Directly proportional amplification gas detector
By introducing shielded grid and high-reducing field strength anode design in the gas detector, the problem of being unable to measure low-energy heavy nuclides in the prior art is solved, and the signal-to-noise ratio and energy resolution are improved, providing a A new detector suitable for low-energy henolic measurements.
Patent Information
- Application Number
- CN202411155062.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-21
- Publication Date
- 2024-12-13
AI Technical Summary
Existing gas detectors cannot effectively measure low-energy heavy nuclides, and their signal-to-noise ratio and energy resolution are insufficient, which cannot meet the needs of nuclear physics research.
A proportional amplification gas detector was designed, using the incident particle range shielding function and anode design with high reduction field strength. Through the voltage control of the shielded grid and anode, electron proportional amplification and signal amplification are realized, thereby improving the signal-to-noise of the detector. ratio and energy resolution.
It effectively blocks the interference of incident ions on the anode, improves the energy resolution and signal-to-noise ratio of the detector, realizes high-quality measurement of low-energy heavy nuclides, and provides a new and efficient detector.
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Figure CN119126185A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of particle detection, and in particular relates to a proportional amplification gas detector. Background Art
[0002] Gas detectors are commonly used in nuclear physics detection. Gas detectors can be divided into gas ionization chambers, proportional counters, etc. according to the reduced field strength (E / P, E is the electric field in the detector working area, P is the working gas pressure of the detector) of the detector. The structure of the gas ionization chamber is as follows Figure 1 As shown in the figure, it mainly includes anode, cathode, grid, incident window and other components. The anode and cathode are used to provide a uniform electric field to the detector. The incident window is used to isolate the detector from the vacuum state of the pipeline to ensure that the working gas in the ionization chamber remains stable. When the ions enter the gas ionization chamber and fly in the gas, they interact with the working gas in the detector to ionize the working gas of the detector into electron-ion pairs. Since the working voltage of the detector is low, the detector works in the ionization zone. The number of electron-ion pairs is proportional to the energy loss of the incident ions in this area. In this process, the number of electrons is not multiplied.
[0003] The particle measurement capability of the detector is of great significance to nuclear physics research. Improving the signal-to-noise ratio and energy resolution of the detector are important technical indicators for developing the detector. Currently, the commonly used gas detectors are mainly used to measure ions with relatively high ion energy (~1MeV / nucleon). With the expansion of application fields, it is necessary to develop detectors suitable for low-energy (~0.01MeV / nucleon) heavy nuclides, but the existing gas detectors cannot meet the measurement of these particles. Summary of the invention
[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a proportional amplification gas detector for the measurement of low-energy heavy nuclides, a gas detector with the ability to shield the range of incident particles and a signal amplification function. The energy resolution of the detector can be improved through the grid shielding function of the incident particle range, and the electron proportional method is realized through the high reduced field strength in the short-range region of the detector anode, thereby effectively improving the ion signal-to-noise ratio.
[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is as follows:
[0006] A proportional amplification gas detector comprises a detector housing, an incident window, an anode, a shielding grid, a grid voltage interface, an anode voltage and signal interface, an air inlet and an exhaust port. The detector housing is provided with an anode and a shielding grid. The incident window is arranged on an end face of the detector housing. The incident window, the shielding grid and the anode are arranged along the axis of the detector housing. The shielding grid is located at an appropriate position between the incident window and the anode. The grid voltage interface, the anode voltage and signal interface, the air inlet and the exhaust port are arranged on the detector housing. The grid voltage interface is used to provide voltage to the shielding grid. The anode voltage and signal interface is used to provide voltage to the anode and receive detector signals.
[0007] Furthermore, the position of the shielding grid is set according to the range of the incident ions in the detector, so that the distance between the incident window and the shielding grid is greater than the range of the ions in the detector, and the shielding grid is used to shield the incident ions and ionized ions from interfering with the signal of the detector anode.
[0008] Furthermore, the incident window is a thin film with a thickness of tens of nanometers.
[0009] Furthermore, the film thickness is 30 nm.
[0010] Furthermore, the thin film material is Si3N4.
[0011] Furthermore, appropriate voltage is applied to the shielding grid and the anode to make the incident direction of the ions parallel to the direction of the electric field.
