Method and device for self-absorption correction of unknown composition radioactive sample

Abstract

The application discloses a self-absorption correction method and device for unknown component radioactive samples, belongs to the technical field of radioactive source detection, and places a gamma radioactive source in a groove at the upper end of an upper fixed plate, so that the gamma radioactive source serves as a photon source; places an empty sample cylinder at the upper end of a lower fixed plate, at this time, the photons emitted by the gamma radioactive source pass through the cylinder through the channel in the inner lead body and are then received by a detector, and the peak area net count rate N1 corresponding to the ray energy is calculated by spectrum analysis. When the application is used, nondestructive measurement can be achieved, compared with the traditional X-ray fluorescence method (XRF), the application does not need to destructively process the radioactive substances to be detected to obtain a sample matrix, and can truly realize nondestructive measurement; the cost is reduced; the traditional method needs to use X-ray fluorescence to detect the sample components, and the method further increases the cost, and the application only needs a lead collimator to realize all functions, and the cost is further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of radioactive source detection, in particular to a method and device for correcting self-absorption of radioactive samples of unknown components. Background Art

[0002] When using a high-purity germanium gamma spectrometer to measure bulk radioactive samples, due to the presence of a certain density and height of the radioactive sample, a portion of the gamma photons will be absorbed by the sample matrix before hitting the detector, causing the number of gamma photons hitting the detector to decrease, ultimately affecting the measurement results. This phenomenon is called the self-absorption effect. Existing solutions are divided into two situations: when the sample composition is known and when the sample composition is unknown. When the sample composition is known, the XCOM database can be used to calculate the mass attenuation coefficient to calculate the self-absorption correction factor, or the Monte Carlo simulation method can be used to directly simulate and calculate the self-absorption correction factor. However, the above methods are all based on the assumption that the sample composition is known. When the sample composition is unknown, the X-ray fluorescence method is often used to detect the sample composition, turning the unknown composition into a known composition, and then using the method with the known sample composition to make corrections.

[0003] X-ray fluorescence is a method of measuring specific components, making the unknown composition of the sample known. However, this method requires destructive treatment of the radioactive sample to obtain the radioactive sample matrix, and cannot achieve non-destructive measurement. X-ray fluorescence is a method of measuring the obtained matrix sample, which on the one hand increases the measurement cost, and on the other hand leads to the loss of the matrix of the radioactive sample.

[0004] Therefore, the present invention provides a method and device for correcting self-absorption of radioactive samples of unknown components to solve the above-mentioned problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and device for correcting self-absorption of radioactive samples of unknown components to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for correcting self-absorption of radioactive samples of unknown components comprises the following steps:

[0008] Select the radiation source:

[0009] The radiation source is a gamma radiation source;

[0010] Step 1: Place the gamma radiation source in the groove at the upper end of the upper fixing plate so that the gamma radiation source serves as a photon source;

[0011] Step 2: Place the empty sample tube on the upper end of the lower fixed plate. The photons emitted by the gamma radiation source will pass through the channel in the inner lead body and then be received by the detector. The spectrum is then analyzed and the net count rate N1 of the peak area corresponding to the energy of the radiation is calculated.

[0012] Step 3: Place the radioactive material into the cylinder, and then place the cylinder on the upper end of the lower fixed plate so that the docking block docks with the rotating column. At this time, the threaded rod will move upward. During the upward movement of the threaded rod, it will rotate downward through the rack block, so that the upper layer of the radioactive material is covered with the compression plate and the retraction plate. Then rotate the cylinder. At this time, since the docking block and the rotating column are in a docking state, the rotating cylinder can drive the movable gear to rotate through the rotating ring. When the movable gear rotates, it will engage with the fixed gear ring and rotate on its own. At this time, the threaded rod will rotate. When the threaded rod rotates, the connecting ear will move downward along the installation cavity, so that the radioactive material is further compressed by a number of compression plates. When the compression is completed, the retraction plate is pushed along the movable track, thereby expanding the retraction plates and exposing the radioactive material.

