High-gain photomultiplier and manufacturing method thereof

Abstract

The invention relates to a high-gain photomultiplier and a manufacturing method thereof, the photomultiplier comprises an upper layer ceramic substrate and a lower layer ceramic substrate, and a photoelectric cathode, a grid mesh, an anode and a plurality of electron dynodes are arranged between the two layers of ceramic substrates; metal conductive films are deposited on the surfaces of the upper and lower layers of ceramic substrates opposite to the electron dynodes, and the metal conductive films are in mechanical contact with the electron dynodes; the photoelectric cathode, the grid mesh, the anode and the electron dynodes are respectively connected and fixed on the ceramic substrate through positioning pins, divider resistors are respectively connected between the photoelectric cathode and the positioning pin of the first-stage electron dynode, between the positioning pins of two adjacent stages of electron dynodes, and between the positioning pin of the last-stage electron dynode and the ground; the potential of each stage of electron dynode is set by regulating and controlling the divider resistor, and the potential difference between every two adjacent stages of electron dynodes and the potential difference between the last stage of electron dynode and the ground are in a differential voltage division form. The gain and the service life of the photomultiplier are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of vacuum electronic devices, and in particular relates to a high-gain photomultiplier tube and a manufacturing method thereof. Background Art

[0002] When initial electrons with a certain energy bombard solid materials, the incident electrons are inelastically scattered inside the material, thereby exciting the electrons inside the material to form internal secondary electrons with a certain energy distribution. Some of the internal secondary electrons move toward the surface, interact with the solid during the movement, and lose some energy. When they reach the surface, some electrons overcome the surface potential barriers and escape from the surface to become secondary electrons. This process is called secondary electron emission.

[0003] Photomultiplier tubes are vacuum electronic devices that convert weak light signals into electrical signals and have an electrical signal multiplication system. They are widely used in high-energy physics detection, radiation medicine and other fields, and have the characteristics of good stability, fast time response and high sensitivity. The side-window type photomultiplier tube is mainly composed of an electron optical input system, a reflective photocathode, an electron multiplication system, an anode and other parts. Its working principle is that after the incident light reaches the photocathode through the electron optical input system, photoelectrons are generated under the action of the external photoelectric effect. The photoelectrons are focused into an electron beam under the action of the electric field to bombard the first-stage electron multiplier to produce secondary electrons. These secondary electrons are accelerated by the electric field and continue to bombard the next-stage electron multiplier and generate more secondary electrons again. The electron multiplication is completed through the secondary electron emission process of the multi-stage electron multiplier. Finally, these multiplied electrons are received by the anode to achieve the amplification and detection of weak light signals. The current side-window type photomultiplier tubes have the problems of low gain and short service life. Summary of the invention

[0004] The purpose of the present invention is to provide a high-gain photomultiplier tube and a method for manufacturing the same in order to address the problems in the prior art, increase the number of secondary electrons emitted by each level of electron multiplier, significantly improve the gain of the photomultiplier tube, and effectively extend the life of the photomultiplier tube.

[0005] In order to achieve the above object, the present invention has the following technical solutions:

[0006] In a first aspect, an embodiment of the present invention provides a high-gain photomultiplier tube, comprising an upper ceramic substrate and a lower ceramic substrate, wherein a photocathode, a grid, an anode and a plurality of electron multipliers are arranged between the upper ceramic substrate and the lower ceramic substrate; a metal conductive film is deposited on the lower surface of the upper ceramic substrate and the upper surface of the lower ceramic substrate opposite to the electron multipliers, and the metal conductive film is in mechanical contact with each electron multiplier, so that the regionalized metal conductive film obtains an electric potential; the photocathode, the grid, the anode and each electron multiplier are respectively connected and fixed on the ceramic substrate through positioning pins, and a voltage divider resistor is respectively connected between the photocathode and the positioning pin of the first-stage electron multiplier, between the two adjacent positioning pins from the first-stage electron multiplier to the last-stage electron multiplier, and between the positioning pin of the last-stage electron multiplier and the ground, and the potential of each stage of the electron multiplier is set by adjusting the voltage divider resistor, and the potential difference between the two adjacent stages of the electron multipliers and the potential difference between the last-stage electron multiplier and the ground are in the form of differential voltage division.

