Composite dielectric anode and composite dielectric anode microchannel plate type photomultiplier tube

Abstract

The present invention belongs to the technical field of photomultiplier tubes, and provides a composite dielectric anode and a composite dielectric anode microchannel plate type photomultiplier tube, which includes a photocathode, a tube shell, a microchannel plate and a composite dielectric anode. The photocathode is hermetically connected to the front end of the tube shell, the microchannel plate is assembled inside the tube shell, and the composite dielectric anode is hermetically connected to the end of the tube shell. The photocathode receives photons and converts the photons into photoelectrons. The photoelectrons are incident into the microchannel plate under the action of a focusing electric field. After electron multiplication by the microchannel plate, an electron cloud signal is output. The electron cloud signal is collected by the composite dielectric anode, and the electron cloud signal is converted into an electrical pulse signal and output to the outside of the photomultiplier tube. The composite dielectric anode is provided with two or more dielectrics with different dielectric constants between the anode core and the anode shell, so that the anode impedance is adjustable and matched with the impedance of the connected electronics at the rear end, and a photomultiplier tube for obtaining an ultrafast pulse signal is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of microchannel plates, and more particularly to a composite dielectric anode and a composite dielectric anode microchannel plate type photomultiplier tube. Background Art

[0002] A photomultiplier tube is a vacuum device that converts a weak optical signal into an electrical signal, and is widely used in fields such as analytical instruments, medical instruments, oil logging, space exploration, high-energy physics, and laser applications. It involves multiple industries in the national economy, and is especially applied in important high-energy physics detections and research experiments such as "ultraviolet warning", "Shenguang III", "ultraviolet communication", positron-electron collider, and neutrino detection.

[0003] With the continuous development of fields such as neutrino detection experiments, nuclear explosion simulation experiments, and ultraviolet communication, the demand for photomultiplier tubes is increasing, especially for the ultrafast time response performance of photomultiplier tubes. For example, "Shenguang III" uses a high-power pulsed laser beam (or particle beam) to uniformly irradiate a microtarget filled with hydrogen isotopes deuterium and tritium, causing ionization and ablation on the surface of the target pellet in a very short time, triggering a fusion nuclear reaction in a short time, and releasing a large amount of fusion energy. To accurately measure the intensity spatial distribution, time evolution, energy spectrum changes, etc. of the plasma during the fusion process, an ultrafast time response photomultiplier tube is required. The Large Hadron Collider at the European Organization for Nuclear Research has been undergoing a major upgrade after eight years of successful operation. The newly built detectors will require a large number of ultrafast time response photomultiplier tubes, and these laboratories have high requirements for the time response performance of photomultiplier tubes.

[0004] Traditional photomultiplier tubes can be divided into dynode type photomultiplier tubes and microchannel plate type photomultiplier tubes. For dynode type photomultiplier tubes, due to the relatively discrete dynodes, the pulse signal generally can only reach the nanosecond level and cannot meet the requirements of the picosecond level; the anodes of ordinary microchannel plate type photomultiplier tubes are all prepared with a single medium. After the model of the photomultiplier is determined, the outer diameter of the photomultiplier tube and the diameter of the anode plate are fixed, resulting in the inability to meet the requirements of structure and impedance. It is very difficult to match the anode impedance with the backend electronics, and there are a large number of reflected signals during the signal transmission process of the anode, resulting in a reduction in the time performance of the pulse signal. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite dielectric anode microchannel plate type photomultiplier tube to solve the problems of mismatched anode impedance, a large number of reflected signals in the pulse signal, and slow pulse signal response time in current photomultiplier tubes.

[0006] To achieve the above object, a first aspect of the present invention provides a composite dielectric anode microchannel plate type photomultiplier tube, including a photocathode, a tube shell, a microchannel plate, and a composite dielectric anode, wherein:

[0007] The photocathode is disposed at the front end of the envelope and is vacuum-sealed and welded to the envelope. The photocathode faces the input surface of the microchannel plate, and is used to receive photon signals and convert photons into photoelectrons.

[0008] The envelope is used to mount and fix the microchannel plate, and is vacuum-sealed and welded to the anode and the cathode, and is used to maintain a vacuum environment for the electron movement in the photomultiplier tube.

