A high-gain photomultiplier tube and its manufacturing method

Abstract

A high-gain photomultiplier tube and a method for manufacturing the same. The photomultiplier tube comprises an upper ceramic substrate and a lower ceramic substrate, with a photocathode, a grid, an anode, and a plurality of electron multipliers disposed between the two ceramic substrates. A metal conductive film is deposited on the surfaces of the upper and lower ceramic substrates opposite the electron multipliers, and the metal conductive film is in mechanical contact with each electron multiplier. The photocathode, grid, anode, and electron multipliers are each connected and fixed to the ceramic substrate via positioning pins. A voltage divider resistor is connected between the photocathode and the positioning pin of the first-stage electron multiplier, between the positioning pins of two adjacent electron multipliers, and between the positioning pin of the last-stage electron multiplier and ground. The potential of each electron multiplier is set by adjusting the voltage divider resistor, and the potential difference between two adjacent electron multipliers and the potential difference between the last-stage electron multiplier and ground is in the form of a differentiated voltage divider. The present invention improves the gain and lifespan of the photomultiplier tube.

Description

Technical Field

[0001] The present 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 a solid material, 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 barrier and escape from the surface to become secondary electrons. This process is called secondary electron emission.

[0003] Photomultiplier tubes (PMTs) are vacuum electron devices that convert weak light signals into electrical signals and incorporate a signal multiplication system. They are widely used in fields such as high-energy physics detection and radiotherapy, and are characterized by excellent stability, fast time response, and high sensitivity. Side-window PMTs primarily consist of an electron optical input system, a reflective photocathode, an electron multiplication system, and an anode. Their operating principle is that incident light passes through the PMT and reaches the photocathode, generating photoelectrons through the external photoelectric effect. These photoelectrons are focused into an electron beam by an electric field and bombard the first-stage electron multiplier, generating secondary electrons. These secondary electrons are accelerated by the electric field and continue to bombard the next-stage electron multiplier, generating more secondary electrons. Electron multiplication is achieved through the secondary electron emission process of multiple electron multipliers. Ultimately, these multiplied electrons are received by the anode, enabling the amplification and detection of weak light signals. Current PMTs suffer from low gain and short lifespans. Summary of the Invention

[0004] The purpose of the present invention is to address the problems in the above-mentioned prior art and provide a high-gain photomultiplier tube and a manufacturing method thereof, thereby increasing the number of secondary electrons emitted by each level of electron multiplier, significantly improving the gain of the photomultiplier tube, and effectively extending 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 disposed 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 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 to the ceramic substrate via positioning pins; a voltage divider resistor is respectively connected between the photocathode and the positioning pin of the first-stage electron multiplier, between 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 ground; the potential of each stage of the electron multiplier is set by regulating the voltage divider resistor, and the potential difference between two adjacent stages of the electron multiplier and the potential difference between the last-stage electron multiplier and ground are in the form of differential voltage division.

[0007] As a preferred solution, there are nine electron multipliers and ten voltage divider resistors. The first voltage divider resistor is connected between the photocathode and the first electron multiplier, the second to ninth voltage divider resistors are respectively connected between the two adjacent electron multipliers from the first to the ninth electron multipliers, and the tenth voltage divider 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-stage electron multiplier is U0, the potential difference between the two adjacent electron multipliers from the first stage to the ninth stage is U1 to U8, the potential difference between the ninth stage 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 to U4, the second level is U5 to U8, and the third level is U9; or the first level is U0 to U2, the second level is U3 to U8, and the third level is U9; or the first level is U0 to U3, the second level is U4 to U8, and the third level is U9; or the first level is U0 to U5, the second level is U6 to U8, and the third level is U9; wherein the potential difference between the photocathode of the first level and the first-stage 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 .

[0009] As a preferred solution, the potential difference conforms to the following proportional relationship: U A :U C In the range of 4 to 1, UB :U C is within 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. The electric field modulation electrode is arranged between the photocathode and the anode. The electric field modulation electrode 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 several electron multipliers;

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

[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 anode;

[0019] Select 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 each intermediate voltage-dividing resistor 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 ground;

[0020] A glass shell is used for packaging, and the positioning pins connected to the photocathode, the ground end of the voltage divider resistor connected to the final 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] Currently, side-window photomultiplier tubes typically use a ceramic substrate with a single metal conductive film on the surface near the electron multiplier. This film is mechanically contacted with the photocathode to maintain the same potential as the photocathode during operation. This suppresses the charge accumulation caused by secondary electrons moving to the surface of the ceramic substrate near the electron multiplier, thereby eliminating the hysteresis effect of the photomultiplier, improving the stability of the photomultiplier, and extending its service life. If the ceramic substrate of the photomultiplier is not covered with a metal conductive film, electrons will more easily bombard the ceramic substrate and glass shell and accumulate. This will not only lead to a charge accumulation effect, thereby reducing the performance of the photomultiplier, but also cause discharge problems, affecting the reliability of the photomultiplier. However, the current method causes the secondary electrons to reach the next electron multiplier to be more concentrated, affecting the gain and life of the photomultiplier. The high-gain photomultiplier tube of the present invention proposes to prepare a metal conductive film with a regionalized, differentiated potential on the surface of the ceramic substrate near the electron multiplier. This allows the secondary electrons to be more dispersed during the multiplication process, reducing the influence of the space charge effect and improving the gain and life of the photomultiplier. 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, which improves the efficiency of the anode in receiving secondary electrons and increases 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 following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. 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 any creative work.

