Trigger system and method for monitoring land traffic

Abstract

A method and a system (101) for monitoring land traffic in an area (103) are disclosed. The method comprises positioning one or more muon detectors (120, 121) in and / or below the area (103), measuring muon flux time series data by the one or more muon detectors (120, 121), processing the muon flux time series data to detect motion in the area (103), determining a motion detection result based on the processing, and causing detonation of one or more explosives based on the motion detection result. The method and system can be particularly applied in the defense sector where the system (101) acts as trigger system for detonating the explosives of a land mine or an anti-tank mine.

Description

[0001] TRIGGER SYSTEM AND METHOD FOR MONITORING LAND TRAFFIC

[0002] Technical Field

[0003] The present solution generally relates to a trigger system and a method for monitoring land traffic.

[0004] Background

[0005] Motion detectors for large moving objects, such as vehicles, aircraft, or large machinery, are designed to detect and / or track movement over significant distances and across various environmental conditions. Such detectors are used in applications like industrial automation, traffic management, security systems, as well as defensive applications. Some examples of motion detectors for detecting large moving objects include radar sensors, lidar sensors, infrared (IR) sensors, ultrasonic sensors, video-based sensors with computer vision analysis, inductive loop sensors embedded e.g. in a road surface, microwave sensors, and photoelectric sensors.

[0006] Many of the above-mentioned motion detectors suffer from various disadvantages. For example, radar sensors may be costly and be affected by interference from other radar devices. Lidar has a high cost and technical complexity, and its performance may be affected by adverse weather conditions like heavy rain or fog. IR has a limited range compared to radar and lidar and its performance may be affected by environmental temperature changes and sunlight. Ultrasonic sensors also have a limited detection range and their performance may be affected by air turbulence and temperature variations. Videobased approaches may be affected by lighting conditions and weather and require substantial computational resources for real-time processing. Installation and maintenance of inductive loop sensors requires road surface modifications, and the performance of such sensors is limited to specific detection zones. Microwave sensors are expensive and can be affected by interference from other microwave devices. Photoelectric sensors have issues with objects blocking the path of light which may cause false positives or negatives, interference from ambient light, and a limited range compared to other motion detection technologies. Further, the presence and / or operation of many of the above-mentioned motion detectors may be detected using further sensors, which is a disadvantage in sensitive application areas such as in the defense sector. Summary of the Invention

[0007] A method of monitoring land traffic in an area comprises positioning one or more muon detectors in and / or below the area, measuring muon flux time series data by the one or more muon detectors, processing the muon flux time series data to detect motion in the area, determining a motion detection result based on the processing, and causing detonation of one or more explosives based on the motion detection result.

[0008] At least one muon detector of the one or more muon detectors may be contained in an auger, and the positioning may comprise drilling the auger containing the at least one muon detector into ground below the area.

[0009] The method may comprise positioning at least one of the one or more muon detectors to a depth of at least 0.5 meters, preferably at least 0.75 meters, most preferably at least 1 meter in the ground below the area.

[0010] The one or more muon detectors may comprise at least two muon detectors, and the method may comprise positioning the at least two muon detectors to a distance from each other.

[0011] The area may comprise at least a part of a natural formation, such as a field, a forest, a meadow, a marsh, a swamp, a shore, a riverbank, and / or a park.

[0012] The area may comprise at least a part of a manmade formation, such as a road, a railroad, a yard, a parking lot, a border zone, an airport, and / or a clearing.

[0013] The muon flux time series data may comprise a total muon flux data and / or an angle of incidence data of the detected muons.

[0014] The processing may comprise comparing the measured muon flux time series data to one or more detection thresholds, such as a velocity threshold and / or a density threshold, and, if the one or more detection thresholds are met, determining a positive motion detection result.

[0015] The method may further comprise transmitting the muon flux time series data to a processing device by at least one of the one or more muon detectors, receiving the muon flux time series data by the processing device, and performing the processing and determining the motion detection result by the processing device.

[0016] The one or more muon detectors may comprise at least two muon detectors, and the method may comprise receiving the muon flux time series data from the at least two muon detectors by the processing device. Furthermore, processing may comprise combining, by the processing device, the muon flux time series data of the at least two muon detectors to determine the motion detection result.

[0017] A trigger system for monitoring land traffic in an area comprises one or more muon detectors configured to be positioned in and / or below the area and to measure muon flux time series data, and one or more processing devices configured to detect motion in the area by processing the muon flux data, determine a motion detection result based on the processing, and cause detonation of one or more explosives based on the motion detection result.

[0018] The one or more processing devices may comprise at least one processor, at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause performance of the one or more processing devices.

[0019] The trigger system may comprise the one or more explosives.

[0020] The trigger system may comprise one or more augers that contain the one or more muon detectors.

[0021] The one or more muon detectors may be configured to measure the total muon flux and / or the angle of incidence of the detected muons.

[0022] The one or more muon detectors may be configured to transmit the muon flux time series data to the one or more processing devices, and the one or more processing devices may be configured to transmit a trigger command to one or more trigger devices which may be coupled to the one or more explosives to cause the detonation of the one or more explosives.