[0013] By increasing the density of the radioactive material inside the cylinder, it is possible to avoid photons being reflected in the gaps between the radioactive material and affecting the accuracy of the inspection;

[0014] At this time, the photons emitted by the gamma radiation source will be received by the detector after passing through the radioactive material, and the spectrum will be analyzed to calculate the peak area net count rate N2 corresponding to the ray energy;

[0015] Step 4: Calculate the mass attenuation coefficient of the energy photon in the sample according to the Beer-Lamber formula;

[0016] Step 5: Replace the gamma radiation source with a different energy, repeat the process from step 2 to step 4, obtain the mass attenuation coefficient at different energies, and record the data;

[0017] Step 6: Obtain a set of data of E (energy) - μ (mass attenuation coefficient), take the natural logarithm of the data, use a fourth-order polynomial fit to obtain the fitting curve and fitting parameters, and realize the fitting output of the mass attenuation coefficient at different energies;

[0018] Step 7: Calculation of self-absorption correction factor: Integrate the sample according to thickness to obtain the self-absorption correction factor.

[0019] As a further embodiment of the present invention, the gamma radiation source comprises 241 Am(@59.56keV), 133 Ba(@80.9979keV, 276.3989keV, 302.851keV, 356.1029keV, 383.8485keV), 137 Cs(@661.67keV), 152Eu(@121.78keV, 964.06keV, 1408.01keV), 60 Co(@1173.2keV, 1332.5keV).

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. When the present invention is used, non-destructive measurement can be achieved. Compared with the traditional X-ray fluorescence method (XRF), this technology does not require the radioactive material to be detected to be destroyed to obtain the sample matrix, and can truly achieve non-destructive measurement;

[0022] Cost reduction: Traditional methods require X-ray fluorescence to detect sample composition, which incurs further costs. This technology only requires a lead collimator to achieve all functions, further reducing costs.

[0023] Clean and environmentally friendly. Since traditional methods need to obtain the matrix components of radioactive materials, the original radioactive materials are destroyed during the processing, which can easily lead to the leakage and loss of radioactive material sample components, causing certain radioactive contamination. This method does not perform destructive processing, so there is no radioactive leakage problem, which is cleaner and more environmentally friendly.

[0024] Compared with the more complicated processes of traditional methods such as matrix sampling, sample processing, and sample composition analysis, this technology only requires placing the lead collimator and corresponding radioactive materials on the detector to complete all operations, making processing and installation more convenient.

[0025] 2. When the present invention is used, by increasing the density of the radioactive material inside the cylinder, it is possible to avoid the reflection of photons in the gaps of the radioactive material and the influence on the accuracy of the inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of a device for self-absorption correction of radioactive samples of unknown composition.

[0027] Figure 2 This is a diagram of the internal structure of a device used for self-absorption correction of radioactive samples of unknown composition.

[0028] Figure 3 This is a diagram showing the internal structure of a device used for self-absorption correction of radioactive samples of unknown composition.

[0029] Figure 4 This is a structural diagram of the lower fixing plate in a device for self-absorption correction of radioactive samples of unknown composition.

[0030] Figure 5 This is a structural diagram of the sample tube in a device for self-absorption correction of radioactive samples of unknown composition.

[0031] Figure 6 A sectional view of a sample cylinder in a device for self-absorption correction of a radioactive sample with unknown composition.

[0032] Figure 7 A structural view of a compression cover in a device for self-absorption correction of a radioactive sample with unknown composition.

[0033] Figure 8 A structural view of a compression plate in a device for self-absorption correction of a radioactive sample with unknown composition.

[0034] Figure 9 A split view of a compression plate in a device for self-absorption correction of a radioactive sample with unknown composition.

[0035] Figure 10 A split view of a lead collimator in a device for self-absorption correction of a radioactive sample with unknown composition.

[0036] Figure 11 A mass attenuation coefficient curve at different energies in the present application.

[0037] Figure 12 A simulation schematic view of a device for self-absorption correction of a radioactive sample with unknown composition.

[0038] Figure 13 A radioactive substance thickness integration schematic view.

