Drift Tube

Abstract

Drift tubes for particle detection, detection systems including one or more of the drift tubes, methods of producing the drift tubes, and detection methods using the drift tubes and / or detection systems are disclosed. The drift tube can include: a housing tube extending along a longitudinal axis and configured to include a first end, a second end, and an inner surface configured as a cathode, and first and second end caps hermetically sealed and electrically insulated, respectively, at the first and second ends of the housing tube; a detection gas enclosed within the housing tube and configured to be ionized by charged particles; and an anode wire configured to traverse the housing tube and detect ionization indicative of tracking of charged particles within the drift tube, the anode wire traversing the housing tube along the longitudinal axis.

Description

[Technical Field]

[0001] <Priority Claim and Related Patent Application Information> This patent document claims priority to and benefit of U.S. Provisional Patent Application No. 63 / 435,481, entitled "Design and Manufacturing of Drift Tube End Caps and Related Drift Tube Applications," filed December 27, 2022, the entire contents of which are incorporated herein by reference as part of the disclosure herein.

[0002] This patent document relates to an apparatus, system, and method for tomographic imaging and detection using ambient cosmic ray charged particles, such as muons and electrons, as passive illumination radiation sources. [Background technology]

[0003] Cosmic ray tomography is a technique that utilizes multiple Coulomb scattering of highly penetrating cosmic ray-produced muons for nondestructive testing of materials without the use of artificial radiation. The Earth is continuously bombarded by energetically stable particles, primarily protons, coming from deep space. These particles interact with atoms in the upper atmosphere, producing particle showers containing many short-lived ions that decay to produce longer-lived muons. Muons interact with matter primarily through the Coulomb force, which has no nuclear interactions and radiates much less readily than electrons. Such cosmic ray-produced particles slowly lose energy through electromagnetic interactions. As a result, many of the cosmic ray-produced muons reach the Earth's surface as highly penetrating charged radiation. The muon flux at sea level is approximately 1 muon per square centimeter per minute.

[0004] As a muon moves through a material, Coulomb scattering of the subatomic particle's charges perturbs its trajectory. The total deflection depends on several material properties, but the primary effect is the atomic number Z of the nucleus. A muon's trajectory is more affected by materials that offer good gamma-ray shielding, such as lead and tungsten, and by special nuclear materials (SNMs), such as uranium and plutonium, than by materials that make up ordinary objects, such as water, plastic, aluminum, and steel. Each muon carries information about the object it penetrates. By measuring and processing the scattering of multiple muons, these objects can be characterized. Materials with high atomic number Z and high density can be detected and identified when they are located inside low- and medium-Z materials.

[0005] In 2003, scientists at Los Alamos National Laboratory developed a new imaging technique called muon scattering tomography (MT). Using muon scattering tomography, both the incoming and outgoing trajectories for each particle are reconstructed. The Los Alamos National Laboratory team was able to image a 1.2m 2 They constructed a muon tracker consisting of sealed, cylindrical aluminum drift tubes grouped into 24 (4-foot) flat panels. The drift tubes measure particle coordinates in X and Y, typically with an accuracy of a few hundred micrometers. Particle detector drift tubes, such as those used in research facilities (e.g., European Council for Nuclear Research (CERN) and Fermi National Accelerator Laboratory (Fermilab)), also detect specific ranges of particles and particle energies to address specific detection problems. Summary of the Invention

[0006] This patent discloses a system and method for detecting charged particles such as muons using a drift tube detector.

[0007] One aspect of the present invention relates to a drift tube. In some embodiments, the drift tube comprises: a housing tube having a first end, a second end, a longitudinal axis, and an inner surface extending along the longitudinal axis and configured as a cathode; a first end cap hermetically engaged with and electrically insulated from the first end of the housing tube; a second end cap hermetically engaged with and electrically insulated from the second end of the housing tube; a detector gas configured to undergo ionization by charged particles within the housing tube; and an anode wire having two wire terminals respectively engaged with the first and second end caps. The anode wire traverses the housing tube along the longitudinal axis, and the anode wire is configured to detect ionization indicative of the trajectories of the charged particles within the drift tube.

[0008] Another aspect of this document relates to a detection system. In some embodiments, the detection system comprises: a plurality of drift tubes according to any one or more of the solutions disclosed herein; a mounting framework for holding the plurality of drift tubes in a predetermined spatial arrangement; and a data acquisition system operably coupled to the plurality of drift tubes for collecting and processing data from the drift tubes.

[0009] A further aspect of this document relates to a method for manufacturing a drift tube. In some embodiments, the method includes the steps of: providing a housing tube, a first end cap, and a second end cap; disposing an anode connector in each opening of the first end cap and the second end cap; forming electrical isolation between the respective anode connector and the first end cap or the second end cap where the respective anode connector is disposed; inserting an anode wire through the housing tube, the first end cap, and the second end cap; bonding the first end cap and the second end cap to two ends of the housing tube; fixing the anode wire to each of the first end cap and the second end cap; filling the housing tube with a detection gas; and hermetically sealing the interfaces between the housing tube and the first end cap and the second end cap, respectively.

[0010] Yet another aspect of this document relates to a muon tomography system for detecting threats in an object, cargo, or vehicle under inspection. In some embodiments, the muon tomography system includes: a first set of position-sensing muon detectors disposed on a first side of the object-holding area to measure the position and direction of incident muons toward the object-holding area; a second set of position-sensing muon detectors disposed on a second side opposite the first side of the object-holding area to measure the position and direction of outgoing muons exiting the object-holding area, each of the first and second sets of position-sensing detectors constructed and arranged to enable at least three charged particle position measurements in a first direction and at least three charged particle position measurements in a second direction different from the first direction; a signal processing unit that receives data of measurement signals of incident muons from a first set of position sensitive muon detectors and measurement signals of exiting muons from a second set of position sensitive muon detectors, the signal processing unit being configured to analyze the scattering behavior of muons caused by the scattering of muons in materials within the object holding area based on the measured incident and exit positions and directions of muons, obtain a tomographic profile or spatial distribution of scattering centers within the object holding area, and generate an acquired space muon image of the object, cargo, or vehicle under inspection, wherein each position sensitive muon detector includes at least one drift tube, similar to any one or more of the solutions disclosed herein.

[0011] A still further aspect of the present document relates to a muon tomography system for detecting threats in an object, cargo, or vehicle under inspection using any one or more detection systems of the embodiments disclosed herein.

[0012] Yet another aspect of the present document relates to a method for detecting a volume exposed to charged particles. In some embodiments, the method includes: measuring the energy loss of charged particles that enter, penetrate, and / or stop within the volume without penetrating; determining a spatial distribution of the charged particles that enter, penetrate, or stop within the volume based on the measured energy loss; reconstructing a three-dimensional distribution of materials within the examination volume using the spatial distribution of the energy loss of the charged particles; measuring the charged particles that enter, penetrate, and / or stop within the volume; and reconstructing the spatial distribution of one or more materials within the volume. The reconstruction can be achieved based on measurements of the energy loss of the charged particles, the angular deflection of the charged particles, etc., or a combination thereof. In some embodiments, a first set of position-sensing detectors disposed on a first side of the volume can be configured to measure the position and direction of incident charged particles that penetrate the first set of position-sensing detectors to enter the volume. In some embodiments, a second set of position sensitive detectors disposed on a second side of the volume opposite the first side can be configured to measure the position and direction, or lack thereof, of the outgoing charged particles exiting the volume. This information obtained by the first set of position sensitive detectors and the second set of position sensitive detectors can be processed to determine the energy loss of the charged particles entering, penetrating, and / or stopping within the volume without penetrating.

[0013] These and other implementations are described in greater detail in the drawings, description, and claims. [Brief explanation of the drawings]

[0014] [Figure 1A] 1 illustrates examples of basic common design features in different drift tube designs, according to some embodiments of the present document.