[0024] Figure 1 A schematic structural diagram 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 A diagram showing the electron motion trajectory of the side-window photomultiplier tube according to Example 1 of the present invention;

[0027] Figure 4 A schematic structural diagram of a side-window type photomultiplier tube according to Example 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 A diagram showing the electron motion trajectory of a side-window photomultiplier tube according to Example 2 of the present invention;

[0030] Figure 7 A schematic structural diagram of a side-window type photomultiplier tube according to Example 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 and the original structure;

[0032] Figure 9 A diagram showing the electron motion trajectory of a side-window photomultiplier tube according to Example 3 of the present invention;

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

[0034] Figure 11 A diagram showing the electron motion trajectory of a side-window photomultiplier tube according to Example 4 of the present invention;

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

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

[0037] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may 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 avoid obscuring the description of the present application with unnecessary detail.

[0038] Example 1

[0039] See also Figure 1The side-window photomultiplier tube of an embodiment of the present invention includes a ceramic substrate 2 on which a metal conductive film 1-1 is deposited near the surface of 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 divider resistor 8, and 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. Each component is provided with a positioning pin 10 on the side for fixing to the ceramic substrate. The positioning pin also serves as a power supply interface for these components. The coverage area of ​​the metal conductive film 1-1 includes the photocathode and the first to eighth stages of the dynodes. The potential of each part 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 the potential.

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

[0043] The electron multipliers D1 to D9 include the first-stage electron multiplier D1, the second-stage electron multiplier D2, the third-stage electron multiplier D3, the fourth-stage electron multiplier D4, the fifth-stage electron multiplier D5, the sixth-stage electron multiplier D6, the seventh-stage electron multiplier D7, the eighth-stage electron multiplier D8, and the ninth-stage electron multiplier D9. The 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 operating 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 to U4, the second level is U5 to U8, and the third level is U9. 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 third-level electron multiplier and the anode 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 as Figure 3 As shown, the gain is significantly improved by 97.67% compared to 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 includes a ceramic substrate 2 with a metal conductive film 1-2 deposited near the surface of the electron multipliers 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 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. The side of each component is provided with a positioning pin 10 for fixing to the ceramic substrate. The positioning pin also serves as the power supply for these components. Interface, the metal conductive film 1-2 is divided into five parts, which are respectively between the grid 5 and the photocathode 3, the second-stage dynode D2, the fourth-stage dynode D4, the sixth-stage dynode D6, the eighth-stage 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-stage electron multiplier D2 is located is -800V, the potential of the metal conductive film 1-2 where the fourth-stage 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 the potential.

[0051] The voltage divider resistor 8 consists of 10 resistors. The first voltage divider resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle 8 voltage divider resistors are respectively connected between the two adjacent electron multipliers from the first to the ninth stage electron multipliers. The last voltage divider resistor is connected between the last stage electron multiplier and the ground. The potential of each stage electron multiplier is set by adjusting these voltage divider 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 ultimately 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 operating 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 to U4, the second level is U5 to U8, and the third level is U9. 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 third-level electron multiplier and the anode 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 as Figure 6 As shown in the figure, 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 includes a ceramic substrate 2 with a metal conductive film 1-3 deposited near the surface of the electron multipliers 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 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. The side of each component is provided with a positioning pin 10 for fixing to the ceramic substrate. The positioning pin also serves as the power supply for these components. Interface, the metal conductive film 1-3 is divided into five parts, which are 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 the potential.

[0060] The voltage divider resistor 8 consists of 10 resistors. The first voltage divider resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle 8 voltage divider resistors are respectively connected between the two adjacent electron multipliers from the second to the ninth stage electron multipliers. The last voltage divider resistor is connected between the last stage electron multiplier and the ground. The potential of each stage electron multiplier is set by adjusting these voltage divider 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 ultimately 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 operating 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 within the same level is the same, the first level is U0 to U4, the second level is U5 to U8, and the third level is U9. 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 third-level electron multiplier and the anode 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 as Figure 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 photomultiplier tube of an embodiment of the present invention includes a ceramic substrate 2 with a metal conductive film 1-3 deposited near the surface of the electron multipliers 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 multipliers D1-D9. The electron multipliers D1-D9, the photocathode 3, the grid 5, and the anode 6 are all located between two ceramic substrates 2. Each component is provided with a positioning pin 10 on the side for fixing to the ceramic substrate. The positioning pin also serves as a power supply interface for these components. The metal conductive film 1-3 is divided into five sections, respectively, between the grid 5 and the photocathode 3, and between the connection points between the first-stage dynode D1, the third-stage dynode D3, the fifth-stage dynode D5, and the seventh-stage dynode D7 and the positioning pins of the ceramic substrate. The potential of each section of the five sections 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 the potential.