[0039] In the figure: 1, outer shell; 2, support seat; 3, support rod; 4, lower fixed plate; 5, upper fixed plate; 6, detector; 7, lead collimator; 8, sample cylinder; 9, compression cover;

[0040] 100, power gear; 101, driven gear; 102, mounting plate; 401, toothed ring; 402, rotating ring; 403, rotating column; 404, movable gear; 700, sleeve; 701, inner lead body; 702, first outer lead sleeve; 703, second outer lead sleeve; 704, third outer lead sleeve;

[0041] 800, cylinder body; 801, bottom cavity; 802, mounting cavity; 803, threaded rod; 804, butt joint block; 805, return spring; 806, shielding curtain;

[0042] 900, fixed ring; 901, movable ring; 902, connecting lug; 903, rack block; 904, compression plate; 905, positioning gear; 906, fixed block; 907, retraction plate; 908, movable track; 909, sliding block; 910, connecting rope. DETAILED DESCRIPTION

[0043] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0044] Please refer to Figures 1-3 In the embodiments of the present application, a device for self-absorption correction of an unknown component radioactive sample comprises a support seat 2, an outer shell 1 which is detachably connected to the outside of the support seat 2, and a plurality of support rods 3 which are rotatably connected to the upper end of the support seat 2. A lower fixed plate 4 is movably connected between the plurality of support rods 3, and an upper fixed plate 5 is fixedly connected above the lower fixed plate 4. The distance between the lower fixed plate 4 and the upper fixed plate 5 can be adjusted. Specifically, to facilitate the up-and-down movement of the lower fixed plate 4 between two support rods 3, the surfaces of the two support rods 3 are provided with threads, and the other support rods 3 are optical shafts. The lower fixed plate 4 is threadedly connected with the support rods 3 and slidably connected with the optical shafts. More specifically, a threaded sleeve is fixedly connected inside the lower fixed plate 4, the threaded sleeve is threadedly connected with the support rods 3, two sliding holes are formed in the lower fixed plate 4, the optical shafts pass through the lower fixed plate 4 through the sliding holes, the upper fixed plate 5 is fixedly connected with the optical shafts, two symmetrical circular holes are formed in the inside of the upper fixed plate 5, the support rods 3 with threads pass through the upper fixed plate 5 through the circular holes and do not contact the upper fixed plate 5. To facilitate the rotation of the support rods 3, a power gear ring 100 is rotatably connected to the upper end of the support seat 2. Two support rods 3 with threads are each fixedly connected with a driven gear 101, and the driven gears 101 are meshed with the power gear ring 100. To facilitate the rotation of the power gear ring 100, a plurality of protruding blocks are fixedly connected to the upper end of the power gear ring 100. The protruding blocks facilitate the user to push the power gear ring 100 to rotate. The rotation of the power gear ring 100 drives the support rods 3 to rotate. When the support rods 3 rotate, the lower fixed plate 4 moves up and down, thereby adjusting the distance between the lower fixed plate 4 and the upper fixed plate 5.

[0045] The upper end of the support seat 2 between the plurality of support rods 3 is also detachably connected with a detector 6 for receiving photons. Specifically, to facilitate the connection between the detector 6 and the support seat 2, an installation plate 102 is fixedly connected inside the support seat 2, and the detector 6 is detachably connected with the installation plate 102 through screws. More specifically, a plurality of extension rods are fixedly connected to the lower end of the installation plate 102, and the extension rods are fixedly connected with the support seat 2 through the power gear ring 100.

[0046] The lower ends of the upper and lower fixing plates 5 and 4 are detachably connected to lead collimators 7 for limiting photons. The upper end of the upper fixing plate 5 is provided with a groove for placing a radioactive source. The upper end of the lower fixing plate 4 is provided with a sample tube 8 for containing radioactive material. The radioactive source is a gamma radiation source, and the specific radioactive source includes: 241 Am(@59.56keV), 133 Ba(@80.9979keV, 276.3989keV, 302.851keV, 356.1029keV, 383.8485keV), 137 Cs(@661.67keV), 152 Eu(@121.78keV, 964.06keV, 1408.01keV), 60 Co(@1173.2keV, 1332.5keV).

