A recoil nuclear capture detection device and a recoil capture detection method

Abstract

The present invention proposes a recoil nuclear capture detection device, including a recoil nuclear capture detector and a neutron source. The recoil nuclear capture detector includes a detector cavity, a nuclear material plating to be tested, and a capture medium. The nuclear material plating to be tested and the capture medium are in contact and arranged inside the detector cavity. The nuclear material plating to be tested undergoes a nuclear reaction after neutron irradiation to produce recoil nuclei and is captured by the capture medium. The neutron source is located on the outer lining side of the detector cavity, and the neutron energy threshold is 5MeV. The present invention also proposes a recoil nuclear capture detection method, which comprises the following steps: assembling the detector, irradiating the nuclear material plating, capturing recoil nuclei, testing radioactivity, and obtaining nuclear reaction cross section parameters through data processing. The device and method described in the present invention avoid the shortcomings of the radiochemical method, such as complicated process, long test cycle, and high cost, realize the separation and enrichment of recoil nuclei and parent nuclei, and solve the problem that the nuclear reaction cross section is difficult to measure when the parent nucleus and daughter nucleus have the same decay type and the emitted rays or particles have equivalent energy.

Description

Technical Field

[0001] The invention belongs to the field of nuclear reaction cross section measurement, and in particular relates to a recoil nuclear capture detector and a recoil nuclear capture detection method. Background Art

[0002] In the field of nuclear physics, the activation method is a common method for measuring nuclear reaction cross sections. The basic principle is: purify the target material and make it into an irradiation target, irradiate the irradiation target with a neutron beam of a certain energy, and the neutrons react with the target material to generate daughter nuclei. By measuring the rays or particles emitted by the daughter nuclei, the amount of daughter nuclei generated can be measured. This technology can meet the measurement of most nuclear material reaction cross sections. However, there are also some nuclides, such as uranium and plutonium, whose parent nuclei and daughter nuclei decay in the same type, and the particles emitted during the decay process are of the same type and close in energy, and the amount of daughter nuclei generated is small, resulting in a great influence of the parent nucleus on the measurement of the daughter nuclei, and the amount of daughter nuclei generated cannot be directly measured.

[0003] In order to solve the problem that the nuclear reaction cross section is difficult to measure when the decay type of the parent nucleus and the daughter nucleus are the same and the energy of the emitted rays (or particles) is equivalent, a radiochemical separation method is proposed, that is, firstly separating the trace daughter nucleus from the parent nucleus, and then measuring the nuclear reaction cross section. However, this method has the following problems: first, it is difficult to prepare a high-purity parent nucleus; second, the radiochemical separation process is cumbersome and complicated, with poor precision and high cost; third, it is impossible to completely extract the micro-daughter nucleus from the parent nucleus. It can be seen that the radiochemical separation method has poor practicality.

[0004] Based on the above reasons, there is an urgent need to design a nuclear reaction cross section measurement device or method that can be used for the parent nucleus and daughter nucleus with the same decay type and equivalent energy of emitted rays (or particles). Summary of the invention

[0005] To achieve this goal, a recoil nuclear capture detector is proposed:

[0006] A recoil nuclear capture detection device comprises a recoil nuclear capture detector and a neutron source, characterized in that the recoil nuclear capture detector comprises a detector cavity, a nuclear material plate to be tested, and a capture medium; the nuclear material plate to be tested and the capture medium are in contact and are both arranged inside the detector cavity, the nuclear material plate to be tested comprises a substrate and a nuclear material coating to be tested located on one side of the substrate, the nuclear material coating to be tested can produce recoil nuclei that rush out of the surface of the nuclear material coating to be tested after nuclear reaction occurs after irradiation by a neutron source, the capture medium is used to capture the recoil nuclei, the neutron source is located outside the recoil nuclear capture detector, the neutron source is located on the substrate side of the nuclear material plate to be tested, and the neutron beam energy threshold emitted by the neutron source is 5MeV.

[0007] Preferably, the capture medium is a polyethylene film or a polyester film, which is laminated on the coating of the nuclear material to be tested, and the gap between the polyethylene film or the polyester film and the coating of the nuclear material to be tested is at the micron level, and the detector cavity is a vacuum cavity at the Pa level.

[0008] Preferably, there are multiple nuclear material plated sheets to be tested and they are stacked and arranged in the same direction.