[0007] As a preferred solution, nine electron multipliers are provided, and ten voltage-dividing resistors are provided. The first voltage-dividing resistor is connected between the photocathode and the first electron multiplier, the second to ninth voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first to ninth electron multipliers, and the tenth voltage-dividing resistor is connected between the ninth electron multiplier and the ground.

[0008] As a preferred solution, the potential difference between the photocathode and the first electron multiplier is U0, the potential difference between the two adjacent electron multipliers from the first electron multiplier to the ninth electron multiplier is U1-U8 in sequence, the potential difference between the ninth electron multiplier and the ground is U9, and the anode potential is 0; it is divided into three levels according to the potential difference, and the potential differences in the same level are the same, and are divided as follows: the first level is U0-U4, the second level is U5-U8, and the third level is U9; or the first level is U0-U2, the second level is U3-U8, and the third level is U9; or the first level is U0-U3, the second level is U4-U8, and the third level is U9; or the first level is U0-U5, the second level is U6-U8, and the third level is U9; wherein the potential difference between the photocathode of the first level and the first electron multiplier or two adjacent electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the third-level electron multiplier and the ground is U C .

[0009] As a preferred solution, the potential difference meets the following proportional relationship: U A :U C In the range of 4 to 1, UB :U C In the range of 4 to 1, and U A :U B ≥1.

[0010] As a preferred solution, the thickness of the metal conductive film is between 10 nm and 10 μm; the metal conductive film is made of any one material among Cr, Au, Ag and Cu.

[0011] As a preferred solution, the positioning pin is a cylindrical structure, and the radius of the cylindrical structure is R=0.4 mm.

[0012] As a preferred solution, the surface of the electron multiplier is plated with a Sb-K-Na-Cs film, and the thickness of the Sb-K-Na-Cs film is between 100 nm and 10 μm.

[0013] As a preferred solution, the grid is composed of two layers of grid frames, both of which are provided with parallel metal wires distributed at intervals, and the positioning pins are arranged between the two layers of grid frames; the grid is arranged between the photocathode and the first-stage electron multiplier, and the electrons emitted from the photocathode are guided to move to the first-stage electron multiplier through the grid.

[0014] As a preferred solution, an electric field modulation electrode is further provided between the upper ceramic substrate and the lower ceramic substrate, and the electric field modulation electrode is arranged between the photocathode and the anode, and is used to enable more electrons to move between the electron multipliers.

[0015] In a second aspect, an embodiment of the present invention further provides a method for manufacturing a high-gain photomultiplier tube, comprising the following steps:

[0016] Depositing secondary electron emission films on the surfaces of a plurality of electron multipliers;

[0017] Depositing a metal conductive film on a lower surface of the upper ceramic substrate opposite to the electron multiplier and on an upper surface of the lower ceramic substrate;

[0018] Assemble the electron multipliers, insert the positioning pins on all the electron multipliers into the mounting holes on the lower ceramic substrate in sequence, insert the positioning pins of the photocathode, grid, and anode into the mounting holes at the designated positions, install the upper ceramic substrate, and insert the fixed electric field modulation electrode between the photocathode and the anode;

[0019] Take multiple voltage-dividing resistors according to the number of electron multipliers, connect the first voltage-dividing resistor between the photocathode and the first-stage electron multiplier, connect the intermediate voltage-dividing resistors between the two adjacent electron multipliers from the first-stage electron multiplier to the last-stage electron multiplier, and connect the last voltage-dividing resistor between the last-stage electron multiplier and the ground;

[0020] A glass shell is used for packaging, and the positioning pins connected to the photocathode, the ground terminal of the voltage divider resistor connected to the last-stage electron multiplier, and the anode are connected to the outside of the glass shell.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] At present, the side window type photomultiplier tube usually uses a ceramic substrate to prepare a layer of integral metal conductive film on the surface of the side close to the electron multiplier, and through mechanical contact with the photocathode, it has the same potential as the photocathode during the operation of the photomultiplier tube, so as to suppress the charge accumulation phenomenon caused by the movement of secondary electrons to the surface of the ceramic substrate close to the electron multiplier, thereby eliminating the hysteresis effect of the photomultiplier tube, improving the stability of the photomultiplier tube, and extending its service life. If the ceramic substrate of the photomultiplier tube is not covered with a metal conductive film, the electrons will be more likely to bombard the ceramic substrate and the glass shell and accumulate, which will not only lead to the charge accumulation effect, thereby reducing the performance of the photomultiplier tube, but also cause discharge and other problems, affecting the reliability of the photomultiplier tube. However, the method currently used will make the area where the secondary electrons reach the next level of electron multiplier more concentrated, affecting the gain and life of the photomultiplier tube. The high-gain photomultiplier tube of the present invention proposes to prepare a layer of regionalized metal conductive film with differentiated potential on the surface of the ceramic substrate close to the electron multiplier, so that the secondary electrons are more dispersed during the multiplication process, reducing the influence of the space charge effect, and improving the gain and life of the photomultiplier tube. By controlling the potential parameters to change the inter-electrode potential difference between the electron multipliers and the inter-electrode potential difference between the electron multipliers and the ground, a differentiated voltage division form is presented, thereby improving the secondary electron collection efficiency of the anode and increasing the gain and life of the photomultiplier tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 A schematic diagram of the structure of a side-window type photomultiplier tube according to Example 1 of the present invention;

