A photomultiplier tube and a detector

Abstract

The application provides a photomultiplier tube and a detector. The photomultiplier tube comprises: a photocathode configured to receive photons and emit photoelectrons based on the received photons; a photomultiplication system located downstream of the photocathode and arranged around a target axis, the target axis coinciding with or being parallel to a central axis of the photomultiplier tube, the photomultiplication system configured to receive the photoelectrons emitted by the photocathode and multiply the photoelectrons; and an anode configured to collect the photoelectrons multiplied by the photomultiplication system and output an anode current based on the collected photoelectrons. According to the embodiments of the application, the carrying capacity of each stage of the multiplication electrode is increased, thereby improving the pulse width response range of the photomultiplier tube and the linear current of the photomultiplier tube.

Description

Technical Field

[0001] This application relates to the field of photoelectric detection, and more specifically, to a photomultiplier tube and detector. Background Technology

[0002] A photomultiplier tube (PMT) is a vacuum electronic device that converts weak light signals into electrical signals. It is typically combined with a scintillator to form a radiation detection device. Currently, PMTs are widely used in optical analysis instruments, medical equipment, environmental monitoring, industrial inspection, and high-energy physics.

[0003] Pulse linearity, also known as photoelectric characteristic, is a crucial indicator of a photomultiplier tube (PMT). Generally, the linearity between the PMT's output current and the incident luminous flux is called the photoelectric characteristic. When a PMT receives weak light, it maintains relatively good linearity. However, when the incident light is strong, linear deviation occurs. The maximum current that a PMT can output within the allowable linear deviation error is usually called the linear current. Most existing PMTs have a narrow dynamic response range, with their linear current limited to below 100mA. A very small number of PMTs can achieve a linear current of 200mA, but this is limited to narrow pulse width signals below 50ns. For wider pulse width signals, such as 500ns, saturation occurs, and the PMT's output current no longer changes with the input. Summary of the Invention

[0004] This application aims to propose a photomultiplier tube and detector to solve the problems of narrow response range and small linear current of current photomultiplier tubes.

[0005] According to one aspect of this application, a photomultiplier tube is proposed, comprising a photocathode for receiving photons and emitting photoelectrons based on the received photons; a photomultiplier system located downstream of the photocathode and arranged around a target axis, the target axis being coincident with or parallel to the central axis of the photomultiplier tube, the photomultiplier system receiving photoelectrons emitted by the photocathode and multiplying the photoelectrons; and an anode for collecting photoelectrons multiplied by the photomultiplier system and outputting an anode current based on the collected photoelectrons.

[0006] According to some embodiments, the photomultiplier system includes multiple levels of annular dynodes, each level of which is arranged around the target axis.

[0007] According to some embodiments, the multi-stage annular dynode comprises one or more of the following materials: copper alloy, stainless steel, nickel alloy, and preferably copper beryllium.

[0008] According to some embodiments, the multi-level annular dynode includes an inner ring dynode and an outer ring dynode, the outer surface of the inner ring dynode serves as a secondary electron emission surface, the inner surface of the outer ring dynode serves as a secondary electron emission surface, and the inner ring dynode and the outer ring dynode are alternately arranged.

[0009] According to some embodiments, the multi-level annular dynode includes an inner ring dynode and an outer ring dynode. The inner ring dynode includes a conical structure and / or a columnar structure, with the conical surface of the conical structure serving as a secondary electron emission surface and the outer cylindrical surface of the columnar structure serving as a secondary electron emission surface. The outer ring dynode includes a circular annular structure and / or a polygonal annular structure, with the inner surfaces of the circular annular structure and the polygonal annular structure serving as secondary electron emission surfaces.

[0010] According to some embodiments, the inner ring dynode includes a first dynode, which is a conical structure. The conical surface of the first dynode serves as a secondary electron emission surface for receiving photoelectrons from the photocathode. The apex of the conical structure faces the photocathode, and the bottom surface of the conical structure faces the anode.

[0011] According to some embodiments, the photomultiplier system further includes a first dynode bracket, on which a first opening is provided for photoelectrons to pass through, and the first dynode bracket is used to fix and support the first dynode.

[0012] According to some embodiments, a first protrusion is provided in the middle portion of the first dynode bracket and in the direction close to the photocathode, and the first opening is provided in the first protrusion.

[0013] According to some embodiments, the height of the first boss is 2-5mm.

[0014] According to some embodiments, a plurality of first legs are provided on the inner side of the first boss, one end of the plurality of first legs is fixedly connected to the first multiplier bracket, and the other end is fixedly connected to the first multiplier.

[0015] According to some embodiments, the outer ring dynode includes one or more second dynodes, the second dynodes including a circular ring structure and / or a polygonal ring structure, the inner surface of the circular ring structure and the polygonal ring structure serving as a secondary electron emission surface for receiving photoelectrons directly or indirectly from the inner ring dynode.

[0016] According to some embodiments, the photomultiplier system further includes one or more second dynode supports, on which a second opening is provided for photoelectrons to pass through, and the second dynode support is used to fix and support the second dynode.

[0017] According to some embodiments, one or more second protrusions are provided in the middle portion of the second dynode bracket and in the direction close to the photocathode, and the second opening is provided in the middle of the second protrusion, and the top of the second dynode is attached to the second protrusion.

[0018] According to some embodiments, the inner ring dynode includes one or more third dynodes, the third dynode being a columnar structure with a flared opening, the outer surface of the columnar structure and the flared opening serving as a secondary electron emitting surface for receiving photoelectrons directly or indirectly from the outer ring dynode, the flared opening facing the photocathode.

[0019] According to some embodiments, the photomultiplier system further includes one or more third dynode supports, on which a third opening is provided for photoelectrons to pass through, and the third dynode support is used to fix and support the third dynode.

[0020] According to some embodiments, a third boss is provided in the middle portion of the third pyrolysis bracket and in the direction close to the anode, and the third opening is provided in the middle of the third boss.