[0015] [Figure 1B]FIG. 1B shows an exemplary drift tube for implementing the basic drift tube design of FIG. 1A.

[0016] [Figure 1C] 1 illustrates an end cap according to some embodiments of the present document. [Figure 1D] 1 illustrates an end cap according to some embodiments of the present document.

[0017] [Figure 2] FIG. 1 illustrates a top view of a male drift tube end cap, according to some embodiments of the present document.

[0018] [Figure 3] FIG. 1 illustrates a side view of a male drift tube end cap, according to some embodiments of the present document.

[0019] [Figure 4] FIG. 1 illustrates a cross-sectional view of a male drift tube end cap according to some embodiments of the present document.

[0020] [Figure 5] FIG. 10 illustrates a top view of a female drift tube end cap, according to some embodiments of the present document.

[0021] [Figure 6] FIG. 10 illustrates a side view of a female drift tube end cap, according to some embodiments of the present document.

[0022] [Figure 7] FIG. 10 illustrates a cross-sectional view of a female drift tube end cap, according to some embodiments of the present document.

[0023] [Figure 8A] 8A and 8B show plan and cross-sectional views of a female drift tube end cap using glass insulators according to some embodiments of the present document. [Figure 8B]8A and 8B show plan and cross-sectional views of a female drift tube end cap using glass insulators according to some embodiments of the present document.

[0024] [Figure 8C] 8C and 8D show plan and cross-sectional views of a male drift tube end cap using glass insulators according to some embodiments of the present document. [Figure 8D] 8C and 8D show plan and cross-sectional views of a male drift tube end cap using glass insulators according to some embodiments of the present document.

[0025] [Figure 9] 1 illustrates a detection system according to some embodiments of the present document.

[0026] [Figure 10] 1 illustrates drift tubes in a series connection, according to some embodiments of the present document.

[0027] [Figure 11] 1 illustrates a flowchart of a process for generating a drift tube, according to some embodiments of the present document. DETAILED DESCRIPTION OF THE INVENTION

[0028] The correct operation of the detector drift tube is critical to the detection of muons. Drift tubes typically include a hermetically sealed, gas-filled tube with a cathode and an anode that conducts the electrical signal generated when muons interact with the gas within the tube. Maintaining a reliable seal to separate the gas from the surrounding atmosphere, along with a good conductive metal for the anode, is critical to the construction of the drift tube in the desired conditions for accurate detection of charged particles.

[0029] However, drift tubes are typically not designed for mobile applications or to withstand extreme conditions of temperature, humidity, and various weather conditions. Therefore, improved drift tube detectors are needed to use muon tomography in practical applications such as cargo inspection, spent nuclear fuel scanning, mining, infrastructure inspection, and nuclear fuel monitoring, and the present subject matter addresses that need.

[0030] The disclosed technology and related exemplary embodiments can be implemented in a specific manner that enables a process for manufacturing drift tube end caps for the detection and measurement of charged particles passing through the drift tube, which further enables the system to interpret measurements for various inspections of interest.

[0031] A drift tube is a gas chamber designed to detect moving charged particles. Figure 1A shows exemplary features within a drift tube. In this example, the drift tube contains a gaseous medium enclosed within a chamber within the drift tube that can be ionized by moving charged particles passing through the gaseous medium. An anode wire conductor is positioned near the center of the drift tube, and the wall of the drift tube serves as a grounded cathode to establish an electric field from the anode wire conductor toward the wall. The incident charged particle ionizes gas molecules in the gaseous medium, generating free electrons that are accelerated toward the anode wire conductor by the electric field. The drift time of these electrons to reach the anode wire conductor can be measured. The drift times of electrons generated at different points along the incident charged particle's path within the drift tube are measured and used to determine the charged particle's trajectory within the drift tube.

[0032] One application of drift tubes is the detection of charged particles (e.g., muons) by using one or more arrays of drift tubes. Examples of muon tomography systems using arrays of drift tubes are disclosed in the following published patent documents:

[0033] 1. U.S. Patent No. 8,536,527 B2, Title: “Imaging based on cosmic-ray produced charged particles”

[0034] 2. U.S. Patent No. 8,288,721 B2, Title of Invention: “Imaging and sensing based on muon tomography”

[0035] The above patents were issued to Decision Sciences International Corporation and Los Alamos National Security LLC, the contents of which are incorporated by reference into this patent document.

[0036] The features described herein can be used to construct various muon tomography detection systems. For example, a muon tomography system can include an object-holding area or volume for placing an object to be inspected, a first set of position-sensing muon detectors disposed on a first side of the object-holding area to measure the position and direction of incident muons toward the object-holding area, a second set of position-sensing muon detectors disposed on a second side of the object-holding area opposite the first side to measure the position and direction of emitted muons exiting the object-holding area, and a signal processing unit, e.g., including a microprocessor, for receiving incident muon measurement signals from the first set of position-sensing muon detectors and receiving output muon measurement signal data from the second set of position-sensing muon detectors. As an example, each of the first and second sets of particle detectors can be implemented to include a drift tube arranged to enable at least three charged particle position measurements in a first direction and at least three charged particle position measurements in a second direction different from the first direction. The signal processing unit is configured to analyze the scattering behavior of muons caused by scattering of muons in materials within the object-holding region based on the measured muon incident and exit positions and directions to obtain a tomographic profile or spatial distribution of scattering centers within the object-holding region. The resulting tomographic profile or spatial distribution of scattering centers can be used to reveal the presence or absence of one or more objects within the object-holding region, such as materials with high atomic numbers, including nuclear materials or devices. Each position-sensing muon detector can be implemented in various configurations, including a drift cell, such as a drift tube filled with a gas that can be ionized by muons. Such a system can be used to utilize natural cosmic ray-produced muons as a muon source for detecting one or more objects within the object-holding region.

[0037] Specifically, FIG. 1A illustrates the operation of an exemplary drift tube for detecting charged particles. The drift tube in this example is a cylindrical tube formed by an outer cylindrical wall 110 and filled with a detection gas, such as argon-isobutane 230, to enable the detection of cosmic ray-produced charged particles, such as muons. An anode wire 120 extends along the length of the cylindrical tube along a longitudinal axis X. The anode wire 120 is electrically biased at a higher potential than the outer wall 110 to generate a positive voltage (e.g., 2-3 kV or more) and is configured to generate a high-voltage electrostatic field within the drift tube, directed radially from the anode wire 120 toward the wall 110, in an ionization region 112 inside the outer wall 110. When a charged particle 130 enters the drift tube and interacts with gas atoms in region 112, multiple electrons 132 can be liberated from these gas atoms. The electrostatic field causes a "string" of electrons to drift toward the positively charged anode wire 120. The anode wire 120 can be thinned to create a high electric field near the anode wire 120, thereby generating an electron avalanche. The anode wire 120 is connected to readout circuitry and electronically read out using a time-to-digital converter included as part of the data acquisition electronics. Thus, a hit signal is generated as the charged particles travel through the drift tube.

[0038] 1B shows an exemplary drift tube 100 for implementing the design of FIG. 1A. The drift tube 100 can include: a housing tube 102; a first end cap 104; a second end cap 106; a detection gas configured to undergo ionization by charged particles within the housing tube 102; and an anode wire 108 having two wire terminals engaged with the first end cap 104 and the second end cap 106, respectively. The anode wire 108 can traverse the housing tube 102 along a longitudinal axis X. The anode wire 108 can be configured to detect ionization indicative of the trajectories of charged particles within the drift tube 100.