[0025] Figure 2 A bar graph comparing the gain of the photomultiplier tube of Example 1 of the present invention and the original structure;

[0026] Figure 3 The electron motion trajectory diagram of the side-window type photomultiplier tube of Example 1 of the present invention;

[0027] Figure 4 A schematic diagram of the structure of a side-window type photomultiplier tube according to Embodiment 2 of the present invention;

[0028] Figure 5 A bar graph comparing the gain of the photomultiplier tube of Example 2 of the present invention and the original structure;

[0029] Figure 6 The electron motion trajectory diagram of the side-window type photomultiplier tube of Example 2 of the present invention;

[0030] Figure 7 A schematic diagram of the structure of a side-window type photomultiplier tube according to Embodiment 3 of the present invention;

[0031] Figure 8 A bar graph comparing the gain of the photomultiplier tube of Example 3 of the present invention with that of the original structure;

[0032] Fig. 9 The electron motion trajectory diagram of the side-window type photomultiplier tube of Example 3 of the present invention;

[0033] Fig.10 A bar graph comparing the gain of the photomultiplier tube of Example 4 of the present invention and the original structure;

[0034] Fig.11 The electron motion trajectory diagram of the side-window type photomultiplier tube of Example 4 of the present invention;

[0035] Fig.12 A bar graph comparing the gain of the photomultiplier tube of Example 5 of the present invention and the original structure;

[0036] Fig.13 A diagram showing the electron motion trajectory of the side-window type photomultiplier tube according to Example 5 of the present invention. DETAILED DESCRIPTION

[0037] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0038] Example 1

[0039] See also Figure 1The side-window type photomultiplier tube of the embodiment of the present invention comprises a ceramic substrate 2 on which a metal conductive film 1-1 is deposited near the surface of the electron multipliers D1~D9, as well as a photocathode 3, an electric field modulation electrode 4, a grid 5, an anode 6, a glass shell 7, a voltage-dividing resistor 8 and the electron multipliers D1~D9. The electron multipliers D1~D9, the photocathode 3, the grid 5 and the anode 6 are all located between the two ceramic substrates 2. A positioning pin 10 for fixing to the ceramic substrate is provided on the side of each component, and the positioning pin also serves as a power supply interface for these components. The coverage of the metal conductive film 1-1 includes the photocathode and the 1st to 8th stage dynodes, and the potential of each part thereof is the same as the potential of the corresponding dynode, that is, the potential of the conductive film where the first stage electron multiplier D1 is located is -900V, the potential of the conductive film where the second stage electron multiplier D2 is located is -800V, and so on.

[0040] The thickness of the metal conductive film 1-1 is 50 nm, and the metal material Cr is selected for deposition.

[0041] The electron multipliers D1 to D9, the photocathode 3, the electric field modulation electrode 4, the grid 5 and the anode 6 are all made of conductive materials. Except for the electric field modulation electrode 4, all of them have positioning pins 10 fixed to the ceramic substrate. The positioning pins 10 are cylindrical, and the radius of the bottom circle of the cylinder is R = 0.4 mm. It is connected to the voltage divider resistor 8 to obtain an electric potential.

[0042] The voltage-dividing resistor 8 is composed of 10 resistors. The first voltage-dividing resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle eight voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first-stage electron multiplier to the ninth-stage electron multiplier. The last voltage-dividing resistor is connected between the last-stage electron multiplier and the ground. The potential of each stage of the electron multiplier is set by adjusting these voltage-dividing resistors.