[0009] The microchannel plate is disposed inside the envelope and is used to rapidly multiply photoelectrons.

[0010] The composite medium anode is disposed at the end of the envelope and is vacuum-sealed and welded to the envelope. The anode faces the output surface of the microchannel plate, and is used to receive the electron cloud signal output by the microchannel plate and convert the electron cloud signal into an electrical pulse signal, and output it outside the photomultiplier tube.

[0011] Preferably, the photocathode includes a light window, a sealing film layer and a photoelectric conversion film layer, wherein:

[0012] The light window serves as a coating substrate for the sealing film layer and the photoelectric conversion film layer, and transmits photons to the photoelectric conversion film layer.

[0013] The sealing film layer is evaporated on the outer edge of the light window, and is used for indium sealing between the photocathode and the envelope, and is also used for conducting electricity to the photoelectric conversion film layer.

[0014] The photoelectric conversion film layer is evaporated at the center position of the light window, and is used to absorb photons and convert photons into photoelectrons.

[0015] Preferably, the light window material is made of glass materials with high light transmittance such as borosilicate glass, high borosilicate glass, magnesium fluoride crystal, etc.

[0016] Preferably, the envelope includes an indium sealing groove, an input ceramic ring, an input electrode, a positioning ceramic ring, an output electrode, an output ceramic ring, a getter electrode, a getter ceramic ring and a spacer ring, wherein:

[0017] The indium sealing groove is used for indium melting, and is indium-sealed with the sealing film layer of the photocathode to realize vacuum sealing between the photocathode and the envelope.

[0018] The input ceramic ring is disposed below the indium sealing groove and is used for insulation between the indium sealing groove and the input electrode.

[0019] The input electrode is disposed below the input ceramic ring and is used to apply a high voltage to the input surface of the microchannel plate.

[0020] The positioning ceramic ring is disposed below the input electrode and is used for insulation between the input electrode and the output electrode, and is also used for positioning the microchannel plate so that the microchannel plate is installed at the center position of the envelope.

[0021] The output electrode is arranged below the positioning ceramic ring and is used to apply a high voltage to the output surface of the microchannel plate.

[0022] The output ceramic ring is arranged below the output electrode and is used for insulation between the output electrode and the getter electrode.

[0023] The getter electrode is arranged below the output ceramic ring and is used to apply a current to the getter.

[0024] The getter ceramic ring is arranged below the getter electrode and is used for insulation between the getter electrode and the isolation ring.

[0025] The isolation ring is arranged below the getter ceramic ring and is used for sealing and welding with the composite dielectric anode housing.

[0026] Preferably, the composite dielectric anode includes an anode housing, a composite dielectric, and an anode core, wherein:

[0027] The anode housing is connected to the composite dielectric and forms a coaxial structure with the anode core, serving as the anode signal ground wire and at the same time used to shield external electromagnetic radiation from interfering with the anode signal.

[0028] The composite dielectric is filled between the anode housing and the anode core and serves as the medium for transmitting signals between the anode core and the anode housing.

[0029] The anode core is connected to the composite dielectric and forms a coaxial structure with the anode housing, used to receive the electron cloud signal output by the microchannel plate, convert the electron cloud signal into a fast pulse signal, and output the pulse signal to the outside of the photomultiplier tube.

[0030] Preferably, the inner side of the anode housing is in a flared shape, and its output port has the same size and thread as the SMA standard interface for matching connection with the SMA standard interface.

[0031] Preferably, the composite dielectric includes two or more transmission media with different dielectric constants.

[0032] Preferably, for the two or more transmission media with different dielectric constants used in the composite dielectric, by adjusting the ratio between the dielectric thicknesses of the two or more different transmission media, the dielectric constant of the composite dielectric can be continuously adjusted.

[0033] Preferably, the impedance values achieved by the two or more transmission media with different dielectric constants used in the composite dielectric are the same as the impedance value of the electronics system connected to the rear end of the photomultiplier tube.

[0034] Preferably, the composite dielectric includes two transmission media, namely a ceramic material medium and a vacuum medium.

