Ultrahigh dose rate dose detection ionization chamber

Abstract

The invention relates to the technical field of radiation detection tools, and discloses an ultrahigh dose rate dose detection ionization chamber, which comprises a signal export part, a signal detection part and an electronic compensation part, in the signal transmission direction, the signal export part and the signal detection part are connected in sequence; and the electronic compensation part is sleeved outside the signal export part and the signal detection part. According to the invention, the problem of insufficient collection efficiency caused by too high ion recombination effect of the ionization chamber in absolute dose measurement of an ultrahigh dose rate X-ray radiation field can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of radiation detection tools, and in particular to an ultra-high dose rate dose detection ionization chamber. Background Art

[0002] Absolute measurement and value transfer of water absorbed dose in ultra-high dose rate radiation fields are the key to ensuring dose delivery in FLASH bioeffect studies and realizing FLASH clinical translation studies. In most reports, preclinical bioeffect studies use passive dosimeters such as thermoluminescence and alanine dosimeters and radiochromic films for dose measurement and monitoring. However, passive dosimeters are affected by readout time and cannot provide real-time doses. Even if the calibration readout protocol is strictly followed, the uncertainty is greater than 3%, which does not meet the clinical dose transfer requirements.

[0003] Ionization chambers are usually used as quality control equipment for traditional radiotherapy prescription doses and accelerator beam calibration. At the same time, ionization chambers are used as secondary standard dosimeters for water absorption dose in standard laboratories. However, the average dose rate of ultra-high dose rate radiation fields is greater than 40Gy / s, and the air ionization in free air ionization chambers produces an ionization electric field of about 1000V / mm, which cannot be ignored. The ionization electric field will offset part of the polarization electric field, causing the ionization chamber collection efficiency to be significantly reduced. Studies have shown that the sensitive volume electric field of ionization chambers in ultra-high dose rate radiation fields is severely distorted. When the pulse dose of a general commercial gas ionization chamber is greater than 0.1Gy / p, the ion collection efficiency drops sharply; when the pulse dose is greater than 1Gy / p, the collection efficiency is usually less than 50%.

[0004] In view of this, this application is hereby filed. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of insufficient collection efficiency caused by excessively high ion recombination effect in an ionization chamber in absolute dose measurement of an ultra-high dose rate X-ray radiation field.

[0006] The present invention is achieved through the following technical solutions: Provided is an ultra-high dose rate dose detection ionization chamber, comprising: a signal derivation part, a signal detection part and an electronic compensation part; in the signal transmission direction, the signal derivation part and the signal detection part are connected in sequence; the electronic compensation part is sleeved outside the signal derivation part and the signal detection part.

[0007] Furthermore, the signal derivation part includes: a first high-voltage electrode, a second high-voltage electrode, a first fixing mechanism, a second fixing mechanism, a grounding terminal assembly, a collector connection mechanism and a connecting shaft; the second high-voltage electrode is sleeved outside the first fixing mechanism; the first high-voltage electrode is sleeved outside the second high-voltage electrode; the second fixing mechanism is sleeved outside the first high-voltage electrode; a first chamber is formed between the first high-voltage electrode and the second high-voltage electrode, and the grounding terminal assembly, the collector connection mechanism and the connecting shaft are all arranged in the first chamber; a high-voltage isolation mechanism is arranged between the grounding terminal assembly and the first high-voltage electrode; the grounding terminal assembly includes a second chamber, and the collector connection mechanism is arranged in the second chamber; a signal isolation mechanism is arranged between the collector connection mechanism and the grounding terminal assembly; the first fixing mechanism A three-coaxial double-shielded wire is pressed between the fixing mechanism and the second high-voltage electrode, and the outer copper wire of the three-coaxial double-shielded wire is connected to an external high-voltage power supply; a three-coaxial double-shielded wire is pressed between the connecting shaft and the grounding terminal assembly, and the middle copper wire of the three-coaxial double-shielded wire is connected to an external high-voltage power supply; the inner copper wire of the three-coaxial double-shielded wire is welded and connected in the collector connecting mechanism; one end of the connecting shaft is connected to the outer copper wire of the three-coaxial double-shielded wire, and the other end of the connecting shaft is connected to the grounding terminal assembly and the middle copper wire of the three-coaxial double-shielded wire; one end of the collector connecting mechanism is connected to the grounding terminal assembly and the middle copper wire of the three-coaxial double-shielded wire, and the other end of the collector connecting mechanism is connected to the signal detection part after passing through the high-voltage isolation mechanism and the first high-voltage electrode.