[0023] The trigger system may comprise a trigger device coupled to the one or more processing devices and configured to be coupled to the one or more explosives, wherein the trigger system may be integrated to a single apparatus.

[0024] The advantages of the present invention compared to the methods and systems of the prior art are, for example:

[0025] • Independent of any current methods,

[0026] • The use of the invention is non-invasive as muon radiation is a part of natural background radiation,

[0027] • The use of the invention is difficult to detect as muon radiation is a part of natural background radiation The system may be passive and thus may not emit sound, radiation, or the like

[0028] Almost impossible to interfere as cosmic-ray induced muons cannot be stopped or reflected by any practical known means.

[0029] Brief Description of the Drawings

[0030] Fig. 1 illustrates an example scenario of monitoring land traffic by a system;

[0031] Fig. 2 is a flow chart illustrating embodiments of a method;

[0032] Fig. 3 is a block diagram illustrating embodiments of an apparatus and the system; and

[0033] Fig. 4 illustrates an embodiment of the system.

[0034] Detailed Description of the Invention

[0035] The following description and drawings are illustrative and are not to be construed as unnecessarily limiting. The specific details are provided for a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. In this specification, reference to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. References to an embodiment can be, but are not necessarily, references to the same embodiment in the present disclosure.

[0036] The present disclosure relates to a method and a (trigger) system for detecting and monitoring traffic, and motion of massive object in general, on land. The objects may include trains, trucks, armored vehicles including tanks, artillery weapons, unmanned vehicles, landing ships, boats, or airplanes, bodies of water or any other liquid flooding on the monitored land area, rockslide, mudflow, or avalanche. For improved detection performance, the objects may be at least 4 or 5 meters long along one dimension. In addition, or alternatively, to monitoring land traffic such as road and railroad traffic, the method and system are not limited to this purpose but are also suitable for other purposes, including border security, or as a warning / emergency system for natural catastrophes, such as flooding, rockslides, or avalanches.

[0037] The invention is based on detecting cosmic-ray-induced muons, which are generated in the upper part of the Earth’s atmosphere. Such high-energy atmospheric muons are heavy, charged, electron-like particles with excellent penetration abilities through various materials. However, muon flux is known to attenuate depending on the density of the material the muons pass through. This attenuation can be detected and measured by muon detectors and the associated processing and analyzing devices. Therefore, cosmic-ray-induced muons may be employed to detect objects on land having structures with higher (or lower) densities than the medium the object occupies in the detection area. In addition, the muon detectors installed below the surface of the area can detect underground objects that have higher or lower density than the soil in the monitored area. The objects may comprise a structure that has a higher density than the surrounding medium, a structure that has a lower density than the surrounding medium, or a combination of both, i.e., the object comprises a first structure with a lower density than the surrounding medium and a second structure with a higher density than the surrounding medium. In either case, both the detectable underground objects and the detectable objects on land attenuate muons at different rates than the surrounding soil and / or the surrounding atmosphere, which may be detected in one or a plurality of muon detectors placed below the object and / or to the object's side.

[0038] An example scenario of monitoring land traffic in an area is presented in Fig. 1. A related method of monitoring land traffic in an area is presented in Fig. 2 and a system for monitoring land traffic in the area is shown in Figs. 1 , 3, and 4.

[0039] Referring now to Fig. 1 , the system 101 , which is preferably a trigger system, is configured to perform at least some of the steps of the method of Fig. 2. The system 101 comprises one or more muon detectors 120, 121 and one or more processing devices. In the system shown in Fig. 1 , the processing device(s) may be integrated with the one or more muon detectors 120, 121 , an external unit 130, and / or a user apparatus 140. The one or more muon detectors 120, 121 are configured to be positioned in and / or below the area 103, and to measure muon flux time series data. The one or more processing devices are configured to detect motion in the area by processing the muon flux data and to determine a motion detection result based on the processing. Optionally, when the system 101 is a trigger system, the one or more processing devices are configured to cause detonation of one or more explosives based on the motion detection result.

[0040] The advantages of the present invention compared to the methods and systems of the prior art are, for example:

[0041] Independent of any current methods, The use of the invention is non-invasive as muon radiation is a part of natural background radiation,

[0042] • The use of the invention is difficult to detect as muon radiation is a part of natural background radiation

[0043] • The system may be passive and thus may not emit sound, radiation, or the like

[0044] • Almost impossible to interfere as cosmic-ray induced muons cannot be stopped or reflected by any practical known means