[0035] Preferably, by setting the thickness ratio of the ceramic material to the vacuum medium, the dielectric constant of the composite medium can be continuously adjusted.

[0036] Preferably, among the two or more transmission media with different dielectric constants in the composite medium, the dielectric constant of the selected ceramic material medium is 9 - 10, and the vacuum dielectric constant is 1. Preferably, the dielectric constant of the selected ceramic material medium is 9.4.

[0037] Preferably, the anode core is set to be conical, and its output end is needle-shaped, which is the same size as the pin of the SMA standard interface to be matched and connected with the SMA standard interface.

[0038] According to the second aspect of the present invention, a composite medium anode for a microchannel plate type photomultiplier tube is also proposed, which includes two or more transmission media with different dielectric constants. By adjusting the thickness of the two different node transmission media above, the impedance of the composite medium anode can be continuously adjusted to achieve impedance matching with the backend electronics system.

[0039] Compared with the prior art, the composite medium anode microchannel plate type photomultiplier tube proposed by the present invention has the following significant beneficial effects:

[0040] 1. The present invention uses a composite medium anode to achieve an anode impedance of 50 ohms or consistent with the impedance of the backend electronics, reducing the reflected signal component of the photomultiplier tube pulse signal and improving the pulse signal response time performance.

[0041] 2. The present invention uses a composite medium to achieve adjustable dielectric constant of the medium. Combining the actual structures of the anode housing and the anode core, the impedance value of the composite medium anode can be adjusted to achieve continuous impedance of the composite anode and impedance matching with the backend connected electronics, so that the anode impedance is 50 ohms or consistent with the impedance of the backend electronics.

[0042] 3. The output port of the composite medium anode adopted by the present invention is set as an SMA interface structure, realizing convenient and impedance-matched connection with the backend electronics instrument, and reducing reflection and attenuation during the signal transmission process between the photomultiplier tube and the backend electronics.

[0043] 4. The present invention uses a microchannel plate as an electron multiplier to achieve an ultrafast time response performance of the electron cloud signal after electron multiplication.

[0044] It should be understood that all combinations of the foregoing concepts and additional concepts described in more detail below can be regarded as part of the inventive subject matter of the present disclosure as long as such concepts do not contradict each other. In addition, all combinations of the claimed subject matter are regarded as part of the inventive subject matter of the present disclosure.

[0045] The foregoing and other aspects, embodiments, and features of the teachings of the present invention can be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as the features and / or beneficial effects of exemplary embodiments, will be apparent from the following description or will be learned from the practice of specific embodiments in accordance with the teachings of the present invention. Brief Description of the Drawings

[0046] The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in each figure may be denoted by the same reference numeral. For clarity, not every component is labeled in each figure. Now, embodiments of various aspects of the present invention will be described by way of example and with reference to the drawings, wherein:

[0047] Figure 1 is a schematic structural diagram of a composite dielectric anode microchannel plate type photomultiplier tube according to an embodiment of the present invention.

[0048] Figure 2 is a schematic structural diagram of a photocathode according to an embodiment of the present invention.

[0049] Figure 3 is a schematic structural diagram of a tube shell according to an embodiment of the present invention.

[0050] Figure 4 is a schematic structural diagram of a composite dielectric anode according to an embodiment of the present invention.

[0051] Figure 5 is a graph of the impedance of a composite dielectric anode according to an embodiment of the present invention.

[0052] Figure 6 is a graph showing the variation of the impedance of a composite dielectric anode with the thickness of the vacuum dielectric according to an embodiment of the present invention.

[0053] Figure 7 is a test graph of pulse signals of a microchannel plate type photomultiplier tube with a common single anode in the prior art.

[0054] Figure 8 is a test graph of pulse signals of a composite dielectric anode microchannel plate type photomultiplier tube according to an embodiment of the present invention. Detailed Embodiments

[0055] To better understand the technical content of the present invention, specific embodiments are hereby given and described in conjunction with the accompanying drawings as follows.

[0056] Aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those concepts and embodiments described in more detail below, can be implemented in any of a number of ways, because the concepts and embodiments disclosed in the present invention are not limited to any particular implementation. Additionally, some aspects of the present invention can be used alone, or in any suitable combination with other aspects of the present invention.

