A gas detector

Abstract

An embodiment of the present application provides a gas detector, which includes a sealed chamber, an incident window, and an electrode assembly. The sealed chamber is used to accommodate a working gas; the incident window is hermetically arranged on one side of the sealed chamber, and incident particles can enter the sealed chamber through the incident window; the electrode assembly includes a first electrode and a second electrode. The second electrode is arranged inside the sealed chamber, and there is a potential difference between the first electrode and the second electrode to form an electric field that gradually increases in the direction from the incident window towards the second electrode. The gas detector provided by the embodiment of the present application forms an electric field that gradually increases in the direction from the incident window towards the second electrode. Near the second electrode, electrons can obtain sufficiently high energy and achieve multiplication, realizing proportional amplification of energy, thereby effectively improving the ion signal-to-noise ratio to realize the measurement of incident particles with low energy such as low-energy heavy nuclides, and further improving the applicability of the gas detector.

Description

Technical Field

[0001] This application relates to the technical field of gas detection, and in particular, to a gas detector. Background Art

[0002] Common gas detectors mainly include gas ionization chambers, Bragg gas detectors, proportional tubes, etc. These gas detectors select different types of detectors according to different uses. For example, a gas ionization chamber is a commonly used gas detector in nuclear physics detection.

[0003] However, the gas detectors in the related art are mainly used to measure ions with relatively high ion energy. When used to measure ions with low ion energy, due to the low ion energy, the generated ion signal overlaps with the electronic noise of the detection system, and the determination of ions cannot be achieved. Therefore, the gas detectors in the related art have the problem of poor applicability. Summary of the Invention

[0004] In view of this, embodiments of this application expect to provide a gas detector with good applicability.

[0005] To achieve the above object, embodiments of this application provide a gas detector, including:

[0006] A sealed chamber for containing a working gas;

[0007] An incident window hermetically arranged on one side of the sealed chamber, and incident particles can enter the sealed chamber through the incident window;

[0008] An electrode assembly including a first electrode and a second electrode, the second electrode is arranged in the sealed chamber, and there is a potential difference between the first electrode and the second electrode to form an electric field that gradually increases in the direction from the incident window towards the second electrode.

[0009] In one embodiment, the direction of the electric field is parallel to the movement direction of the incident particles.

[0010] In one embodiment, the incident window and the second electrode are located on opposite sides of the sealed chamber.

[0011] In one embodiment, the potential difference is 300 - 500V.

[0012] In one embodiment, the incident window includes a connecting bracket and a window body arranged on the connecting bracket, the connecting bracket is hermetically fitted with the side wall on one side of the sealed chamber, and the incident particles can enter the sealed chamber through the window body.

[0013] In one embodiment, the material of the window body is Si 3 N4 。

[0014] In one embodiment, the thickness of the window is 20 nm - 40 nm.

[0015] In one embodiment, the connection bracket is made of a conductive material, and the connection bracket constitutes the first electrode.

[0016] In one embodiment, the cross-sectional shape of the sealed chamber is circular.

[0017] In one embodiment, the cross-sectional shape of the second electrode is circular.

[0018] In one embodiment, the distance between the connection bracket and the second electrode is L, the diameter of the cross-section of the sealed chamber is D1, and the ratio between L and D1 is 1 ± 15%.

[0019] In one embodiment, the diameter of the cross-section of the sealed chamber is D1, the diameter of the cross-section of the second electrode is D2, and the ratio between D2 and D1 is 0.5 ± 15%.

[0020] The embodiments of the present application provide a gas detector, which includes a sealed chamber, an incident window, and an electrode assembly. The sealed chamber is used to contain a working gas. The incident window is hermetically arranged on one side of the sealed chamber. Incident particles can enter the sealed chamber through the incident window. For example, low-energy incident particles such as low-energy heavy nuclides will ionize the working gas in the sealed chamber into electrons and cations after entering the sealed chamber. In addition, the gas detector further includes an electrode having a first electrode and a second electrode. A potential difference is provided between the first electrode and the second electrode to form a non-uniform electric field that gradually increases in the direction from the incident window towards the second electrode. Thus, electrons drift towards the second electrode under the action of the non-uniform electric field. Since the non-uniform electric field gradually increases as it approaches the second electrode, near the vicinity of the second electrode, the electrons can obtain a sufficiently high energy and achieve multiplication, realizing proportional amplification of energy, thereby effectively improving the ion signal-to-noise ratio to achieve the measurement of low-energy incident particles such as low-energy heavy nuclides, and further improving the applicability of the gas detector. Description of the Drawings

[0021] Figure 1 is a schematic structural diagram of the gas detector according to an embodiment of the present application;

[0022] Figure 2 is Figure 1 a schematic diagram of the voltage equipotential surface in the sealed chamber of the gas detector shown.