[0021] According to some embodiments, a plurality of second legs are provided on the inner side of the third protrusion. One end of the second leg is fixedly connected to the third dynode bracket, and the other end is fixedly connected to the third dynode. According to some embodiments, the inner ring dynode includes a fourth dynode. The fourth dynode has a columnar structure and a flared opening. The outer side of the columnar structure and the flared opening serves as a secondary electron emission surface for receiving photoelectrons from the outer ring dynode. The flared opening faces the photocathode.

[0022] According to some embodiments, the photomultiplier system further includes a fourth pyrolyte support, which has a columnar structure, and the bottom surface of the fourth pyrolyte is fixedly connected to the fourth pyrolyte support.

[0023] According to some embodiments, the outer ring dynode includes a fifth dynode, which is a circular or polygonal ring structure. The inner surface of the circular or polygonal ring structure serves as a secondary electron emission surface for receiving photoelectrons from the inner ring dynode.

[0024] According to some embodiments, the photomultiplier system further includes a fifth pyrolyte bracket, which has a circular or polygonal ring shape and is arranged around the fifth pyrolyte and fixedly connected to the fifth pyrolyte.

[0025] According to embodiments of this application, by increasing the electron carrying capacity of each dynode, the pulse width response range and linear current of the photomultiplier tube are improved.

[0026] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The above and other objectives, features, and advantages of this application will become more apparent by referring to the accompanying drawings and describing exemplary embodiments in detail.

[0028] Figure 1 This diagram illustrates a photomultiplier tube structure according to an example embodiment of this application.

[0029] Figure 2a A schematic diagram of the structure of a first dynode unit provided according to an example embodiment of this application is shown.

[0030] Figure 2b A schematic diagram showing the structural breakdown of a first dynode unit according to an embodiment of this application is provided.

[0031] Figure 3a A schematic diagram of a second pyrolysis unit provided according to an example embodiment of this application is shown.

[0032] Figure 3b A schematic diagram showing the structural breakdown of a second pyrolysis unit according to an embodiment of this application is shown.

[0033] Figure 4a A schematic diagram of a third pyrolysis unit provided according to an example embodiment of this application is shown.

[0034] Figure 4b A schematic diagram showing the structural breakdown of a third pyrolysis unit according to an embodiment of this application is shown.

[0035] Figure 5a A schematic diagram of a fourth pyrolysis unit provided according to an example embodiment of this application is shown.

[0036] Figure 5b A schematic diagram showing the structural breakdown of a fourth pyrolysis unit according to an embodiment of this application is shown.

[0037] Figure 6a A schematic diagram of a fifth pyrolysis unit provided according to an example embodiment of this application is shown.

[0038] Figure 6bA schematic diagram showing the structural breakdown of a fifth pyrolysis unit according to an embodiment of this application is shown.

[0039] Figure 7a A schematic diagram of a photomultiplier tube according to an example embodiment of this application is shown.

[0040] Figure 7b A schematic diagram of electron trajectories in a photomultiplier tube according to an example embodiment of this application is shown.

[0041] Figure 8 A schematic diagram of the disassembled structure of a photomultiplier tube according to an example embodiment of this application is shown.

[0042] Figure 9 A schematic diagram of linear current comparison provided according to an example embodiment of this application is shown. Detailed Implementation

[0043] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that this application will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same drawings in the figures show the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0044] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, apparatus, or operations may be employed. In these cases, well-known structures, methods, apparatuses, implementations, materials, or operations will not be shown or described in detail.

[0045] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0046] The terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0047] Existing photomultiplier tubes (PMTs) have relatively low linear currents, generally below 100 mA, with very few reaching 200 mA, and even then, only with narrow pulse widths of less than 50 ns. The pulse width determines the size of the incident photon cluster; the wider the pulse, the larger the cluster, the more photons the photocathode receives, and the more photoelectrons are emitted. This makes PMTs more prone to linear deviation and even saturation, where the PMT's output current no longer changes with the input. Existing PMTs saturate at pulse widths of 500 ns and above, making it impossible to detect the true values ​​of light and X-ray radiation.

[0048] The inventors discovered that the main reason for this phenomenon is that after photoelectrons emitted from the photocathode are multiplied by the first few stages of the dynode system, the number of electrons surges. This results in an excessive number of electrons reaching the nth stage dynode, causing an electron cloud to form above it. This electron cloud hinders subsequent incident electrons from reaching the dynode surface, impeding electron multiplication. Consequently, the output current of the photomultiplier tube experiences a plateau; that is, the output current does not increase linearly with the increase of incident light, exhibiting a linear deviation. This phenomenon is particularly pronounced when the signal pulse width increases.

[0049] According to embodiments of this application, by designing the photomultiplier system to surround the target axis, wherein the target axis coincides with or is parallel to the central axis of the photomultiplier tube, the photomultiplier system is arranged to surround and distribute itself in the radial direction of the photomultiplier tube. Facing the photoelectrons emitted from the upstream photocathode, the distributed structure can achieve electron distribution, reducing the number of electrons accumulating and the probability of electron clouds forming by distributing electrons to different regions. This improves the linear current of the photomultiplier tube and also increases its pulse width response range. The linear current of the photomultiplier tube in this embodiment can be increased to 200mA to 1000mA, or even above 1000mA, while simultaneously responding to pulse width signals in the range of 500ns to 10 microseconds.

[0050] The specific embodiments according to this application will now be described in detail with reference to the accompanying drawings.

[0051] Figure 1 This diagram illustrates a photomultiplier tube structure according to an example embodiment of this application. Figure 1 The photomultiplier tube shown includes a photocathode 101, a photomultiplier system 103, and an anode 105. The photocathode 101 receives photons and emits photoelectrons based on the received photons. The photomultiplier system 103 is located downstream of the photocathode 101 and is arranged around a target axis, which coincides with or is parallel to the central axis of the photomultiplier tube. The photomultiplier system 103 receives and multiplies the photoelectrons emitted by the photocathode 101. The anode 105 collects the photoelectrons multiplied by the photomultiplier system 103 and outputs an anode current based on the collected photoelectrons.