[0045] Referring now to Figs. 1 and 2, the method may comprise positioning 200 the one or more muon detectors 120, 121 in and / or below any type of an area 103 or any combination of areas, such as those listed hereinbelow. In the example shown in Fig. 1 , a first muon detector 120 is positioned in the area 103, more specifically at the bottom of the area on a ground surface 105. A second muon detector 121 is positioned below the area 103, more specifically below the ground surface 105. Combining positioning muon detectors both in and below a monitored area has a benefit of hiding one or more muon detectors when e.g. a hostile party is dismantling, removing, displacing, and / or destroying visible one or more muon detectors. While detectors (visibly) positioned in the area may be easy to move or tamper with, detectors below the area (i.e. underground) are more difficult to notice and may be missed due to the distraction provided by the detectors positioned within the area. When detectors are positioned in the area, the bottom of the area, e.g. the ground surface 105, provides for the widest detection angle. Even broader angles are available below the area. However, the skilled person will appreciate that the positioning 200 may be excluded from the method, e.g. if the muon detectors 120, 121 are already positioned below the monitored area 103 and / or on a bottom of the area 104. This might be the case if existing muon detectors positioned in the area for e.g. research purposes are to be redeployed for the method of the invention.

[0046] The area 103 may refer to e.g. a zone or region. It may extend along a surface of the area, such as along the ground surface in a forest, and / or any other land type listed below. The area may also comprise the atmosphere and / or other objects within the area and the top of the area may be limited by the practical resolution of the one or more muon detectors. The sides of the area may be limited by the maximal detectable muon angle of incidence, i.e. solid angle, of the peripheral muon detector(s) of the one or more muon detectors positioned in and / or below the area. The area may extend into the ground, especially when underground land vehicles are a target of the monitoring. The invention has applications in any type of land area. The area may comprise at least a part of a natural formation, such as a field, a forest, a meadow, a marsh, a swamp, a shore, a riverbank, and / or a park. For example, the invention can be deployed detect and monitor the immediate vicinity of a shore or a riverbank, i.e. an interface between land and a body of water such as ocean, sea, lake, canal, or a river. Furthermore, the area may comprise either as a part or parts of the aforementioned land types or solely at least a part of a manmade formation, such as a road, a railroad, a yard, a parking lot, a border zone, an airport, and / or a clearing.

[0047] The muon detectors 120, 121 may comprise e.g. plastic scintillation detectors, gas-based muon detectors, drift chambers, micromesh gaseous structures, resistive plate chambers, multiwire proportional chambers, chemical nuclear emulsions, or muon detectors of any other type suitable for positioning on or at least partially below the ground surface 105. The invention may be implemented with active, or preferably passive muon detection. In an active implementation, a muon generator is included and configured to emit muons to the one or more muon detectors. In contrast, the passive implementation relies on naturally occurring muons.

[0048] Muons produced by cosmic rays travel along trajectories 106-111 from above towards the monitored area 103. The muon flux is attenuated in different amounts by different densities. Some of the muons, such as muons with trajectories 106 and 109, may decay before reaching any of the muon detectors 120, 121. The muons 107, 110 that arrive at the muon detectors 120, 121 are detected by the muon detectors. The detections are measured as muon flux time series data representing detections over time.

[0049] The detectors may be positioned in any suitable position from the land surface 105 to the ground underneath a land area 103. For example, the detectors 120, 121 may be positioned to a depth of at least 0.5 meters, preferably at least 0.75 meters, most preferably at least 1 meter in the ground below the area 103. An advantage of muon detectors placed deep underground is that they are able to monitor a larger area or volume above the detector compared to detectors positioned at shallower depths or on the ground surface 105, especially when also configured to measure muon angles of incidence 112A-112C. In addition, muon detectors placed deep underground are more difficult to detect and to remove or displace by hostile parties (using e.g. mine clearing vehicles) or natural phenomena (e.g. landslides). The above-mentioned depths correspond to maximum clearing depths of some mine clearing vehicles. The area 103 may comprise at least a part of a natural formation, such as a field, a forest, a meadow, a marsh, a swamp, a shore, a riverbank, and / or a park. Furthermore, the area may comprise either as a part or parts of the aforementioned land types or solely at least a part of a manmade formation, such as a road, a railroad, a yard, a parking lot, a border zone, an airport, and / or a clearing.

[0050] In an embodiment discussed in more detail below with reference to Fig. 4, at least one muon detector 120, 121 of the one or more muon detectors is contained in an auger, and the positioning 200 comprises drilling the auger containing the at least one muon detector into ground below the area 103.

[0051] Once the one or more muon detectors are positioned and optionally activated either remotely or by the user positioning the muon detectors, they measure 202 (see Fig. 2) muon flux time series data of the incident muons 107, 110. The muon flux time series data may comprise total muon flux data and / or angle of incidence data of the detected muons.

[0052] Muon flux expresses the number of muons passing through a given area (e.g., the crosssection of the muon detector volume) within a given time period. Muon flux therefore represents the number of muons detected by a particular detector per unit time and it can be expressed in units of muons per square meter per second (m“2s“1). Thus, the muons that annihilate either in atmosphere (muon 106), in the object (muon 109), or in the ground (muon 111 ), or the muons 108 that pass muon detectors 120, 121 , do not contribute to the flux. Other operating alternative is using muon (counting) rate, which is usually expressed in units of counts per second (cps) or events per second (eps). The invention may be implemented using the muon (counting) rate or muon flux with appropriate measures in the data processing to account for the choice of the unit.