[0047] Example 2, please refer to Figure 4 -

[0048] Figure 7 , combined with the basis of Example 1, the difference is that the sample tube 8 is movably connected to the compression cover 9 for compressing the radioactive material. The sample tube 8 includes a cylinder 800. The lower end of the cylinder 800 is provided with a bottom cavity 801 connected to the lower fixed plate 4, and the bottom cavity 801 is fixedly connected to the interior of the magnet ring;

[0049] The interior of the cylinder 800 is also rotatably connected to a threaded rod 803 for driving the compression cover 9 to move up and down. The lower end of the threaded rod 803 passes through the bottom end of the cylinder 800. The lower end of the threaded rod 803 is fixedly connected to a docking block 804. The docking block 804 is set to a polygon and is located in the bottom cavity 801. A return spring 805 is provided between the docking block 804 and the inner top of the bottom cavity 801. The return spring 805 is sleeved on the outside of the threaded rod 803. Specifically, two mounting cavities 802 are symmetrically provided on the inner wall of the cylinder 800. The threaded rod 803 is located in the installation cavity 802. In order to prevent radioactive substances from affecting the rotation of the threaded rod 803, a foldable shielding curtain 806 is slidably connected to the interior of the installation cavity 802, and the upper end of the shielding curtain 806 is fixedly connected to the compression cover 9. Specifically, limiting grooves are symmetrically opened on the inner wall of the installation cavity 802, and the side ends of the shielding curtain 806 are located in the limiting grooves. The limiting grooves can be used to position the shielding curtain 806, and at the same time, radioactive substances can be prevented from entering the installation cavity 802 through the gap between the shielding curtain 806 and the installation cavity 802.

[0050] Please refer to Figure 4, the upper end of the lower fixed plate 4 is fixedly connected to the fixed gear ring 401, the fixed gear ring 401 is magnetic and can attract each other with the magnet ring, the upper end of the lower fixed plate 4 is also rotatably connected to the rotating ring 402, the rotating ring 402 is located outside the fixed gear ring 401, the upper end of the rotating ring 402 is symmetrically rotatably connected to the rotating column 403, the outside of the rotating column 403 is fixedly connected to the movable gear 404, the movable gear 404 is meshed with the fixed gear ring 401, and the upper end of the rotating column 403 is provided with a slot hole for docking with the docking block 804, and the shape of the slot hole corresponds to the shape of the docking block 804;

[0051] Please refer to Figure 7 The compression cover 9 includes a fixed ring 900, a movable ring 901 is slidably connected to the interior of the fixed ring 900, and the movable ring 901 and the fixed ring 900 are fixedly connected by a plurality of connecting ropes 910. When the movable ring 901 does not move, the connecting ropes 910 are in a loose state. A rubber ring is fixedly connected to the outer wall of the fixed ring 900, and the rubber ring can increase the friction between the fixed ring 900 and the cylinder 800, and can also prevent radioactive substances from overflowing from the gap between the fixed ring 900 and the cylinder 800.

[0052] Two connecting ears 902 are symmetrically fixedly connected to the outer wall of the movable ring 901. The two connecting ears 902 are threadedly connected to the threaded rod 803. The connecting ears 902 are located in the installation cavity 802 and can slide in the installation cavity 802.

[0053] Please refer to Figure 7 , the upper end of the movable ring 901 is fixedly connected to a plurality of rack blocks 903, the rack blocks 903 pass through the fixed ring 900, the internal rotation of the fixed ring 900 is connected to a plurality of compression plates 904, and the compression plate 904 is fixedly connected to one end close to the fixed ring 900 with a positioning gear 905, and the positioning gear 905 is meshed with the rack block 903;

[0054] Specifically, a plurality of fixed blocks 906 are fixedly connected to the inner wall of the fixed ring 900, and a plurality of compression plates 904 are rotatably connected to the fixed blocks 906 via rotating shafts.

[0055] See also Figure 8 , the upper end of the compression plate 904 is slidably connected to the retracted plate 907, and the compression plate 904 and the retracted plate 907 can be spliced ​​to form a triangular plate. Specifically, the upper end of the compression plate 904 is provided with a movable track 908, and the lower end of the retracted plate 907 is rotatably connected to a sliding block 909, and the sliding block 909 is located in the movable track 908. More specifically, the upper end of the compression plate 904 is provided with an inclined surface, and the lower end of the retracted plate 907 is provided with a slope adapted to the inclined surface on the compression plate 904. Please refer to Figure 9 .