[0043] The electron multipliers D1 to D9 include a first-stage electron multiplier D1, a second-stage electron multiplier D2, a third-stage electron multiplier D3, a fourth-stage electron multiplier D4, a fifth-stage electron multiplier D5, a sixth-stage electron multiplier D6, a seventh-stage electron multiplier D7, an eighth-stage electron multiplier D8, and a ninth-stage electron multiplier D9. Electrons are finally collected by the anode 6. The multiplication surface of each multiplier is covered with a 400nm thick Sb-K-Na-Cs film. When the potential difference is 100V, the secondary electron emission coefficient SEY of the film is 6.37.

[0044] The working voltage of the photomultiplier tube is -1000V, wherein the potentials of the photocathode 3, the electric field modulation electrode 4 and the grid 5 are all -1000V, and the potential difference between the photocathode and the electron multiplier and the anode is divided into three levels, and the potential differences in the same level are the same, the first level is U0 to U4, the second level is U5 to U8, the third level is U9, and the anode potential is 0. The potential difference between the first level photocathode and the first level electron multiplier or the two adjacent levels of electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the electron multiplier and the anode of the third level is U C .

[0045] The potential difference of the three levels of the photomultiplier tube satisfies: U A :U C =1,U B :U C =1,U A :U B =1.

[0046] By measuring the gain of the photomultiplier tube of this embodiment and comparing it with the gain of the original structure, the test results are as follows: Figure 2 The electron motion trajectory is shown in Figure 3 As shown, the gain is significantly improved by 97.67% compared with the original photomultiplier tube covered with a conductive film.

[0047] Example 2

[0048] See also Figure 4 The side-window type photomultiplier tube of the embodiment of the present invention comprises a ceramic substrate 2 on which a metal conductive film 1-2 is deposited near the surface of the electron multiplier electrodes D1-D9, as well as a photocathode 3, an electric field modulation electrode 4, a grid 5, an anode 6, a glass shell 7, a voltage divider resistor 8 and the electron multiplier electrodes D1-D9. The electron multiplier electrodes D1-D9, the photocathode 3, the grid 5 and the anode 6 are all located between the two ceramic substrates 2. A positioning pin 10 for fixing to the ceramic substrate is provided on the side of each component, and the positioning pin also serves as a power supply for these components. Interface, the metal conductive film 1-2 is divided into five parts, respectively between the grid 5 and the photocathode 3, the second dynode D2, the fourth dynode D4, the sixth dynode D6, the eighth dynode D8 and the positioning pin connection of the ceramic substrate, the potential of each part of the five parts of the conductive film is the same as the potential of the corresponding dynode, that is, the potential of the metal conductive film 1-2 where the second electron multiplier D2 is located is -800V, the potential of the metal conductive film 1-2 where the fourth electron multiplier D4 is located is -600V, and so on.

[0049] The thickness of the metal conductive film 1-2 is 50 nm, and the metal material Cr is selected for deposition.

[0050] The electron multipliers D1 to D9, the photocathode 3, the electric field modulation electrode 4, the grid 5 and the anode 6 are all made of conductive materials. Except for the electric field modulation electrode 4, all of them have positioning pins 10 fixed to the ceramic substrate. The positioning pins 10 are cylindrical, and the radius of the bottom circle of the cylinder is R = 0.4 mm. It is connected to the voltage divider resistor 8 to obtain an electric potential.

[0051] The voltage-dividing resistor 8 is composed of 10 resistors. The first voltage-dividing resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle eight voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first-stage electron multiplier to the ninth-stage electron multiplier. The last voltage-dividing resistor is connected between the last-stage electron multiplier and the ground. The potential of each stage of the electron multiplier is set by adjusting these voltage-dividing resistors.

[0052] The electron multipliers D1 to D9 include a first-stage electron multiplier D1, a second-stage electron multiplier D2, a third-stage electron multiplier D3, a fourth-stage electron multiplier D4, a fifth-stage electron multiplier D5, a sixth-stage electron multiplier D6, a seventh-stage electron multiplier D7, an eighth-stage electron multiplier D8, and a ninth-stage electron multiplier D9. Electrons are finally collected by the anode 6. The multiplication surface of each multiplier is covered with a 400nm thick Sb-K-Na-Cs film. When the potential difference is 100V, the secondary electron emission coefficient SEY of the film is 6.37.