[0052] The photomultiplier tube in the embodiments of this application reduces the number of electrons accumulating and the probability of electron cloud formation by designing the photomultiplier system to be arranged around the target axis, thereby improving the linear current of the photomultiplier tube and increasing the pulse width response range of the photomultiplier tube.

[0053] According to some embodiments, the photomultiplier system 103 is arranged around the target axis, wherein the target axis coincides with the central axis of the photomultiplier tube.

[0054] At this time, the photomultiplier system 103 can be aligned with the photocathode 101 (the photocathode 101 and the photomultiplier tube are coaxially arranged), so that the photoelectrons emitted from the photocathode 101 can enter the photomultiplier system 103 through a relatively short path to achieve distribution and multiplication. In addition to improving the linear current and pulse width response range of the photomultiplier tube, it also has the effect of improving the response speed.

[0055] It should be noted that in actual operation, due to factors such as processing technology, deviations may occur, causing the target axis to be parallel to the central axis of the photomultiplier tube, but not coincident, but rather near the central axis. However, since the photomultiplier system 103 is set around the target axis in this case, even if the target axis and the central axis deviate slightly, the photomultiplier system 103 is still basically aligned with the photocathode 101. This still improves the linear current and pulse width response range of the photomultiplier tube, thereby increasing the response speed. When the target axis is parallel to the central axis of the photomultiplier tube, but not near the central axis, the photomultiplier system 103 is set off-center. In this case, although the photomultiplier system 103 is not aligned with the photocathode 101, photoelectrons emitted from the photocathode 101 can still enter the photomultiplier system 103 to achieve electron distribution and multiplication, thus improving the linear current and pulse width response range of the photomultiplier tube, but the response speed decreases.

[0056] According to some embodiments of this application, the photomultiplier system 103 includes multiple levels of annular dynodes, each level of which is arranged around the target axis.

[0057] Typically, photomultiplier tubes (PMTs) are cylindrical, while their dynodes are tile-shaped, resulting in a relatively small multiplication surface and poor space utilization. This also leads to electron aggregation and the formation of electron clouds. This embodiment breaks with tradition by employing a multi-stage annular dynode design, with each stage surrounding the target axis. This annular layout not only achieves electron distribution but also better adapts to the shape of the PMT, improving space utilization. Consequently, when photoelectrons reach each stage of the dynode, they are distributed through the annular structure, preventing electron aggregation and thus improving linear current and pulse width response range.

[0058] Of course, the purpose of setting the photomultiplier system around the target axis can also be achieved in other ways in the embodiments of this application, such as setting multiple multiplier systems around the target axis.

[0059] According to some embodiments of this application, the multi-stage annular dynode comprises one or more of the following materials: copper alloy, stainless steel, and nickel alloy. However, it is not limited to these, and other suitable materials may also be used.

[0060] Preferably, the material of the multi-stage annular dynode comprises copper beryllium. Specifically, the copper beryllium can be copper beryllium that has undergone special processing, including but not limited to activation processes for copper beryllium alloys, magnetron sputtering processes, and chemical vapor deposition processes. By performing special processing on the copper beryllium material during the manufacturing process, the dynode can achieve a stable emission coefficient on the secondary electron emission surface while maintaining good conductivity, and can also withstand the scouring of high-current electrons.

[0061] According to some embodiments of this application, the multi-level ring dynode includes an inner ring dynode and an outer ring dynode. The outer surface of the inner ring dynode serves as a secondary electron emission surface, and the inner surface of the outer ring dynode serves as a secondary electron emission surface; the inner and outer ring dynodes are alternately arranged.

[0062] At this point, the inner and outer ring dynodes combine to form an inner-outer hybrid structure, enabling photoelectrons to multiply sequentially, such as... Figure 7b As shown, electrons can be distributed through the annular dynode at each stage, avoiding electron accumulation, thereby improving the linear current and pulse width response range.

[0063] Preferably, an electric field shielding structure can be provided at the adjacent positions of adjacent inner and outer stages to prevent photoelectrons from leaking out of the photomultiplier system 103, thereby further improving the linear current of the photomultiplier tube. The electric field shielding structure can be achieved through a concave-convex mating structure between two adjacent dynode supports and between adjacent dynodes and dynode supports, which will be described in detail later.

[0064] In some embodiments, the inner ring multiplier includes a conical structure and / or a columnar structure, wherein the conical surface of the conical structure serves as a secondary electron emission surface, and the outer cylindrical surface of the columnar structure serves as a secondary electron emission surface.

[0065] It should be noted that conical structures can include conical, pyramidal, or truncated conical structures, and the generatrix of a conical structure can be a straight line or a curve. Columnar structures can include regular columnar structures, such as cylinders or polygonal prisms, as well as columnar structures that approximate columns, whose top and / or bottom surfaces can be convex or concave, for example, columnar structures with a flared opening. Furthermore, the bottom of a columnar structure can be closed.

[0066] In some embodiments, the outer ring multiplier includes a circular ring structure and / or a polygonal ring structure, and the inner surface of the circular ring structure and the polygonal ring structure serves as a secondary electron emission surface.

[0067] Among them, polygonal ring structure refers to a ring structure formed by polygons, such as ring structures formed by triangles, trapezoids, hexagons, etc.

[0068] At this point, photoelectrons emitted from the inner ring dynode can be successfully received and multiplied by the adjacent circular or polygonal outer ring dynode before being emitted. Photoelectrons emitted from the outer ring dynode can be received and multiplied by the adjacent conical or cylindrical inner ring dynode before being emitted again. This cycle repeats, achieving a good combination of inner and outer rings. Moreover, electrons can be distributed through the ring dynodes at each stage, avoiding electron aggregation, thereby improving the linear current and pulse width response range.

[0069] Of course, other ring structures can be used for the inner and outer ring multipliers, as long as they can achieve good internal and external matching and electron distribution effect.

[0070] As not mentioned above, those skilled in the art should understand that the outer ring dynode should partially or completely surround the adjacent inner ring dynode so that the outer ring dynode can receive photoelectrons emitted from the inner ring dynode, multiply them, and then inject them into the next-stage inner ring dynode, thereby realizing the step-by-step transmission of photoelectrons between the inner and outer ring dynodes.