[0056] For example three, please refer toFigure 10 Based on Example 1, the lead collimator 7 includes a shell 700, a circular hole is opened at the bottom end of the shell 700, and the shell 700 is detachably connected to the lower fixing plate 4 and the upper fixing plate 5 by bolts. An inner lead body 701 is placed inside the shell 700, and a channel for allowing photons to pass through is opened in the middle of the inner lead body 701, and the channel corresponds to the circular hole. The outside of the inner lead body 701 is sequentially covered with a first outer lead sleeve 702, a second outer lead sleeve 703 and a third outer lead sleeve 704. Specifically, the inner lead body 701, the first outer lead sleeve 702, the second outer lead sleeve 703 and the third outer lead sleeve 704 are all set to a truncated cone shape, and when the first outer lead sleeve 702, the second outer lead sleeve 703 and the third outer lead sleeve 704 are covered with each other, the gaps between them will be filled with lead paste.

[0057] Example 4, based on Examples 1-3, the detection method is as follows:

[0058] Step 1: Place the gamma radiation source in the groove at the upper end of the upper fixing plate 5 so that the gamma radiation source serves as a photon source;

[0059] Step 2: Place the empty sample tube 8 on the upper end of the lower fixed plate 4. The photons emitted by the gamma radiation source will pass through the channel in the inner lead body 701, pass through the tube 800, and then be received by the detector 6. The spectrum is analyzed and the net count rate N1 of the peak area corresponding to the radiation energy is calculated.

[0060] Step 3: Place the radioactive material into the cylinder 800, then place the cylinder 800 on the upper end of the lower fixed plate 4, so that the docking block 804 docks with the rotating column 403. At this time, the threaded rod 803 will move upward. During the upward movement of the threaded rod 803, it will rotate downward through the rack block 903, so that the upper layer of the radioactive material is covered by the compression plate 904 and the retraction plate 907. Then rotate the cylinder 800. At this time, since the docking block 804 and the rotating column 403 are in a docking state, the rotating cylinder 800 can drive the movable gear 404 to rotate through the rotating ring 402. When the movable gear 404 rotates, it will engage with the fixed gear ring 401 and rotate on its own. At this time, the threaded rod 803 will rotate. When the threaded rod 803 rotates, the connecting ear 902 will move downward along the installation cavity 802, so that the radioactive material is further compressed by the compression plates 904. When the compression is completed, the retraction plate 907 is pushed along the movable track 908, thereby expanding the retraction plates 907 to expose the radioactive material.

[0061] By increasing the density of the radioactive material inside the cylinder 800, it is possible to prevent photons from being reflected in the gaps between the radioactive material and affecting the accuracy of the inspection;

[0062] At this time, the photons emitted by the gamma radiation source will be received by the detector 6 after passing through the radioactive material, and the spectrum will be analyzed to calculate the net count rate N2 of the peak area corresponding to the energy of the ray;

[0063] Step 4: Calculate the mass attenuation coefficient of the energy photon in the sample according to the Beer-Lamber formula;

[0064] The formula is:

[0065]

[0066] Step 5: Replace the gamma radiation source with different energy. The gamma radiation source includes: 241 Am(@59.56keV), 133 Ba(@80.9979keV、276.3989keV、302.851keV、356.1029keV、383.8485

[0067] keV), 137 Cs(@661.67keV), 152 Eu(@121.78keV, 964.06keV, 1408.01keV), 60 Co (@1173.2keV, 1332.5keV). 5 other γ point sources covering low, medium and high energy ranges, repeat steps 2 to 4 to obtain the mass attenuation coefficient at different energies and record the data. Please refer to Figure 11 .

[0068] Step 6: Obtain a set of data of E (energy) - μ (mass attenuation coefficient), take the natural logarithm of the data, use a fourth-order polynomial fit to obtain the fitting curve and fitting parameters, and realize the fitting output of the mass attenuation coefficient at different energies.

[0069] Fitting formula: ln(μ)=a+bln(E)+cln(E) 2 +dln(E) 3 +eln(E) 4

[0070] Step 7: Calculate the self-absorption correction factor using a simple analytical method. Integrate the sample by thickness to obtain the self-absorption correction factor: For a cylindrical sample with a thickness of h as shown in the figure below, please refer to Figure 13 ;

[0071] Beer-Lamber using rays

[0072] Formula, integrating the entire sample by thickness, yields the following relationship:

[0073] I=∫0 h I0*exp(-μ*x)·dx / h=I0*1-exp(-μ·h) / μ*h

[0074] Thus, the self-absorption correction factor C is obtained att for:

[0075] C att =I / I0=1-exp(-μ·h) / μ*h

[0076] The working principle of the present invention is:

[0077] When the thickness of the lead collimator 7 needs to be changed during use of the present invention, the housing 700 can be opened and the first outer lead sleeve 702, the second outer lead sleeve 703 and the third outer lead sleeve 704 can be sequentially installed to prevent photons from deviating from their trajectory, thereby increasing the accuracy of detection.