[0009] Preferably, the capture medium is a liquid capture liquid, the capture liquid fills the entire detector cavity, and the nuclear material plated sheets to be tested are multiple and are stacked in the same direction.

[0010] A recoil nuclear capture detection method based on the recoil nuclear capture detection device, characterized in that the recoil nuclear capture detection method comprises the following steps:

[0011] S1: stacking and fixing a plurality of nuclear material coating sheets to be tested in the detector cavity with the nuclear material coating layers to be tested facing the same direction, and a polyethylene film or a polyester film is laminated on each nuclear material coating layer to be tested;

[0012] S2: Evacuate the detector cavity to Pa level and maintain it;

[0013] S3: Turn on the neutron source, so that the neutron beam irradiates the nuclear material coating to be tested from the substrate side of the nuclear material coating to be tested to cause a nuclear reaction and generate recoil nuclei. The neutron beam energy threshold is 5MeV;

[0014] S4: polyethylene or polyester membrane captures the recoil nuclei;

[0015] S5: Take out the polyethylene or polyester film and test the radioactivity;

[0016] S6: Data processing, obtaining nuclear reaction cross section parameters.

[0017] Another recoil nuclear capture detection method based on the recoil nuclear capture detection device is characterized in that the recoil nuclear capture detection method comprises the following steps:

[0018] S1: Stack and fix multiple nuclear material plates to be tested in the detector cavity with the nuclear material plates to be tested facing the same direction;

[0019] S2: Fill the entire detector cavity with the capture liquid;

[0020] S3: Turn on the neutron source, so that the neutron beam irradiates the nuclear material coating to be tested from the substrate side of the nuclear material coating to be tested to cause a nuclear reaction and generate recoil nuclei. The neutron beam energy threshold is 5MeV;

[0021] S4: the trapping fluid captures the recoil nucleus;

[0022] S5: Concentrate the captured liquid, make a source, and measure the radioactivity;

[0023] S6: Data processing, obtaining nuclear reaction cross section parameters.

[0024] The working principle of the present invention is as follows: a neutron source emits a neutron beam, and the neutrons react with the nuclear materials in the coating to generate daughter nuclei, which recoil out of the coating surface and are then captured by a capture medium to separate the parent nucleus from the daughter nucleus. Finally, the radioactivity of the daughter nuclei (i.e., recoil nuclei) in the capture medium is measured, and after data processing, parameters such as the nuclear reaction cross section are obtained.

[0025] The beneficial effects of the present invention are as follows: (1) Compared with the radiochemical method, the device and method of the present invention creatively utilize the principle of capturing recoil nuclei, cleverly avoiding the shortcomings of complicated radiochemical separation process, poor precision, long test cycle and high cost, and realizing the separation, collection and enrichment of recoil nuclei, and finally realizing the physical measurement of daughter nuclei. (2) The device and method of the present invention obtain nuclear reaction cross section parameters through the recoil, collection, enrichment and testing of daughter nuclei, thus solving the problem that the nuclear reaction cross section is difficult to measure when the parent nucleus and daughter nucleus have the same decay type and the energy of the emitted rays (or particles) is equivalent. (3) The coating of the nuclear material to be measured in the device and method of the present invention is optional, and the energy of the neutron beam is adjustable, which can realize the measurement of various nuclear material parameters, and has strong applicability and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Recoil Nuclear Capture Detection Device I;

[0027] Figure 2 Capture medium I and the nuclear material plate to be tested;

[0028] Figure 3 Recoil Nuclear Capture Detector II;

[0029] In the figure: 1. neutron source, 2. recoil nuclear capture detector, 21. detector cavity, 22. capture medium I, 23. nuclear material plating to be tested, 24. pressure ring, 25. bolt, 26. capture medium II, 231. bottom lining, 232. nuclear material plating to be tested. DETAILED DESCRIPTION

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. The present invention is described in detail below in conjunction with the drawings.

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods and drawings.