[0053] The total muon flux data expresses the total amount of muons incident on a muon detector per unit area per unit time. A change in the total muon flux may indicate a change in the density of the medium the incident muons are passing through before hitting the detector, thus indicating motion of an object in the monitoring area of the muon detector. A medium, such as iron, denser than the surrounding medium it replaces, such as air, absorbs lower energy muons 109, although high energy muon 110 may still penetrate through the dense medium and be detected by a muon detector 121. Thus, in this case, the total muon flux decreases. Temporal information of a change in the total muon flux data may indicate the moment the object moves in and / or out of the detection area of the muon detector, and in can also be utilized to calculate the speed of the object, e.g. based on the rate the total muon flux changes. The muon angle of incidence data expresses the angle 112A-112C at which a muon hits a muon detector, and it may provide further information e.g. on the velocity of a detected object. The angles 112A-112C may comprise inclination angle and / or azimuthal angle to determine the direction of the incident muons, thus revealing the direction of motion in the monitoring area of the muon detector when the muon flux data is processed. The speed of the motion can be calculated e.g. from the rate of change in the muon angle of incidence data. In the example scenario of Fig. 1 , the incident muons 107 and 110 with angles of incidence 112A and 112C, respectively, are detected, whereas the incident muon 109 with a projected angle of incidence 112B is absorbed by the object 102 moving in the monitored area of the muon detector 121. Processing the measured muon angle of incidence data may determinate the direction and speed, i.e. the velocity v, of the motion of the object 102. The muon angle of incidence may be measured utilizing e.g. an apparatus 401 of Fig. 4 comprising one or more muon detectors, wherein the muon detector comprises two muon detector plates 402 and 403 facing each other and having a distance 404, which determines the solid angle. A muon angle of incidence 112A-112C is measured by detecting the position of an incident muon in the upper plate 402 and subsequently the position of the (most probably) same incident muon in the lower plate 403 and calculating the muon angle of incidence based on these positions and the distance 404.

[0054] The muon flux time series data may be transmitted by the muon detector(s) 120, 121 to the processing device, e.g. when the processing device is or is integrated into the external unit 130 and / or the user apparatus 140. The processing device may be correspondingly configured to receive the muon flux time series data. The processing device, and one or more of the muon detectors may alternatively or additionally be directly coupled to each other or comprised in the same device. Connections between the muon detectors 120, 121 , one or more external units 130 and one or more user apparatuses 140 may be implemented with wired and / or wireless connections, such as electronic, cellular, satellite, acoustic, lightemitting diode (LED), laser-based, or fiber optic connections.

[0055] The processing device is configured to process the muon flux time series data measured by the muon detector(s). When an object 102 or a plurality of objects pass(es) or moves and stops over one or more muon detectors 120, 121 , the muon flux detected by the detector(s) is altered, and the processing device detects the object(s) 102 and / or their motion in the area 103 by processing 204 the muon flux time series data. The processing device determines 208 a motion detection result based on the processing 204 of the muon flux time series data. A motion detection result may be negative, i.e. the processing 204 of the muon flux time series data does not indicate motion in the area or at least detection threshold is not met, or a motion detection result may be positive, i.e. the processing 204 of the muon flux data does indicate motion in the area and at least one detection threshold is met. A positive motion detection result may comprise further processed information about the detected motion, such as the computed velocity v of the detected motion.

[0056] The method may further comprise causing, e.g. triggering, detonation 210 of one or more explosives based on the (positive) motion detection result by e.g. a trigger system 101. Triggering 210 may be a subject of counting the amount of positive motion detection results, such that a processing device sends a trigger command only if the amount of positive motion results within a time frame meets a threshold value. The trigger system 101 may comprise the one or more explosives.

[0057] Fig. 3 is a block diagram illustrating embodiments of the processing device 100 and the system 150. The processing device 100, which may be or form part of e.g., one or more of the muon detectors 120, 121 , the external unit 130, or the user apparatus 140 of Fig. 1 , is configured to perform computer-implemented steps of the method of Fig. 2 or any of its embodiments. In other words, the processing device 100 comprises means for performing the computer-implemented steps of the method of Fig. 2 or any of its embodiments. Referring again to Fig. 3, the means may comprise at least one processor 10, at least one memory 20 including computer program code 22, wherein the at least one memory 20 and the computer program code 22 are configured to, with the at least one processor 10, cause the processing device 100 to perform the computer-implemented steps of the method of Fig. 2 or any of its embodiments. These computer-implemented steps may include one or more of steps 204, 206, 208, 210 of Fig. 2, for example.