[0023] Description of the Reference Numerals

[0024] 10. Gas detector; 10a. Sealed chamber; 10b. Air extraction port; 10c. Gas filling port; 11. Incident window; 12. First electrode; 13. Second electrode; 14. Incident particle; 15. Barometer. Detailed implementation mode

[0025] It should be noted that, without conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other. The detailed description in the specific implementation mode should be understood as an explanatory illustration of the purpose of this application and should not be regarded as an improper limitation of this application.

[0026] In the description of the embodiments of this application, it should be noted that the orientation or positional relationship indicated by terms such as "left" and "right" is based on the Figure 1 orientation or positional relationship shown, and the orientation or positional relationship indicated by "length" is based on the Figure 1 left - right direction shown. It is only for the convenience of describing the embodiments of this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation of the embodiments of this application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] The embodiments of this application provide a gas detector. Please refer to Figure 1 , the gas detector 10 includes a sealed chamber 10a, an incident window 11 and an electrode assembly.

[0028] The sealed chamber 10a is used to contain the working gas. When the incident particle 14 enters the sealed chamber 10a and drifts in the working gas, the incident particle 14 interacts with the working gas in the sealed chamber 10a and ionizes the working gas into electron - ion pairs. The number of electron - ion pairs is proportional to the energy lost by the incident ion in ionizing the working gas in the sealed chamber 10a.

[0029] Among them, the working gas can be an organic gas. Exemplarily, in one embodiment, the working gas is propane.

[0030] The incident window 11 is hermetically arranged on one side of the sealed chamber 10a. The incident particle 14 can enter the sealed chamber 10a through the incident window 11. That is to say, the incident window 11 can be used to isolate the sealed chamber 10a of the detector from the vacuum state of the pipeline, so as to keep the working gas in the sealed chamber 10a stable.

[0031] Please refer to Figure 1 and Figure 2, the electrode assembly includes a first electrode 12 and a second electrode 13. The second electrode 13 is disposed within a sealed chamber 10a. There is a potential difference between the first electrode 12 and the second electrode 13 to form an electric field that gradually increases in the direction towards the second electrode 13 along the incident window 11. It should be noted that the specific types of the first electrode 12 and the second electrode 13 are not limited here. The first electrode 12 is a low-voltage electrode, and the first electrode 12 is electrically connected to the low-voltage end of a high-voltage power supply or directly grounded. The second electrode 13 is a high-voltage electrode, and the second electrode 13 is electrically connected to the high-voltage end of a high-voltage power supply. Exemplarily, the first electrode 12 is a cathode and the second electrode 13 is an anode.

[0032] The gas ionization chamber in the related art mainly includes an anode, a cathode, a grid, an incident window, etc. The anode and the cathode are used to provide a uniform electric field for the gas ionization chamber, and the electric field direction of the gas ionization chamber is perpendicular to the movement direction of the incident ions. In order to avoid the electron pulse amplitude being related to the ionization position of the incident particles, a grid is installed between the incident particles and the anode. Only when electrons pass through the grid and drift in the space between the grid and the anode, a voltage pulse will be induced on the anode. When ions enter the gas ionization chamber and drift in the working gas, the ions interact with the working gas in the gas ionization chamber and ionize the working gas in the gas ionization chamber into electron-ion pairs. Since the working voltage of the gas ionization chamber is relatively low, the detector operates in the ionization region, and the number of electron-ion pairs is proportional to the energy loss of the incident ions in the ionization region. These electron-ion pairs drift towards the anode and the cathode respectively under the action of a transverse electric field, thereby generating voltage pulse signals on the anode and the cathode, and the voltage pulse signal amplitude is proportional to the number of electrons or ions collected. Thus, the energy loss of particles on the anode and the cathode is measured through the pulse voltage amplitude generated by the detector. In this process, the number of electrons is not multiplied and amplified. Therefore, for example, the ion signals generated by low-energy incident particles such as low-energy heavy nuclides will overlap with the electronic noise of the detection system, and it is impossible to measure low-energy incident particles such as low-energy heavy nuclides. That is to say, the gas detectors in the related art are mainly used to measure ions with relatively high ion energies (such as 1 MeV / nucleon). With the continuous expansion of the application fields, it is necessary to develop a gas detector applicable to the measurement of low-energy (such as 0.01 MeV / nucleon) heavy nuclides.