[0071] The specific structure of the photomultiplier electrode of this application will be described in detail below with reference to the accompanying drawings.

[0072] Figure 2a This diagram illustrates the structure of a first pyrolysis unit according to an example embodiment of this application. Figure 2b A schematic diagram showing the structural breakdown of a first pyrolysis unit according to an embodiment of this application is shown. Figure 2a and 2b The first dynode unit shown includes a first dynode 201 and a first dynode support 203.

[0073] According to some embodiments of this application, the first dynode 201 is an inner-ring dynode and has a conical structure. The conical surface of the conical structure serves as a secondary electron emission surface, used to receive photoelectrons from the photocathode. The apex of the conical structure faces the photocathode, and the bottom surface faces the anode.

[0074] At this time, the first dynode 201 of the conical structure is arranged around the target axis, such as the central axis of the photomultiplier tube, so that the first dynode 201 of the conical structure is arranged around the downstream of the photocathode, so that the photoelectrons emitted from the photocathode can be effectively distributed to all parts of the first dynode 201, achieving a good electron reception and distribution effect.

[0075] Among them, such as Figure 2a and Figure 2b As shown, the first multiplier 201 can be conical or quasi-conical (such as pyramidal). In a specific embodiment, the top and / or sides of the first multiplier 201 can have a curved arc.

[0076] According to some embodiments of this application, a first dynode support 203 has a first opening 207 for photoelectrons to pass through, and the first dynode support 203 is used to fix and support the first dynode 201. The first dynode 201 can be fixed downstream of the first opening 207, or the first dynode 201 can pass through the first opening 207. In this case, the first dynode 201 can achieve good fixation and support through the first dynode support 203, and can receive photoelectrons emitted from the photocathode through the first opening 207.

[0077] Preferably, the first opening 207 can be coaxially arranged with the target axis. In this case, the first dynode 201 is aligned with the first opening 207, which can better receive photoelectrons passing through the first opening 207. Of course, the first opening 207 can also be eccentrically arranged with respect to the target axis, so that the first dynode 201 is eccentrically arranged with respect to the first opening 207. In this case, the receiving effect will be reduced.

[0078] Furthermore, the first dynode 201 is partially or completely surrounded by an adjacent outer ring dynode (e.g., a second dynode) so that photoelectrons emitted by the first dynode 201 are received by the next-level outer ring dynode.

[0079] According to some embodiments of this application, the middle portion of the first dynode support 203 protrudes to one side, that is, to the side closer to the photocathode, forming a first boss 205. A first opening 207 is formed in the middle of the first boss 205. A welding pad can be provided on the outer surface 209 of the first boss 205 for welding the focusing disk of the photomultiplier tube. The focusing disk enables electron focusing, allowing as many photoelectrons emitted from the photocathode as possible to enter the multiplication system and achieve multiplication.

[0080] The outer diameter of the first protrusion 205 can be the same as the outer diameter of the focusing disk so that the focusing disk and the first dynode support 203 are concentric when assembling and welding the photomultiplier tube.

[0081] Of course, in some other embodiments of this application, a focusing disk may not be provided, but the electronic focusing effect will be relatively poor.

[0082] When the first dynode 201 is a conical structure, if photoelectrons hit the top of the conical structure, the photoelectrons may not be multiplied. In this embodiment, the height of the first protrusion 205 can be adjusted to change the position of the focusing disk from the first dynode 201, thereby affecting the electric field distribution near the first opening 207. This causes the focal point of the photoelectrons being focused by the nearby electric field when passing through the first opening 207 to shift downward, so that the photoelectrons can hit the conical surface of the secondary electron emission surface of the first dynode 201 evenly, rather than at the top, thereby increasing the effective emission efficiency of the secondary electron emission surface of the first dynode 201.

[0083] According to some embodiments of this application, the height of the first protrusion 205 can be 2-5mm. In this case, the focal point of photoelectrons being focused by the nearby electric field when passing through the first opening 207 can be shifted downward, so that the photoelectrons can uniformly strike the surface of the secondary electron emission surface of the first dynode 201, thereby increasing the effective emission efficiency of the secondary electron emission surface of the first dynode 201 and improving its secondary electron emission coefficient.

[0084] In some embodiments, the inner surface of the first boss 205 may be provided with a plurality of first legs 211 of the same size. In a specific embodiment, the plurality of first legs may be evenly distributed around the first opening 207. Figure 2a and Figure 2bAs shown, one end of each of the multiple first legs 211 is connected to the first dynode bracket 203, and the other end is connected to the first dynode 201. In this case, the first dynode 201 can be fixed downstream of the first opening 207 by the first legs 211, or the first dynode 201 can pass through the first opening 207 by the first legs 211. By connecting the first dynode 201 and the first dynode bracket 203 with relatively small first legs 211, the interference and influence of the connecting components on photoelectron emission can be minimized.

[0085] Of course, the first dynode 201 can also be connected to the first dynode support 203 in other ways, such as by setting a mesh structure to connect the first dynode 201 and the first dynode support 203, etc.

[0086] In some embodiments, a plurality of first legs 211 may be connected to the conical bottom surface of the first multiplier 201, for example, at the bottom edge of the first multiplier 201 or at other suitable locations.

[0087] In some embodiments, the first dynode support 203 can be annular to better fit the shape of the photomultiplier tube. Of course, the first dynode support 203 can also be configured in other shapes, such as square, as long as reasonable installation can be achieved.

[0088] Figure 3a This diagram illustrates a structural schematic of a second pyrolysis unit according to an example embodiment of this application. Figure 3b A schematic diagram showing the structural breakdown of a second pyrolysis unit according to an embodiment of this application is provided. For example... Figure 3a and 3b The second pyrolysis unit shown includes a second pyrolysis electrode 301 and a second pyrolysis electrode support 303.

[0089] According to some embodiments of this application, the second dynode 301 is an outer ring dynode, which includes a circular ring structure and / or a polygonal ring structure. The inner surfaces of the circular ring structure and the polygonal ring structure serve as secondary electron emission surfaces for receiving photoelectrons directly or indirectly from the inner ring dynode (e.g., the first dynode).

