An alpha instrument calibration source

Abstract

The utility model relates to a radioactive source technical field especially relates to a kind of alpha instrument scale source and its preparation method.The alpha instrument scale source includes source core and substrate;The source core includes first polycarbonate film and second polycarbonate film, the side of the first polycarbonate film is adsorbed with the precipitate containing radionuclide, the other side of the first polycarbonate film is connected with the substrate by conductive glue, the side of the first polycarbonate film adsorbed with the precipitate containing radionuclide is integrated structure with the second polycarbonate film by hot-press packaging.The novel structure's alpha instrument scale source provided by the utility model is firm in structure, safe and reliable, and excellent in performance, and nuclide universality is good and easy to quantify.

Description

Technical Field

[0001] This utility model relates to the field of radiation source technology, and in particular to an α instrument scale source. Background Technology

[0002] Alpha instrument calibration sources are prepared using alpha radionuclides. To ensure that the energy of alpha particles does not decay significantly within the source and to reduce self-absorption, the active layer must be extremely thin. Domestically produced alpha instrument calibration sources mainly include... 241 Am、 238 Pu and 244 Cm, etc.

[0003] In the 1960s, Parker, Kitoff, and others developed a new method for preparing radioactive sources and targets for nuclear physics experiments in weakly polar organic solvents. They used organic solvents such as isopropanol and an electroplating solution containing trace amounts of radioactive material in the form of inorganic acids for source preparation. The electroplating was carried out under high DC voltage and low current density. The radionuclide was deposited on the cathode in the form of hydroxides or other compounds. This method is called molecular electroplating and is widely used in the preparation of alpha instrument calibration sources. The advantages of molecular electroplating are: 1) More than 60% of the elements in the periodic table can be electrodeposited on metal substrates using this method; 2) The deposits are thin and uniform; 3) The cathode substrate can be a metal like aluminum without worrying about corrosion by the electroplating solution. Conventional molecular electroplating has the following main drawbacks: 1) About 40% of the elements in the periodic table are not suitable for this method; 2) The deposition curve of the nuclide on the cathode substrate is not linear, making it difficult to quantify the activity, with a first-pass yield of only about 15%. 3) Electroplating at high voltage (500~1000V) for more than 30 minutes results in severe boiling, rapid evaporation of the solution, and even combustion, posing significant safety hazards. 4) Since workers are handling radioactive nuclides, the long electroplating time increases their radiation dose. There is an urgent need for a novel alpha instrument calibration source. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides an α instrument scale source.

[0005] Specifically, this invention provides an alpha instrument calibration source, comprising a source core and a substrate. The source core includes a first polycarbonate film and a second polycarbonate film. One side of the first polycarbonate film adsorbs a precipitate containing a radionuclide, and the other side of the first polycarbonate film is connected to the substrate via conductive adhesive. The side of the first polycarbonate film adsorbing the precipitate containing the radionuclide and the second polycarbonate film are thermo-pressed into an integral structure. This novel alpha instrument calibration source provides a stable seal for the radionuclide-containing precipitate by encapsulating it in the first and second polycarbonate films. The precipitate is adsorbed on one side of the first polycarbonate film, and the conductive adhesive is fixed to the substrate, achieving stable sealing of the radioactive material and preventing leakage, while ensuring effective penetration of alpha particles. It has advantages such as robust structure, safety and reliability, excellent performance, good radionuclide universality, and ease of quantification.

[0006] Preferably, the radionuclide is an alpha radionuclide, which includes... 241 Am、 238 Pu or 244 Cm.

[0007] More preferably, the precipitate containing the radionuclide is a hydroxide precipitate of α-radionuclide and cerium.

[0008] Preferably, the precipitate containing radionuclides is electrostatically adsorbed onto the first polycarbonate membrane.

[0009] Further preferably, the thickness of the first polycarbonate film is 15~30μm; the pore size of the first polycarbonate film is 0.005~0.015μm.

[0010] More preferably, the thickness of the second polycarbonate film is 0.1~0.2μm.