[0012] Furthermore, the grid voltage interface and the anode voltage and signal interface provide appropriate voltages to the shielding grid and the anode respectively, the incident window is at zero potential, and a weak electric field is formed between the incident window and the shielding grid, which draws out the secondary electrons generated by the interaction between the incident ions and the gas and enters the non-uniform longitudinal electric field interval formed between the shielding grid and the anode. The closer to the anode, the stronger the electric field. Near the anode, after reaching a certain reduced field strength, the number of electrons begins to amplify proportionally.
[0013] Furthermore, the grid voltage interface provides a voltage of 30-50V to the shielding grid, and the anode voltage and signal interface provides a voltage of 500V to the anode.
[0014] Furthermore, the gas filled into the detector is isobutane or propane.
[0015] Furthermore, the detector housing is a hollow cylindrical structure with both ends closed.
[0016] Furthermore, an air pressure measuring instrument is also provided on the detector housing.
[0017] Furthermore, the communicating position between the air inlet and the detector housing is close to the shielding grid, and the communicating position between the air outlet and the detector housing is close to the anode.
[0018] Furthermore, the outer surface of the anode is spherically designed, and a plane treatment is performed at 1 / 4 of the spherical radius along the axial direction to ensure that an ideal equipotential surface is formed on the anode surface to achieve signal amplification.
[0019] Furthermore, the ratio of the diameter of the anode to the inner diameter of the detector housing is 1:1.6 to 1:2.
[0020] Furthermore, the anode material is oxygen-free copper.
[0021] The beneficial effects of the present invention are as follows:
[0022] 1. It shields the signal interference of incident ions and ions generated by ionization on the detector anode, and improves the energy resolution of the detector;
[0023] 2. The longitudinal non-uniform electric field structure design can not only realize the proportional amplification of the signal, but also collect all the electrons generated by the incident ions, thus improving the signal-to-noise ratio of the detector;
[0024] 3. It realizes the measurement of low-energy heavy nuclides, solves the problem of being unable to measure low-energy heavy nuclides, and provides a new type of high-quality detector. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 Schematic diagram of the gas ionization chamber structure.
[0026] Figure 2 It is a schematic diagram of a proportional amplification gas detector structure of the present invention.
[0027] Figure 3 Schematic diagram of the potential distribution of the detector. DETAILED DESCRIPTION
[0028] The present invention is described in detail below with reference to the accompanying drawings and embodiments.
[0029] The present invention designs a proportional amplification gas detector, including a detector housing, an incident window, an anode, a shielding grid, a grid voltage interface, an anode voltage and signal interface, an air inlet and an exhaust port. The detector housing is provided with an anode and a shielding grid, the incident window is arranged on an end face of the detector housing, the incident window, the shielding grid and the anode are arranged along the axis of the detector housing, the shielding grid is located at an appropriate position between the incident window and the anode, the grid voltage interface, the anode voltage and signal interface, the air inlet and the exhaust port are arranged on the detector housing, the grid voltage interface is used to provide voltage to the shielding grid, and the anode voltage and signal interface is used to provide voltage to the anode and receive detector signals. The specific technical scheme is as follows:
[0030] The gas detector structure of the present invention is as follows Figure 2As shown. It includes the incident window and anode of the detector, and a shielding grid is set at an appropriate position between the incident window and the anode. In addition, there are an air inlet and an exhaust port for providing working gas to the detector, a grid voltage interface and an anode voltage and signal interface for providing voltage to the shielding grid and the anode respectively, and the detector signal is also led out by the anode voltage and signal interface. Appropriate voltage is applied to the shielding grid and the anode so that the incident direction of the ions is parallel to the direction of the electric field, which is different from the gas ionization chamber where the direction of the electric field is perpendicular to the direction of the incident ions.
[0031] The incident window is made of thin window material, and generally a film with a thickness of tens of nanometers is used as the incident window of the detector.
[0032] The anode material is oxygen-free copper. The outer surface of the oxygen-free copper anode is spherical, and a flat surface is made at 1 / 4 of the axial spherical radius. The ratio of the anode diameter to the inner diameter of the detector shell is between 1:1.6 and 1:2. The design of this part is to ensure the formation of an ideal equipotential surface on the anode surface to better achieve signal amplification.