[0090] At this time, the second dynode 301, which has a circular or polygonal ring structure, is arranged around the target axis, such as the central axis of the photomultiplier tube. This allows the second dynode 301 to be arranged around the downstream of the photocathode, so that the photoelectrons emitted from the inner ring dynode (such as the first dynode) can be effectively distributed to all parts of the second dynode 301, achieving a good electron reception and distribution effect.

[0091] Furthermore, the second dynode 301 should partially or completely surround the adjacent inner ring dynode so that the second dynode 301 can receive photoelectrons output from the previous inner ring dynode and emit photoelectrons emitted after its own multiplication to the next inner ring dynode.

[0092] According to some embodiments, the second dynode support 303 has a second opening 305 for photoelectrons to pass through, and the second dynode support 303 is used to fix and support the second dynode 301. At this time, the second dynode 301 can achieve good fixation and support through the second dynode support 303, and can receive photoelectrons emitted from the previous dynode (such as the first dynode) through the second opening 305.

[0093] Preferably, the second opening 305 can be coaxially arranged with the target axis. In this case, the second dermis 301 is aligned with the second opening 305, which can better receive photoelectrons passing through the second opening 305. Of course, the second opening 305 can also be eccentrically arranged with the target axis, so that the second dermis 301 and the second opening 305 are eccentrically arranged, in which case the receiving effect will be reduced.

[0094] According to some embodiments of this application, one or more levels of second protrusions 307 are provided in the middle portion of the second dynode support 303 and in the direction close to the photocathode. If there are multiple levels of second protrusions 307, the size of the multiple levels of second protrusions 307 decreases progressively along the second dynode support 303 towards the photocathode. In a specific embodiment, a second opening 305 for photoelectrons to pass through is provided in the middle of the second protrusion 307, and the top of the second dynode 301 is in contact with the second protrusion 307.

[0095] At this time, the second pyromultiplier bracket 303 can form a concave-convex mating structure 720 with the previous pyromultiplier bracket (e.g., the first pyromultiplier bracket) through one or more stages of second protrusions 307, such as... Figure 7b As shown, the two do not come into contact, forming a good electric field shielding structure to prevent electrons from escaping from the gap.

[0096] For example, such as Figure 3a and 3b As shown, the middle portion of the second dynode support 303 protrudes to one side, that is, towards the photocathode, forming a three-tiered second protrusion 307. The size of each protrusion increases progressively from top to bottom, with the topmost protrusion being the smallest, the middle protrusions being of medium size, and the bottommost protrusion being the largest. A second opening 305 for photoelectrons to pass through is provided in the middle of the second dynode support 303, that is, in the middle of the second protrusion 307. A second dynode 301 is provided on the side of the second dynode support 303 where there is no protrusion. At this time, as... Figure 7bAs shown, the topmost protrusion of the second dynode bracket 303 is close to the inner side of the first protrusion of the first dynode bracket. The second dynode bracket 303 and the first dynode bracket fit together but do not contact each other, so as to form a good electric field shielding structure, thereby preventing electrons from leaking out of the gap and further improving the linear current of the photomultiplier tube.

[0097] In some embodiments, the second synergist bracket 303 can be annular to better fit the shape of the photomultiplier tube. Of course, the second synergist bracket 303 can also be configured in other shapes, such as square, as long as reasonable installation can be achieved.

[0098] In some embodiments, the top of the second dynode 301 may be located between the inner edge of the intermediate second protrusion 307 and the inner edge of the lowest second protrusion 307, or may coincide with the inner edge of the lowest second protrusion 307. The inner surface of the second dynode 301 is a secondary electron emission surface.

[0099] Figure 4a This diagram illustrates a structural schematic of a third pyrolysis unit according to an example embodiment of this application. Figure 4b A schematic diagram showing the structural breakdown of a third pyrolysis unit according to an embodiment of this application is shown. Figure 4a and 4b The third pyrolysis unit shown includes a third pyrolysis unit 401 and a third pyrolysis support 403.

[0100] According to some embodiments of this application, the third dynode 401 is an inner ring dynode. In a specific embodiment, the third dynode 401 is a columnar structure with a flared opening. The outer surfaces of the columnar structure and the flared opening serve as secondary electron emission surfaces for receiving photoelectrons from the outer ring dynode (e.g., the second dynode). The flared opening faces the photocathode.

[0101] At this time, the columnar structure and the flared mouth of the third dynode 401 are arranged around the target axis, such as the central axis of the photomultiplier tube, so that the third dynode 401 is arranged around the downstream of the photocathode, so that the photoelectrons emitted from the outer ring dynode (such as the second dynode) can be effectively distributed to all parts of the third dynode 401, achieving a good electron reception and distribution effect.

[0102] Furthermore, the third dynode 401 is partially or completely surrounded by its adjacent outer ring dynode (e.g., the second dynode), so that photoelectrons emitted by the third dynode 401 are received by the next-level outer ring dynode and receive photoelectrons emitted by the previous-level outer ring dynode.

[0103] According to some embodiments, a third dynode support 403 is used to fix and support the third dynode 401. A third opening 407 is provided on the third dynode support 403 for photoelectrons to pass through. In this case, the third dynode 401 can achieve good fixation and support through the third dynode support 403, and can receive photoelectrons emitted from the previous dynode (such as the second dynode) through the third opening 407.

[0104] Preferably, the third opening 407 can be coaxially arranged with the target axis. In this case, the third derrick 401 is aligned with the third opening 407, which can better receive photoelectrons passing through the third opening 407. Of course, the third opening 407 can also be eccentrically arranged with the target axis, so that the third derrick 401 and the third opening 407 are eccentrically arranged, in which case the receiving effect will be reduced.

[0105] According to some embodiments of this application, a third boss 405 is provided in the middle portion of the third dynode support 403 and in the direction close to the anode, and a third opening 407 for photoelectrons to pass through is provided in the middle of the third boss 405.