[0039] The housing tube 102 may include a cylindrical tube of a desired length and first and second end caps 104, 106 at each end of the housing tube 102 along the longitudinal axis X. The housing tube 102 may provide a structural frame for the drift tube 100. Depending on the application, the housing tube 102 may need to be resistant to various environmental factors, such as radiation, extreme temperatures, and / or corrosive substances. The material of the housing tube 102 may be selected based on one or more factors, including strength, durability, and non-magnetic properties. The housing tube 102 may be formed from at least one of stainless steel, aluminum, carbon fiber, and the like. In various examples, the housing tube 102 may be implemented using a reamed aluminum tube having a central hollow channel defining the region 112, as shown in FIG. 1A.

[0040] The housing tube 102 may be configured to allow penetration of incident particles, such as muons. Charged particles can enter the drift tube 100 through the sidewalls of the housing tube 102. This allows the charged particles to traverse the length of the housing tube 102 along the longitudinal axis X, improving or maximizing their interaction with the detection gas inside. The impact on the trajectory and / or energy loss of such charged particles passing through the sidewalls of the housing tube 102 may be reduced or minimized by one or more means. The housing tube 102 may be fabricated from a material with a low atomic number (Z), such as aluminum, to reduce or minimize scattering and / or absorption of charged particles, such as muons. The sidewalls of the housing tube 102 may be thin to reduce or minimize interaction with charged particles while maintaining structural integrity. For example, the wall thickness of the housing tube 102 may range from a few tenths of a millimeter (e.g., 0.1 mm to 0.5 mm), or from 0.5 mm to several millimeters (up to about 2-3 mm) (e.g., when structural robustness is more important). In addition to its impact on particle interactions, the wall thickness may be selected based on one or more factors including the material of the housing tube 102, the energy level of the particles of interest (e.g., muons), environmental considerations (e.g., mechanical stress, temperature fluctuations, radiation exposure, portability), etc. The interaction of the sidewall of the housing tube 102 with the charged particles may be predetermined, for example, by experiment and / or numerical analysis (e.g., simulation), to understand and / or correct for systematic effects introduced by the wall material of the housing tube 102.

[0041] The cylindrical shape of the housing tube 102 can help generate a substantially uniform electric field within the housing tube 102. The size (length and diameter) of the housing tube 102 can be varied depending on the particular application. For example, a larger housing tube 102 (or drift tube 100) can cover more area but have lower spatial resolution, while a smaller housing tube 102 (or drift tube 100) can provide greater precision. The length of the housing tube 102 can range from a few centimeters (e.g., 10 cm to 30 cm) to approximately one meter (100 cm).

[0042] The housing tube 102 can have an inner surface 114 that faces the interior of the housing tube 102 and / or interfaces with the region 112. The inner surface 114 may face the anode wire 108. The inner surface 114 may extend along the longitudinal axis X and be configured as a cathode. For example, the inner surface 114 of the housing tube 102 may be grounded. The inner surface 114 may be electrically conductive and substantially uniform to ensure a consistent electric field within the housing tube 102. For example, the inner surface 114 may undergo a surface treatment to improve its electrical properties, reduce outgassing in vacuum conditions, and / or minimize background noise in the detector signal.

[0043] The housing tube 102 may be designed to allow for the integration of the anode wire 108, a gas fill system, electrical connections, and / or a mounting system, which often involves ports, feedthroughs for electrical connections, and mounting brackets.

[0044] The housing tube 102 may be gas-tight to contain a detection gas to enable the ionization process that detects passing charged particles. This may require precision in manufacturing to ensure a good seal and / or maintain the correct gas pressure inside the tube. In some embodiments, a first end cap 104 and a second end cap 106 may each be sealingly engaged with and electrically insulated from the first end of the housing tube 102. The end caps 104 and 106 may be constructed from a material that is resistant to radiation and thermal fluctuations, such as stainless steel, aluminum, or a radiation-cured polymer. In some embodiments, the end caps 104 and 106 may be identical. In some embodiments, one end cap may be a male end cap 104 and the other end cap may be a female end cap 106, such that multiple drift tubes 100 may be modular, with the male end cap 104 of one drift tube mating with the female end cap 106 of an adjacent drift tube 100. Further inventions regarding first end cap 104 and second end cap 106 can be found elsewhere herein, see, for example, Figures 1C-8D and their associated discussion.

[0045] The detection gas can include a noble gas, such as argon. In some embodiments, the detection gas can include a mixture of a noble gas and a quencher gas. Examples of such quencher gases include carbon dioxide or methane. Such quencher gases can include organic compounds such as methane (CH), ethane (C2H6), and carbon dioxide (CO2), as well as their chemical and physical equivalents to the noble gas used, based on their ability to effectively absorb energy and prevent secondary ionization. This detection gas is ionized by passing charged particles, resulting in electron-ion pairs. By using a mixture, the noble gas (such as argon) can be primarily responsible for this ionization. However, without a quencher gas, electrons can gain enough energy from the electric field to cause further ionization themselves, resulting in a runaway effect known as Townsend discharge. By including a quencher gas, the quencher gas can absorb some of the energy of these electrons, preventing them from causing further ionization and thereby avoiding the occurrence of an uncontrolled amplification cascade. By limiting secondary ionization, the quencher gas can ensure that the drift tube 100's response to charged particles is proportional and consistent. The quencher gas can help reduce background noise within the drift tube 100 or a detection system (e.g., system 900) that includes it, improving the detection system's signal-to-noise ratio and overall sensitivity. Continuous or excessive gas amplification can damage the drift tube 100, e.g., the anode wire 108. The quencher gas reduces this risk by reducing the electron energy. Over time, the detection gas within the drift tube 100 can degrade due to ionization and resulting chemical reactions. The quencher gas can help slow this degradation process. The quencher gas can affect the electron drift velocity, resulting in faster, more uniform drift times, which is beneficial for drift tubes 100 that require high time resolution.

[0046] The anode wire 108 may function as the anode. The anode wire 108 traverses the length of the housing tube 102 and may be securely connected to the end caps 104, 106 on each end of the housing tube 102. The first end cap 104 and the second end cap 106 may include a first anode connector and a second anode connector, respectively, electrically connected to one of the two wire terminals. Examples of the first and / or second anode connectors include 612 in FIG. 1C , 602 in FIG. 1D , 312 in FIGS. 4 and 7 , 812 in FIG. 8B , and 822 in FIG. 8D . The first anode connector may be electrically insulated from the first end cap 104 using an electrically insulating material. The second anode connector may be electrically insulated from the second end cap 106 using an electrically insulating material. Examples of applicable electrically insulating materials include at least one of glass or epoxy. The anode wire 108 may be substantially centered along the longitudinal axis X of the housing tube 102. One or each of the first end cap 104 and the second end cap 106 can include a tensioning mechanism 626 configured to apply tension to the anode wire 108. The tensioning mechanism 626 can be adjustable to apply a predetermined tension to the anode wire 108. For example, the tensioning mechanism 626 can include a spring-loaded assembly configured to compensate for thermal expansion and contraction of the anode wire 108. In some embodiments, at least one of the end caps 104 and 106 can include an integrated electrical feedthrough for connecting the anode wire 108 to an external power source and signal processing electronics.

[0047] The anode wire 108 can be made using one or more of a variety of conductive metals capable of receiving electrons generated by the reaction between the detection gas and muons entering the drift tube 100 from the upper atmosphere. The anode wire 108 can be made from a variety of materials, including, for example, copper, aluminum, tungsten (e.g., gold-plated tungsten), stainless steel, graphite, etc., or alloys thereof, or combinations thereof. The anode wire 108 can be, for example, a tungsten alloy or an alloy of other metals. The anode wire 108 can further conduct electrons throughout its length, and can be connected to a connector anode (not shown) from which an instrument can connect and receive a signal from the anode wire 108. One end cap 106 can further include a fill tube 420 (see FIGS. 6 and 7) through which gas enters the housing tube 102. The gas completely occupies the housing tube 102, displacing any atmospheric gases pre-existing within the housing tube 102. The gas is filled to a neutral pressure. The fill tube 420 may be sealed, e.g., crimped, after the detection gas fills the housing tube 102, sealing the gas within the exemplary drift tube 100. The exemplary drift tube 100 can then be assembled with a group of similar drift tubes to detect and measure charged particles for further interpretation and analysis.