[0058] The processing device 100 of Fig. 3 may further comprise a communication interface 40, comprising, e.g., a transmitter (TX), a receiver (RX), and / or a transceiver. The communication interface may be used for communication between the processing device 100 and one or more (external) muon detectors 50, a user device 60, and / or one or more (external) trigger devices 70. When the processing device 100 of Fig. 3 corresponds to the external unit 130 of Fig. 1 , the muon detectors 50, 52 of Fig. 3 may correspond to the detectors 120, 121 of Fig. 1 , and the user device 60 of Fig. 3 to the user apparatus 140 of Fig. 1. The one or more muon detectors 50, the user device 60, and / or the one or more trigger devices 70 may be configured to communicate with the processing device 100 using respective communication interfaces 51 , 61 , 71 that may be similar to the communication interface 40 of the processing device 100 described above. As discussed in relation to FIG. 1 , the communication connections between the processing device 100, the muon detectors 50, the user device 60, and the trigger devices 70 of Fig. 3 may be implemented with wired or wireless connections, such as electronic, cellular, satellite, acoustic, LED, laser-based, or fiber optic connections.

[0059] Referring now to Fig. 1 and Fig. 3, in general, communication between the muon detectors 120, 121 , the external unit 130, and / or the user apparatus 140 of Fig. 1 , and between the muon detectors 50, the processing device 100, the trigger device(s) 70, and the user device 60 of Fig. 3 may be performed in several ways. For example, one or more of the above- mentioned devices may be configured to periodically transmit status information comprising, e.g., the muon flux time series data and / or the motion detection result. The transmission interval may be 1 day or 1 week, for example. Alternatively, or additionally, the transmission may be performed at random and / or upon request.

[0060] Alternatively, or additionally to communicating with the external muon detectors 50 and the user device 60, the processing device 100 may comprise or be directly coupled to one or more muon detectors 52, a user interface 62, and / or one or more trigger devices 72. One or more of these components may thus be integrated into a single apparatus.

[0061] The user interface 62 may comprise one or more output devices, such as one or more displays, one or more speakers, and / or one or more haptic output devices. Additionally, the user interface may comprise one or more input devices, such as one or more microphones, keyboards, touch panels, buttons, or switches. The user device 60 may comprise a similar user interface as the user interface 62 described above.

[0062] While the external muon detectors 50 have been described above together with the user device 60 and the external trigger device(s) 70, and the muon detectors 52 together with the user interface 62 and the trigger device(s) 72, other combinations of the features shown in Fig. 3 are also possible, such as: the processing device 100 with muon detectors 52, wherein the processing device 100 is configured to communicate with external user device 60; the processing device 100 with user interface 62, wherein the processing device 100 is configured to communicate with external muon detectors 50; the processing device 100 with trigger devices 72, wherein the processing device 100 is configured to communicate with external muon detectors 50; the processing device 100 with muon detectors 52, wherein the processing device 100 is configured to communicate with external trigger devices 70; and combinations of the above. According to another aspect, a computer program product comprises computer program code 22 configured to, when executed by at least one processor 10, cause the processing device 100 or the system 150 to perform (computer-implemented steps of) the method of Fig. 2 or any one of its embodiments. The computer program product may refer to a software as shown in FIG. 3 that may include at least one selected from a computer program, computer code, computer script, computer macro, computer library, algorithm or user interface.

[0063] In an embodiment, the computer program product is embodied on a computer-readable medium 30. In an embodiment, the computer-readable medium 30 is a non-transitory computer-readable medium.

[0064] The system 150 of Fig. 3 comprises at least the processing device 100 and the one or more muon detectors 50, 52. Preferably, the system also comprises the one or more trigger devices 70, 72. In addition, the system may comprise other components such as the user device 60. The system may comprise, e.g., one or more power supplies, such as one or more batteries, solar panels, windmills, and / or mains power supplies, which are integrated into the processing device, the muon detectors, and / or the user device, and / or as separate components of the system. The system may further comprise communication means such as cables connecting the components of the system.

[0065] Details of the method performed by the processing device 100 (or system 150) are now described with reference to Fig. 1 and Fig. 3. The processing device obtains the muon flux time series data e.g. by reading the muon flux time series data from the memory of the processing device, such as from a database 24 (see Fig. 3) stored in the at least one memory 20. Alternatively, or additionally, the muon flux time series data may be obtained from the one or more muon detectors 50 via the communication interface 40 or directly from the one or more muon detectors 52 coupled to or comprised in the processing device. The muon flux time series data may be transmitted via one or more intermediate devices; for example, the external unit 130 of Fig. 1 may receive the muon flux time series data from the muon detector 120 and transmit it to the user apparatus 140 for processing as shown in Fig. 1. In this case, the external unit 130 may act as a modem, such as a cable modem, digital subscriber line (DSL) modem, satellite modem, mobile broadband modem, or the like, between the user apparatus 140 and the muon detector 120. Yet alternatively or additionally, the processing device may perform measuring the muon flux time series data by the one or more muon detectors 52 included as part of the processing device 100. The one or more muon detectors may be further configured to measure muon arrival angles or angles of incidence. In this case, the muon flux time series data may further comprise muon angle of incidence data, as explained hereinbefore. The angle of incidence data may be processed by the processing device to determine information on the location of the object and / or its direction of movement and / or its speed, and / or to remove noise or other artifacts that the raw muon flux time series data may contain e.g. by distinguishing muons produced by cosmic rays from other types of radiation and reduce the impact of background radiation on the measurement.