[0053] The working voltage of the photomultiplier tube is -1000V, wherein the potentials of the photocathode 3, the electric field modulation electrode 4 and the grid 5 are all -1000V, and the potential difference between the photocathode and the electron multiplier and the anode is divided into three levels, and the potential differences in the same level are the same, the first level is U0 to U4, the second level is U5 to U8, the third level is U9, and the anode potential is 0. The potential difference between the first level photocathode and the first level electron multiplier or the two adjacent levels of electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the electron multiplier and the anode of the third level is U C .

[0054] The potential difference of the three levels of the photomultiplier tube satisfies: U A :U C =1,U B :U C =1,U A :U B =1.

[0055] By measuring the gain of the photomultiplier tube of this embodiment and comparing it with the gain of the original structure, the test results are as follows: Figure 5 The electron motion trajectory is shown in Figure 6 As shown, the gain is significantly improved by 32.56% compared with the original photomultiplier tube covered with a conductive film.

[0056] Example 3

[0057] See also Figure 7 The side-window type photomultiplier tube of the embodiment of the present invention comprises a ceramic substrate 2 on which a metal conductive film 1-3 is deposited near the surface of the electron multiplier electrodes D1-D9, a photocathode 3, an electric field modulation electrode 4, a grid 5, an anode 6, a glass shell 7, a voltage divider resistor 8 and the electron multiplier electrodes D1-D9. The electron multiplier electrodes D1-D9, the photocathode 3, the grid 5 and the anode 6 are all located between two ceramic substrates 2. A positioning pin 10 for fixing to the ceramic substrate is provided on the side of each component, and the positioning pin also serves as a power supply for these components. Interface, the metal conductive film 1-3 is divided into five parts, respectively between the grid 5 and the photocathode 3, the first-stage dynode D1, the third-stage dynode D3, the fifth-stage dynode D5, the seventh-stage dynode D7 and the positioning pin connection of the ceramic substrate, the potential of each part of the five parts of the conductive film is the same as the potential of the corresponding dynode, that is, the potential of the metal conductive film 1-3 where the first-stage electron multiplier D1 is located is -900V, the potential of the metal conductive film 1-3 where the third-stage electron multiplier D3 is located is -700V, and so on.

[0058] The thickness of the metal conductive film 1-3 is 50 nm, and the metal material Cr is selected for deposition.

[0059] The electron multipliers D1 to D9, the photocathode 3, the electric field modulation electrode 4, the grid 5 and the anode 6 are all made of conductive materials. Except for the electric field modulation electrode 4, all of them have positioning pins 10 fixed to the ceramic substrate. The positioning pins 10 are cylindrical, and the radius of the bottom circle of the cylinder is R = 0.4 mm. It is connected to the voltage divider resistor 8 to obtain an electric potential.

[0060] The voltage-dividing resistor 8 is composed of 10 resistors. The first voltage-dividing resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle eight voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the second-stage electron multiplier to the ninth-stage electron multiplier. The last voltage-dividing resistor is connected between the last-stage electron multiplier and the ground. The potential of each electron multiplier is set by adjusting these voltage-dividing resistors.

[0061] The electron multipliers D1 to D9 include a first-stage electron multiplier D1, a second-stage electron multiplier D2, a third-stage electron multiplier D3, a fourth-stage electron multiplier D4, a fifth-stage electron multiplier D5, a sixth-stage electron multiplier D6, a seventh-stage electron multiplier D7, an eighth-stage electron multiplier D8, and a ninth-stage electron multiplier D9. Electrons are finally collected by the anode 6. The multiplication surface of each multiplier is covered with a 400nm thick Sb-K-Na-Cs film. When the potential difference is 100V, the secondary electron emission coefficient SEY of the film is 6.37.

[0062] The working voltage of the photomultiplier tube is -1000V, wherein the potential of the photocathode 3, the electric field modulation electrode 4 and the grid 5 are all -1000V, and the potential difference between the photocathode and the electron multiplier and the anode is divided into three levels, and the potential difference in the same level is the same, the first level is U0~U4, the second level is U5~U8, the third level is U9, and the anode potential is 0. The potential difference between the first level photocathode and the first level electron multiplier or the adjacent two levels of electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the electron multiplier and the anode of the third level is U C .

[0063] The potential difference of the three levels of the photomultiplier tube satisfies: U A :U C =1,U B :U C =1,U A :U B =1.