[0057] Combined with Figures 1-4 The composite dielectric anode microchannel plate type photomultiplier tube of the illustrated embodiment includes a photocathode 100, a tube shell 200, a microchannel plate 300, and a composite dielectric anode 400.

[0058] The photocathode 100 is disposed at the front end of the tube shell 200 and is vacuum-sealed and welded to the indium sealing groove 201 of the tube shell 200 by a thermal indium sealing technique.

[0059] The photoelectric conversion film layer 103 of the photocathode 100 faces the input surface of the microchannel plate, and is used to receive photon signals and convert photons into photoelectrons.

[0060] The tube shell 200 is used to mount and fix the microchannel plate 300, and is vacuum-sealed and welded to the anode 400 and the photocathode 100, and is used to maintain a vacuum environment for the electron movement of the photomultiplier tube.

[0061] The microchannel plate 300 is disposed inside the tube shell 200 and is used to rapidly multiply photoelectrons.

[0062] The composite dielectric anode 400 is disposed at the end of the tube shell 200. The anode housing 404 of the composite dielectric anode 400 is vacuum-sealed and welded to the isolation ring 209 of the tube shell 200 by a laser welding technique. The anode core 401 faces the output surface of the microchannel plate 300, and is used to receive the electron cloud signal output by the microchannel plate 300 and convert the electron cloud signal into an electrical pulse signal, and output it to the outside of the photomultiplier tube.

[0063] Preferably, combined with Figure 2 , the photocathode 100 includes a light window 101, a sealing film layer 102, and a photoelectric conversion film layer 103.

[0064] The light window 101 serves as a coating substrate for the sealing film layer 102 and the photoelectric conversion film layer 103, and transmits photons to the photoelectric conversion film layer. The light window material is preferably a glass material with high light transmittance such as borosilicate glass, high borosilicate glass, magnesium fluoride crystal, etc.;

[0065] The sealing film layer 102 is vapor-deposited on the outer edge of the optical window 101, which is used for the indium sealing of the photocathode 100 and the shell 200, and is also used for conducting electricity to the photoelectric conversion film layer 103.

[0066] The photoelectric conversion film layer 103 is vapor-deposited at the center of the optical window 101, which is used for absorbing photons and converting photons into photoelectrons.

[0067] Preferably, combined with Figure 3 , the shell 200 includes an indium sealing groove 201, an input ceramic ring 202, an input electrode 203, a positioning ceramic ring 204, an output electrode 205, an output ceramic ring 206, a getter electrode 207, a getter ceramic ring 208, and a spacer ring 209.

[0068] The indium sealing groove 201 is used for melting indium and performing indium sealing with the sealing film layer 102 of the photocathode 100 to achieve a vacuum tight seal between the photocathode 100 and the shell 200.

[0069] The input ceramic ring 202 is arranged below the indium sealing groove 201 and is hermetically welded together through ceramic metallization technology, which is used for insulation between the indium sealing groove 201 and the input electrode 203.

[0070] The input electrode 203 is arranged below the input ceramic ring 202 and is hermetically welded together through ceramic metallization technology, which is used for applying a high voltage to the input surface of the microchannel plate 300.

[0071] The positioning ceramic ring 204 is arranged below the input electrode 203 and is hermetically welded together through ceramic metallization technology, which is used for insulation between the input electrode 203 and the output electrode 205, and is also used for positioning the microchannel plate 300 so that the microchannel plate 300 is installed at the center of the shell.

[0072] The output electrode 205 is arranged below the positioning ceramic ring 204 and is hermetically welded together through ceramic metallization technology, which is used for applying a high voltage to the output surface of the microchannel plate 300.

[0073] The output ceramic ring 206 is arranged below the output electrode 205 and is hermetically welded together through ceramic metallization technology, which is used for insulation between the output electrode 205 and the getter electrode 207.

[0074] The getter electrode 207 is arranged below the output ceramic ring 206 and is hermetically welded together through ceramic metallization technology, which is used for applying a current to the getter.

[0075] The getter ceramic ring 208 is arranged below the getter electrode 207 and is hermetically welded together through ceramic metallization technology, which is used for insulation between the getter electrode 207 and the spacer ring 209.