[0032] Embodiment 1

[0033] The recoil nuclear capture detection device 1 includes a recoil nuclear capture detector 2 and a neutron source 1. The recoil nuclear capture detector 2 mainly includes a detector cavity 21, a nuclear material plate 23 to be tested, and a capture medium 122. The nuclear material plate 23 to be tested is composed of a substrate 231 and a nuclear material coating 232 to be tested located on the substrate, wherein the nuclear material coating 232 to be tested is uranium, plutonium or other nuclear materials. In this embodiment, the capture medium 122 is a polyethylene film or a polyester film, which is fitted on the nuclear material coating 232 to be tested. The best effect is achieved if there is no gap between the two. If there is a gap, the maximum gap is recommended to be micron-level. In order to ensure that the polyethylene film or polyester film is tightly fitted on the nuclear material coating 232 to be tested, a ring-mounted pressure ring 24 is respectively arranged at the bottom of the substrate 231 and the top of the polyethylene film or the polyester film, and a fastener is used to achieve a tight fit between the nuclear material coating 232 to be tested and the capture medium 122 such as the polyethylene film or the polyester film. The combination of the nuclear material plate 23 to be tested, the capture medium I22 and the top and bottom pressure rings 24 is called a detection unit. In practical applications, there are multiple groups of detection units. Figure 1 Four groups are shown in the figure, and they are stacked and fixed in the detector cavity 21 in the same direction. The neutron source 1 is located outside the recoil nuclear capture detector 2 and on the side of the substrate 231 of the nuclear material plate 23 to be detected.

[0034] The assembly process of the detector 2 is as follows: (1) Place the bottom pressure ring 24 (with the limit groove facing upward) on a horizontal surface; (2) Place the nuclear material coating 232 of the nuclear material coating 23 to be tested facing upward in the limit groove of the pressure ring 24; (3) Place a capture medium I22 such as a polyethylene film or a polyester film tightly against the coating surface; (4) Press the top pressure ring 24 (with the limit groove facing downward) onto the capture sheet, and then fix the two pressure rings together with screws to form a group of detection units; (5) Stack multiple groups of detection units together to ensure that the nuclear material coating 232 of the nuclear material coating 23 to be tested is in the same direction, and then use screws to penetrate them together and fix them at the bottom of the detector cavity 21; (6) The detector cavity 21 is sealed with vacuum glue to complete the assembly.

[0035] When conducting a neutron irradiation experiment, the main steps are as follows:

[0036] (1) Assembling the recoil nuclear capture detector 2;

[0037] (2) Connect the vacuum port of the detector cavity 21 to the vacuum system through a vacuum valve, evacuate the detector cavity 21 to the Pa level, and then close the vacuum valve and disconnect it from the vacuum system.

[0038] (3) Turn on the neutron source 1, so that the neutron beam irradiates the nuclear material coating 232 to be tested from the substrate 231 side of the nuclear material plate 23 to be tested to cause a nuclear reaction and generate recoil nuclei, and the neutron beam energy threshold is adjusted to 5 MeV;

[0039] (4) The polyethylene film or polyester film captures the recoil nuclei; after the irradiation is completed, the vacuum valve is opened to allow air to enter the detector cavity 21, the upper cover of the detector cavity 21 is opened, each detection unit is disassembled, and the capture medium I such as the polyethylene film or polyester film is taken out.

[0040] (5) Measuring the radioactivity of polyethylene or polyester films;

[0041] (6) Data processing to obtain nuclear reaction cross section parameters.

[0042] Embodiment 2

[0043] The recoil nuclear capture detection device II includes a recoil nuclear capture detector 2 and a neutron source 1. The recoil nuclear capture detector 2 mainly includes a detector cavity 21, a nuclear material plate 23 to be tested, and a capture medium II26. The nuclear material plate 23 to be tested is composed of a substrate 231 and a nuclear material coating 232 to be tested located on the substrate, wherein the nuclear material coating 232 to be tested is uranium, plutonium or other nuclear materials. In this embodiment, the capture medium II26 is a liquid capture liquid, such as alcohol. The capture liquid fills the entire detector cavity 21 and is used to capture recoil nuclei. Multiple nuclear material plates 23 to be tested are stacked and arranged at the bottom of the detector cavity 21 in a consistent direction by bolts 25 and a limiting device, and gaps are maintained between the nuclear material plates 23 to be tested. The neutron source 1 is located outside the recoil nuclear capture detector 2 and on the side of the substrate 231 of the nuclear material plate 23 to be tested.