[0064] By measuring the gain of the photomultiplier tube of this embodiment and comparing it with the gain of the original structure, the test results are as follows: Figure 8 The electron motion trajectory is shown in Fig. 9 As shown, the gain is significantly improved by 115.12% compared with the original photomultiplier tube covered with a conductive film.

[0065] Example 4

[0066] See also Figure 7The side-window type photomultiplier tube of the embodiment of the present invention comprises a ceramic substrate 2 on which a metal conductive film 1-3 is deposited near the surface of the electron multiplier D1-D9, a photocathode 3, an electric field modulation electrode 4, a grid 5, an anode 6, a glass shell 7, a voltage-dividing resistor 8 and the electron multiplier D1-D9. The electron multiplier D1-D9, the photocathode 3, the grid 5 and the anode 6 are all located between two ceramic substrates 2. A positioning pin 10 for fixing to the ceramic substrate is provided on the side of each component. The positioning pin also serves as a power supply interface for these components. The metal conductive film 1-3 is divided into five parts, which are respectively between the grid 5 and the photocathode 3, the first dynode D1, the third dynode D3, the fifth dynode D5, the seventh dynode D7 and the ceramic substrate. The potential of each part of the five parts of the metal conductive film is the same as the potential of the corresponding dynode.

[0067] The thickness of the metal conductive film 1-3 is 50 nm, and the metal material Cr is selected for deposition.

[0068] The electron multipliers D1 to D9, the photocathode 3, the electric field modulation electrode 4, the grid 5 and the anode 6 are all made of conductive materials. Except for the electric field modulation electrode 4, all of them have positioning pins 10 fixed to the ceramic substrate. The positioning pins 10 are cylindrical, and the radius of the bottom circle of the cylinder is R = 0.4 mm. It is connected to the voltage divider resistor 8 to obtain an electric potential.

[0069] The voltage-dividing resistor 8 is composed of 10 resistors. The first voltage-dividing resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle eight voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first-stage electron multiplier to the ninth-stage electron multiplier. The last voltage-dividing resistor is connected between the last-stage electron multiplier and the ground. The potential of each stage of the electron multiplier is set by adjusting these voltage-dividing resistors.

[0070] The electron multipliers D1 to D9 include a first-stage electron multiplier D1, a second-stage electron multiplier D2, a third-stage electron multiplier D3, a fourth-stage electron multiplier D4, a fifth-stage electron multiplier D5, a sixth-stage electron multiplier D6, a seventh-stage electron multiplier D7, an eighth-stage electron multiplier D8, and a ninth-stage electron multiplier D9. Electrons are finally collected by the anode 6. The multiplication surface of each multiplier is covered with a 400nm thick Sb-K-Na-Cs film. When the potential difference is 100V, the secondary electron emission coefficient SEY of the film is 6.37.

[0071] The working voltage of the photomultiplier tube is -1000V, wherein the potential of the photocathode 3, the electric field modulation electrode 4 and the grid 5 are all -1000V, and the potential difference between the photocathode and the electron multiplier and the anode is divided into three levels, and the potential difference in the same level is the same, the first level is U0~U4, the second level is U5~U8, the third level is U9, and the anode potential is 0. The potential difference between the first level photocathode and the first level electron multiplier or the adjacent two levels of electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the electron multiplier and the anode of the third level is U C .

[0072] The potential difference of the three levels of the photomultiplier tube satisfies: U A :U C =2,U B :U C =2,U A :U B =1.

[0073] By measuring the gain of the photomultiplier tube of this embodiment and comparing it with the gain of the original structure, the test results are as follows: Fig.10 The electron motion trajectory is shown in Fig.11 As shown, the gain is significantly improved by 163.41% compared with the original photomultiplier tube covered with a conductive film.

[0074] Example 5

[0075] See also Figure 7 The side-window type photomultiplier tube of the embodiment of the present invention comprises a ceramic substrate 2 on which a metal conductive film 1-3 is deposited near the surface of the electron multiplier D1-D9, a photocathode 3, an electric field modulation electrode 4, a grid 5, an anode 6, a glass shell 7, a voltage-dividing resistor 8 and the electron multiplier D1-D9. The electron multiplier D1-D9, the photocathode 3, the grid 5 and the anode 6 are all located between two ceramic substrates 2. A positioning pin 10 for fixing to the ceramic substrate is provided on the side of each component. The positioning pin also serves as a power supply interface for these components. The metal conductive film 1-3 is divided into five parts, which are respectively between the grid 5 and the photocathode 3, the first dynode D1, the third dynode D3, the fifth dynode D5, the seventh dynode D7 and the ceramic substrate. The potential of each part of the five conductive films is the same as the potential of the corresponding dynode.