[0033] A shielding grid is set at an appropriate position between the incident window and the anode. The position of the shielding grid should be set according to the range of the incident ions in the detector. The distance between the incident window and the shielding grid should be slightly larger than the range of the incident ions. In this way, the shielding grid can be used to shield the interference of the incident ions and the ions generated by them on the anode, thus shielding the signal. The shielding failure rate of the grid is:
[0034]
[0035] In the formula, d is the distance between the grid wires, b is the distance between the grid and the anode, and r is the radius of the grid wire. When d is 1 mm, b is 20 mm, and r is 50 μm, the shielding failure rate of the detector grid is 0.009, which almost completely shields the influence on the anode, thereby effectively avoiding the charge difference induced on the detector anode by the incident ions due to the range divergence, which is an important factor affecting the energy resolution of the detector and is conducive to improving the energy resolution of the detector.
[0036] A voltage of about +500V is applied to the anode and a voltage of about +50V is applied to the grid. The incident window of the detector is at zero potential, so the voltage equipotential surface inside the detector is as follows: Figure 3 As shown in the figure, there is a weak electric field between the incident window and the grid, which can lead the secondary electrons generated by the reaction of the incident ions with the working gas (such as isobutane, propane, etc.) and enter the non-uniform longitudinal electric field interval formed between the grid and the anode. The closer to the anode, the stronger the electric field. When the reduced field strength is reached near the anode, the number of electrons begins to amplify proportionally. The electron gain can be described by the following formula:
[0037]
[0038] Where x corresponds to the total drift path of the electron. When the reduced field strength (E / P) and gas type remain unchanged, the amplification gain G is a constant. This achieves proportional amplification of the detector energy and improves the detector's signal-to-noise ratio. In addition, the detector's electric field direction is parallel to the incident ion direction, so all the electrons in the detector can be collected, which is also conducive to improving the signal-to-noise ratio.
[0039] Take the proportional amplification gas detector as an example:
[0040] Embodiment 1
[0041] The specific structure of the proportional amplification gas detector of this embodiment is as follows: Figure 2 As shown, it includes a detector housing, an incident window, an anode, a shielding grid, a grid voltage interface, an anode voltage and signal interface, an air inlet and an exhaust port. The detector housing is provided with an anode and a shielding grid. The incident window is arranged on an end face of the detector housing. The incident window, the shielding grid and the anode are arranged along the axis of the detector housing. The shielding grid is located at an appropriate position between the incident window and the anode. The grid voltage interface, the anode voltage and signal interface, the air inlet and the exhaust port are arranged on the detector housing. The grid voltage interface is used to provide voltage to the shielding grid. The anode voltage and signal interface is used to provide voltage to the anode and receive detector signals.
[0042] The detector shell is a circular cavity, the front end of the cavity is the incident window of the detector, the middle is a shielding grid, and the rear end is an anode; the cavity is provided with an exhaust port, an air filling port and an air pressure measuring instrument.
[0043] The incident window uses a Si3N4 film with a thickness of about 30nm as the incident window of the detector.
[0044] The anode material is oxygen-free copper, the outer surface of the oxygen-free copper anode is spherical, and a flat surface is made at 1 / 4 of the axial spherical radius. The ratio of the anode diameter to the inner diameter of the detector shell is 1:1.6.
[0045] The detector cavity is filled with isobutane as the working gas.
[0046] The incident window voltage was set to 0V, the shielding grid voltage was set to 30V, and the anode voltage was set to 500V.
[0047] Connect the anode of the detector using a preamplifier.
[0048] Embodiment 2
[0049] The specific structure of the proportional amplification gas detector of this embodiment is as follows: Figure 2As shown, it includes a detector housing, an incident window, an anode, a shielding grid, a grid voltage interface, an anode voltage and signal interface, an air inlet and an exhaust port. The detector housing is provided with an anode and a shielding grid. The incident window is arranged on an end face of the detector housing. The incident window, the shielding grid and the anode are arranged along the axis of the detector housing. The shielding grid is located at an appropriate position between the incident window and the anode. The grid voltage interface, the anode voltage and signal interface, the air inlet and the exhaust port are arranged on the detector housing. The grid voltage interface is used to provide voltage to the shielding grid. The anode voltage and signal interface is used to provide voltage to the anode and receive detector signals.