[0048] Single uniform end cap Referring to FIG. 1C , one exemplary embodiment of the end cap 104 is circular, having a first side 602 and a second side 604, and may be constructed from, for example, aluminum. The end cap 104 can be any shape and will be described herein as circular for simplicity. The first side 602 is on the inner surface of the end cap 104 that faces the interior volume of the housing tube 102. The first end 602 can fit tightly with the reamed inner wall of the housing tube 102 to form a leak-proof seal when the end cap 104 and housing tube 102 are mated, and can be further fastened and sealed by various methods, including welding, adhesives, and other methods to prevent any leakage of gas. A surface of the first end 602 may reside within the housing tube 102 when mated.

[0049] The exemplary end cap 104 includes an anode connector 612 that extends through the end cap 104 from the first side 602 to the second side 604. The anode connector 612 may include a seal (not shown) on the exterior of the anode connector 612 facing the interior opening of the end cap 104. The seal may be established by molding the anode connector 612 into the end cap 104 during manufacturing, or the seal may be created after inserting the anode connector 612 into the end cap 104 using an appropriate sealant. For example, an epoxy seal that can respond to temperature changes may be used.

[0050] Referring now to FIG. 1D , the exemplary end cap described with respect to FIG. 1C can further include a fill tube 702 within the end cap 106, for example. The fill cap can be made from a variety of materials that allow access to the interior volume of the housing tube 102. For example, plastic or metal. In one embodiment, a copper alloy can be used. The fill tube 702 extends through the end cap 106 and can be sealed with a variety of suitable sealants. For example, an epoxy seal can be used that can respond to temperature fluctuations while maintaining an intact seal. In some embodiments, both end caps 104 and 106 can include a fill tube 702, or one end cap 104, 106 can include two fill tubes 702.

[0051] Male and female end cap variations In some embodiments, an exemplary male end cap 104 can be manufactured. FIGS. 2-4 show various views of the exemplary male end cap 104, with FIG. 4 being a DD cross-sectional view shown in FIG. 2. The end cap 104 is substantially circular with two ends. The end cap 104 may be constructed of, for example, aluminum. A first end 202 on the inner surface of the male end cap 104 may be larger than a second end 204 on the outer surface 206 of the end cap 104. The first end 202 may include an outer wall 208 surrounding the periphery of the first end 202. The outer wall 208 may be sized to fit tightly with the inner wall of the reamed housing tube 102 to form a leak-tight seal when the male end cap 104 and the housing tube 102 are mated together. The leak-proof seal can be reinforced by a solder seal or by chemical bonding to essentially ensure that gases inside the drift tube 100 do not escape to the atmosphere at the interface between the male end cap 104 and the housing tube 102. The surface of the first end 202 may then reside within the housing tube 102 when mated.

[0052] In some embodiments, the male end cap 104 includes a smaller cylindrical enclosure 210 on the second end 204 that extends from the base outer surface 206 of the second end 204 of the male end cap 104. The cylindrical enclosure 210 includes an inner surface 212. With reference to FIGS. 2-4 , the center of the first end 202 includes an opening 308. The opening 308 in the first end 202 is accessible through the second end 204 within a volume enclosed by the inner wall 212. The circumference of the inner wall 212 of the second end 204 may be substantially concentric with the opening 308 in the first end 202. In some embodiments, the male end cap 104 of a drift tube 100 can be configured to mate with the female end cap 106 of an adjacent drift tube 100 by connecting the second end 204 of the male end cap 104 to the end of the female end cap 106 (e.g., end 406 of side 404 as shown in FIG. 6 ).

[0053] In some embodiments, the end cap 104 may be further treated with sandblasting. For example, 220-grit aluminum oxide may be applied to the inner wall 212 and first end 202 of the end cap 104. The purpose of the sandblasting is to promote adhesion of an epoxy resin that may be included in the center of the opening, as described further below. The end cap 104 may be further sonicated, for example, in pure isopropanol to remove aluminum dust after sandblasting.

[0054] 2-4, in some embodiments, a coating can be applied to the inner wall of the opening 308 of the first end 202 where the epoxy resin 320 contacts the opening 308. The coating can include a chromate coating. The end cap 104 can then be dried on a substantially completely water-free surface for the required time. In some embodiments, a drying time of, for example, 90 minutes can be required. Drying times vary depending on various conditions; therefore, a 90-minute drying time is intended herein as one exemplary duration for substantially complete drying of the epoxy resin 320.

[0055] 2-4, in some embodiments, an epoxy holder 310 may be pressed, for example, by an arbor press, into the opening 308 of the first end 202. The epoxy holder 310 may further function as a wall extension to extend the inner wall 212 of the opening 308.

[0056] 2-4, in some embodiments, an anode connector 312 may be securely mounted within the opening 308 of the first end 202 on the outer surface within the inner wall of the second end 204. The anode connector 312 may comprise, for example, a tungsten alloy. The first end of the anode connector 312 extends outward from the outer surface 206 of the second end 204 of the end cap 104, and the second end of the anode connector 312 extends partially inward from the inner surface of the first end 202 of the end cap 104 into the interior of the housing tube 102 when mated.

[0057] The female end cap 106 can be manufactured similarly. Either or both of the male end cap 104 and the female end cap 106 can include at least one fill tube (e.g., fill tube 702, fill tube 420).

[0058] Epoxy Process Epoxy resin 320 is available from many manufacturers. For example, ResinLab EP 1350 can be used. ResinLab EP1350 is a two-part (e.g., resin as part A and hardener as part B) high-performance epoxy encapsulant designed for electronic potting and encapsulation. By way of example only, 3.25 parts of part A to 1 part of part B can be used by weight of the epoxy mixture. Air bubbles in the epoxy mixture can be removed by placing the mixture in a vacuum chamber for degassing. A substantially bubble-free epoxy mixture is beneficial for the end cap 104 to function properly within the drift tube 100.

[0059] In some embodiments, the epoxy mixture can be contained in a syringe, which can be attached to, for example, a pneumatic dispenser unit. The epoxy mixture can then be potted into the center of the opening 308 in the first end 202 of the end cap 104. The epoxy resin 320 can be applied so as not to cover the end of the anode connector 312, which can protrude slightly beyond the epoxy resin 320.

[0060] The end caps 104 may then be placed in an oven for curing. For example, in some exemplary embodiments, temperatures of approximately 90°C for 2 hours, 150°C for 3 hours, and 180°C for 3 hours may be used. Curing times may vary. These curing times and temperatures are provided here by way of example only and are not intended to be limiting. The end caps 104 may then be placed to cool, for example, at room temperature. Additionally, surface air bubbles may be removed.

[0061] The female end cap 106 can be manufactured similarly to the male end cap 104 .

[0062] Filling tube 1C-7, in some embodiments, the methods for manufacturing each of the male end cap 104 and the female end cap 106 are substantially the same, except that the female end cap 106 may further include a fill tube (e.g., a copper fill tube) 420. The female end cap 106 may further include a second opening 414 at a first end of the female end cap 106. The second opening 414 may be smaller than the opening 308, as shown in FIG. 7 (cross-sectional view of the female end cap 106 taken along line AA in FIG. 5). The opening 308 in FIG. 7 of the female end cap 106 is manufactured in the same or similar manner as described above with respect to the male end cap 104. The second opening 414 may extend from the outer surface on the second side 404 of the female end cap 106 through the inner surface (referred to as the inner or first side) 402 of the female end cap 106. A fill tube (e.g., copper tubing) 420 is inserted through the second opening 414, allowing gas to fill within the housing-tube 102 when mated with the end caps 104, 106. In some exemplary embodiments, the fill tube 420 may then be sealed with epoxy 320, as described above with respect to the male end cap 104. The epoxy 320 may be injected around the fill tube 420 on the inner surface 402 of the female end cap 106 and allowed to harden as described above.