[0008] Furthermore, the first high-voltage electrode includes: a bottom and a side wall; the bottom of the first high-voltage electrode is a disc-shaped structure, and the side wall of the first high-voltage electrode is a tubular structure; one end of the side wall of the first high-voltage electrode is connected to the outer edge of the bottom of the first high-voltage electrode to form a hollow columnar structure with one end open; the second high-voltage electrode includes: a bottom and a side wall; the bottom of the second high-voltage electrode is a disc-shaped structure, and the side wall of the second high-voltage electrode is a tubular structure; one end of the side wall of the second high-voltage electrode is connected to the outer edge of the bottom of the second high-voltage electrode to form a hollow columnar structure with one end open; the outer copper wire of the three-coaxial double-shielded conductor is connected to the bottom of the second high-voltage electrode; the inner surface of the side wall of the first high-voltage electrode is in contact with the outer surface of the side wall of the second high-voltage electrode; the opening of the first high-voltage electrode is flush with the opening of the second high-voltage electrode; the bottom of the second high-voltage electrode, the bottom of the first high-voltage electrode and the side wall of the first high-voltage electrode together form a first chamber.

[0009] Furthermore, the grounding terminal assembly includes: a first grounding terminal, a second grounding terminal and a third grounding terminal; the first grounding terminal is a tubular structure; the second grounding terminal includes: a bottom and a side wall; the bottom of the second grounding terminal is a disc-shaped structure, and the side wall of the second grounding terminal is a tubular structure; one end of the side wall of the second grounding terminal is connected to the outer edge of the bottom of the second grounding terminal to form a hollow cylindrical structure with one end open; the middle layer copper wire of the three coaxial double-shielded conductor is connected to the bottom of the second grounding terminal; the third grounding terminal includes: a bottom and a side wall; the bottom of the third grounding terminal is a ring-shaped structure, and the side wall of the third grounding terminal is a tubular structure; one end of the side wall of the third grounding terminal is connected to the third grounding terminal The inner edge of the bottom of the first grounding end is connected to form a hollow columnar structure with one end including an outer eaves and two ends opening; the first grounding end is sleeved outside the second grounding end, and the inner surface of the first grounding end contacts the outer surface of the side wall of the second grounding end; the opening at one end of the first grounding end is flush with the opening of the second grounding end; the side wall of the first grounding end and the bottom of the second grounding end form a second chamber; the third grounding end is buckled at the opening at one end of the first grounding end and the opening of the second grounding end; the outer surface of the side wall of the third grounding end contacts the inner surface of the side wall of the second grounding end, and the opening at one end of the first grounding end and the opening of the second grounding end are both in contact with the upper surface of the outer eaves of the third grounding end.

[0010] Furthermore, the high-voltage isolation mechanism includes: a first high-voltage isolation end and a second high-voltage isolation end; the first high-voltage isolation end is a tubular structure, and the length of the first high-voltage isolation end is the same as the length of the first grounding end; the first high-voltage isolation end is arranged between the first grounding end and the first high-voltage electrode, the inner wall of the first high-voltage isolation end contacts the outer wall of the first grounding end, and the outer wall of the first high-voltage isolation end contacts the inner wall of the first high-voltage electrode; the second high-voltage isolation end is a disc-shaped structure; the second high-voltage isolation end is arranged between the first grounding end and the first high-voltage electrode, the upper surface of the second high-voltage isolation end contacts the other end opening of the first grounding end and one end of the first high-voltage isolation end, and the lower surface of the second high-voltage isolation end contacts the bottom of the first high-voltage electrode.

[0011] Furthermore, the collector connecting mechanism includes: a pad and a collector connector; one end of the pad is connected to the bottom of the second grounding terminal and the middle copper wire of the three coaxial double-shielded conductors, the other end of the pad is connected to one end of the collector connector and the inner copper wire of the three coaxial double-shielded conductors, and the other end of the collector connector passes through the second high-voltage isolation terminal and the bottom of the first high-voltage electrode to be connected to the signal detection part; the signal isolation mechanism is a hollow tubular structure; the inner surface of the signal isolation mechanism contacts the outer surface of the pad and the outer surface of the collector connector, the outer surface of the signal isolation mechanism contacts the inner surface of the first grounding terminal, one end of the signal isolation mechanism contacts the bottom of the second isolation terminal, and the other end of the signal isolation mechanism contacts the second high-voltage isolation terminal.

[0012] Furthermore, one end of the connecting shaft is connected to the outer copper wire of the three coaxial double-shielded conductor, and the other end of the connecting head passes through the third grounding terminal and is connected to the bottom of the first grounding terminal and the middle copper wire of the three coaxial double-shielded conductor.

[0013] Furthermore, the signal detection part includes: a central pole, a first central pole fixing mechanism, a second central pole fixing mechanism and a cavity wall; the upper half of the first central pole fixing mechanism passes through the bottom of the first high-voltage electrode and is connected to the second high-voltage isolation end, and the other end of the collector connector passes through the second high-voltage isolation end and the upper half of the second central pole fixing mechanism; one end of the central pole passes through the lower half of the first central pole and is connected to the other end of the collector connector, and the other end of the central pole passes through the second central pole fixing mechanism and is connected to the electronic compensation part; the cavity wall is a tubular structure; the cavity wall is sleeved on the central pole, the lower half of the first central pole fixing mechanism and the second central pole fixing mechanism; one end of the cavity wall is in contact with the bottom of the first high-voltage electrode, and the other end of the cavity wall is in contact with the electronic compensation part; the inter-pole distance between the inner surface of the cavity wall and the outer surface of the central pole is 0.2 mm.

