooling is performed on the back side of the boron target substrate with a water layer thickness of 5 mm, a flow rate of 3.2 m / s, and a flow rate of 50 L / min. This controls the maximum temperature at the target center to 757℃, far below the melting point of the boron target, meeting the application requirements. Measurements showed that the irradiated object received 4.43 MeV of high-energy photon radiation, with a dose rate of approximately 100 μSv / h.

[0028] Application Example 2 A method for generating a high-energy photon radiation field, the method comprising: bombarding a boron target with protons from an accelerator, the boron target being the boron target prepared in Example 2.

[0029] High-energy photon radiation based on a boron target is... 11 B(p,γ) 12 C-nuclear reactions produce this, considering the low photon yield (approximately 10). 7 ( / s), to ensure a sufficient photon count, place the object to be irradiated close to the target.

[0030] A proton incidence of 240 keV was selected. Since the high-energy photon radiation dose rate of the boron target is linearly positively correlated with the incident proton beam intensity, a proton beam intensity of 16 μA was chosen. Considering the melting point of the boron target (B-11) is 2076℃, the energy deposited during accelerator proton incidence will be entirely deposited on the target material as heat power. Failure to dissipate this heat in time will lead to the melting of the target material. When the incident proton energy is 240 keV, the penetration depth in the boron target is 2.3 μm, and the Bragg peak is mainly deposited on the tantalum substrate, allowing for timely heat conduction. At a high beam intensity of 16 μA, the heat power is 4.1 W. Circulating water cooling is performed on the back side of the boron target substrate with a water layer thickness of 5 mm, a flow rate of 3.6 m / s, and a flow rate of 56.25 L / min. This controls the maximum temperature at the target center to 815℃, far below the melting point of the boron target, meeting the application requirements. Measurements showed that the irradiated object received 11.7 MeV of high-energy photon radiation, with a dose rate of approximately 264 μSv / h.

[0031] Application Example 3 A method for generating a high-energy photon radiation field, the method comprising: bombarding a boron target with protons from an accelerator, the boron target being the boron target prepared in Example 3.

[0032] High-energy photon radiation based on a boron target is... 11 B(p,γ) 12 C-nuclear reactions produce this, considering the low photon yield (approximately 10). 7 ( / s), to ensure a sufficient photon count, place the object to be irradiated close to the target.

[0033] A proton incidence of 7.2 MeV was selected. Since the high-energy photon radiation dose rate of the boron target is linearly positively correlated with the incident proton beam intensity, a proton beam intensity of 17 μA was chosen. Considering the melting point of the boron target (B-11) is 2076℃, the energy deposited during accelerator proton incidence will be entirely deposited on the target material as heat power. Failure to dissipate this heat in time will lead to target melting. When the incident proton energy is 7.2 MeV, the penetration depth in the boron target is 6.5 μm, and the Bragg peak is mainly deposited on the tantalum substrate, allowing for timely heat conduction. At a high beam intensity of 17 μA, the heat power is 90 W. Circulating water cooling is performed on the back side of the boron target substrate with a water layer thickness of 5 mm, a flow rate of 5 m / s, and a flow rate of 78.12 L / min. This controls the maximum temperature at the target center to 975℃, far below the melting point of the boron target, meeting the application requirements. Measurements showed that the irradiated object received 15.7 MeV of high-energy photon radiation, with a dose rate of approximately 354 μSv / h.

[0034] As can be seen, the boron target preparation methods described in Examples 1-3 provide a simple and convenient way to prepare boron targets for generating high-energy photon radiation fields in accelerators. By using the methods described in Examples 1-3 to generate high-energy photon radiation fields, proton beam bombardment of the boron targets prepared in Examples 1-3 can form stable high-energy photon radiation fields. These high-energy photon radiation fields can be used for testing radiation protection level monitoring instruments and human radiation protection equipment, for formulating radiation protection standards and specifications, and for related scientific research.

[0035] All materials used in this invention are commercially available and can be purchased from retail sources.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a boron target for generating a high-energy photon radiation field, characterized in that, The preparation method includes the following steps: The boron element filtered through a filter screen is mixed and stirred with mineral oil until it is evenly mixed. Let it stand for a certain period of time until the boron element is evenly suspended. Use a brush to dip the boron element in the mineral oil and coat it evenly on the dry substrate surface. The boron-coated substrate is placed in a drying oven and baked under flowing air until the mineral oil is completely evaporated, resulting in a boron target coated with a boron layer.

2. The method for preparing a boron target according to claim 1, characterized in that, The boron is analytical grade B-11 amorphous boron.

3. The method for preparing a boron target according to claim 1, characterized in that, The particle size of the filter screen is 200 mesh or larger.

4. The method for preparing a boron target according to claim 1, characterized in that, The weight ratio of boron to mineral oil is 1:3~5.

5. The method for preparing a boron target according to claim 1, characterized in that, The substrate is 0.2 mm thick tantalum metal.

6. The method for preparing a boron target according to claim 1, characterized in that, Before coating with boron, the substrate was cleaned by ultrasonic oscillation using anhydrous ethanol.

7. The method for preparing a boron target according to claim 1, characterized in that, Baking temperature is 600~900℃, baking time is ≥10h.

8. The method for preparing a boron target according to claim 1, characterized in that, The thickness of the boron elemental layer is 0.005~0.015μm.

9. A method for generating a high-energy photon radiation field, characterized in that, The method includes: bombarding a boron target with protons from an accelerator, the boron target being prepared by the boron target preparation method for generating a high-energy photon radiation field as described in any one of claims 1-8; performing circulating water cooling on the back side of the boron target substrate, controlling the maximum temperature at the center of the target material to be lower than the melting point of the substrate and elemental boron, and the temperature difference between the maximum temperature at the center of the target material and the melting point of the substrate or elemental boron being greater than 500°C.

10. The method for generating a high-energy photon radiation field according to claim 9, characterized in that, The accelerator has an incident proton energy ≥240keV and a proton beam intensity ≥15μA.