[0066] The muon flux time series data may be processed 202 (see Fig. 2) by the processing device 100 of Fig. 3 to detect a change in the muon flux. The change may indicate the motion of an object in the monitoring area due to a change in density with respect to the surrounding atmosphere and / or soil. The change may occur over time when the object is introduced to or leaves the monitoring area of the muon detector(s). The change may therefore be a spatial and / or a temporal change.

[0067] The muon flux time series data may be processed using various statistical and computational techniques to extract relevant information about the measured muon rate and to understand the possible reasons for the changed or changing muon rate. Processing the muon flux time series data may comprise one or more of the following:

[0068] Data preprocessing is a technique used to remove noise or other artifacts that the raw muon flux time series data may contain. This may involve filtering the data or applying corrections to account for variations in detector efficiency. Detector efficiency corrections may be performed at the end of the processing, or as a part of the data analysis described below.

[0069] Data analysis is a technique used for analyzing the measured muon flux. The muon flux time series data is analyzed using statistical methods to extract relevant information, such as the mean muon flux, the muon energy spectrum, or the directional muon distribution. Some common methods used in muon rate analysis include maximum likelihood estimation, Bayesian inference, and Monte Carlo simulation.

[0070] Model fitting is a technique used for fitting the muon flux time series data to describe the underlying processes that generate the measured muon rate. This may involve modeling the muon production and propagation in the atmosphere and through the investigated media, as well as the interaction of muons with the detector or a plurality of detectors. Error estimation uses statistical and / or systematic error estimation methods to estimate the uncertainties associated with the muon flux measurements and the model parameters. This allows for quantifying the accuracy and precision of the measured and processed muon flux results.

[0071] Interpretation is a procedure for interpreting the muon flux results in the context of the questions being addressed (i.e., detecting motion), such as the cause of the change in the measured muon flux time series data.

[0072] Other data processing methods suitable for detecting changes in the muon rate may be used alternatively or in addition to the above techniques.

[0073] In an embodiment, the muon flux time series data comprises muon angle of incidence data. In this case, the one or more muon detectors are configured to measure the muon angle of incidence data, i.e., the angles of arrival of the muons detected by the detector(s). The muon angle of incidence data may be processed as described above to reduce background noise, to determine a position and / or location of the object, and / or to determine the movement direction of the object, for example.

[0074] The motion detection result is determined 208 (see Fig. 2) by the processing device 100 of Fig. 3. The motion detection result may be positive if change(s) indicating motion were detected in the measured muon flux, and otherwise the detection result may be negative. The result may be output by the processing device 100 e.g. via an interface, such as a software interface, an application programming interface (API), the user interface 62, and / or the communication interface 40. For example, the processing device 100 may transmit the motion detection result to the user device 60, e.g., via the communication interface 40. Upon receiving the result, the user interface 62 of the processing device 100 and / or the user interface of the user device 60 may output the result of the processing to a user via one or more of their output devices.

[0075] When the processing device 100 comprises the user interface, the processing device 100 may be the user apparatus 140 of Fig. 1. When the processing device 100 transmits the result of the processing to the user device, the processing device 100 may be, e.g., one of the muon detectors 120, 121 or the external unit 130, and the user device may be the user apparatus 140 of Fig. 1.

[0076] The motion detection result may trigger further actions to be performed by the processing device 100 or another device and / or component of the system 150. For example, the processing device 100 may be configured to trigger performing an action, such as outputting an alarm in response to a positive motion detection result. The action may be performed by the processing device 100 itself, and / or the processing device 100 may, e.g., send a command to a second apparatus that causes the second apparatus to perform the action. The second apparatus may be part of the system 150 of Fig. 3; for example, it may be the user device 60 or the trigger device 70. Examples of the action to be performed include outputting the alarm via the user interface 62 of the apparatus and / or via the user interface of the user device 60, activating a further monitoring system to obtain more information about the object, dispatching a vehicle to obtain more information of the object, and activating a defense system for protection against neutral, hostile, and / or unwanted (unmanned) objects, such as tanks, or other objects that may present a danger.

[0077] For example, as discussed above, the processing device 100 may be communicatively coupled (optionally via another device) to the one or more trigger devices 70, 72, which are in turn coupled to one or more explosives. The processing device may send a trigger command to the one or more trigger devices 70, 72 in response to a positive motion detection result. The one or more trigger devices 70, 72 are configured to trigger detonation 210 (see Fig. 2) of the one or more explosives in response to receiving the trigger command from the processing device 100. This results in a controlled explosion based on the detected motion. When testing the operation of the invention, the object may evidently be a friendly or neutral “dummy” object that has been deployed, for example, by the user of the apparatus or system.

[0078] The above example of a trigger system has applications e.g. in the defense sector. A land mine or an anti-tank mine may be formed by the combination of the explosive(s) and the trigger system including the muon detector(s), the processing device(s), and the trigger device(s). Such a system or mine may be positioned to e.g. a border zone. Preferably, components of the trigger system, with or without the explosive(s), are integrated into a single apparatus for convenient installation at the site of use.