[0011] More preferably, the thickness of the conductive adhesive is 10~30μm; and the thickness of the substrate is 1~5mm.

[0012] More preferably, the diameter of the substrate is 55~70mm, and the diameter of the source chip is 40~50mm.

[0013] Preferably, the substrate is a stainless steel substrate.

[0014] Preferably, the conductive adhesive is a graphene conductive adhesive.

[0015] The beneficial effects of this invention are at least as follows: The novel α-instrument calibration source structure of this invention greatly improves the source's robustness, with an active material shedding rate far lower than that of traditional molecular plating sources, ensuring the source's long service life and safety. This invention's structure, with its sandwich structure completely sealing the radioactive nuclide-containing precipitate, forms a tight, complete, integrated source core with the active material through hot-pressing two layers of film. This structure effectively protects the extremely thin internal active layer from scratches, abrasion, and other external mechanical damage, greatly improving the overall robustness and durability of the radioactive source. The improved structural robustness allows it to better maintain its integrity under physical impact, preventing the active material from shedding. The structure of this invention enhances safety in use; the sandwich encapsulation structure provides a reliable physical barrier for the radioactive material. The active precipitate is firmly sealed between two tough polycarbonate films, effectively preventing leakage or shedding of radioactive powder, avoiding the risk of surface contamination to personnel and the environment during use and storage, making the daily operation and management of the radioactive source safer. The structure of this invention can maintain the flatness and uniform distribution of the active precipitate layer for a long time, preventing it from curling, peeling or shifting, thus ensuring the long-term consistency of key performance indicators such as surface emissivity and energy spectrum of the radioactive source, and providing a reliable guarantee for accurate instrument calibration. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to actual scale. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A schematic diagram of the structure of the α instrument scale source provided in this embodiment of the utility model.

[0018] Figure 2 A cross-sectional view of the α instrument scale source provided for an embodiment of this utility model.

[0019] In the figure: 1-Stainless steel substrate, 2-Conductive adhesive, 3-Deposit containing radioactive nuclides, 4-First polycarbonate film, 5-Second polycarbonate film, 6-Source core. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0021] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Any modifications or substitutions made to the methods, steps, or conditions of the present invention without departing from the spirit and substance of the present invention shall fall within the scope of the present invention.

[0022] The endpoints and any values ​​of the ranges disclosed in this utility model are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this utility model.

[0023] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. All reagents or instruments without specified manufacturers are conventional products that can be purchased through legitimate channels.

[0024] This invention provides an alpha instrument calibration source, comprising a source core and a substrate. The source core includes a first polycarbonate film and a second polycarbonate film. One side of the first polycarbonate film adsorbs a precipitate containing a radionuclide, and the other side of the first polycarbonate film is connected to the substrate via conductive adhesive. The side of the first polycarbonate film adsorbing the precipitate containing the radionuclide and the second polycarbonate film are thermo-pressed into an integral structure. The novel alpha instrument calibration source provided by this invention encapsulates the precipitate containing the radionuclide within the first and second polycarbonate films. The precipitate is adsorbed on one side of the first polycarbonate film, and the conductive adhesive is fixed to the substrate, achieving stable sealing of the radioactive material and preventing leakage, while ensuring effective penetration of alpha particles. It has advantages such as robust structure, safety and reliability, excellent performance, good radionuclide universality, and ease of quantification.

[0025] In a preferred embodiment, the precipitate containing the radionuclide is a hydroxide precipitate of an alpha radionuclide and cerium. By using an alpha radionuclide and cerium hydroxide, the structure of this invention exhibits excellent performance and is suitable for various alpha radionuclides. In a further preferred embodiment, the radionuclide is an alpha radionuclide, and the alpha radionuclide includes…241 Am、 238 Pu or 244 Cm.

[0026] In a preferred embodiment, the precipitate containing radionuclides is electrostatically adsorbed onto the first polycarbonate membrane.

[0027] In a further preferred embodiment, the thickness of the first polycarbonate membrane is 15~30 μm; the pore size of the first polycarbonate membrane is 0.005~0.015 μm. The micron-sized pores of the first membrane, in conjunction with electrostatic adsorption, further ensure uniform distribution of the precipitate.