[0076] The isolation ring 209 is arranged below the getter ceramic ring 208 and is hermetically welded together by ceramic metallization technology for laser hermetic welding with the anode housing 404 of the composite dielectric anode 400.

[0077] Preferably, in combination Figure 4 , the composite dielectric anode 400 includes an anode housing 404, a composite dielectric, and an anode core 401.

[0078] The output port of the composite dielectric anode 400 is set to an SMA interface structure and can be connected in a matching manner with a standard SMA interface.

[0079] The anode housing 404 is connected to the composite dielectric and forms a coaxial structure with the anode core 401, serving as the anode signal ground wire and at the same time used to shield the external electromagnetic radiation from interfering with the anode signal.

[0080] The composite dielectric is filled between the anode housing 404 and the anode core 401 and serves as the medium for transmitting signals between the anode core and the anode housing.

[0081] The anode core 401 is connected to the composite dielectric and forms a coaxial structure with the anode housing 404, used to receive the electron cloud signal output by the microchannel plate, convert the electron cloud signal into a fast pulse signal, and output the pulse signal to the outside of the photomultiplier tube.

[0082] In the embodiment of the present invention, the composite dielectric includes more than two transmission media with different dielectric constants to form a composite dielectric. By adjusting the ratio between the medium thicknesses of more than two different transmission media, the dielectric constant of the composite dielectric can be continuously adjusted.

[0083] Moreover, the impedance values achieved by the more than two transmission media with different dielectric constants used in the composite dielectric can be set and adjusted to be the same as the impedance value of the electronics system connected to the rear end of the photomultiplier tube.

[0084] In the embodiment of the present invention, the composite dielectric is described by taking ceramic material and vacuum as two examples.

[0085] In this embodiment, the composite dielectric includes two transmission media, namely a ceramic material medium and a vacuum medium. Among them, the dielectric constant of the selected ceramic material medium is between 9 and 10, and the vacuum dielectric constant is 1. Preferably, the dielectric constant of the selected ceramic material medium is 9.4.

[0086] In this way, the tapered part of the anode housing 404 is hermetically welded and connected to the ceramic dielectric 402 of the composite dielectric through ceramic metallization technology, and the cylindrical part of the anode housing 404 is connected to the vacuum dielectric 403 of the composite dielectric.

[0087] The anode housing 404 and the anode core 401 form a coaxial structure, serving as the anode signal ground wire and at the same time used to shield the external electromagnetic radiation from interfering with the anode signal.

[0088] A composite medium is filled between the anode housing 404 and the anode core 401 and serves as the medium for transmitting signals between the anode core and the anode housing.

[0089] The tapered part of the anode core 401 is connected to the vacuum medium 403 of the composite medium, and the needle-like part of the anode core 401 is hermetically welded to the ceramic medium 402 of the composite medium through ceramic metallization technology.

[0090] The anode core 401 and the anode housing 404 form a coaxial structure for receiving the electron cloud signal output by the microchannel plate. At the same time, the electron cloud signal is converted into a fast pulse signal, and the pulse signal is output outside the photomultiplier tube.

[0091] Preferably, the inner side of the anode housing 404 is in a flared shape, and its output port has the same size and thread as the SMA standard interface for mating connection with the SMA standard interface.

[0092] As described above, by setting the ratio of the thickness of the ceramic material to the thickness of the vacuum, the dielectric constant of the composite medium can be continuously adjusted. For example, in combination with the actual structures of the anode housing 404 and the anode core 401, the impedance value of the composite medium anode 400 can be adjusted to achieve continuous impedance of the composite anode and matching with the impedance of the electronics connected to the backend.

[0093] The impedance value of the composite medium anode is preferably selected to be 50 ohms, and it can also be adjusted to the same impedance value as the electronics connected to the backend.

[0094] Preferably, the anode core 401 is set to be tapered, and the output end is set to be needle-like, with the same size as the pin of the SMA interface, and can be connected to the hole of the SMA interface in a matching manner.