[0014] Furthermore, the electronic compensation part includes a first built-in cap and a second built-in cap; the first built-in cap is a tubular structure; the first built-in cap is sleeved outside the second fixing mechanism, the first high-voltage electrode and the cavity wall; the second built-in cap has an outer disk structure; the other end of the center pole passes through the second center pole fixing mechanism and is embedded in the second built-in cap; the second built-in cap is connected to one end of the first built-in cap.

[0015] Furthermore, the volume of the signal detection part is 0.00377cm 3 ; The diameter of the central pole is 1mm; the inner diameter of the cavity wall is 1.4mm, and the outer diameter of the cavity wall is 6mm; the cylindricality of the central pole and the cavity wall is 0.01, the coaxiality of the central pole and the cavity wall is 0.08, and the surface verticality of the central pole and the cavity wall is 0.08; the equivalent thickness of the chamber wall is 1.421g / cm 2 ; The outer diameter of the first built cap and the outer diameter of the second built cap are both 3mm.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: an improvement is made on the basis of an ultra-high dose rate high-energy X-ray water absorption dose secondary standard detector to obtain a micro-pitch free cavity ionization chamber with a pole spacing of 0.2 mm. The collection efficiency is greater than 99% under the conditions of a 120V polarization voltage and a pulse dose of less than 25Gy / pulse, which can solve the problem of insufficient collection efficiency caused by excessive ion recombination effect in the ionization chamber in absolute dose measurement of ultra-high dose rate X-ray radiation fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A cross-sectional view of an ultra-high dose rate dose detection ionization chamber provided by an embodiment of the present invention; Figure 2 A schematic diagram showing a comparison of theoretical calculations of the collection efficiency of ionization chambers with different inter-pole spacings under different pulse dose conditions provided in an embodiment of the present invention.

[0019] Marks and corresponding parts names in the attached drawings: 1-signal derivation part, 2-signal detection part, 3-electronic compensation part, 4-outer copper wire, 5-middle copper wire, 6-inner copper wire, 11-first high-voltage electrode, 12-second high-voltage electrode, 13-first fixing mechanism, 14-second fixing mechanism, 15-grounding terminal assembly, 16-collector connection mechanism, 17-connecting axis, 18-high-voltage isolation mechanism, 19-signal isolation mechanism, 21-center pole, 22-first center pole fixing mechanism, 23-second center pole fixing mechanism, 24-cavity wall, 31-first built-in cap, 32-second built-in cap, 151-first grounding terminal, 152-second grounding terminal, 153-third grounding terminal, 161-gasket, 162-collector connection head, 181-first high-voltage isolation terminal, 182-second high-voltage isolation terminal. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0021] In the following description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is apparent to one of ordinary skill in the art that these specific details are not necessarily employed to practice the present invention. In other embodiments, in order to avoid obscuring the present invention, well-known structures, circuits, materials, or methods are not specifically described.

[0022] Throughout the specification, references to "one embodiment," "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in conjunction with the embodiment or example is included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment," "an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily all refer to the same embodiment or example. In addition, particular features, structures, or characteristics may be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. In addition, it will be appreciated by those of ordinary skill in the art that the figures provided herein are for illustrative purposes and that the figures are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] In the description of the present invention, the directions or positional relationships indicated by terms such as “front”, “rear”, “left”, “right”, “up”, “down”, “vertical”, “horizontal”, “high”, “low”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they should not be understood as limiting the scope of protection of the present invention.

[0024] Example: Figure 1 As shown, an embodiment of the present invention provides an ultra-high dose rate dose detection ionization chamber, which is composed of a signal derivation part 1, a signal detection part 2 and an electronic compensation part 3. Figure 1 , the structures and positional relationships of the signal derivation part 1, the signal detection part 2 and the electronic compensation part 3 are described in detail respectively.

[0025] 1. Signal export part The signal derivation part 1 is composed of a first high-voltage electrode 11, a second high-voltage electrode 12, a first fixing mechanism 13, a second fixing mechanism 14, a grounding terminal assembly 15, a collector connecting mechanism 16, a connecting shaft 17, a high-voltage isolation mechanism 18 and a signal isolation mechanism 19.

[0026] Among them, the first high-voltage electrode 11 and the second high-voltage electrode 12 are both hollow cylindrical structures with an open top, and both include a bottom and a side wall, the bottom is a disc-shaped structure, the side wall is a tubular structure, and one end of the side wall is connected to the outer edge of the bottom. The first high-voltage electrode 11 and the second high-voltage electrode 12 form the positive and negative poles of the power supply, providing high voltage for the signal detection part 2. The first high-voltage electrode 11 and the second high-voltage electrode 12 can be made of conductive materials such as copper or aluminum.