[0063] In some embodiments, an anode wire 108 may be inserted through each anode connector 312 in each of the female 106 and male end caps 104. The male and female end caps 104, 106 are then mated to the housing tube 102, and the anode wire 108 traverses along the length of the housing tube 102 and is connected to each end cap 104, 106. Once mated, the wire 108 (e.g., a copper wire) is then tightly secured in each of the end caps 104, 106. The anode wire 108 may be substantially centered along (or along) the entire longitudinal axis X of the housing tube 102.

[0064] In some embodiments, the now assembled drift tube 100 can be filled with an inert gas through the fill tube 420. The gas fill can be monitored and continued until an appropriate pressure is reached within the housing tube 102. The fill tube 420 can then be crimped and sealed.

[0065] Final process The male and female end caps 104 , 106 may then be further sealed with a solder seal around the interface between the end caps 104 , 106 and the housing tube 102 .

[0066] The assembled drift tube 100 is then tested for leaks and other necessary tests.

[0067] The second threaded end 204 of each of the male end cap 104 and the female end cap 106 can be further connected to electronic circuitry (not shown) so that the electrical signal activated on the anode wire 108 as a result of the reaction between the charged particles and the inert gas can be received for measurement and analysis.

[0068] It is noted that much experimentation, analysis from deployments, and further research has been expended to determine the sensitivity and specifications for enhanced resolution of muons through the use of the subject drift tube.

[0069] Glass insulators in end caps In some implementations, the drift tube can use glass insulators in aluminum end caps, with the glass insulators selected to have a coefficient of thermal expansion (CTE) sufficiently close to that of the end caps to withstand the expansion and contraction of aluminum and copper over the serviceable temperature range.

[0070] 8A-8D show an example. This design provides a highly reliable airtight, moisture-proof seal at each end of the drift tube.

[0071] Reference is made to an exemplary female end cap 806 of this embodiment shown in FIGS. 8A and 8B. FIG. 8B is a cross-sectional view of the female end cap 806 taken from the EE side of FIG. 8A. A glass insulator 810 is used to connect the outer periphery of the anode connector 812 to the inner diameter of the end cap 806. The end cap 806 can include a cap body 814. This design keeps the anode connector 812 centered in the tube and the wiring centered in the tube wall. In an implementation, an aluminum fill tube 816 can be pressed into the end cap 806 (e.g., through an opening 818 on the end cap 806). The joint between the end cap 806 and the fill tube 816 can be formed using a suitable method, such as laser welding, to provide a robust joint that is leak-tight and resistant to damage from crimping forces applied to the fill tube during manufacturing.

[0072] Reference is made to an exemplary male end cap 804 of this embodiment shown in FIGS. 8C and 8D. FIG. 8D is a cross-sectional view of the male end cap 804 taken from the F-F direction shown in FIG. 8C. A glass insulator 820 may be used to connect the outer periphery of the anode connector 822 to the inner diameter of the end cap 804. The end cap 804 may include a cap body 824. This design holds the anode connector 822 in the center of the tube (e.g., the housing tube 102) and allows the anode wire (e.g., the anode wire 108) to be substantially centered within the housing tube (e.g., the housing tube 102). In implementations, the end caps 804 and / or 806 may be engaged to the tube wall of the housing tube 102 via welding without using any material metal therebetween. If desired, a nylon or other insulator 826 may be pressed into the inner diameter of the end caps 804 and / or 806 up to the glass insulator 820 to add additional electrical standoff and resist surface creepage / tracking.

[0073] The epoxy filling / bonding, replaced by the fiberglass bonding, significantly increases the hermetic sealing of the "end cap." Various aluminum alloy materials can be used in the implementation, including commercially available aluminum alloys 6061 and 5083. Aluminum alloy 6061 (Unified Numbering System (UNS) A96061) is a precipitation-hardened aluminum alloy containing magnesium and silicon. Commercially available 5083 aluminum alloy, containing magnesium and traces of manganese and chromium, can be used to create manufactured end caps, allowing the end caps to be directly welded to the tube (without the use of a weld ring), providing an improved hermetic sealing of the tube, shortening assembly time, and improving the welding process.

[0074] 9 illustrates a detection system according to some embodiments of the present document. The detection system 900 includes: a first set of position-sensing muon detectors 910 disposed on a first side of an object-holding area 930 to measure the position and direction of incident muons toward the object-holding area 930; a second set of position-sensing muon detectors 920 disposed on a second side of the object-holding area 930 opposite the first side to measure the position and direction of emitted muons exiting the object-holding area 930; and a signal processing unit 960 that receives data of the measurement signals of the emitted muons from the first set of position-sensing muon detectors and the second set of position-sensing muon detectors. The first and second sets of position-sensing detectors 910 and 920 can be configured and arranged to enable at least three charged particle position measurements in a first direction and at least three charged particle position measurements in a second direction different from the first direction. The system 900 can include a mounting framework 940 configured to support various components of the system 900. For example, mounting framework 940 may be configured to hold multiple drift tubes in a predetermined spatial arrangement within first and second sets of position-sensing detectors 910 and 920. In some embodiments, mounting framework 940 may include adjustable supports (e.g., spring-coupled supports) for aligning the drift tubes in the predetermined spatial arrangement. System 900 may include a data acquisition system 945 operatively connected to first and second sets of position-sensing detectors 910 and 920 to acquire signals related to the incoming and outgoing positions and directions of muons, or changes therein, that reflect the behavior and / or energy of the muons, which is associated with the material within object-holding region 930. Signal processing unit 960 may be configured to analyze the scattering behavior of the muons caused by scattering of the muons in the material within object-holding region 930 based on the measured incoming and outgoing positions and directions of the muons to obtain a tomographic profile or spatial distribution of scattering centers within object-holding region 930 and generate an acquired space muon image of the object, cargo, or vehicle under inspection.The left diagram (a) is a diagram of a penetrating cosmic ray, and the right diagram (b) is a diagram of a stationary cosmic ray. The system 900 may be configured to detect threats in an object, cargo, or vehicle under inspection.

[0075] The first and second sets of position sensing detectors 910 and 920 can each include multiple drift tubes. The multiple drift tubes may be coupled in a series connection. For example, as shown in FIG. 10 , system 900 includes a first drift tube 1010, a second drift tube 1020, and a third drift tube 1030 connected in series, each of which includes at least one of a male end cap or a female end cap, and the first, second, and third drift tubes are connected in series; the series connection is formed by the male end cap of the first drift tube 1010 being connected to the female end cap of the second drift tube 1020 at connection 1015, and the male end cap of the second drift tube 1020 being connected to the female end cap of the third drift tube 1030 at connection 1025. The male and female end caps may include complementary threads for a threaded connection, facilitating easy assembly and disassembly of the drift tubes 1010, 1020, and 1030. Connection between adjacent drift tubes is facilitated by the male and female end caps, with the male end cap of one drift tube designed to tightly mate with the female end cap of the adjacent drift tube. The male and female end caps may include a threaded connection mechanism, enabling a threaded assembly that provides both mechanical stability and ease of modular construction. The connection between the male and female end caps includes a sealing mechanism, such as an O-ring or gasket, to maintain an airtight seal within each drift tube. One or more of the end caps of the drift tubes 1010, 1020, and 1030 may include an adjustment mechanism (e.g., guide pin, groove) configured to achieve adjustment of the drift tube when connected. System 900 can include multiple drift tubes connected in series to achieve one or more technical benefits, including, for example, space efficiency and a larger effective detection area, while maintaining individual measurement capabilities. This configuration allows for accurate detection and tracking of particles over a larger volume.