[0028] In a further preferred embodiment, the thickness of the second polycarbonate film is 0.1~0.2 μm. The ultrathin second film further reduces alpha particle energy decay.

[0029] In a further preferred embodiment, the thickness of the conductive adhesive is 10~30μm; the thickness of the substrate is 1~5mm. The thickness of the conductive adhesive and the substrate further ensures structural strength and conductivity.

[0030] In a further preferred embodiment, the diameter of the substrate is 55-70 mm, and the diameter of the source chip is 40-50 mm. The dimensions are compatible with mainstream α-instruments.

[0031] In a preferred embodiment, the substrate is a stainless steel substrate.

[0032] In a preferred embodiment, the conductive adhesive is a graphene conductive adhesive.

[0033] The novel α-meter calibration source structure provided by this embodiment of the invention greatly improves the robustness of the source, with an active material shedding rate far lower than that of traditional molecular plating sources, ensuring the long service life and safety of the source. This invention features a sandwich structure that completely seals the radioactive nuclide-containing precipitate within, forming a tight and complete integrated source core with the active material through hot pressing of two layers of film. This structure effectively protects the extremely thin internal active layer from scratches, abrasion, and other external mechanical damage, greatly enhancing the overall robustness and durability of the radioactive source. The improved structural robustness allows it to better maintain its integrity under physical impact, preventing the active material from shedding. The structure of this invention also enhances safety, as the sandwich encapsulation structure provides a reliable physical barrier for the radioactive material. The active precipitate is firmly sealed between two tough polycarbonate films, effectively preventing leakage or shedding of radioactive powder, avoiding the risk of surface contamination to personnel and the environment during use and storage, and making the daily operation and management of the radioactive source safer. The structure of this invention can maintain the flatness and uniform distribution of the active precipitate layer for a long time, preventing it from curling, peeling or shifting, thus ensuring the long-term consistency of key performance indicators such as surface emissivity and energy spectrum of the radioactive source, and providing a reliable guarantee for accurate instrument calibration.

[0034] This utility model also provides a method for preparing the α instrument calibration source in a specific embodiment, including:

[0035] A) A solution containing a radioactive nuclide is mixed with a carrier solution containing cerium, the pH is adjusted to alkaline and stirred to obtain a suspension of the precipitate containing the radioactive nuclide.

[0036] B) The suspension is vacuum filtered using a first polycarbonate membrane, so that the precipitate containing radioactive nuclides is uniformly deposited on the surface of the first polycarbonate membrane through electrostatic adsorption, thus obtaining a first polycarbonate membrane that adsorbs the precipitate.

[0037] C) Cover the side of the first polycarbonate membrane with the adsorbed precipitate by the second polycarbonate membrane and hot press it to obtain the source core.

[0038] D) Fix the source core to the active area of ​​the substrate using conductive adhesive.

[0039] In step A), the pH value is adjusted to 8-9. In step B), the vacuum filtration pressure is 0.2-0.3 bar. In step C), the hot-pressing temperature is 120-130°C. Step C) further includes applying conductive adhesive to the edges of the second polycarbonate film and the first polycarbonate film, followed by hot pressing. In step A), the cerium-containing carrier solution contains Ce... 3+The amount added is 1-2 mg, and the concentration of the cerium-containing carrier solution is 0.2-0.8 mg / mL. In step A), the concentration of the solution containing the radionuclide is 150-250 μCi / mL, and the amount of the solution containing the radionuclide used is 15-25 mL. Step B) further includes a pretreatment step for the first polycarbonate membrane: the first polycarbonate membrane is treated with an ion fan, immersed in an ethanol solution, and then rinsed with deionized water.

[0040] In a further preferred embodiment, step B) further includes washing the precipitate on the surface of the first polycarbonate film. The washing includes one or more of acid washing, water washing, and anhydrous ethanol rinsing, followed by air drying at room temperature or low-temperature drying. Preferably, the room temperature air drying time is ≥1 hour, and the low-temperature drying temperature is 30~40°C for 10~30 minutes. Washing removes impurity ions to ensure background counting of the calibration source; low-temperature drying avoids precipitate aggregation and maintains the uniformity of the active layer.