[0033] The embodiment of the present application provides a gas detector. The gas detector 10 includes a sealed chamber 10a, an incident window 11, and an electrode assembly. The sealed chamber 10a is used to contain a working gas. The incident window 11 is hermetically arranged on one side of the sealed chamber 10a. Incident particles 14 can enter the sealed chamber 10a through the incident window 11. After low-energy incident particles 14 such as low-energy heavy nuclides enter the sealed chamber 10a, the working gas in the sealed chamber 10a is ionized into electrons and cations. In addition, the gas detector 10 further includes an electrode assembly having a first electrode 12 and a second electrode 13. A potential difference exists between the first electrode 12 and the second electrode 13 to form a non-uniform electric field that gradually increases in the direction from the incident window 11 towards the second electrode 13. In this way, under the action of the non-uniform electric field, electrons drift towards the second electrode 13. Since the non-uniform electric field gradually increases as it approaches the second electrode 13, near the second electrode 13, electrons can obtain a high enough energy and achieve multiplication, realizing proportional amplification of energy, thereby effectively improving the ion signal-to-noise ratio to measure low-energy incident particles 14 such as low-energy heavy nuclides, and further improving the applicability of the gas detector 10.

[0034] In one embodiment, please refer to Figure 1 and Figure 2 , the direction of the electric field is parallel to the moving direction of the incident particles 14. That is to say, the electric field of the gas detector 10 is a longitudinal electric field, and the direction of the electric field extends along the length direction of the gas detector 10. The incident particles 14 also move along the length direction of the gas detector 10. In this way, it is beneficial for the second electrode 13 to collect all the electrons generated by the incident particles 14 ionizing the working gas as much as possible, eliminating the influence of the dead zone existing in the gas detector 10 in the related art, and while improving the detection accuracy, it is also beneficial to improve the signal-to-noise ratio of the ions.

[0035] In one embodiment, please refer to Figure 1 and Figure 2, the incident window 11 and the second electrode 13 are located on opposite sides of the sealed chamber 10a. There is a potential difference between the first electrode 12 and the second electrode 13 to form an electric field that gradually increases in the direction from the incident window 11 towards the second electrode 13. The incident window 11 and the second electrode 13 are located on opposite sides of the sealed chamber 10a so that the gas detector 10 forms a longitudinal electric field. The incident particle 14 can enter the sealed chamber 10a through the incident window 11. After the incident particle 14 enters the sealed chamber 10a, it ionizes the working gas in the sealed chamber 10a into electrons and cations. The electrons drift towards the second electrode 13 under the action of the non-uniform electric field, that is, approach the second electrode 13 along the direction of the electric field, to obtain sufficiently high energy and achieve multiplication, realizing proportional amplification of energy, thereby effectively improving the ion signal-to-noise ratio, to achieve the measurement of low-energy incident particles 14 such as low-energy heavy nuclides, and further improving the applicability of the gas detector 10.

[0036] The potential difference between the first electrode 12 and the second electrode 13 is not limited herein, as long as it can form an electric field that gradually increases in the direction from the incident window 11 towards the second electrode 13 between the first electrode 12 and the second electrode 13, so as to further enable the electrons to obtain sufficiently high energy and achieve multiplication, realizing proportional amplification of energy. Exemplarily, in one embodiment, the potential difference is 300 - 500V, for example, it can be 300V, 350V, 400V, 425V, 450V, 480V, 500V, etc.

[0037] The specific method of forming a potential difference between the first electrode 12 and the second electrode 13 is not limited herein. Exemplarily, in one embodiment, the first electrode 12 is at zero potential, and the potential value of the second electrode 13 is 300 - 500V, so that the potential difference between the first electrode 12 and the second electrode 13 is 300 - 500V. In some other embodiments, the first electrode 12 is conductively connected to the low-voltage end of the high-voltage power supply or directly grounded, and the second electrode 13 is conductively connected to the high-voltage end of the high-voltage power supply.

[0038] In a specific embodiment, the potential value of the second electrode 13 is about 500V, and the incident window 11 of the gas detector 10 is at zero potential. Thus, the voltage equipotential surfaces in the sealed chamber 10a of the gas detector 10 are as Figure 2 shown, that is, a non-uniform electric field is formed in the length direction of the gas detector 10. The closer to the second electrode 13, the stronger the electric field. Near the second electrode 13, the electrons can obtain sufficiently high energy and achieve multiplication, realizing proportional amplification of energy, thereby effectively improving the ion signal-to-noise ratio, to achieve the measurement of low-energy incident particles 14 such as low-energy heavy nuclides, and further improving the applicability of the gas detector 10.