[0076] The thickness of the metal conductive film 1-3 is 50 nm, and the metal material Cr is selected for deposition.

[0077] The electron multipliers D1 to D9, the photocathode 3, the electric field modulation electrode 4, the grid 5 and the anode 6 are all made of conductive materials. Except for the electric field modulation electrode 4, all of them have positioning pins 10 fixed to the ceramic substrate. The positioning pins 10 are cylindrical, and the radius of the bottom circle of the cylinder is R = 0.4 mm. It is connected to the voltage divider resistor 8 to obtain an electric potential.

[0078] The voltage-dividing resistor 8 is composed of 10 resistors. The first voltage-dividing resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle eight voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first-stage electron multiplier to the ninth-stage electron multiplier. The last voltage-dividing resistor is connected between the last-stage electron multiplier and the ground. The potential of each stage of the electron multiplier is set by adjusting these voltage-dividing resistors.

[0079] The electron multipliers D1 to D9 include a first-stage electron multiplier D1, a second-stage electron multiplier D2, a third-stage electron multiplier D3, a fourth-stage electron multiplier D4, a fifth-stage electron multiplier D5, a sixth-stage electron multiplier D6, a seventh-stage electron multiplier D7, an eighth-stage electron multiplier D8, and a ninth-stage electron multiplier D9. Electrons are finally collected by the anode 6. The multiplication surface of each multiplier is covered with a 400nm thick Sb-K-Na-Cs film. When the potential difference is 100V, the secondary electron emission coefficient SEY of the film is 6.37.

[0080] The working voltage of the photomultiplier tube is -1000V, wherein the potential of the photocathode 3, the electric field modulation electrode 4 and the grid 5 are all -1000V, and the potential difference between the photocathode and the electron multiplier and the anode is divided into three levels, and the potential difference in the same level is the same, the first level is U0~U4, the second level is U5~U8, the third level is U9, and the anode potential is 0. The potential difference between the first level photocathode and the first level electron multiplier or the adjacent two levels of electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the electron multiplier and the anode of the third level is U C .

[0081] The potential difference of the three levels of the photomultiplier tube satisfies: U A :U C =4,U B :U C =4,U A :U B =1.

[0082] By measuring the gain of the photomultiplier tube of this embodiment and comparing it with the gain of the original structure, the test results are as follows: Fig.12 The electron motion trajectory is shown in Fig.13As shown, the gain is significantly improved by 198.28% compared with the original photomultiplier tube covered with a conductive film.

[0083] It can be seen from the above specific embodiments and related descriptions that, compared with the existing side-window type photomultiplier tube, the conductive film structure using the embodiment of the present invention has a higher gain than the traditional side-window type photomultiplier tube, can reduce its secondary electron emission coefficient and operating voltage, and provide reference value for subsequent research work.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the present technical solution can also be subjected to a number of simple modifications and substitutions, and these modifications and substitutions also fall within the scope of protection covered by the claims.

Claims

1. A high-gain photomultiplier tube, It is characterized in that The invention comprises an upper ceramic substrate and a lower ceramic substrate, wherein a photocathode (3), a grid (5), an anode (6) and a plurality of electron multipliers are arranged between the upper ceramic substrate and the lower ceramic substrate; a metal conductive film is deposited on the lower surface of the upper ceramic substrate and the upper surface of the lower ceramic substrate opposite to the electron multipliers, and the metal conductive film is in mechanical contact with each electron multiplier so that the regionalized metal conductive film obtains an electric potential; the photocathode (3), the grid (5), the anode (6) and each electron multiplier are respectively connected to the photocathode by positioning pins (10 ) are connected and fixed on a ceramic substrate, and voltage-dividing resistors (8) are respectively connected between the photocathode (3) and the positioning pin (10) of the first-stage electron multiplier, between two adjacent positioning pins (10) from the first-stage electron multiplier to the last-stage electron multiplier, and between the positioning pin of the last-stage electron multiplier and the ground (10). The potential of each stage of the electron multiplier is set by adjusting the voltage-dividing resistor (8), and the potential difference between two adjacent stages of the electron multiplier and the potential difference between the last-stage electron multiplier and the ground presents a form of differential voltage division.