[0027] The top opening of the second high-voltage electrode 12 is placed in the same direction as the top opening of the first high-voltage electrode 11, and then the bottom of the second high-voltage electrode 12 is fed in from the top opening of the first high-voltage electrode 11 until the top opening of the second high-voltage electrode 12 is flush with the top opening of the first high-voltage electrode 11, forming a nested structure in which the first high-voltage electrode 11 is outside and the second high-voltage electrode 12 is inside; the outer diameter of the second high-voltage electrode 12 is the same as the inner diameter of the first high-voltage electrode 11, and after nesting, the inner surface of the side wall of the first high-voltage electrode 11 contacts the outer surface of the side wall of the second high-voltage electrode 12. Since the height of the first high-voltage electrode 11 is greater than the height of the second high-voltage electrode 12, a first chamber is formed between the first high-voltage electrode 11 and the second high-voltage electrode 12. The ground terminal assembly 15, the collector connection mechanism 16 and the connecting shaft 17 are all arranged in the first chamber.

[0028] (1) Ground terminal components like Figure 1 As shown, the grounding terminal assembly 15 is composed of a first grounding terminal 151, a second grounding terminal 152 and a third grounding terminal 153. Among them, the first grounding terminal 151 is a tubular structure; the shape of the second grounding terminal 152 is the same as that of the first high-voltage electrode 11 or the second high-voltage electrode 12, which is a hollow columnar structure with an open top, including a bottom and a side wall, the bottom is a disc-shaped structure, the side wall is a tubular structure, and one end of the side wall is connected to the outer edge of the bottom. The first grounding terminal 151 and the second grounding terminal 152 are made of conductive materials such as copper or aluminum.

[0029] The top opening of the second grounding terminal 152 is placed in the same direction as the top opening of the first high-voltage electrode 11 or the top opening of the second high-voltage electrode 12, and then the bottom of the second grounding terminal 152 is inserted from the opening of one end of the first grounding terminal 151 until the top opening of the second grounding terminal 152 is flush with the opening of one end of the first grounding terminal 151, forming a nested structure in which the first grounding terminal 151 is outside and the second grounding terminal 152 is inside; the outer diameter of the second grounding terminal 152 is the same as the inner diameter of the first grounding terminal 151, and after nesting, the inner surface of the side wall of the first grounding terminal 151 contacts the outer surface of the side wall of the second grounding terminal 152. Since the height of the first grounding terminal 151 is greater than the height of the second grounding terminal 152, a second chamber is formed between the first grounding terminal 151 and the second grounding terminal 152. The collector connection mechanism 16 is arranged in the second chamber.

[0030] Furthermore, the third ground terminal 153 is Figure 1 The hollow columnar structure shown includes an outer edge at one end and openings at both ends, including a bottom and a side wall, the bottom is an annular structure, the side wall is a tubular structure, and one end of the side wall is connected to the inner edge of the bottom. The third grounding terminal 153 can be made of conductive materials such as copper or aluminum.

[0031] The side wall of the third grounding end 153 is fed in from the opening of the second grounding end 152 until the opening of the first grounding end 151 and the opening of the second grounding end 152 are in contact with the outer edge of the third grounding end 153 and the top of the side wall of the third grounding end 153 is in contact with the bottom of the second grounding end 152, forming a buckling structure with the first grounding end 151 on the outside, the second grounding end 152 in the middle, and the third grounding end 153 in the inner layer. Since the outer diameter of the side wall of the third grounding end 153 is the same as the inner diameter of the side wall of the second grounding end 152, after buckling, the outer surface of the side wall of the third grounding end 153 is in contact with the inner surface of the side wall of the second grounding end 152.

[0032] The first ground terminal 151 , the second ground terminal 152 and the third ground terminal 153 are all made of conductive materials such as copper or aluminum.

[0033] (2) High voltage isolation mechanism like Figure 1 As shown, the high-voltage isolation mechanism 18 is composed of a first high-voltage isolation end 181 and a second high-voltage isolation end 182. Among them, the first high-voltage isolation end 181 is a tubular structure, and its length is the same as the length of the first grounding end 151. The first high-voltage isolation end 181 is arranged between the first grounding end 151 and the first high-voltage electrode 11, and its inner wall contacts the outer wall of the first grounding end 151, and its outer wall contacts the inner wall of the first high-voltage electrode 11. The second high-voltage isolation end 182 is a disc-shaped structure, and its diameter is the same as the inner diameter of the first high-voltage electrode 11 or the outer diameter of the second high-voltage electrode 12. The second high-voltage isolation end 182 is arranged between the first grounding end 151 and the first high-voltage electrode 11, and its upper surface contacts the opening of the first grounding end 151 and the first high-voltage isolation end 181, and its lower surface contacts the bottom of the first high-voltage electrode 11.

[0034] The first high voltage isolation terminal 181 and the second high voltage isolation terminal 182 play the role of isolating the high voltage from the ground, and both are made of PEEK.