[0076] In some embodiments, at least two of the first drift tube 1010, second drift tube 1020, and third drift tube 1030 can be electrically or fluidically isolated from one another. For example, the drift tubes 1010-1030 can be connected in series while each has its own separate anode wire and readout electronics 1110-1130, respectively, so that each drift tube is designed to independently measure the position and time of ionization events within its own volume, thereby enabling precise localization of these events. The readout electronics 1110-1130 can be operably connected to the drift tubes 1010-1030 at the end caps 1005 and 1035 and to the connections 1015 and 1025. Having individual anode wires and / or separate readout electronics helps maintain clarity and distinguishability of the signal from each drift tube, which is important for accurate data analysis. The anode wires can operate under high voltage to generate the electric fields necessary for the drift tubes to function. Independent wiring and / or separate readout electronics may allow for more precise control of this voltage within each drift tube. Separate anode wires and / or separate readout electronics may provide electrical isolation between drift tubes, reducing the risk of electrical interference and enabling more stable operation. Individual anode wires and / or separate readout electronics may provide greater modularity and flexibility in the design and configuration of the detection system. Drift tubes may be added, removed, or replaced without affecting the entire array. Using separate anode wires makes maintenance and repair of individual drift tubes easier. Failure of the wiring of one tube does not necessitate disassembly or destruction of the entire series. In some embodiments, two or more drift tubes may be electrically and / or fluidically connected to simplify setup (e.g., readout electronics setup).

[0077] In some embodiments, system 900 can include a portable power supply unit 950 for powering the first and second sets 910 and 920 of drift tubes, a data acquisition system 945, a signal processing unit 960, and communication between these and / or other components of system 900 or their external components. For example, portable power supply unit 950 can include one or more batteries, or solar panels, wind turbines, etc. Data acquisition system 945 and / or signal processing unit 960 can include wireless communication capabilities for remote data transmission and system control.

[0078] 11 illustrates a flowchart of a process for producing a drift tube according to some embodiments of the present document. Method 1100 of producing a drift tube may include: providing a housing tube, a first end cap, and a second end cap at 1110; disposing an anode connector in the opening of each of the first and second end caps at 1120; forming electrical isolation between the anode connector and the first or second end cap at 1130; inserting an anode wire through the housing tube, the first end cap, and the second end cap at 1140; bonding the first and second end caps to the two ends of the housing tube at 1150; securing the anode wire in each of the first and second end caps at 1160; filling the housing tube with a detection gas at 1170; and hermetically sealing the interfaces between the housing tube and the first and second end caps at 1180.

[0079] Method 1100 may include, at 1130, forming electrical isolation by applying an epoxy encapsulant within the respective openings of the first and second end caps around the anode connector; and curing the first and second end caps in an oven for a curing period. Method 1100 may further include degassing the epoxy encapsulant before applying it around the anode connector within the openings. Method 1100 may further include sandblasting the openings of the first and second end caps before applying the epoxy encapsulant within the openings. Method 1100 may further include removing dust from the openings by sonication after sandblasting and before applying the epoxy encapsulant within the openings.

[0080] The method 1100 may include, at 1130, forming electrical isolation by snugly fitting an electrical insulator between each anode connector and the first end cap or the second end cap in which the each anode connector is disposed. The electrical insulator may include a glass insulator.

[0081] Method 1100 may further include securing a fill tube to at least one of the first end cap or the second end cap. The detection gas may be filled into the housing tube through the fill tube. Method 1100 may include sealing the fill tube after filling with the detection gas, for example, by crimping, epoxy sealant, etc. For example, the fill tube may be deformed (e.g., manually by a user using a tool or automatically using a machine) such that an opening of the fill tube to the environment is sealed.

[0082] The disclosed techniques for drift tubes can be implemented in a variety of ways. Below are some example implementations:

[0083] Embodiment 1. A drift tube for detecting charged particles within said drift tube, comprising:

[0084] a housing tube extending along a longitudinal axis and constructed to include a first end configured as a cathode, a second end, and an interior surface;

[0085] a first end cap sealingly engaged with and electrically insulated from the first end of the housing tube;

[0086] a second end cap sealingly engaged with and electrically insulated from the second end of the housing tube;

[0087] a detector gas enclosed within the housing tube and configured to undergo ionization by the charged particles;

[0088] an anode wire having two wire terminals engaged to a first end cap and a second end cap, respectively, the anode wire adapted to traverse the housing tube along the longitudinal axis, the anode wire configured to detect ionization indicative of the trajectories of charged particles within the drift tube;

[0089] Embodiment 2. The drift tube of embodiment 1 or any one or more of the other embodiments disclosed herein, wherein the first end cap comprises a first anode connector electrically connected to one of the two wire terminals.

[0090] Embodiment 3. The drift tube of any one or more of embodiment 2 or any other embodiment disclosed herein, wherein the first anode connector is electrically insulated from the first end cap using an electrically insulating material.

[0091] Embodiment 4. The drift tube of embodiment 3 or any one or more of the other embodiments disclosed herein, wherein the electrically insulating material comprises at least one of glass or epoxy.

[0092] Embodiment 5. The drift tube of embodiment 2 or any one or more of the other embodiments disclosed herein, wherein the first anode connector extends into the housing tube.

[0093] Embodiment 6. The drift tube of any one or more of embodiment 2 or other embodiments disclosed herein, wherein the first anode connector extends beyond the first end cap and outside the housing tube.

[0094] Embodiment 7. The drift tube of embodiment 2 or any one or more of the other embodiments disclosed herein, comprising:

[0095] the first anode connector is electrically insulated from the first end cap using an insulator;

[0096] the first anode connector has an outer periphery facing the inner wall of the first end cap;

[0097] The insulator fits snugly between the outer periphery of the first anode connector and the inner wall of the first end cap.

[0098] Embodiment 8. The drift tube of embodiment 1 or any one or more of the other embodiments disclosed herein, wherein the anode wire is substantially centered along the longitudinal axis of the housing tube.

[0099] Embodiment 9. The drift tube of any one or more of embodiment 1 or other embodiments disclosed herein, wherein each of the first end cap and the second end cap comprises a tensioning mechanism configured to apply tension to the anode wire.

[0100] Embodiment 10. The drift tube of any one or more of embodiment 9 or other embodiments disclosed herein, wherein the tensioning mechanism is configured to be adjustable to provide a predetermined tension to the anode wire.

[0101] Embodiment 11. A drift tube as described in any one or more of embodiment 9 or other embodiments disclosed herein, wherein the tensioning mechanism comprises a spring-loaded assembly configured to compensate for thermal expansion and contraction of the anode wire.

[0102] Embodiment 12. The drift tube of any one or more of embodiment 1 or other embodiments disclosed herein, wherein at least one of the first end cap or the second end cap is made from at least one of aluminum fiber or carbon fiber.

[0103] Embodiment 13. Any one or more drift tubes of embodiment 1 or other embodiments disclosed herein, wherein one of the first end cap or the second end cap is a male end cap and the other is a female end cap designed to allow modular connection with an adjacent drift tube in a series configuration.

[0104] Embodiment 14. The drift tube of any one or more of embodiment 13 or other embodiments disclosed herein, wherein the male and female end caps include complementary threads for a screw-type connection.

[0105] Embodiment 15. The drift tube of any one or more of embodiment 1 or other embodiments disclosed herein further comprises a fill tube sealingly coupled to the first end cap through which a detection gas is filled into the housing tube.

[0106] Embodiment 16. The drift tube of any one or more of embodiment 1 or any other embodiment disclosed herein, wherein the detection gas comprises a noble gas.

[0107] Embodiment 17. The drift tube of embodiment 16 or any one or more of other embodiments disclosed herein, wherein the detection gas further comprises a quencher gas.