[0106] At this point, the third pyrolysis bracket 403, through the third protrusion 405, can form a concave-convex mating structure 720 with the previous pyrolysis stage, such as the second pyrolysis stage. Figure 7b As shown, the two do not come into contact, forming a good electric field shielding structure to prevent electrons from escaping from the gap.

[0107] For example, such as Figure 4a and Figure 4b As shown, the middle portion of the third dynode support 403 protrudes to one side, that is, towards the anode, forming a third boss 405. A third opening 407 is provided in the middle of the third boss 405. At this time, the bottom of the previous stage dynode is close to the inner side of the third boss 405 on the third dynode support 403 to form a blocking structure, thereby preventing photoelectrons from escaping. At the same time, the third boss 405 on the third dynode support 403 and the boss on the adjacent next stage dynode support form a concave-convex but non-contact structure, which shields the electric field and prevents photoelectrons from escaping.

[0108] Furthermore, a shielding portion 409 can be provided on the inner arc edge of the third protrusion 405. When the bottom of the previous stage multiplier electrode is close to the inner side of the third protrusion 405, the shielding portion 409 further prevents photoelectrons from overflowing.

[0109] In some embodiments, a plurality of second legs may be provided on the inner surface of the third boss 405. One end of each second leg is fixedly connected to the third dermis bracket 403, and the other end is fixedly connected to the third dermis 401. For example, a plurality of second legs of the same size extending away from the third dermis bracket 403 may be provided on the inner surface of the third boss 405, and the plurality of second legs may be evenly distributed around the third opening. One end of each second leg is connected to the third dermis bracket 403, and the other end is connected to the third dermis 401. In this case, the third dermis 401 can be fixed downstream of the third opening 407 by the second legs, or the third dermis 401 can pass through the third opening 407 by the second legs. In this case, by connecting the third dermis 401 and the third dermis bracket 403 with relatively small second legs, the interference and influence of the connecting components on photoelectron emission can be minimized.

[0110] Of course, the third pyrolysis electrode 401 can also be connected to the third pyrolysis electrode support 403 in other ways, such as by setting a mesh structure to connect the third pyrolysis electrode 401 and the third pyrolysis electrode support 403, etc.

[0111] In some embodiments, the third synergist bracket 403 can be annular to better fit the shape of the photomultiplier tube. Of course, the third synergist bracket 403 can also be configured in other shapes, such as square, as long as it can be installed reasonably.

[0112] The following is a specific example to illustrate this, such as Figure 4b As shown, the third dynode 401 includes a first bottom surface 4011, a first sidewall 4013, and a first flared opening 4015. The third dynode 401 extends through a third opening 407, with the first bottom surface 4011 and the first flared opening 4015 located on opposite sides of the third opening 407. The first bottom surface 4011 faces the anode, and the first flared opening 4015 faces the photocathode. Multiple second legs are connected to the edge of the first flared opening 4015, and the outer surfaces of the first sidewall 4013 and the first flared opening 4015 serve as secondary electron emission surfaces. Figures 7a-7b As shown, at this time, the third dynode 401 is arranged around the downstream of the photocathode, so that the photoelectrons emitted from the outer ring dynode (e.g., the second dynode) can be effectively distributed to all parts of the third dynode 401, achieving a good electron reception and distribution effect. Furthermore, the third dynode 401 and the upper and lower dynodes can form a concave-convex fitting structure 720, forming a good electric field shielding structure to prevent electrons from escaping from the gaps.

[0113] Figure 5a This diagram illustrates a structural schematic of a fourth pyrolysis unit according to an example embodiment of this application. Figure 5bA schematic diagram showing the structural breakdown of a fourth pyrolysis unit according to an embodiment of this application is provided. Figure 5a and 5b The fourth pyrolysis unit shown includes a fourth pyrolysis unit 501 and a fourth pyrolysis support 503.

[0114] According to some embodiments of this application, the fourth dynode 501 is an inner ring dynode, and the fourth dynode 501 has a columnar structure with a flared opening. The outer surfaces of the columnar structure and the flared opening serve as secondary electron emitting surfaces for receiving photoelectrons from its adjacent outer ring dynode. In a specific embodiment, the flared opening faces the photocathode.

[0115] According to some embodiments, the fourth pyrolysis bracket 503 has a columnar shape, and the bottom surface of the fourth pyrolysis 501 is fixedly connected to the fourth pyrolysis bracket 503.

[0116] For example, such as Figure 5a and 5b As shown, the fourth pyrolysis electrode 501 includes a second bottom surface 5011, a second side wall 5013, and a second horn opening 5015. The second bottom surface 5011 of the fourth pyrolysis electrode 501 is connected to the shielding plate of the fourth pyrolysis electrode unit through the fourth pyrolysis electrode bracket 503.

[0117] At this time, the fourth dynode 501 is arranged around the downstream of the photocathode, so that the photoelectrons emitted from the outer ring dynode (e.g., the second dynode) can be effectively distributed to all parts of the fourth dynode 501, achieving a good electron reception and distribution effect, and can be installed on the shielding plate to achieve the final electron collection.

[0118] Figure 6a This diagram illustrates a structural schematic of a fifth pyrolysis unit according to an example embodiment of this application. Figure 6b A schematic diagram showing the structural breakdown of a fifth pyrolysis unit according to an embodiment of this application is shown. Figure 6a and 6b The fifth pyrolysis unit shown includes a fifth pyrolysis electrode 601 and a fifth pyrolysis electrode support 603.

[0119] According to some embodiments of this application, the fifth dynode 601 is an outer ring dynode, and the fifth dynode 601 is a circular or polygonal ring structure. The inner surface of the circular or polygonal ring structure serves as a secondary electron emission surface for receiving photoelectrons from its adjacent inner ring dynode.

[0120] According to some embodiments, the fifth pyrolysis bracket 603 has an annular or polygonal annular shape and is disposed around the fifth pyrolysis electrode 601 and is fixedly connected to the fifth pyrolysis electrode 601.