[0035] (3) Collector connection mechanism like Figure 1 As shown, the collector connection mechanism 16 is composed of a pad 161 and a collector connector 162. One end of the pad 161 is connected to the bottom of the second ground terminal 152, the other end of the pad 161 is connected to one end of the collector connector 162, and the other end of the collector connector 162 passes through the mounting hole of the second high-voltage isolation terminal 182 and the mounting hole at the bottom of the first high-voltage electrode 11 to connect to the signal detection part 2. The pad 161 is made of PEEK material, and the collector connector 162 is made of conductive materials such as copper or aluminum.

[0036] (4) Signal isolation mechanism like Figure 1As shown, the signal isolation mechanism 19 is a hollow tubular structure, which is arranged between the collector connection mechanism 16 and the first high-voltage electrode 11, and plays the role of isolating the signal from the ground. The inner surface of the signal isolation mechanism 19 contacts the outer surface of the pad 161 and the outer surface of the collector connection head 162, the outer surface of the signal isolation mechanism 19 contacts the inner surface of the first grounding terminal 151, one end of the signal isolation mechanism 19 contacts the bottom of the second isolation terminal 152, and the other end of the signal isolation mechanism 19 contacts the second high-voltage isolation terminal 182. The signal isolation mechanism 19 is made of PEEK material.

[0037] (5) Connecting shaft like Figure 1 As shown, the connecting shaft 17 is arranged between the grounding terminal assembly 15 and the second high voltage electrode 12, and plays the role of isolating the high voltage from the ground. One end of the connecting shaft 17 is connected to the second high voltage electrode 12, and the other end passes through the third grounding terminal 153 and is connected to the bottom of the first grounding terminal 151. The connecting shaft 17 is made of PEEK material.

[0038] (6) First fixing mechanism and second fixing mechanism like Figure 1 As shown, the second high-voltage electrode 12 is sleeved outside the first fixing mechanism 13. The second fixing mechanism 14 is a hollow columnar structure with an inner eaves at one end and an opening at the other end, including a bottom and a side wall, the bottom is an annular structure, the side wall is a tubular structure, one end of the side wall is connected to the outer edge of the bottom, and the second fixing mechanism 14 is sleeved outside the first high-voltage electrode 11.

[0039] The first fixing structure is made of PEEK material, and the second fixing structure 14 is made of conductive materials such as copper or aluminum.

[0040] (7) Triaxial double shielded wire Based on the structure and positional relationship of each device in the signal conductor part, a three-coaxial double-shielded wire is pressed between the first fixing mechanism 13 and the second high-voltage electrode 12, and the outer copper wire 4 of the three-coaxial double-shielded wire is connected to an external high-voltage power supply; a three-coaxial double-shielded wire is pressed between the connecting shaft 17 and the grounding terminal component 15, and the middle copper wire 5 of the three-coaxial double-shielded wire is connected to an external high-voltage power supply; the inner copper wire 6 of the three-coaxial double-shielded wire is welded and connected in the collector connection mechanism 16. Figure 1 As shown, the outer copper wire 4 of the three-coaxial double-shielded conductor is embedded in the bottom of the second high-voltage electrode 12 for signal introduction; the middle copper wire 5 is embedded in the bottom of the second ground terminal 152 for frequency-closing signal; the inner copper wire 6 is welded into the collector connector 162 for signal export.

[0041] Figure 1In the figure, one end of the connecting shaft 17 is connected to the outer copper wire 4 of the three coaxial double-shielded conductor, and the other end is connected to the grounding terminal component 15 and the middle copper wire 5 of the three coaxial double-shielded conductor; one end of the pad 161 is connected to the bottom of the second grounding terminal 152 and the middle copper wire 5 of the three coaxial double-shielded conductor, and the other end is connected to one end of the collector connector 162 and the inner copper wire 6 of the three coaxial double-shielded conductor.

[0042] 2. Signal detection part like Figure 1 As shown, the signal detection part 2 is a sensitive volume, which is composed of a central pole 21, a first central pole fixing mechanism 22, a second central pole fixing mechanism 23 and a cavity wall 24. Among them, the upper half of the first central pole fixing mechanism 22 passes through the bottom of the first high-voltage electrode 11 and is connected to the second high-voltage isolation end 182, and the collector connector 162 passes through the second high-voltage isolation end 182 and the upper half of the second central pole fixing mechanism 23; one end of the central pole 21 passes through the lower half of the first central pole fixing mechanism 22 and is connected to the other end of the collector connector 162, and the other end passes through the second central pole fixing mechanism 23 and is connected to the electronic compensation part 3. The cavity wall 24 is a tubular structure; the cavity wall 24 is sleeved on the center pole 21, the lower half of the first center pole fixing mechanism 22 and the outside of the second center pole fixing mechanism 23; one end of the cavity wall 24 contacts the bottom of the first high-voltage electrode 11, and the other end of the cavity wall 24 contacts the electron compensation part 3; the inter-pole distance between the inner surface of the cavity wall 24 and the outer surface of the center pole 21 is 0.2 mm.