[0041] The main equipment and reagents for preparing the α instrument calibration source in the following embodiments of the present invention are shown in Tables 1 and 2.

[0042] Table 1 Main Equipment

[0043]

[0044] Table 2 Main Reagents

[0045]

[0046] Example 1

[0047] The α instrument calibration source provided by this utility model, such as Figure 1 and Figure 2 As shown, from bottom to top, the structure includes a stainless steel substrate 1, a conductive adhesive layer 2, and a source core 6. The source core 6 is constructed by hot-pressing a first polycarbonate film 4 and a second polycarbonate film 5. A precipitate 3 containing a radioactive nuclide is electrostatically adsorbed and sealed between the two films. Specifically, the precipitate 3 containing the radioactive nuclide is attached to the upper surface of the first polycarbonate film 4, while the lower surface of the first polycarbonate film 4 is connected to the stainless steel substrate 1 via the conductive adhesive 2. The precipitate 4 containing the radioactive nuclide is an alpha radioactive nuclide. 241 Am and cerium hydroxide precipitate; the first polycarbonate film 4 has a thickness of 20 μm and a pore size of 0.01 μm. The second polycarbonate film 5 has a thickness of 0.15 μm, the conductive adhesive source core has a thickness of 20 μm, the stainless steel substrate 1 has a thickness of 3 mm, a diameter of φ60 mm, and an active area diameter of φ50 mm (source core). 241The Am instrument calibration source and the α instrument calibration source have a flat plate structure. The emitting surface of the α instrument calibration source consists of an active region and an inactive region. The active region emits α particles, and the active region corresponds to the source core.

[0048] The preparation process of the α instrument calibration source provided in this embodiment is as follows:

[0049] 1. By adjusting the pH and adding a carrier, 241 Am forms hydroxide coprecipitate.

[0050] Take 20 mL 241 The Am solution was acidified using 4 M HCl. A cerium carrier solution (0.5 mg Ce) was added. 3+ ( / mL) to promote co-precipitation. Slowly add concentrated ammonia solution while stirring until the pH≈8.5 and the phenolphthalein indicator turns pink. The key point is to avoid localized over-alkalinity, which can lead to uneven precipitation. Cool in an ice bath for 10 minutes to increase the size of the precipitate particles and improve filtration efficiency.

[0051] 2. Polycarbonate membrane pretreatment and filtration

[0052] A 0.01 μm pore size and 20 μm thickness polycarbonate membrane was selected. The membrane was treated with an ion blower for 5 seconds to remove static electricity and reduce dust adsorption. It was then immersed in 80% ethanol for 5 minutes, followed by rinsing with deionized water to enhance hydrophilicity. The membrane was installed on a glass frit filter with the smooth side facing upwards and the rough side in contact with the support mesh. A vacuum pump was connected, and the pressure was controlled at 0.2–0.3 bar to prevent membrane rupture. The precipitate suspension from the first step was slowly poured into the filter, and filtration was performed until all liquid passed through. The membrane was washed once with 5 mL of 50% ethanol to initially remove soluble salts (such as NH4Cl).

[0053] Wash once with 5 mL of 50% ethanol to initially remove soluble salts (such as NH4Cl).

[0054] This step is primarily used for the initial removal of soluble salts such as NH4Cl to prevent salt clogging of the filter membrane during vacuum filtration. While there is some overlap between the two washing steps, the ethanol wash in step 3.2.2 reduces initial salt deposition on the filter membrane and improves subsequent washing efficiency. Removing this step might result in some NH4Cl remaining on the membrane during vacuum filtration, increasing the washing burden in step 3.3.3. Salt crystallization could also affect precipitation uniformity (especially during rapid drying). However, it can be further optimized by washing once with 5 mL of 50% ethanol.