[0108] Embodiment 18. The drift tube of any one or more of embodiment 1 or other embodiments disclosed herein, wherein the housing tube is made from at least one of aluminum or carbon fiber.

[0109] Embodiment 19. The drift tube of embodiment 1 or any one or more of the other embodiments disclosed herein, wherein the anode wire is made from at least one of copper, aluminum, tungsten, stainless steel, graphite, or an alloy thereof.

[0110] Embodiment 20. The drift tube of one or more of embodiment 1 or other embodiments disclosed herein, wherein at least one of the first end cap or the second end cap includes an integrated electrical feedthrough for connecting the anode wire to an external power source and signal processing electronics.

[0111] Embodiment 21. A detection system comprising:

[0112] A plurality of drift tubes according to any one or more of embodiments 1-20 or other embodiments disclosed herein;

[0113] a mounting framework for holding multiple drift tubes in a predetermined spatial arrangement;

[0114] a data acquisition system operatively coupled to the plurality of drift tubes for acquiring and processing data from the drift tubes;

[0115] Embodiment 22. A detection system according to any one or more of embodiment 21 or other embodiments disclosed herein, comprising a first drift tube, a second drift tube, and a third drift tube, wherein:

[0116] each of the first drift tube, the second drift tube, and the third drift tube includes at least one of a male end cap or a female end cap;

[0117] The first, second, and third drift tubes are connected in series;

[0118] The series connection is formed by the male end cap of a first drift tube mated to the female end cap of a second drift tube and the male end cap of the second drift tube mated to the female end cap of a third drift tube.

[0119] Embodiment 23. A detection system of any one or more of implementations 22 or other implementations disclosed herein, wherein the male end cap of the first drift tube and the female end cap of the second drift tube include a threaded connection mechanism configured to enable a threaded connection of the first drift tube and the second drift tube.

[0120] Embodiment 24. The detection system of embodiment 22 or any one or more of the other embodiments disclosed herein, wherein at least two of the first drift tube, the second drift tube, and the third drift tube are electrically or fluidically isolated from each other.

[0121] Embodiment 25. A detection system of any one or more of implementations 21 or other implementations disclosed herein, wherein the end cap comprises an alignment feature configured to achieve alignment of the drift tube when connected.

[0122] Embodiment 26. A detection system of any one or more of implementations 21 or other implementations disclosed herein, wherein the mounting framework includes adjustable supports for aligning the drift tube in a predetermined spatial arrangement.

[0123] Embodiment 27. A detection system as described in any one or more of embodiment 21 or other embodiments disclosed herein, further comprising a portable power supply unit for powering the drift tube and the data acquisition system.

[0124] Embodiment 28. A detection system of any one or more of implementations 21 or other implementations disclosed herein, wherein the data acquisition system includes wireless communication capabilities for remote data transmission and system control.

[0125] Embodiment 29. A method of manufacturing a drift tube, comprising:

[0126] providing a housing tube, a first end cap, and a second end cap;

[0127] placing an anode connector in each opening of the first end cap and the second end cap;

[0128] forming electrical isolation between each anode connector and the first end cap or the second end cap in which the respective anode connector is disposed;

[0129] inserting an anode wire through the housing tube, the first end cap, and the second end cap;

[0130] coupling a first end cap and a second end cap to the two ends of the housing tube;

[0131] securing an anode wire in each of the first end cap and the second end cap;

[0132] Filling the housing tube with a detection gas;

[0133] The interfaces between the housing tube and the first and second end caps are hermetically sealed, respectively.

[0134] Embodiment 30 The method of embodiment 29, or any one or more of the other embodiments disclosed herein, wherein the step of forming electrical isolation includes:

[0135] applying an epoxy sealant around the anode connector within the openings in each of the first and second end caps;

[0136] curing the first end cap and the second end cap in an oven for a curing period;

[0137] Embodiment 31 The method of embodiment 30 or any one or more of the other embodiments disclosed herein, further comprising:

[0138] The epoxy encapsulant is degassed before being applied around the anode connector in the opening.

[0139] Embodiment 32 The method of any one or more of embodiment 30 or any other embodiment disclosed herein, further comprising:

[0140] The openings in the first and second end caps are sandblasted before applying an epoxy encapsulant into the openings.

[0141] Embodiment 33 The method of any one or more of embodiment 32 or any other embodiment disclosed herein, further comprising:

[0142] Ultrasonic treatment removes dust from the openings after sandblasting and before application of the epoxy encapsulant within the openings.

[0143] Embodiment 34 The method of embodiment 29 or any one or more of the other embodiments disclosed herein, wherein forming the electrical isolation comprises:

[0144] An electrical insulator is tightly fitted between each anode connector and the first or second end cap in which the respective anode connector is disposed.

[0145] Embodiment 35. The method of any one or more of embodiment 34 or other embodiments disclosed herein, wherein the electrical insulator comprises a glass insulator.

[0146] Embodiment 36 The method of any one or more of embodiment 29 or any other embodiment disclosed herein further comprises:

[0147] A fill tube is secured to at least one of the first end cap or the second end cap.

[0148] Embodiment 37. The method of embodiment 36 or any one or more of the other embodiments disclosed herein, wherein the detection gas is filled into the housing tube via a filling tube.

[0149] Embodiment 38. A method according to any one or more of embodiment 37 or other embodiments disclosed herein, further comprising sealing the filling tube after filling with the detection gas.

[0150] Embodiment 39. A muon tomography system for detecting threats in an object, cargo, or vehicle under inspection, comprising:

[0151] a first set of position-sensing muon detectors disposed on a first side of the object-holding region to measure the position and direction of incident muons toward the object-holding region;

[0152] a second set of position sensitive muon detectors disposed on a second side of the object-holding region opposite the first side for measuring positions and directions of emitted muons exiting the object-holding region, each of the first and second sets of position sensitive detectors constructed and arranged to enable at least three charged particle position measurements in a first direction and at least three charged particle position measurements in a second direction different from the first direction;

[0153] a signal processing unit configured to receive data of measurement signals of incident muons from a first set of position sensitive muon detectors and measurement signals of exiting muons from a second set of position sensitive muon detectors, and to analyze scattering behavior of the muons caused by scattering of the muons in material within the object holding region based on the measured incident and exit positions and directions of the muons to obtain a tomographic profile or spatial distribution of scattering centers within the object holding region and generate a resultant space muon image of the object, cargo, or vehicle under inspection, wherein each position sensitive muon detector includes at least one drift tube such as any one or more of embodiments 1-20 or other implementations disclosed herein.

[0154] Embodiment 40. A muon tomography system for detecting threats in an object, cargo, or vehicle under inspection using any one or more detection systems of embodiments 21-28 or other embodiments disclosed herein.

[0155] Embodiment 41. A method for detecting threats in an object, cargo, or vehicle under inspection using the detection system of any one or more of the embodiments disclosed herein.

[0156] It will be appreciated that this specification discloses techniques that can be implemented in various embodiments to enable UE-triggered reporting of beam report information. Specifically, events for beam reporting are defined based on monitoring measurement quality variations between beams at different time instances / beam groups or for different channels / RSs. A beam report is triggered when one of the predefined events occurs. Because event-triggered beam reporting is initiated by the UE upon request, reporting latency and uplink reporting resource consumption can be significantly reduced compared to conventional beam reporting methods.

[0157] The disclosed and other embodiments, modules, and functional operations described herein may be implemented in digital electronic circuitry, or computer software, firmware, or hardware, including the structures disclosed herein and their structural equivalents, or in one or more combinations thereof. The disclosed and other embodiments may be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by or to control the operation of a data processing apparatus. The computer-readable medium may be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter providing a machine-readable propagated signal, or one or more combinations thereof. The term "data processing apparatus" encompasses all apparatuses, devices, and machines for processing data, including, by way of example, a programmable processor, a computer, or multiple processors or computers. In addition to hardware, an apparatus may include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or one or more combinations thereof. A propagated signal is an artificially generated signal, for example, a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to an appropriate receiving device.