[0043] In addition, the center pole 21 is made of conductive materials such as aluminum or aluminum alloy, and has a diameter of 1 mm. The first center pole fixing mechanism 22 and the second center pole fixing mechanism 23 are both made of PEEK material. The cavity wall 24 is made of conductive materials such as aluminum or aluminum alloy, and has an inner diameter of 1.4 mm and an outer diameter of 6 mm. The cylindricity of the center pole 21 and the cavity wall 24 is 0.01, the coaxiality is 0.08, and the surface verticality is 0.08. The equivalent thickness of the chamber wall is 1.421 g / cm2. The sensitive volume of the signal detection part 2 is 0.00377 cm3.

[0044] 3. Electronic compensation part like Figure 1As shown, the electronic compensation part 3 is composed of a first built cap 31 and a second built cap 32, both of which are made of PEEK material and have an outer diameter of 3 mm. Among them, the first built cap 31 is a tubular structure; the first built cap 31 is sleeved outside the second fixing mechanism 14, the first high-voltage electrode 11 and the cavity wall 24, and is fixedly connected to the second fixing mechanism 14 by threads. The second built cap 32 has an outer disc structure; the other end of the center pole 21 passes through the second center pole fixing mechanism 23 and is embedded in the second built cap 32; the second built cap 32 is fixedly connected to the first built cap 31 by JL-655PE plastic conversion glue.

[0045] When an ultra-high dose rate dose detection ionization chamber based on the above structural features is working, after the radiation emitted by the radiation release device enters the cavity, it interacts with the electrons and nuclei of the copper atoms in the cavity wall 24 to generate secondary charged particles. The secondary charged particles are ionized and excited with the cavity air to form electrons and positive ions. Due to the potential difference formed between the central pole 21 and the cavity wall 24, the electrons move toward the cavity wall 24 at a high potential, and the positive ions move toward the central pole 21 at a low potential. Since a large number of charged particles gather around the central pole 21, charges are induced on the central pole 21, and the generated current is derived from the signal line. In this way, the signal line is connected to the detection module, and the dose of the incident radiation can be determined by detecting the current in the signal line.

[0046] To further illustrate the effect of an ultra-high dose rate dose detection ionization chamber provided in this embodiment, this embodiment constructs a carrier partial differential equation through the generation, transmission and recombination process of carriers in the electric field, and calculates the collection efficiency of different ionization chamber inter-electrode spacings. The details are as follows: The carrier partial differential equation for the relationship between the density of positive ions, negative ions and electrons and time: (1), (2), (3); In equations (1) to (3), 𝜌𝑖 represents the density of carrier i, including 𝜌 + represents the density of positive ions, 𝜌 — represents the density of negative ions; e represents electrons; R(t) represents the amount of free charge released due to radiation ionization; α represents the coincidence rate; represents the charge loss caused by the recombination of positive and negative ions; 𝛾𝜌e represents the electron attachment term, which leads to the reduction of electrons and the increase of negative ions; γ represents the electron attachment rate constant; v + represents the speed of positive ions moving along the electric field, v — represents the speed of negative ions moving along the electric field, 𝑣 eThe speed at which electrons move along an electric field.

[0047] Carrier i will move along the electric field at a speed of 𝑣i(x), which will cause the carrier density at position x to change. The spatial derivatives are used to discretize each term into a relationship with time:

[0048] (4), (5),

[0049] (6), (7); In equations (4) to (7), 𝜌𝑖 represents the density of carrier i at position r at time t; h is the numerical diffusion step in space; 𝜇i is the mobility of type i carriers, and E is the electric field strength at position r.

[0050] Obtain a numerical solution to the difference equation by solving it using the explicit Euler method: (8), (9), (10); The collection efficiency of the ionization chambers with different inter-electrode spacings at pulse dose rates of 5, 10, 15, 20, 25, and 30 Gy / pulse was calculated. The results are shown in Figure 2 As shown in the figure, at a polarization voltage of 120V, the collection efficiency of the ionization chamber with an inter-electrode spacing of 0.2mm is greater than 99% when the pulse dose is less than 25Gy / pulse.

[0051] The above specific implementation methods further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An ultra-high dose rate dose detection ionization chamber, characterized in that: include: A signal derivation part (1), a signal detection part (2) and an electronic compensation part (3); In the signal transmission direction, the signal derivation part (1) and the signal detection part (2) are connected in sequence; the electronic compensation part (3) is sleeved outside the signal derivation part (1) and the signal detection part (2).