[0079] The above defensive applications are preferably combined with the use of various thresholds, which are described in more detail below. For completeness, it is noted that the use of thresholds is not limited to these applications. Referring again to Fig. 2, the processing 204 may comprise comparing 206 the measured muon flux time series data to one or more detection thresholds, such as a velocity threshold and / or a density threshold, and if the one or more detection thresholds are met, determining 208 a positive motion detection result. Referring now to Fig. 3, the processing device 100 may be configured to store the one or more detection thresholds e.g. in the memory of the device 100, such as in the database 24. The processing device 100 may read the detection threshold(s) from the memory to perform the comparing to the measured muon flux time series data. Angle of incidence data included in the measured muon flux time series data can be employed to define the direction of the detected motion, and furthermore, the rate of change of the angle of incidence can be employed to calculate the velocity v of the detected motion, as explained hereinbefore. The processing device 100 may store velocity thresholds which define thresholds for the direction and / or the speed of the detected motion. For example, motion exceeding a set speed threshold or having a first predetermined direction may cause a determination of a negative motion detection result, whereas motion with slower speed or having a second predetermined direction may cause a determination of a positive motion detection result. Such an upper threshold for the speed may avoid false detections for objects that seem to have an unrealistically high speed, or unnecessary detection of objects that are moving so fast that they will have likely left the monitored area before the processing is completed.

[0080] The processing device 100 may store a density threshold which defines e.g. a minimum and / or maximum density. The density threshold(s) can be set e.g. so that only objects 102 massive or dense enough cause a determination of a positive motion detection result. For example, the density threshold can be set so that only objects 102 weighing approximately one ton or more, assuming they are mostly comprised of steel, cause a determination of a positive motion detection result. The skilled person is able to select suitable density thresholds based on e.g. known material densities and compositions of selected land vehicles. Like velocity threshold(s), density threshold(s) may avoid false detections and be used to selectively monitor the area for vehicles with certain densities.

[0081] Fig. 4 presents a trigger system embodied as an integrated single apparatus 401 for monitoring land traffic in an area. A trigger system may comprise one or more apparatuses 401 , or parts of a trigger system may be physically scattered to different locations. Below, the integrated single apparatus 401 is referred to as a trigger system. The trigger system 401 may comprise a casing 405 which contains one or more muon detectors 402, 403 to aid positioning the one or more muon detectors in and / or below the area and to protect them mechanically. The casing 405 may comprise, for example, a sharp-headed tube configured to be pushed by force to the ground. Alternatively, or in addition, the trigger system may comprise one or more augers that contain the one or more muon detectors, wherein the positioning comprises drilling the one or more augers containing the one or more muon detectors into ground below the area. The blades 408 of the one or more augers make it easier to drive the device into, for example, a rocky soil. The one or more augers may comprise parts such as spurs, cutting edges, twist, a shank, and / or a tang where the latter may be removable. Alternatively, positioning may comprise boring a hole to ground for each of the on or more muon detector using e.g. an auger and / or an excavator, placing the one or more muon detectors to the corresponding holes, and optionally covering the holes. Another alternative for the casing 405 is a plate-like structure (e.g. square or circular crosssection) which allows larger detector areas and thus more efficient muon detection. Such a plate can be installed, for example, by digging it into the soil or simply leaving it on the ground if the device does not need to be hidden and it is strong enough to withstand a direct impact of the object on the detector device.

[0082] The one or more muon detectors 402, 403 may comprise, for example, one scintillation plastic plate 402, which may be equipped with a light-sensing diode (e.g., SiPM), or at least two of such plates 402, 403 facing each other to enable the solid angle adjustment by adjusting the distance 405 between the plates 402, 403. Angles of incidence of the incident muons may be determined by the detector(s) and / or the processing device based on locations where muons are detected on the location-sensitive plates stacked on top of each other e.g. as shown in Fig. 4. Alternatively, or in addition, the one or more muon detectors 402, 403 may comprise e.g. gas-based muon detectors, drift chambers, micromesh gaseous structures, resistive plate chambers, multiwire proportional chambers, chemical nuclear emulsions, and / or any other particle detector that allows the muon flux time series data to be processed online or offline.

[0083] The one or more muon detectors 402, 403 may be configured to measure the total muon flux and / or the angle of incidence of the detected muons. In Fig. 4, incident muons 409-411 are detected by the muon detector 402, 403 of the trigger system 401 . The muon 409 only hits the lower muon detector plate 403, the muon 410 is absorbed by the object 420, whereas the muon 411 penetrates through the object 420 and is incident to the muon detector 402, 403 within its solid angle such that the muon 411 is detected by both muon detector plates 403, 403. Thus, the angle of incidence 412 of the incident muon 411 may be computed to obtain muon angle of incidence data, whereas the incident muon 409 may be, but not necessarily, ignored in processing the muon flux data. Subsequently, a processing device 100 processes the muon flux data to detect motion in the area and determines a motion detection result. For example, in the scenario of Fig. 4, the motion of the object 420 may be detected based on the processing of the muon flux data which reveals a reduced total muon flux due to the absorbed muon 410, and a positive motion detection result may be determined.