[0078] When the radioactive material in the cylinder 800 needs to be taken out, the cylinder 800 is pulled upward. After the cylinder 800 is separated from the fixed gear ring 401, the threaded rod 803 will be reset under the action of the reset spring 805. At this time, the compression plate 904 will open, making it easier to pour out the radioactive material.

[0079] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A device for self-absorption correction of radioactive samples of unknown components, comprising a support seat (2), characterized in that: The outer portion of the support seat (2) is detachably connected to a housing (1); the upper end of the support seat (2) is rotatably connected to a plurality of support rods (3); a lower fixed plate (4) is movably connected between the plurality of support rods (3); an upper fixed plate (5) is fixedly connected above the lower fixed plate (4); and the spacing between the lower fixed plate (4) and the upper fixed plate (5) can be adjusted; in order to facilitate the rotation of the support rods (3), the upper end of the support seat (2) is rotatably connected to a power gear ring (100); and driven gears (101) are fixedly connected to the outer walls of the two support rods (3) with threads, and the driven gears (101) and the power gear ring (100) are meshed with each other; The lower ends of the upper fixing plate (5) and the lower fixing plate (4) are detachably connected to a lead collimator (7) for limiting photons, the upper end of the upper fixing plate (5) is provided with a groove for placing a radioactive source, and the upper end of the lower fixing plate (4) is provided with a sample cylinder (8) for containing radioactive substances; The sample cylinder (8) is internally movably connected to a compression cover (9) for compressing radioactive substances. The sample cylinder (8) comprises a cylinder body (800). The lower end of the cylinder body (800) is provided with a bottom cavity (801) that is docked with the lower fixed plate (4), and a magnet ring is fixedly connected to the interior of the bottom cavity (801); The compression cover (9) includes a fixed ring (900), a movable ring (901) is slidably connected to the interior of the fixed ring (900), the movable ring (901) and the fixed ring (900) are fixedly connected via a plurality of connecting ropes (910), a rubber ring is fixedly connected to the outer wall of the fixed ring (900), and the rubber ring can increase the friction between the fixed ring (900) and the cylinder (800); Two connecting ears (902) are symmetrically fixedly connected to the outer wall of the movable ring (901), the two connecting ears (902) are threadedly connected to the threaded rod (803), and the connecting ears (902) are located in the installation cavity (802); The upper end of the movable ring (901) is fixedly connected to a plurality of rack blocks (903), the rack blocks (903) pass through the fixed ring (900), the interior of the fixed ring (900) is rotatably connected to a plurality of compression plates (904), and one end of the compression plate (904) close to the fixed ring (900) is fixedly connected to a positioning gear (905), and the positioning gear (905) is meshed with the rack blocks (903); The upper end of the compression plate (904) is slidably connected to a retracting plate (907), and the compression plate (904) and the retracting plate (907) can be spliced ​​together to form a triangular plate. The upper end of the compression plate (904) is provided with a movable track (908); The lead collimator (7) comprises a housing (700), a circular hole is provided at the bottom end of the housing (700), the housing (700) is detachably connected to the lower fixing plate (4) and the upper fixing plate (5) by bolts, an inner lead body (701) is placed inside the housing (700), a channel for allowing photons to pass through is provided in the middle of the inner lead body (701), and the channel corresponds to the circular hole, and the outside of the inner lead body (701) is sequentially covered with a first outer lead sleeve (702), a second outer lead sleeve (703) and a third outer lead sleeve (704).

2. The device for correcting self-absorption of radioactive samples of unknown components according to claim 1, characterized in that: The upper end of the support seat (2) is located between a plurality of support rods (3) and is detachably connected to a detector (6) for receiving photons.