2. The ultra-high dose rate dose detection ionization chamber according to claim 1, characterized in that: The signal derivation part (1) comprises: a first high-voltage electrode (11), a second high-voltage electrode (12), a first fixing mechanism (13), a second fixing mechanism (14), a ground terminal assembly (15), a collector connection mechanism (16) and a connection shaft (17); The second high-voltage electrode (12) is sleeved outside the first fixing mechanism (13); the first high-voltage electrode (11) is sleeved outside the second high-voltage electrode (12); and the second fixing mechanism (14) is sleeved outside the first high-voltage electrode (11); A first chamber is formed between the first high-voltage electrode (11) and the second high-voltage electrode (12), and the grounding terminal assembly (15), the collector connecting mechanism (16) and the connecting shaft (17) are all arranged in the first chamber; a high-voltage isolation mechanism (18) is arranged between the grounding terminal assembly (15) and the first high-voltage electrode (11); the grounding terminal assembly (15) includes a second chamber, and the collector connecting mechanism (16) is arranged in the second chamber; a signal isolation mechanism (19) is arranged between the collector connecting mechanism (16) and the grounding terminal assembly (15); A triaxial double-shielded wire is pressed between the first fixing mechanism (13) and the second high-voltage electrode (12), and the outer copper wire of the triaxial double-shielded wire is connected to an external high-voltage power supply; a triaxial double-shielded wire is pressed between the connecting shaft (17) and the grounding terminal component (15), and the middle copper wire of the triaxial double-shielded wire is connected to an external high-voltage power supply; and the inner copper wire of the triaxial double-shielded wire is welded and connected to the collector connecting mechanism (16); One end of the connecting shaft (17) is connected to the outer copper wire of the triaxial double-shielded wire, and the other end of the connecting shaft (17) is connected to the ground terminal assembly (15) and the middle copper wire of the triaxial double-shielded wire; one end of the collector connecting mechanism (16) is connected to the ground terminal assembly (15) and the middle copper wire of the triaxial double-shielded wire, and the other end of the collector connecting mechanism (16) is connected to the signal detection part (2) after passing through the high-voltage isolation mechanism (18) and the first high-voltage electrode (11).

3. The ultra-high dose rate dose detection ionization chamber according to claim 2, characterized in that: The first high-voltage electrode (11) comprises: a bottom and a side wall; the bottom of the first high-voltage electrode (11) is a disc-shaped structure, and the side wall of the first high-voltage electrode (11) is a tubular structure; one end of the side wall of the first high-voltage electrode (11) is connected to the outer edge of the bottom of the first high-voltage electrode (11), forming a hollow columnar structure with one end open; The second high-voltage electrode (12) comprises: a bottom and a side wall; the bottom of the second high-voltage electrode (12) is a disc-shaped structure, and the side wall of the second high-voltage electrode (12) is a tubular structure; one end of the side wall of the second high-voltage electrode (12) is connected to the outer edge of the bottom of the second high-voltage electrode (12), forming a hollow columnar structure with one end open; the outer copper wire of the triaxial double-shielded conductor is connected to the bottom of the second high-voltage electrode; The inner surface of the side wall of the first high-voltage electrode (11) contacts the outer surface of the side wall of the second high-voltage electrode (12); the opening of the first high-voltage electrode (11) is flush with the opening of the second high-voltage electrode (12); and the bottom of the second high-voltage electrode (12), the bottom of the first high-voltage electrode (11) and the side wall of the first high-voltage electrode (11) together form a first chamber.

4. The ultra-high dose rate dose detection ionization chamber according to claim 3, characterized in that: The ground terminal assembly (15) comprises: a first ground terminal (151), a second ground terminal (152) and a third ground terminal (153); The first grounding end (151) is a tubular structure; The second grounding end (152) comprises: a bottom and a side wall; the bottom of the second grounding end (152) is a disc-shaped structure, and the side wall of the second grounding end (152) is a tubular structure; one end of the side wall of the second grounding end (152) is connected to the outer edge of the bottom of the second grounding end (152) to form a hollow columnar structure with one end open; the middle layer copper wire of the triaxial double-shielded conductor is connected to the bottom of the second grounding end (152); The third grounding end (153) comprises: a bottom and a side wall; the bottom of the third grounding end (153) is a ring-shaped structure, and the side wall of the third grounding end (153) is a tubular structure; one end of the side wall of the third grounding end (153) is connected to the inner edge of the bottom of the third grounding end (153), forming a hollow columnar structure with one end including an outer edge and two ends being open; The first grounding end (151) is sleeved outside the second grounding end (152), the inner surface of the first grounding end (151) contacts the outer surface of the side wall of the second grounding end (152); an opening at one end of the first grounding end (151) is flush with the opening of the second grounding end (152); the side wall of the first grounding end (151) and the bottom of the second grounding end (152) form a second chamber; The third grounding end (153) is buckled at an opening at one end of the first grounding end (151) and an opening of the second grounding end (152); The outer surface of the side wall of the third grounding terminal (153) contacts the inner surface of the side wall of the second grounding terminal (152), and an opening at one end of the first grounding terminal (151) and an opening of the second grounding terminal (152) both contact the upper surface of the outer edge of the third grounding terminal (153).