[0069] The voltage divider resistor 8 consists of 10 resistors. The first voltage divider resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle 8 voltage divider resistors are respectively connected between the two adjacent electron multipliers from the first to the ninth stage electron multipliers. The last voltage divider resistor is connected between the last stage electron multiplier and the ground. The potential of each stage electron multiplier is set by adjusting these voltage divider 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 ultimately 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 operating 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 within the same level is the same, the first level is U0 to U4, the second level is U5 to U8, and the third level is U9. 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 third-level electron multiplier and the anode 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: Figure 10 The electron motion trajectory is shown as Figure 11 As shown in the figure, 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 photomultiplier tube of an embodiment of the present invention includes a ceramic substrate 2 with a metal conductive film 1-3 deposited near the surface of the electron multipliers 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 multipliers D1-D9. The electron multipliers D1-D9, the photocathode 3, the grid 5, and the anode 6 are all located between two ceramic substrates 2. Each component is provided with a positioning pin 10 on the side for fixing to the ceramic substrate. The positioning pin also serves as a power supply interface for these components. The metal conductive film 1-3 is divided into five parts, respectively, between the grid 5 and the photocathode 3, and between the connection points of the first-stage dynode D1, the third-stage dynode D3, the fifth-stage dynode D5, and the seventh-stage dynode D7 with the positioning pins of 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 the potential.

[0078] The voltage divider resistor 8 consists of 10 resistors. The first voltage divider resistor is connected between the photocathode 3 and the first-stage electron multiplier. The middle 8 voltage divider resistors are respectively connected between the two adjacent electron multipliers from the first to the ninth stage electron multipliers. The last voltage divider resistor is connected between the last stage electron multiplier and the ground. The potential of each stage electron multiplier is set by adjusting these voltage divider 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 ultimately 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 operating 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 within the same level is the same, the first level is U0 to U4, the second level is U5 to U8, and the third level is U9. 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 third-level electron multiplier and the anode 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: Figure 12 The electron motion trajectory is shown as Figure 13As shown, the gain is significantly improved by 198.28% compared to 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 thin film structure of 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 provides reference value for subsequent research work.

[0084] The above description is merely 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 replacements, and these modifications and replacements also fall within the scope of protection covered by the claims.

Claims

1. A high-gain photomultiplier tube, 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 regionalized 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 each regionalized metal conductive film is in mechanical contact with each corresponding 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 upper surface of the upper ceramic substrate and the upper surface of the lower ceramic substrate. The positioning pin (10) is connected and fixed on the ceramic substrate. A voltage divider resistor (8) is 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. The potential of each stage of the electron multiplier is set by adjusting the voltage divider resistor (8). The potential difference between the two adjacent stages of the electron multiplier and the potential difference between the last-stage electron multiplier and the ground presents a differential voltage divider form. The electron multipliers are provided with nine, and the voltage-dividing resistors (8) are provided with ten, the first voltage-dividing resistor is connected between the photocathode (3) and the first-stage electron multiplier, the second to ninth voltage-dividing resistors are respectively connected between two adjacent electron multipliers from the first to the ninth stage electron multipliers, and the tenth voltage-dividing resistor is connected between the ninth stage electron multiplier and the ground; The potential difference between the photocathode (3) and the first-stage electron multiplier is U0, the potential difference between the two adjacent electron multipliers from the first stage to the ninth stage is U1-U8, the potential difference between the ninth stage 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 (3) of the first level and the first-stage 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 ; The potential difference complies with the following proportional relationship: U A :U C In the range of 4 to 1, U B :U C is within the range of 4 to 1, and U A :U B ≥1.

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

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

4. The high-gain photomultiplier tube according to claim 1, wherein: 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.

5. The high-gain photomultiplier tube according to claim 1, characterized in that: The grid (5) is composed of two layers of grid frames, and parallel metal wires are arranged in the two layers of grid frames at intervals. The positioning pin (10) is arranged 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).

6. The high-gain photomultiplier tube according to claim 1 or 5, characterized in that: An electric field modulation electrode (4) is further 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.

7. A method for manufacturing a high-gain photomultiplier tube according to any one of claims 1 to 6, characterized in that: The following steps are involved: Depositing secondary electron emission films on the surfaces of several electron multipliers; depositing a regionalized metal conductive film on the lower surface of the upper ceramic substrate and the upper surface of the lower ceramic substrate opposite to the electron multiplier; Assemble the electron multiplier electrodes, insert the positioning pins (10) on all the electron multiplier electrodes into the mounting holes on the lower ceramic substrate in sequence, insert the positioning pins (10) of the photocathode (3), the grid (5), and the anode (6) into the mounting holes at designated positions, install the upper ceramic substrate, and insert 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 the 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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