[0044] The assembly process of the detector 2 is as follows: (1) Place the bottom pressure ring 24 (with the limit groove facing upward) on a horizontal surface; (2) Place the nuclear material coating 232 of the nuclear material coating 23 to be tested upward in the limit groove of the pressure ring 24 and fix them together to form a unit to be tested; (3) Place multiple groups of units to be tested facing upward to ensure that the nuclear material coating 232 of the nuclear material coating 23 to be tested is in the same direction; and fix them at intervals at the bottom of the detector cavity 21 by bolts 25 and limit devices to complete the assembly.

[0045] When conducting a neutron irradiation experiment, the main steps are as follows:

[0046] (1) Assembling the recoil nuclear capture detector 2;

[0047] (2) Open the capture liquid filling port of the detector cavity 21 and fill the cavity with capture liquid.

[0048] (3) Turn on the neutron source 1, so that the neutron beam irradiates the nuclear material coating 232 to be tested from the substrate 231 side of the nuclear material plate 23 to be tested to cause a nuclear reaction and generate recoil nuclei, and the neutron beam energy threshold is adjusted to 5 MeV;

[0049] (4) The trapping fluid captures the recoil nucleus;

[0050] (5) Concentrating, evaporating, preparing sources, and measuring radioactivity of the captured liquid;

[0051] (6) Data processing to obtain nuclear reaction cross section parameters.

Claims

1. A recoil nuclear capture detection device, comprising a recoil nuclear capture detector and a neutron source, characterized in that: The recoil nuclear capture detector comprises a detector cavity, a nuclear material plating to be tested, and a capture medium; the nuclear material plating to be tested and the capture medium are in contact and arranged inside the detector cavity; the nuclear material plating to be tested comprises a substrate and a nuclear material plating to be tested located on one side of the substrate; the nuclear material plating to be tested can produce recoil nuclei that punch out of the surface of the nuclear material plating to be tested after neutron irradiation; the capture medium is used to capture the recoil nuclei; the neutron source is located outside the recoil nuclear capture detector; the neutron source is located on the substrate side of the nuclear material plating to be tested; and the energy threshold of the neutron beam emitted by the neutron source is 5MeV.

2. The recoil nuclear capture detection device according to claim 1, characterized in that: The capture medium is a polyethylene film or a polyester film, and the polyethylene film or the polyester film is laminated on the coating of the nuclear material to be detected, and the detector cavity is a vacuum cavity of the Pa order.

3. The recoil nuclear capture detection device according to claim 2, characterized in that: The nuclear material plated sheets to be tested are multiple and are stacked and arranged in the same direction.

4. The recoil nuclear capture detection device according to claim 1, characterized in that: The capture medium is a liquid capture liquid, and the capture liquid fills the entire detector cavity. The nuclear material plated sheets to be tested are multiple and are stacked in the same direction.

5. A recoil nuclear capture detection method based on the recoil nuclear capture detection device according to claim 2 or 3, characterized in that: The recoil nuclear capture detection method comprises the following steps: S1: stacking and fixing a plurality of nuclear material coating sheets to be tested in the detector cavity with the nuclear material coating layers to be tested facing the same direction, and a polyethylene film or a polyester film is laminated on each nuclear material coating layer to be tested; S2: Evacuate the detector cavity to Pa level and maintain it; S3: Turn on the neutron source, so that the neutron beam irradiates the nuclear material coating to be tested from the substrate side of the nuclear material coating to be tested to cause a nuclear reaction and generate recoil nuclei. The neutron beam energy threshold is 5MeV; S4: polyethylene or polyester membrane captures recoil nuclei; S5: Take out the polyethylene or polyester film and test the radioactivity; S6: Data processing, obtaining nuclear reaction cross section parameters.

6. A recoil nuclear capture detection method based on the recoil nuclear capture detection device according to claim 4, characterized in that: The recoil nuclear capture detection method comprises the following steps: S1: Stack and fix multiple nuclear material plates to be tested in the detector cavity with the nuclear material plates to be tested facing the same direction; S2: Fill the entire detector cavity with the capture liquid; S3: Turn on the neutron source, so that the neutron beam irradiates the nuclear material coating to be tested from the substrate side of the nuclear material coating to be tested to cause a nuclear reaction and generate recoil nuclei. The neutron beam energy threshold is 5MeV; S4: the trapping fluid captures the recoil nucleus; S5: Concentrate the captured liquid, make a source, and test the radioactivity; S6: Data processing, obtaining nuclear reaction cross section parameters.

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