3. The device for correcting self-absorption of radioactive samples of unknown components according to claim 2, characterized in that: The interior of the cylinder (800) is also rotatably connected to a threaded rod (803) for driving the compression cover (9) to move up and down. The lower end of the threaded rod (803) passes through the bottom end of the cylinder (800). The lower end of the threaded rod (803) is fixedly connected to a docking block (804). A return spring (805) is provided between the docking block (804) and the top end of the bottom cavity (801). In order to prevent radioactive substances from affecting the rotation of the threaded rod (803), the interior of the installation cavity (802) is slidably connected to a foldable shielding curtain (806), and the upper end of the shielding curtain (806) is fixedly connected to the compression cover (9).

4. The device for correcting self-absorption of radioactive samples of unknown components according to claim 3, characterized in that: The upper end of the lower fixed plate (4) is fixedly connected to a fixed gear ring (401), the fixed gear ring (401) is magnetic and can attract the magnet ring, the upper end of the lower fixed plate (4) is also rotatably connected to a rotating ring (402), the upper end of the rotating ring (402) is symmetrically rotatably connected to a rotating column (403), the outside of the rotating column (403) is fixedly connected to a movable gear (404), the movable gear (404) is meshed with the fixed gear ring (401), and the upper end of the rotating column (403) is provided with a slot hole for docking with a docking block (804).

5. A method for correcting the self-absorption of radioactive samples of unknown components, used in the device for correcting the self-absorption of radioactive samples of unknown components according to claim 4, characterized in that: The following steps are involved: Select the radiation source: The radiation source is a gamma radiation source; Step 1: Place the gamma radiation source in the groove at the upper end of the upper fixing plate (5) so that the gamma radiation source serves as a photon source; Step 2: Place the empty sample tube (8) on the upper end of the lower fixed plate (4). At this time, the photons emitted by the gamma radiation source will pass through the channel in the inner lead body (701) and pass through the tube (800) and then be received by the detector (6). The spectrum is analyzed and the net count rate N1 of the peak area corresponding to the energy of the ray is calculated; Step 3: Place the radioactive material into the cylinder (800), then place the cylinder (800) on the upper end of the lower fixed plate (4), so that the docking block (804) and the rotating column (403) are docked. At this time, the threaded rod (803) will move upward. During the upward movement of the threaded rod (803), it will rotate downward through the rack block (903), so that the upper layer of the radioactive material is covered by the compression plate (904) and the retraction plate (907). Then, the cylinder (800) is rotated. At this time, since the docking block (804) and the rotating column (403) are in the docking state, the rotating cylinder ( 800) can drive the movable gear (404) to rotate through the rotating ring (402), and when the movable gear (404) rotates, it will mesh with the fixed gear ring (401) and rotate on its own. At this time, the threaded rod (803) will rotate. When the threaded rod (803) rotates, the connecting ear (902) will move downward along the installation cavity (802), thereby using the plurality of compression plates (904) to further compress the radioactive material. When the compression is completed, the retraction plate (907) is pushed along the movable track (908), thereby causing the plurality of retraction plates (907) to expand and expose the radioactive material. By increasing the density of the radioactive material inside the cylinder (800), it is possible to prevent photons from being reflected in the gaps between the radioactive material and affecting the accuracy of the inspection; At this time, the photons emitted by the gamma radiation source will be received by the detector (6) after passing through the radioactive material, and the spectrum will be analyzed to calculate the net count rate N2 of the peak area corresponding to the energy of the ray; Step 4: Calculate the mass attenuation coefficient of the energy photon in the sample according to the Beer-Lamber formula; Step 5: Replace the gamma radiation source with a different energy, repeat the process from step 2 to step 4, obtain the mass attenuation coefficient at different energies, and record the data; Step 6: Obtain a set of data of E (energy) - μ (mass attenuation coefficient), take the natural logarithm of the data, use a fourth-order polynomial fit to obtain the fitting curve and fitting parameters, and realize the fitting output of the mass attenuation coefficient at different energies; Step 7: Calculation of self-absorption correction factor: Integrate the sample according to thickness to obtain the self-absorption correction factor.

6. The method for correcting self-absorption of radioactive samples of unknown components according to claim 5, characterized in that: The γ radiation source includes 241 Am(@59.56 keV), 133 Ba(@80.9979 keV, 276.3989 keV, 302.851 keV, 356.1029 keV, 383.8485 keV), 137 Cs(@661.67 keV), 152 Eu(@121.78 keV, 964.06 keV, 1408.01 keV), 60 Co(@1173.2 keV, 1332.5 keV).

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