[0095] Combined with the structural design of the composite medium anode 400 of the present invention, the anode housing 404, the ceramic medium, the vacuum medium, and the anode core 401 of the composite medium form a coaxial structure, and the impedance value of the coaxial structure is calculated according to the following formula (1):

[0096]

[0097] where: ε r is the dielectric constant between the coaxial structures, that is, the equivalent dielectric constant of the coaxial structure composite medium, D is the outer diameter of the coaxial structure, that is, the inner diameter of the anode housing, and d is the inner diameter of the coaxial structure, that is, the outer diameter of the anode core;

[0098] The equivalent dielectric constant of the coaxial structure composite medium is set to be calculated according to the following formula (2):

[0099]

[0100] where: εr is the equivalent dielectric constant of the coaxial structure composite medium, ε1 is the dielectric constant value of medium 1, d1 is the thickness of medium 1, ε2 is the dielectric constant value of medium 2, and d2 is the thickness of medium 2.

[0101] In an alternative embodiment of the present invention, as described above, medium 1 is selected as a ceramic material and medium 2 is selected as a vacuum medium.

[0102] It is obtained from formula (2) that by setting the thickness of the ceramic material and the thickness of the vacuum medium, the dielectric constant of the composite medium can be continuously adjusted between ε1 and ε2.

[0103] It is obtained from formula (1) that when the anode housing and anode core structures are fixed, the impedance value of the composite medium anode can be adjusted by adjusting the dielectric constant value, so that the impedance of the composite anode can be continuously adjusted within a certain range to match the impedance of the backend connected electronics.

[0104] In an embodiment of the present invention, the impedance value of the composite medium anode is preferably selected as 50 ohms, or it can also be adjusted to the same impedance value as the backend connected electronics.

[0105] Combined with Figure 5 According to the simulated impedance curve of the composite medium anode of the present invention shown in, the simulation results show that the anode is basically around 50Ω from the end face to the output face, realizing a matching connection with the 50-ohm electronics at the backend.

[0106] The anode housing 404, ceramic medium 402, vacuum medium 403, and anode core 401 of the composite medium anode 400 form a coaxial structure. The impedance of the coaxial structure can be calculated according to formula (1):

[0107] After the photomultiplier model is determined, the outer diameter of the anode and the diameter of the anode plate are fixed. It is obtained from formula (2) that by adjusting the thickness of the ceramic medium 402 and the thickness of the vacuum medium 403, the equivalent dielectric constant of the medium can be changed, so that the anode impedance value can be adjusted to realize impedance matching with the backend electronics.

[0108] Combined with Figure 6 According to the graph showing the change of the composite medium anode impedance with the thickness of the vacuum medium shown in, under the condition that the structures of the anode housing 404 and the anode core 401 are fixed, by adjusting the thickness of the ceramic medium 402 and the thickness of the vacuum medium 403, the anode impedance can be continuously adjusted between 34Ω and 88Ω. In an embodiment of the present invention, the impedance of the electronics system connected to the backend of the photomultiplier is generally 50Ω or 75Ω. Therefore, by adjusting the thickness of the ceramic medium 402 and the thickness of the vacuum medium 403, the impedance matching between the anode and the backend electronics can be realized.

[0109] Combined with Figure 7The pulse signal curve of the single-anode microchannel plate photomultiplier tube in the prior art shown below has reflection signals during the connection process between the signal output from the anode and the electronics due to the mismatch between the impedance of the common anode and the impedance of the backend electronics, resulting in a decrease in the rise time performance. As can be seen from Figure 7 , the rise time of the pulse signal is approximately 1 ns, and there are significant reflection signals at the trailing edge of the pulse.

[0110] Combined with Figure 8 the pulse signal curve of the composite dielectric anode microchannel plate photomultiplier tube of the present invention shown below, by adjusting the thickness of the ceramic dielectric 402 and the thickness of the vacuum dielectric 403, the equivalent dielectric constant of the dielectric can be changed, thereby the anode impedance value can be adjusted to achieve impedance matching with the backend electronics, reduce reflection signals, and improve the rise time performance. As can be seen from Figure 8 , the rise time of the pulse signal is approximately 0.3 ns, and the trailing edge of the pulse is smooth without obvious reflection signals. Compared with the pulse signal of the common anode microchannel plate photomultiplier tube in Figure 7 , the quality of the pulse signal of the composite dielectric anode microchannel plate photomultiplier tube proposed by the present invention has been significantly improved.