[0039] It should be noted that the specific structure of the incident window 11 is not limited herein. Exemplarily, in one embodiment, the incident window 11 includes a connecting bracket (not shown in the figure) and a window body (not shown in the figure) provided on the connecting bracket. The connecting bracket is in sealing cooperation with the side wall on one side of the sealed chamber 10a, and the incident particles 14 can enter the sealed chamber 10a through the window body. That is to say, by providing the connecting bracket, it is beneficial to the sealing cooperation between the connecting bracket and the side wall of the sealed chamber 10a. While improving the sealing performance between the incident window 11 and the sealed chamber 10a, it also improves the connection strength between the incident window 11 and the sealed chamber 10a. In addition, the connecting bracket can also provide a certain protection for the window body to prevent the window body from being damaged, and thus can prevent the entry of the incident particles 14 from being affected due to the damage of the window body. Therefore, the structure of the incident window 11 is beneficial to improving the service life of the gas detector 10.

[0040] In other embodiments, the incident window 11 may not include a connecting bracket, that is, it is directly in sealing cooperation with the side wall on one side of the sealed chamber 10a through the window body.

[0041] In one embodiment, the connecting bracket is made of a conductive material, and the connecting bracket constitutes the first electrode 12. That is to say, on the one hand, the window body is in sealing cooperation with the side wall on one side of the sealed chamber 10a through the connecting bracket, and on the other hand, the connecting bracket constitutes the first electrode 12, that is, it has the function of conducting electricity at the same time. That is to say, the gas detector 10 does not need to additionally provide the first electrode 12, which can effectively simplify the structure of the gas detector 10, reduce the number of components, reduce the assembly time, improve the assembly efficiency, and in addition, can also save costs.

[0042] It should be noted that the material of the window body is not limited herein, as long as it can facilitate the incident particles 14 to enter the sealed chamber 10a through the window body. Exemplarily, the material of the window body includes but is not limited to Si 3 N 4 , Si 3 N 4 is a thin film material with a relatively thin thickness and a uniform thickness and strong structure, thereby effectively reducing the energy loss of the incident particles 14 when passing through the window body, and can improve the detection efficiency and detection accuracy of the gas detector 10.

[0043] It should be noted that the thickness of the window is not limited here. As long as it is convenient for the incident particles 14 to enter the sealed chamber 10a through the window, and at the same time has a certain strength. Exemplarily, the thickness of the window is 20nm - 40nm. For example, it can be 20nm, 25nm, 30nm, 35nm, 40nm, etc. The window within this thickness range can facilitate the incident particles 14 to enter the sealed chamber 10a through the window, and at the same time has a certain strength, which can effectively reduce the energy loss of the incident particles 14 when passing through the window, and can improve the detection efficiency and detection accuracy of the gas detector 10.

[0044] The cross-sectional shape of the sealed chamber 10a is not limited here, including but not limited to square, circular, elliptical or polygon with rounded corners, etc. Exemplarily, please refer to Figure 1 , the cross-sectional shape of the sealed chamber 10a is circular. In this way, it is beneficial to the drift of all electrons generated by the incident particles 14 ionizing the working gas in the sealed chamber 10a, and it is beneficial for the second electrode 13 to collect electrons as much as possible, eliminating the influence of the dead zone existing in the gas detector 10 in the related art. While improving the detection accuracy, it is also beneficial to improve the signal-to-noise ratio of ions. Among them, the cross-sectional shape of the sealed chamber 10a refers to the cross-sectional shape of the sealed chamber 10a obtained by a plane perpendicular to the axial direction of the sealed chamber 10a.

[0045] The cross-sectional shape of the second electrode 13 is not limited here, including but not limited to square, circular, elliptical or polygon with rounded corners, etc. Exemplarily, please refer to Figure 1 , the cross-sectional shape of the second electrode 13 is circular. In this way, it is beneficial for the second electrode 13 to better collect all electrons generated by the incident particles 14 ionizing the working gas. For example, it can also collect the electrons close to the side wall of the sealed chamber 10a, eliminating the influence of the dead zone existing in the gas detector 10 in the related art, and then improving the detection efficiency and detection accuracy of the gas detector 10. Among them, the cross-sectional shape of the second electrode 13 refers to the cross-sectional shape of the second electrode 13 obtained by a plane perpendicular to the axial direction of the second electrode 13.