5. The ultra-high dose rate dose detection ionization chamber according to claim 4, characterized in that: The high-voltage isolation mechanism (18) comprises: a first high-voltage isolation terminal (181) and a second high-voltage isolation terminal (182); The first high-voltage isolation end (181) is a tubular structure, and the length of the first high-voltage isolation end (181) is the same as the length of the first grounding end (151); the first high-voltage isolation end (181) is arranged between the first grounding end (151) and the first high-voltage electrode (11), the inner wall of the first high-voltage isolation end (181) contacts the outer wall of the first grounding end (151), and the outer wall of the first high-voltage isolation end (181) contacts the inner wall of the first high-voltage electrode (11); The second high-voltage isolation terminal (182) is a disc-shaped structure; the second high-voltage isolation terminal (182) is arranged between the first ground terminal (151) and the first high-voltage electrode (11); the upper surface of the second high-voltage isolation terminal (182) contacts the other end opening of the first ground terminal (151) and one end of the first high-voltage isolation terminal (181); and the lower surface of the second high-voltage isolation terminal (182) contacts the bottom of the first high-voltage electrode (11).

6. The ultra-high dose rate dose detection ionization chamber according to claim 5, characterized in that: The collector connection mechanism (16) comprises: a pad (161) and a collector connector (162); one end of the pad (161) is connected to the bottom of the second ground terminal (152) and the middle copper wire of the triaxial double-shielded wire, the other end of the pad (161) is connected to one end of the collector connector (162) and the inner copper wire of the triaxial double-shielded wire, and the other end of the collector connector (162) passes through the second high-voltage isolation terminal (182) and the bottom of the first high-voltage electrode (11) to be connected to the signal detection part (2); The signal isolation mechanism (19) is a hollow tubular structure; the inner surface of the signal isolation mechanism (19) contacts the outer surface of the pad head (161) and the outer surface of the collector connector (162); the outer surface of the signal isolation mechanism (19) contacts the inner surface of the first grounding terminal (151); one end of the signal isolation mechanism (19) contacts the bottom of the second isolation terminal (152); and the other end of the signal isolation mechanism (19) contacts the second high-voltage isolation terminal (182).

7. The ultra-high dose rate dose detection ionization chamber according to claim 6, characterized in that: One end of the connecting shaft (17) is connected to the outer copper wire of the triaxial double-shielded wire, and the other end of the connecting head (17) passes through the third grounding terminal (153) and is connected to the bottom of the first grounding terminal (151) and the middle copper wire of the triaxial double-shielded wire.

8. The ultra-high dose rate dose detection ionization chamber according to claim 7, characterized in that: The signal detection part (2) comprises: a central pole (21), a first central pole fixing mechanism (22), a second central pole fixing mechanism (23) and a cavity wall (24); The upper half of the first center pole fixing mechanism (22) passes through the bottom of the first high-voltage electrode (11) and is connected to the second high-voltage isolation end (182), and the other end of the collector connector (162) passes through the second high-voltage isolation end (182) and the upper half of the second center pole fixing mechanism (23); one end of the center pole (21) passes through the lower half of the first center pole (22) and is connected to the other end of the collector connector (162), and the other end of the center pole (21) passes through the second center pole fixing mechanism (23) and is connected to the electron compensation part (3); The cavity wall (24) is a tubular structure; the cavity wall (24) is sleeved on the center pole (21), the lower half of the first center pole fixing mechanism (22) and the outside of the second center pole fixing mechanism (23); one end of the cavity wall (24) contacts the bottom of the first high-voltage electrode (11), and the other end of the cavity wall (24) contacts the electron compensation part (3); the inter-polar distance between the inner surface of the cavity wall (24) and the outer surface of the center pole (21) is 0.2 mm.

9. The ultra-high dose rate dose detection ionization chamber according to claim 8, characterized in that: The electronic compensation part (3) comprises a first built-in cap (31) and a second built-in cap (32); The first built cap (31) is a tubular structure; the first built cap (31) is sleeved outside the second fixing mechanism (14), the first high-voltage electrode (11) and the cavity wall (24); The second built cap (32) has an outer disk-shaped structure; the other end of the central pole (21) passes through the second central pole fixing mechanism (23) and is then embedded in the second built cap (32); the second built cap (32) is connected to one end of the first built cap (31).

10. An ultra-high dose rate dose detection ionization chamber according to claim 9, characterized in that: The volume of the signal detection part is 0.00377cm 3 ; The diameter of the central pole (21) is 1 mm; The inner diameter of the cavity wall (24) is 1.4 mm, and the outer diameter of the cavity wall (24) is 6 mm; The cylindricality of the central pole (21) and the cavity wall (24) is 0.01, the coaxiality of the central pole (21) and the cavity wall (24) is 0.08, and the surface perpendicularity of the central pole (21) and the cavity wall (24) is 0.08; The equivalent thickness of the chamber wall is 1.421 g / cm 2 ; The outer diameter of the first built cap (31) and the outer diameter of the second built cap (32) are both 3 mm.

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