[0111] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the scope defined in the claims.

[0112] In the Figures 1-8 appendix, the meanings of the respective reference numerals are as follows:

[0113]

[0114]

Claims

1. A composite dielectric anode microchannel plate type photomultiplier tube, characterized in that, It includes a photocathode, a tube shell, a microchannel plate and a composite dielectric anode; The photocathode is arranged at the front end of the tube shell and is vacuum-sealed and welded to the tube shell. The photocathode faces the input surface of the microchannel plate and is used to receive photon signals and convert photons into photoelectrons; The tube shell is used to install and fix the microchannel plate and is vacuum-sealed and welded to the anode and the cathode, and is used to maintain the vacuum environment for the electron movement inside the photomultiplier tube; The microchannel plate is arranged inside the tube shell and is used to rapidly multiply photoelectrons; The composite dielectric anode is arranged at the end of the tube shell and is vacuum-sealed and welded to the tube shell. The anode faces the output surface of the microchannel plate and is used to receive the electron cloud signal output by the microchannel plate and convert the electron cloud signal into an electrical pulse signal, which is output outside the photomultiplier tube; Among them, the composite dielectric anode includes an anode housing, a composite dielectric and an anode core. The composite dielectric is filled between the anode housing and the anode core and is used as a medium for transmitting signals between the anode core and the anode housing; the composite dielectric includes more than two transmission media with different dielectric constants.

2. The composite medium anode microchannel plate type photomultiplier tube according to claim 1, characterized in that, The photocathode includes a light window, a sealing film layer and a photoelectric conversion film layer, where: The light window serves as a coating substrate for the sealing film layer and the photoelectric conversion film layer and transmits photons to the photoelectric conversion film layer; The sealing film layer is evaporated on the outer edge of the light window and is used for indium sealing the photocathode and the tube shell, and is also used for conducting electricity to the photoelectric conversion film layer; The photoelectric conversion film layer is evaporated at the center position of the light window and is used to absorb photons and convert photons into photoelectrons.

3. The composite medium anode microchannel plate type photomultiplier tube according to claim 2, characterized in that, The light window material uses borosilicate glass, high borosilicate glass, magnesium fluoride crystal glass material.

4. The composite medium anode microchannel plate type photomultiplier tube according to claim 1, characterized in that, The tube shell includes an indium sealing groove, an input ceramic ring, an input electrode, a positioning ceramic ring, an output electrode, an output ceramic ring, a getter electrode, a getter ceramic ring and an isolation ring, where: The indium sealing groove is used for indium melting and is indium-sealed with the sealing film layer of the photocathode to achieve vacuum-sealed connection between the photocathode and the tube shell; The input ceramic ring is arranged under the indium sealing groove and is used for insulation between the indium sealing groove and the input electrode; The input electrode is arranged under the input ceramic ring and is used to apply a high voltage to the input surface of the microchannel plate; The positioning ceramic ring is arranged under the input electrode and is used for insulation between the input electrode and the output electrode, and is also used for positioning the microchannel plate so that the microchannel plate is installed at the center position of the tube shell; The output electrode is arranged under the positioning ceramic ring and is used to apply a high voltage to the output surface of the microchannel plate; The output ceramic ring is arranged under the output electrode and is used for insulation between the output electrode and the getter electrode; The getter electrode is arranged under the output ceramic ring and is used to apply a current to the getter; The getter ceramic ring is arranged under the getter electrode and is used for insulation between the getter electrode and the isolation ring; The isolation ring is arranged under the getter ceramic ring and is used for sealing and welding with the composite dielectric anode housing.

5. The composite medium anode microchannel plate type photomultiplier tube according to claim 1, characterized in that, The anode housing is connected to the composite dielectric and forms a coaxial structure with the anode core, serves as an anode signal ground wire, and is also used to shield external electromagnetic radiation from interfering with the anode signal; The anode core is connected to the composite medium and forms a coaxial structure with the anode housing. It is used to receive the electron cloud signal output by the microchannel plate, convert the electron cloud signal into a fast pulse signal, and output the pulse signal to the outside of the photomultiplier tube.