[0158] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored as part of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple cooperating files (e.g., files that store one or more modules, subprograms, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers located at one site or distributed across multiple sites and interconnected by a communications network.

[0159] The processes and logic flows described herein may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and an apparatus may be implemented as, special purpose logic circuitry, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0160] Processors suitable for executing a computer program include, by way of example, both general-purpose and special-purpose microprocessors, and any one or more processors of any kind of digital computer. Typically, a processor receives instructions and data from a read-only memory or a random-access memory, or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Typically, a computer is also operatively coupled to receive data from, transfer data to, or both of, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical, or optical disks. However, a computer need not have such devices. Computer-readable media suitable for storing computer program instructions and data include, by way of example, all forms of non-volatile memory, media, and memory devices, including semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices, magnetic disks, e.g., internal hard disks or removable disks, magneto-optical disks, and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by, or incorporated in, special-purpose logic circuitry.

[0161] Some of the embodiments described herein are described in the general context of a method or process, which in one embodiment may be implemented by a computer program product embodied in a computer-readable medium that includes computer-executable instructions, such as program code, executed by computers in a network environment. Computer-readable media includes removable and non-removable storage devices, such as read-only memory (ROM), random-access memory (RAM), compact discs (CDs), digital multimedia discs (DVDs), and the like. Thus, computer-readable media may include non-transitory storage media. Generally, program modules may include routines, programs, objects, components, and data structures that perform particular tasks or implement particular abstract data types. Computer- or processor-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. A particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

[0162] Some of the disclosed embodiments may be implemented as devices or modules using hardware circuits, software, or a combination thereof. For example, a hardware circuit implementation may include discrete analog and / or digital components integrated, for example, as part of a printed circuit board. Alternatively, or additionally, the disclosed components or modules may be implemented as application-specific integrated circuits (ASICs) and / or field-programmable gate array (FPGA) devices. Some implementations may additionally or alternatively include a digital signal processor (DSP), which is a dedicated microprocessor with an architecture optimized for the operational needs of digital signal processing associated with the disclosed functionality of the present application. Similarly, various components or subcomponents within each module may be implemented in software, hardware, or firmware. Solar cell modules and / or connectivity between components within solar cell modules may be provided using any one of connection methods and mediums known in the art, including, but not limited to, communication via the Internet, wired, or wireless networks using appropriate protocols.

[0163] While this patent document contains many details, these should not be construed as limiting the scope of any invention or what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of a particular invention. Certain features described in this patent document in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as working in particular combinations, even as originally claimed, one or more features from a claimed combination may in some cases be separated from the combination, and the claimed combination may be directed to subcombinations or variations of the subcombination.

[0164] Similarly, although operations are depicted in the figures in a particular order, this should not be understood as requiring such operations to be performed in the particular order shown, or in any sequential order, or that all of the illustrated operations be performed, to achieve desired results. Furthermore, the separation of various system components in the embodiments described in this patent document should not be understood as requiring such separation in all embodiments.

[0165] Only some implementations and examples are described; other implementations, extensions, and variations can be made based on what is described and illustrated in this patent document.

Claims

1. A drift tube for detecting charged particles therein, a housing tube configured to extend along a longitudinal axis and include a first end, a second end, and an interior surface configured as a cathode; a first end cap sealingly engaging the first end of the housing tube and electrically insulated from the first end; a second end cap sealingly engaging the second end of the housing tube and electrically insulated from the second end; a detection gas enclosed within the housing tube and configured to undergo ionization by the charged particles; an anode wire having two wire terminals engaged to the first end cap and the second end cap, respectively, the anode wire traversing the housing tube along the longitudinal axis, the anode wire configured to detect the ionization indicative of the trajectories of the charged particles within the drift tube; A drift tube comprising:

2. The drift tube of claim 1 , wherein the first end cap comprises a first anode connector electrically connected to one of the two wire terminals.

3. The drift tube of claim 2 , wherein the first anode connector is electrically insulated from the first end cap using an electrically insulating material.

4. The drift tube of claim 3 , wherein the electrically insulating material comprises at least one of glass or epoxy.

5. The drift tube of claim 2 , wherein the first anode connector extends into the housing tube.

6. The drift tube of claim 2 , wherein the first anode connector extends beyond the first end cap and outside the housing tube.

7. the first anode connector is electrically insulated from the first end cap using an insulator; the first anode connector has an outer periphery facing the inner wall of the first end cap; the insulator fits snugly between the outer periphery of the first anode connector and the inner wall of the first end cap. The drift tube of claim 2.

8. The drift tube of claim 1 , wherein the anode wire is substantially centered along the longitudinal axis of the housing tube.

9. The drift tube of claim 1 , wherein the first end cap and the second end cap each comprise a tensioning mechanism configured to apply tension to the anode wire.

10. The drift tube of claim 9 , wherein the tensioning mechanism is adjustable to maintain a predetermined tension on the anode wire.

11. The drift tube of claim 9 , wherein the tensioning mechanism comprises a spring-loaded assembly configured to compensate for thermal expansion and contraction of the anode wire.

12. The drift tube of claim 1 , wherein at least one of the first end cap or the second end cap is made of at least one of aluminum or carbon fiber.

13. 10. The drift tube of claim 1, wherein one of the first end cap or the second end cap is a male end cap and the other is a female end cap designed to allow modular connection with an adjacent drift tube in an in-line configuration.

14. The drift tube of claim 13 , wherein the male end cap and the female end cap include complementary threads for a threaded connection.

15. 2. The drift tube of claim 1, further comprising a fill tube hermetically coupled to the first end cap, the detector gas being filled into the housing tube through the first end cap.

16. The drift tube of claim 1 , wherein the detection gas comprises a noble gas.

17. The drift tube of claim 16 , wherein the detection gas further comprises a quencher gas.

18. The drift tube of claim 1 , wherein the housing tube is made from at least one of aluminum or carbon fiber.

19. The drift tube of claim 1 , wherein the anode wire is made from at least one of copper, aluminum, tungsten, stainless steel, graphite, or alloys thereof.

20. 1. A detection system comprising: A plurality of drift tubes according to any one of claims 1 to 19; a mounting framework that holds the plurality of drift tubes in a predetermined spatial arrangement; a data acquisition system operatively coupled to the plurality of drift tubes to collect and process data from the drift tubes; A detection system comprising:

21. a first drift tube, a second drift tube, and a third drift tube; each of the first drift tube, the second drift tube, and the third drift tube includes at least one of a male end cap or a female end cap; the first drift tube, the second drift tube, and the third drift tube are connected in series; the series connection is formed by the male end cap of the first drift tube mated to the female end cap of the second drift tube, and the male end cap of the second drift tube mated to the female end cap of the third drift tube; 21. The detection system of claim 20.

22. 22. The detection system of claim 21 , wherein the male end cap of the first drift tube and the female end cap of the second drift tube include a threaded connection mechanism configured to enable a threaded connection of the first drift tube and the second drift tube.

23. 22. The detection system of claim 21, wherein at least two of the first drift tube, the second drift tube, and the third drift tube are electrically or fluidically isolated from one another.

24. 21. The detection system of claim 20, wherein the end caps comprise alignment features configured to achieve alignment of the drift tube when connected.

25. 21. The detection system of claim 20, wherein the mounting framework includes adjustable supports for aligning the drift tubes in the predetermined spatial arrangement.

26. 21. The detection system of claim 20, further comprising a portable power unit for powering the drift tube and the data acquisition system.

27. 21. The detection system of claim 20, wherein the data acquisition system has wireless communication capabilities for remote data transmission and system control.

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