[0055] 3. Washing and drying

[0056] The precipitate was gently washed with 2 mL of 0.1 M HNO3 to remove residual ammonia, followed by rinsing with 5 mL of ultrapure water. Finally, it was rinsed with 2 mL of anhydrous ethanol to accelerate drying. The filter membrane was then laid flat in a clean petri dish and allowed to air dry at room temperature, avoiding high temperatures to prevent the volatilization of the radionuclide. The drying time was 2 hours.

[0057] 4. Polycarbonate film encapsulation

[0058] Apply 1-2 μL of conductive adhesive to the edge of the first film using a micro-dispenser, avoiding covering the central deposition area. Align and cover with the second pretreated polycarbonate film, smooth side down. Gently press the edges with tweezers to ensure initial adhesion of the conductive adhesive. Place the laminated films between two hot presses. Temperature: 125°C (below the polycarbonate Tg of 147°C). Maintain pressure during cooling to room temperature to prevent delamination.

[0059] 5. Fix it onto the stainless steel substrate.

[0060] Wipe the stainless steel substrate with acetone to remove grease. Apply a small amount of conductive adhesive to the center area of ​​the substrate. Place the encapsulated polycarbonate film, deposited side up, onto the adhesive and gently press to remove air bubbles. Allow to air dry at room temperature for 10 minutes to ensure a firm bond. Inspect the edges under a magnifying glass to ensure a complete seal and check for any lifting or cracks. Wipe the radiation source with an alcohol swab to remove surface substances and allow to dry. Visual inspection: The surface is smooth and flat, and the polycarbonate film shows no peeling. Surface emissivity inspection: The radiation source was measured using a multi-wire proportional counter calibrated to the standard source of the national legal metrology department.

[0061] Experimental Example 1

[0062] In some embodiments provided by this utility model, the same α-instrument calibration source and method as in Embodiment 1 are used, and the results obtained after changing the following conditions by a single factor are as follows:

[0063] 1. pH value 241 Impact of Am load factor

[0064] The experimental procedure is to adjust the content of 241 The pH of the Am (approximately 5000 Bq) solution was adjusted by adding ammonia. After co-precipitation, the solution was filtered, and the activity of the filtrate was measured (using a high-purity germanium gamma spectrometer). The variables in the experiment were pH = 6.0, 7.0, 8.0, 9.0, and 10.0, while other conditions were kept constant: 1 mg Ce³⁺ carrier was used, and the solution was aged in an ice bath for 20 minutes. The loading rate was calculated as (initial activity - filtrate activity) / initial activity * 100%. The experimental results showed that the loading rate was highest at pH 8-9.

[0065] 2. Ce 3+ The effect of carrier dosage on loading rate

[0066] The experimental procedure is to introduce... 241Different amounts of Ce³⁺ were added to a solution of Am, and after co-precipitation, the mixture was filtered. The activity of the filtrate was measured (using a high-purity germanium gamma spectrometer), and the loading rate was calculated. The variable in the experiment was Ce. 3+ Carrier dosages of 0, 0.5, 1.0, 2.0, and 5.0 mg were used, with a fixed pH of 8.5. Experimental results showed that 1–2 mg Ce... 3+ That would be the best.

[0067] 3. The effect of filtration pressure on source uniformity

[0068] The experimental procedure involved adjusting the filtration pressure to 0.1, 0.3, 0.5, and 0.7 bar under the same precipitation conditions to measure source uniformity. The test method and procedure are as follows: 1. Instrument preparation: A flow-type proportional counter was selected, with the working gas being (90% Ar + 10% CH4), and the flow rate controlled at 20~30 mL / min to ensure stable counting efficiency. High pressure was set (α mode: 1.2~1.5 kV; β mode: 1.8~2.2 kV). 2. Background test: The passive background was measured first, and the count on the display screen was observed. Multiple measurements were taken, and the readings were recorded after the values ​​stabilized. The measurements were repeated 3 times, and the average background value A0 was taken. 3. Source test: The source to be tested was placed in the instrument's measuring tray, with the radioactive source positioned in the center of the tray. The start button was pressed, and the count on the display screen was observed. Multiple measurements were taken, and the readings of the three sources to be tested were recorded after the values ​​stabilized, and the average value A1 was taken. Finally, the emissivity of the source was calculated as A1-A0. Experimental results show that the optimal pressure range is 0.2~0.3 bar, balancing efficiency and uniformity.