[0121] For example, such as Figure 6a and 6b As shown, the fifth pyrolysis electrode 601 has a ring-shaped structure, and the fifth pyrolysis electrode bracket 603 is arranged around the fifth pyrolysis electrode 601. The fifth pyrolysis electrode 601 is connected to the shielding plate through the fifth pyrolysis electrode bracket 603.

[0122] At this point, the fifth dynode 601 is arranged around the downstream of the photocathode, so that the photoelectrons emitted from the inner ring dynode (e.g., the third dynode) can be effectively distributed to all parts of the fifth dynode 601, achieving good electron reception and distribution, and can be installed on the shielding plate to achieve final electron collection.

[0123] After a detailed description of the photomultiplier electrode of this application, a photomultiplier tube composed of the photomultiplier unit as described above will be described in detail below with reference to the accompanying drawings, according to an example embodiment of this application.

[0124] Figure 7a A schematic diagram of a photomultiplier tube according to an example embodiment of this application is shown, as follows: Figure 7a The photomultiplier tube shown includes an entrance window 701, a photocathode 101, an accelerating electrode 705, a focusing disk 707, a photomultiplier system 103, an anode 105, a shielding plate 709, and a core column 711 arranged sequentially along the axial direction of the tube shell 703.

[0125] like Figure 7a As shown, the photomultiplier tube includes multiple levels of annular dynodes, and the dynode support corresponding to each level of annular dynode is fixed by a column 713. Structures for connecting the column 713 can be provided on the dynode support (the aforementioned first dynode support, second dynode support, and third dynode support) and the shielding plate 709.

[0126] According to some embodiments, the column 713 can be made of insulating and tough materials, such as glass, ceramics, etc.

[0127] According to some embodiments, the interval between two adjacent dynode supports can be 4-6 mm, so that the multiple dynodes of the photomultiplier tube can be optimally matched, thereby ensuring that photoelectrons are effectively multiplied through each dynode and reducing overflow.

[0128] Figure 7b This illustration shows a schematic diagram of electron trajectories in a photomultiplier tube according to an example embodiment of this application, such as... Figure 7b The electron trajectory 719 shown is shown. The photocathode 101 is used to convert light entering through the incident window into photoelectrons. The photoelectrons are focused by the focusing disk 707 and converged into the photomultiplier system 103. After passing through the annular multiplier stages, the electrons are distributed and multiplied, and finally output through the anode 105.

[0129] Figure 8 This diagram illustrates a disassembled structure of a photomultiplier tube according to an example embodiment of this application. Figure 8 The photomultiplier tube shown includes eight dynodes, each coaxially arranged with the tube housing 703. The secondary electron emission surfaces of the dynodes form a ring shape, greatly increasing the area of ​​the secondary electron emission surface. Furthermore, the support structure of the next-stage dynode forms a concave-convex fit with the support structure of the previous-stage dynode, but without contact, such as... Figure 7b As shown, a good electric field shielding structure is formed, preventing electrons from escaping from the gaps.

[0130] According to an embodiment of this application, the photomultiplier system of the photomultiplier tube includes a multi-level annular dynode, which includes an inner ring dynode and an outer ring dynode, and the inner ring dynode and the outer ring dynode are alternately arranged.

[0131] Specifically, such as Figure 8 As shown, it includes a first-stage dynode unit 801, a second-stage dynode unit 802, a third-stage dynode unit 803, a fourth-stage dynode unit 804, a fifth-stage dynode unit 805, a sixth-stage dynode unit 806, a seventh-stage dynode unit 807, and an eighth-stage dynode unit 808.

[0132] In a specific embodiment, each stage of the dynode unit includes a photomultiplier and a photomultiplier support. Except for the first stage dynode unit 801, the seventh stage dynode unit 807 and the eighth stage dynode unit 808, the other intermediate stage dynode units cyclically repeat the photomultiplier structure in the second stage dynode unit 802 and the third stage dynode unit 803.

[0133] According to an embodiment of this application, the first-stage pyrolysis unit 801 includes a first pyrolysis electrode 201 and a first pyrolysis electrode support 203, the specific structure of which is as follows: Figure 2a and 2b As shown, to avoid repetition, it will not be repeated here.

[0134] According to other embodiments, the second-stage pyrolysis unit 802 includes a second pyrolysis electrode 301 and a second pyrolysis electrode support 303, as shown in the specific structure. Figure 3a and 3b As shown, to avoid repetition, it will not be repeated here.

[0135] According to other embodiments, the third-stage pyrolysis unit 803 includes a third pyrolysis electrode 401 and a third pyrolysis electrode support 403, as shown in the specific structure below. Figure 4a and 4b As shown, to avoid repetition, it will not be repeated here.

[0136] According to other embodiments, the fourth-stage dynode unit 804, the sixth-stage dynode unit 806, and the second-stage dynode unit 802 have the same structure, and the fifth-stage dynode unit 805 and the third-stage dynode unit 803 have the same structure.

[0137] According to other embodiments, the seventh-stage pyrolysis unit 807 includes a fourth pyrolysis unit 501 and a fourth pyrolysis support 503, as shown in the specific structure below. Figure 5a and Figure 5b As shown, it will not be elaborated further here.

[0138] According to other embodiments, the eighth-stage pyrolysis unit 808 includes a fifth pyrolysis electrode 601 and a fifth pyrolysis electrode support 603, as shown in the specific structure. Figure 6a and Figure 6b As shown, to avoid repetition, it will not be repeated here.

[0139] The photomultiplier tube provided in this application reduces the number of electrons accumulating and the probability of electron clouds appearing by designing the photomultiplier system to surround the target axis, thereby improving the linear current of the photomultiplier tube and increasing its pulse width response range. Furthermore, the lower-stage dynode support forms a concave-convex fitting structure with the upper-stage dynode support, creating a good electric field shielding structure and preventing electrons from escaping from the gaps.

[0140] Figure 9 This diagram illustrates a linear current comparison according to an example embodiment of this application, such as... Figure 9 As shown, under the conditions of a light source pulse width of 500ns and a light source frequency of 100Hz, the linear current of a conventional photomultiplier tube is below 100mA, while the linear current of the photomultiplier tube according to the example embodiment of this application can be increased to the ampere level, and at the same time the pulse width response range of the photomultiplier tube is improved, which can respond to pulse width signals in the range of 500ns to 3 microseconds.