[0050] The detector shell is a circular cavity, the front end of the cavity is the incident window of the detector, the middle is a shielding grid, and the rear end is an anode; the cavity is provided with an exhaust port, an air filling port and an air pressure measuring instrument.
[0051] The incident window uses a Si3N4 film with a thickness of about 30nm as the incident window of the detector.
[0052] The anode material is oxygen-free copper, the outer surface of the oxygen-free copper anode is spherical, and a flat surface is made at 1 / 4 of the spherical radius along the axial direction. The ratio of the anode diameter to the inner diameter of the detector shell is 1:2.
[0053] The detector cavity is filled with propane as the working gas.
[0054] The incident window voltage was set to 0V, the shielding grid voltage was set to 50V, and the anode voltage was set to 500V.
[0055] Connect the anode of the detector using a preamplifier.
[0056] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.
Claims
1. A proportional amplification gas detector, comprising a detector housing, an incident window, an anode, a shielding grid, a grid voltage interface, an anode voltage and signal interface, an air inlet and an exhaust port, characterized in that: An anode and a shielding grid are provided in the detector housing, an incident window is provided on an end face of the detector housing, the incident window, the shielding grid and the anode are provided along the axis of the detector housing, the shielding grid is located at an appropriate position between the incident window and the anode, a grid voltage interface, an anode voltage and signal interface, an air inlet and an exhaust port are provided on the detector housing, the grid voltage interface is used to provide voltage to the shielding grid, and the anode voltage and signal interface is used to provide voltage to the anode and receive detector signals.
2. The proportional amplification gas detector according to claim 1, characterized in that: The position of the shielding grid is set according to the range of the incident ions in the detector, so that the distance between the incident window and the shielding grid is greater than the range of the ions in the detector. The shielding grid is used to shield the incident ions and the ions generated by ionization from signal interference on the detector anode.
3. The proportional amplification gas detector according to claim 1, characterized in that: The incident window is a thin film with a thickness of tens of nanometers.
4. The proportional amplification gas detector according to claim 3, characterized in that: The film thickness is 30 nm.
5. The proportional amplification gas detector according to claim 3, characterized in that: The thin film material is Si3N4.
6. The proportional amplification gas detector according to claim 1, characterized in that: Appropriate voltage is applied to the shielding grid and the anode to make the incident direction of the ions parallel to the direction of the electric field.
7. The proportional amplification gas detector according to claim 6, characterized in that: The grid voltage interface and the anode voltage and signal interface provide appropriate voltages to the shielding grid and the anode respectively. The incident window is at zero potential, and a weak electric field is formed between the incident window and the shielding grid. The secondary electrons generated by the interaction between the incident ions and the gas are drawn out and enter the non-uniform longitudinal electric field interval formed between the shielding grid and the anode. The closer to the anode, the stronger the electric field. Near the anode, after reaching a certain reduced field strength, the number of electrons begins to amplify proportionally.
8. The proportional amplification gas detector according to claim 6 or 7, characterized in that: The grid voltage interface provides a voltage of 30-50V to the shielding grid, and the anode voltage and signal interface provides a voltage of 500V to the anode.
9. The proportional amplification gas detector according to claim 1, characterized in that: The detector is filled with isobutane or propane gas.
10. The proportional amplification gas detector according to claim 1, characterized in that: The detector housing is a hollow cylindrical structure with closed ends.
11. The proportional amplification gas detector according to claim 1, characterized in that: An air pressure measuring instrument is also provided on the detector housing.
12. The proportional amplification gas detector according to claim 1, characterized in that: The communicating position between the air inlet and the detector housing is close to the shielding grid, and the communicating position between the air outlet and the detector housing is close to the anode.
13. The proportional amplification gas detector according to claim 1, characterized in that: The outer surface of the anode is spherical in design, and is plane-processed at 1 / 4 of the spherical radius along the axial direction to ensure that an ideal equipotential surface is formed on the anode surface to achieve signal amplification.
14. The proportional amplification gas detector according to claim 13, characterized in that: The ratio of the diameter of the anode to the inner diameter of the detector housing is 1:1.6 to 1:
2.
15. The proportional amplification gas detector according to claim 13, characterized in that: The anode material is oxygen-free copper.