[0069] 4. The effect of hot pressing temperature on the film

[0070] The effects of different hot-pressing temperatures (100, 120, 130, 140°C) on sealing film were investigated. Experimental results showed that sealing film at 120~130°C was optimal.

[0071] Table 3 Effect of hot pressing temperature on sealing film

[0072]

[0073] This invention also provides a source (pH=8; Ce) provided in the above embodiments. 3+ The following performance tests were conducted (2mg; filtration pressure 0.3 bar; hot-pressing temperature 120℃).

[0074] 1. Source robustness test

[0075] The source was placed in a protective sleeve and dropped freely from a height of 1 meter onto a plastic floor once in each of three different orientations (front, back, and side). After each drop, the surface emissivity of the radioactive source was measured.

[0076] Table 4 Comparison of source robustness testing between polycarbonate film method and traditional molecular plating method

[0077]

[0078] 2. Source uniformity test

[0079] The uniformity of a radioactive source characterizes its quality. This invention employs a self-made measuring device to measure the uniformity of a radioactive source. The device consists of a stainless steel base and a top cover. The top cover has a 30° opening and can rotate on the base. The base edge is marked with graduations. A piece of the prepared radioactive source is extracted, and its uniformity is measured. Counts are taken from 12 regions of the radioactive source, with each region measured three times and the average value calculated. The measurement time for each region is 60 seconds. Finally, the relative standard deviation of the counts from the 12 regions is calculated.

[0080] Table 5. Comparison of uniformity testing of sources prepared by polycarbonate film method and traditional molecular plating method

[0081]

[0082] The above embodiments provide 241 Am instrument calibration source (pH=8; Ce) 3+ =2mg; filtration pressure 0.3bar; hot pressing temperature 120℃) Energy spectrum test was performed using an ORTEC energy spectrometer. The energy spectrum showed very good energy resolution, with a very sharp 5486 keV main peak, extremely small half-width, almost no low-energy tails and impurity peaks, and an extremely thin active layer with excellent energy resolution.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. An α-meter calibration source, characterized in that, It includes a source core and a substrate; the source core includes a first polycarbonate film and a second polycarbonate film, one side of the first polycarbonate film adsorbs a precipitate containing a radionuclide, the other side of the first polycarbonate film is connected to the substrate through conductive adhesive, and the side of the first polycarbonate film adsorbing the precipitate containing the radionuclide and the second polycarbonate film are heat-pressed into an integral structure.

2. The α instrument scale source according to claim 1, characterized in that, The radionuclide is an alpha radionuclide, which includes... 241 Am、 238 Pu or 244 Cm.

3. The α instrument calibration source according to claim 2, characterized in that, The precipitate containing the radionuclide is a hydroxide precipitate of α-radioactive nuclide and cerium.

4. The α instrument scale source according to claim 1, characterized in that, The precipitate containing the radionuclide is electrostatically adsorbed onto the first polycarbonate membrane.

5. The α instrument calibration source according to claim 4, characterized in that, The thickness of the first polycarbonate film is 15~30μm; the pore size of the first polycarbonate film is 0.005~0.015μm.

6. The α instrument calibration source according to claim 5, characterized in that, The thickness of the second polycarbonate film is 0.1~0.2μm.

7. The α instrument scale source according to claim 6, characterized in that, The thickness of the conductive adhesive is 10~30μm; the thickness of the substrate is 1~5mm.

8. The α instrument scale source according to claim 7, characterized in that, The diameter of the substrate is 55~70mm, and the diameter of the source core is 40~50mm.

9. The α instrument calibration source according to any one of claims 1-8, characterized in that, The substrate is a stainless steel substrate.

10. The α instrument scale source according to any one of claims 1-8, characterized in that, The conductive adhesive is a graphene conductive adhesive.

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