[0046] In one embodiment, the distance between the connecting bracket and the second electrode 13 is L, the diameter of the cross-section of the sealed chamber 10a is D1, and the ratio between L and D1 is 1 ± 15%. It can be understood that after low-energy incident particles 14 such as low-energy heavy nuclides enter the sealed chamber 10a, the working gas in the sealed chamber 10a is ionized into electrons and cations. The electrons drift towards the second electrode 13 under the action of the non-uniform electric field. Therefore, the distance L between the connecting bracket and the second electrode 13 will have a certain impact on the drift of electrons, that is, if the distance L between the connecting bracket and the second electrode 13 is too far, it is not conducive to the second electrode 13 to collect electrons. At the same time, the multiplication factor of electrons can be controlled by controlling the distance L between the connecting bracket and the second electrode 13. In addition, the diameter D1 of the cross-section of the sealed chamber 10a will have a certain impact on the drift of electrons, and the multiplication factor of electrons can be controlled by controlling the diameter D1 of the cross-section of the sealed chamber 10a. Exemplarily, the ratio between L and D1 is 1 ± 15%.

[0047] In one embodiment, the diameter of the cross-section of the sealed chamber 10a is D1, and the diameter of the cross-section of the second electrode 13 is D2. The ratio between D2 and D1 is 0.5 ± 15%. It can be understood that the sizes of the cross-section of the sealed chamber 10a and the cross-section of the second electrode 13 will affect the formation of the non-uniform electric field, and the diameter D2 of the cross-section of the second electrode 13 will also affect the electron collection efficiency. Exemplarily, the ratio between D2 and D1 is 0.5 ± 15%. On the one hand, it improves the electron collection efficiency, and on the other hand, it can also collect the electrons near the side wall of the sealed chamber 10a, eliminating the influence of the dead zone existing in the gas detector 10 in the related art, thereby improving the detection efficiency and detection accuracy of the gas detector 10.

[0048] In one embodiment, a charge-sensitive amplifier can be used to collect the pulse signal induced by the second electrode 13, and the ion energy can be measured according to the amount of induced charge on the second electrode 13.

[0049] In one embodiment, please refer to Figure 1 , the gas detector 10 includes an air extraction port 10b, an air filling port 10c, and a barometer 15. The sealed chamber 10a can be evacuated through the air extraction port, the working gas can be filled into the sealed chamber 10a through the air filling port, and the barometer can detect the air pressure in the sealed chamber 10a.

[0050] In one embodiment, a preamplifier can be used to connect the signal of the second electrode 13 of the gas detector 10.

[0051] In the description of the present application, the description with reference to terms such as "an embodiment", "some embodiments", "examples", "specific examples", or "other embodiments" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In the present application, the schematic expression of the above terms is not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine the different embodiments or examples described in the present application and the features of different embodiments or examples.

[0052] The various embodiments / implementations provided in the present application can be combined with each other without contradiction.

[0053] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application are included within the protection scope of the present application.

Claims

1. A gas detector, characterized in that, comprising: A sealed chamber (10a) for containing a working gas; An incident window (11) sealed on one side of the sealed chamber (10a), and incident particles (14) enter the sealed chamber (10a) through the incident window (11); An electrode assembly including a first electrode (12) and a second electrode (13), the second electrode (13) is disposed within the sealed chamber (10a), and there is a potential difference between the first electrode (12) and the second electrode (13) to form an electric field that gradually increases in the direction from the incident window (11) towards the second electrode (13).

2. The gas detector according to claim 1, characterized in that, The direction of the electric field is parallel to the movement direction of the incident particles (14).

3. The gas detector according to claim 1, characterized in that, The incident window (11) and the second electrode (13) are located on opposite sides of the sealed chamber (10a).

4. The gas detector according to claim 1, characterized in that, The potential difference is 300 - 500V.

5. The gas detector according to claim 1, characterized in that, The incident window (11) includes a connecting bracket and a window body disposed on the connecting bracket, the connecting bracket is sealingly fitted with the side wall on one side of the sealed chamber (10a), and the incident particles (14) enter the sealed chamber (10a) through the window body.

6. The gas detector according to claim 5, characterized in that, The material of the window is Si 3 N 4 ; and / or, the thickness of the window is 20 nm - 40 nm.

7. The gas detector according to claim 5, characterized in that, The connecting bracket is made of a conductive material, and the connecting bracket constitutes the first electrode (12).

8. The gas detector according to claim 7, characterized in that, The cross-sectional shape of the sealed chamber (10a) is circular; and / or, the cross-sectional shape of the second electrode (13) is circular.

9. The gas detector according to claim 8, characterized in that, The distance between the connecting bracket and the second electrode (13) is L, the diameter of the cross-section of the sealed chamber (10a) is D1, and the ratio of L to D1 is 1 ± 15%.

10. The gas detector according to claim 8, characterized in that, The diameter of the cross-section of the sealed chamber (10a) is D1, the diameter of the cross-section of the second electrode (13) is D2, and the ratio of D2 to D1 is 0.5 ± 15%.

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