6. The composite medium anode microchannel plate type photomultiplier tube according to claim 5, characterized in that, The inner side of the anode housing is in a flared shape, and its output port has the same size and thread as the SMA standard interface for mating connection with the SMA standard interface.

7. The composite medium anode microchannel plate type photomultiplier tube according to claim 1, wherein The composite medium uses two or more transmission media with different dielectric constants. By adjusting the ratio between the medium thicknesses of the two or more different transmission media, the dielectric constant of the composite medium can be continuously adjusted.

8. The composite medium anode microchannel plate type photomultiplier tube according to claim 7, characterized in that, The impedance values achieved by the two or more transmission media with different dielectric constants used in the composite medium are the same as the impedance value of the electronics system connected to the rear end of the photomultiplier tube.

9. The composite medium anode microchannel plate type photomultiplier tube according to claim 7 or 8, characterized in that, The composite medium includes two transmission media, namely a ceramic material medium and a vacuum medium.

10. The composite medium anode microchannel plate type photomultiplier tube according to claim 9, characterized in that, By setting the thickness ratio of the ceramic material and the vacuum medium, the dielectric constant of the composite medium can be continuously adjusted.

11. The composite medium anode microchannel plate type photomultiplier tube according to claim 1, characterized in that, The anode core is set in a conical shape, and its output end is in a needle shape, with the same size as the pin of the SMA standard interface for mating connection with the SMA standard interface.

12. A composite dielectric anode for a microchannel plate type photomultiplier tube, characterized in that, The composite medium anode includes an anode housing, a composite medium, and an anode core; The anode housing is connected to the composite medium and forms a coaxial structure with the anode core, serving as the anode signal ground wire and also used to shield external electromagnetic radiation from interfering with the anode signal; The composite medium is filled between the anode housing and the anode core and serves as the medium for transmitting signals between the anode core and the anode housing; The anode core is connected to the composite medium and forms a coaxial structure with the anode housing. It is used to receive the electron cloud signal output by the microchannel plate, convert the electron cloud signal into a fast pulse signal, and output the pulse signal to the outside of the photomultiplier tube; Among them, the composite medium includes two or more transmission media with different dielectric constants to form a composite medium; by adjusting the ratio between the medium thicknesses of the two or more different transmission media, the dielectric constant of the composite medium can be continuously adjusted.

13. The composite dielectric anode for a microchannel plate type photomultiplier tube according to claim 12, wherein The impedance values achieved by the two or more transmission media with different dielectric constants used in the composite medium can be set and adjusted to be the same as the impedance value of the electronics system connected to the rear end of the photomultiplier tube.

14. The composite dielectric anode for a microchannel plate type photomultiplier tube according to claim 12, characterized in that, The composite medium includes two transmission media, namely a ceramic material medium and a vacuum medium. Among them, the dielectric constant of the selected ceramic material medium is between 9 and 10, and the vacuum dielectric constant is 1.

15. The composite dielectric anode for a microchannel plate type photomultiplier tube according to claim 14, characterized in that, The conical part of the anode housing is hermetically welded to the ceramic medium of the composite medium through ceramic metallization technology, and the cylindrical part of the anode housing is connected to the vacuum medium of the composite medium; The conical part of the anode core is connected to the vacuum medium of the composite medium, and the needle-shaped part of the anode core is hermetically welded to the ceramic medium of the composite medium through ceramic metallization technology; The anode housing, ceramic medium, vacuum medium, and anode core form a coaxial structure. The impedance value of the coaxial structure is calculated according to the following formula (1): Where: ε r is the dielectric constant between coaxial structures, i.e., the equivalent dielectric constant of the coaxial structure composite medium, D is the outer diameter of the coaxial structure, i.e., the inner diameter of the anode housing, and d is the inner diameter of the coaxial structure, i.e., the outer diameter of the anode core; The equivalent dielectric constant of the composite medium is set to be calculated according to the following formula (2): Where: ε1 is the dielectric constant value of the ceramic material medium, d1 is the thickness of the ceramic material medium, ε2 is the dielectric constant value of the vacuum medium, and d2 is the thickness of the vacuum medium.

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