2. The high-gain photomultiplier tube according to claim 1, It is characterized in that There are nine electron multipliers, and ten voltage-dividing resistors (8), the first voltage-dividing resistor is connected between the photocathode (3) and the first electron multiplier, the second to ninth voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first to ninth electron multipliers, and the tenth voltage-dividing resistor is connected between the ninth electron multiplier and the ground.

3. The high-gain photomultiplier tube according to claim 2, It is characterized in that The potential difference between the photocathode (3) and the first-stage electron multiplier is U 0 The potential difference between the two adjacent electron multipliers from the first to the ninth electron multiplier is U 1 ~U 8 , the potential difference between the ninth electron multiplier and the ground is U 9 , the anode potential is 0; divided into three levels according to the potential difference, the potential difference in the same level is the same, divided as follows: the first level is U 0 ~U 4 , the second level is U 5 ~U 8 , the third level is U 9 ; or the first level is U 0 ~U 2 , the second level is U 3 ~U 8 , the third level is U 9 ; or the first level is U 0 ~U 3 , the second level is U 4 ~U 8 , the third level is U 9 ; or the first level is U 0 ~U 5 , the second level is U 6 ~U 8 , the third level is U 9 ; wherein the potential difference between the first-level photocathode (3) and the first-level electron multiplier or the two adjacent electron multipliers is U A The potential difference between the two adjacent electron multipliers in the second level is U B The potential difference between the third-level electron multiplier and the ground is U C .

4. The high-gain photomultiplier tube according to claim 3, It is characterized in that The potential difference meets the following proportional relationship: U A :U C In the range of 4 to 1, U B :U C is in the range of 4 to 1, and U A :U B ≥1.

5. The high-gain photomultiplier tube according to claim 1, It is characterized in that The thickness of the metal conductive film is between 10 nm and 10 μm; the metal conductive film is made of any one material among Cr, Au, Ag and Cu.

6. The high-gain photomultiplier tube according to claim 1, It is characterized in that The positioning pin (10) is a cylindrical structure, and the radius of the cylindrical structure is R=0.4 mm.

7. The high-gain photomultiplier tube according to claim 1, It is characterized in that The surface of the electron multiplier is plated with a Sb-K-Na-Cs film, and the thickness of the Sb-K-Na-Cs film is between 100nm and 10μm.

8. The high-gain photomultiplier tube according to claim 1, It is characterized in that The grid (5) is composed of two layers of grid frames, each of which is provided with spaced parallel metal wires, and the positioning pin (10) is provided between the two layers of grid frames; the grid (5) is arranged between the photocathode (3) and the first-stage electron multiplier, and the electrons emitted by the photocathode (3) are guided to move to the first-stage electron multiplier through the grid (5).

9. The high-gain photomultiplier tube according to claim 1 or 8, It is characterized in that An electric field modulation electrode (4) is also provided between the upper ceramic substrate and the lower ceramic substrate. The electric field modulation electrode (4) is arranged between the photocathode (3) and the anode (6). The electric field modulation electrode (4) is used to enable more electrons to move between the electron multipliers.

10. A method for manufacturing a high-gain photomultiplier tube, It is characterized in that The following steps are involved: Depositing secondary electron emission films on the surfaces of a plurality of electron multipliers; Depositing a metal conductive film on a lower surface of the upper ceramic substrate opposite to the electron multiplier and on an upper surface of the lower ceramic substrate; Assembling the electron multipliers, inserting the positioning pins (10) on all the electron multipliers into the mounting holes on the lower ceramic substrate in sequence, inserting the positioning pins (10) of the photocathode (3), the grid (5), and the anode (6) into the mounting holes at the designated positions, installing the upper ceramic substrate, and inserting the fixed electric field modulation electrode (4) between the photocathode (3) and the anode (6); A plurality of voltage-dividing resistors (8) are selected according to the number of electron multipliers, the first voltage-dividing resistor is connected between the photocathode (3) and the first-stage electron multiplier, the intermediate voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first-stage electron multiplier to the last-stage electron multiplier, and the last voltage-dividing resistor is connected between the last-stage electron multiplier and the ground; A glass shell (7) is used for packaging, and a positioning pin (10) connected to the photocathode (3), the ground terminal of the voltage divider resistor (8) connected to the final electron multiplier, and the anode (6) is connected to the outside of the glass shell (7).

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