[0141] The embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. Furthermore, any changes or modifications made by those skilled in the art based on the ideas of this application, and on the specific implementation methods and application scope of this application, are all within the scope of protection of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A photomultiplier tube, characterized by, The photomultiplier tube comprises: a photocathode for receiving photons and emitting photoelectrons based on the received photons; a photomultiplier system downstream of the photocathode and arranged around a target axis, the target axis coinciding with or being parallel to a central axis of the photomultiplier tube, the photomultiplier system receiving the photoelectrons emitted by the photocathode and multiplying the photoelectrons; and an anode for collecting the photoelectrons multiplied by the photomultiplier system and outputting an anode current based on the collected photoelectrons; wherein the photomultiplier system comprises a plurality of annular dynodes arranged around the target axis; the plurality of annular dynodes comprises inner annular dynodes and outer annular dynodes, an outer side of each of the inner annular dynodes serving as a secondary electron emission surface, and an inner side of each of the outer annular dynodes serving as a secondary electron emission surface, the inner annular dynodes and the outer annular dynodes being arranged alternately; the plurality of annular dynodes comprises one or more of the following materials: copper alloy, stainless steel, and / or nickel alloy.

2. The photomultiplier tube according to claim 1, wherein: the plurality of annular dynodes comprises copper beryllium. the plurality of annular dynodes comprises inner annular dynodes and outer annular dynodes; 3. The photomultiplier tube of claim 1, wherein, the inner annular dynodes comprise a conical structure and / or a columnar structure, a conical surface of the conical structure serving as a secondary electron emission surface, and an outer columnar surface of the columnar structure serving as a secondary electron emission surface; the outer annular dynodes comprise a circular ring structure and / or a polygonal ring structure, an inner side of each of the circular ring structure and the polygonal ring structure serving as a secondary electron emission surface. the inner annular dynodes comprise a first dynode, the first dynode being a conical structure, a conical surface of the conical structure serving as a secondary electron emission surface, the first dynode being arranged to receive photoelectrons from the photocathode, a vertex of the conical structure being directed towards the photocathode, and a base of the conical structure being directed towards the anode.

4. The photomultiplier tube of claim 1, wherein, the photomultiplier system further comprises a first dynode support, the first dynode support being arranged to support the first dynode, and the first dynode support being provided with a first opening for the photoelectrons to pass through.

5. The photomultiplier tube of claim 4, wherein, 6. The photomultiplier tube according to claim 5, wherein: a first boss is arranged on a middle portion of the first dynode support and directed towards the photocathode, and the first opening is arranged on the first boss.

7. The photomultiplier tube according to claim 6, wherein: a height of the first boss is 2-5 mm.

8. The photomultiplier tube according to claim 6, wherein: a plurality of first legs are arranged on an inner side of the first boss, one end of each of the first legs being fixedly connected to the first dynode support, and the other end of each of the first legs being fixedly connected to the first dynode. the outer annular dynodes comprise one or more second dynodes, each of the second dynodes comprising a circular ring structure and / or a polygonal ring structure, an inner side of each of the circular ring structure and the polygonal ring structure serving as a secondary electron emission surface, and each of the second dynodes being arranged to receive photoelectrons directly or indirectly from the inner annular dynodes.

9. The photomultiplier tube of claim 1, wherein, ​ 10. The photomultiplier tube of claim 9, wherein, The photoelectric multiplication system further comprises one or more second dynode supports, each of which has a second opening for the passage of photoelectrons, and is used to fix and support the second dynodes.

11. The photomultiplier tube according to claim 10, wherein, The second dynode support has one or more second bosses arranged in the middle part thereof and in the direction close to the photocathode, and the second opening is arranged in the middle of the second boss, and the top of the second dynode is attached to the second boss.

12. The photomultiplier tube of claim 1, wherein, The inner ring dynode comprises one or more third dynodes, each of which has a columnar structure and a flared mouth, the outer surface of the columnar structure and the flared mouth serving as a secondary electron emission surface for receiving photoelectrons directly or indirectly from the outer ring dynode, and the flared mouth is directed towards the photocathode.

13. The photomultiplier tube of claim 12, wherein, The photoelectric multiplication system further comprises one or more third dynode supports, each of which has a third opening for the passage of photoelectrons, and is used to fix and support the third dynodes.

14. The photomultiplier tube according to claim 13, wherein, The third dynode support has a third boss arranged in the middle part thereof and in the direction close to the anode, and the third opening is arranged in the middle of the third boss.

15. The photomultiplier tube according to claim 14, wherein, The third boss has a plurality of second legs arranged on the inner side thereof, one end of each of the second legs being fixedly connected to the third dynode support, and the other end being fixedly connected to the third dynode.

16. The photomultiplier tube of claim 1, wherein, The inner ring dynode comprises a fourth dynode, which has a columnar structure and a flared mouth, the outer surface of the columnar structure and the flared mouth serving as a secondary electron emission surface for receiving photoelectrons from the outer ring dynode, and the flared mouth is directed towards the photocathode.

17. The photomultiplier tube according to claim 16, wherein, The photoelectric multiplication system further comprises a fourth dynode support, which has a columnar structure, and the bottom surface of the fourth dynode is fixedly connected to the fourth dynode support.

18. The photomultiplier tube of claim 1, wherein, The outer ring dynode comprises a fifth dynode, which has a circular or polygonal ring structure, and the inner surface of the circular or polygonal ring structure serves as a secondary electron emission surface for receiving photoelectrons from the inner ring dynode.

19. The photomultiplier tube according to claim 18, wherein, The photoelectric multiplication system further comprises a fifth dynode support, which has a circular or polygonal ring structure and surrounds the fifth dynode, and is fixedly connected to the fifth dynode.

20. A probe, characterized in that The photoelectric multiplication system comprises the photomultiplier tube according to any one of claims 1 to 19.

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