[0084] The trigger system 401 may further comprise a data acquisition (DAQ) unit 406 configured to collect the muon flux time series data from the muon detectors 402, 403 and optionally to communicate with an external device 130 (see Fig. 1 ). As was discussed in relation to Fig. 3, the trigger system 401 may further comprise a power unit 407 to provide power for the trigger system 401. The power unit 407 may be, for example, an internal or external battery-based system or one relaying on an external power supply.

[0085] The operational electronics of the trigger system 401 and / or its DAQ unit 406 may be based on simple electronics (e.g., a simple counter) or it may be more sophisticated, e.g., based on machine learning (ML) and / or artificial Intelligence (Al). The DAQ unit 406 may be, for example, programmed to operate independently using Al-driven programming and / or it may be programmed to operate using a man-driven algorithm. In both cases the unit may be able to run in a mode that it is configured to receive external commands from an external (either Al or human-based) user. The DAQ unit 406 may receive external commands, operate autonomously and / or it may be ML / AI assisted. It may also be self-sufficient and based on ML / AI, and / or or its operation may be based on preprogrammed algorithms for e.g., counting the number of vehicles rolling above it. In addition to the embodiment of Fig. 4, these aspects may be applied to other embodiments of the system as well.

[0086] When the trigger system 401 of Fig. 4 is implemented in the muon detector 120, 121 of Fig. 1 , the DAQ unit 406 may also be configured to communicate with the user apparatus 140 via the external unit 130. Furthermore, the external unit 130 may be configured to execute the computer program product for processing the data and determining the motion detection result and / or the optional following commands, either independently or operated via a user apparatus 140, or a combination of these two.

[0087] Referring again to Fig. 3, in an embodiment of the trigger system 150, the one or more muon detectors 50 are configured to transmit the muon flux time series data to the processing device 100 contained e.g. in the external unit 130 of Fig. 1 , and the processing device 100 is configured to transmit a trigger command to one or more trigger devices 70 coupled to the one or more explosives to cause the detonation of the one or more explosives. In this embodiment, both the muon detectors and the trigger device are external to the processing device. The transmissions may be performed e.g. wirelessly via the respective interfaces 40, 51 , 71 , for example.

[0088] In a preferred embodiment of the trigger system, the trigger system 150 comprises a trigger device 72 coupled to the one or more processing devices 100, e.g. DAQ unit 406 of Fig. 4, and configured to be coupled to one or more explosives, wherein the trigger system is integrated to a single apparatus 401 , which can be positioned as a whole in and / or below the monitored area. In an embodiment, the one or more muon detectors comprise at least two muon detectors 120, 121 of Fig. 1 , wherein the at least two muon detectors 120, 121 are positioned to distance from each other, for example one or more meters apart. Thus, the trigger system corresponding to the embodiment may comprise at least two integrated single apparatuses 401 of Fig. 4, or at the least two muon detectors 120, 121 (see Fig. 1 ) physically scattered in different locations. Below, the detection units of the embodiment are referred to simply as muon detectors. The muon detector array geometry may be, but need not be, fixed, and their pattern or mutual distances may be, but need not be, respectively symmetric or equal. For example, the at least two muon detectors 120, 121 may comprise at least four or at least seven muon detectors, and they may be arranged into a square pattern and / or a hexagonal pattern such that their mutual distances are optimized so that all the surface area 105 in the monitored area 103 in Fig. 1 is covered by the solid angle of at least one muon detector 120, 121. The amount of muon detectors 120, 121 or the amount of trigger systems 401 in the array does not have an upper limit: The larger the amount of muon detectors 120, 121 or the trigger systems 401 , the larger area 103 it may be possible to monitor.

[0089] In an embodiment, a processing device 100 may be configured to receive muon flux time series data from at least two muon detectors 120, 121 of Fig. 1 or at least two trigger devices 401 of Fig. 4. Processing the muon flux time series data may comprise combining, by the processing device 100, the muon flux time series data of the at least two muon detectors to determine the motion detection result. The processing device 100 may, for example, receive and process first muon flux time series data from a first muon detector 120, 121 and second muon flux time series data from a second muon detector 120, 121 , and detect motion in the monitored area 103 of each muon detector 120, 121 based on the processing. The processing may further comprise computing e.g. the velocity v of the detected motion based on the combined muon flux data of the first muon detector 120, 121 and the second muon detector 120, 121 and comparing the processed muon flux data to one or more thresholds, such as velocity and / or density thresholds. The processing device 100 may then determine a motion detection result. For example, if one or more thresholds are met, the processing device 100 may determine a positive motion detection result, and, optionally, send a trigger command to one or more trigger devices 70, 72, which may or may not be associated with the first muon detector 120, 121 and / or the second muon detector 120, 121. For example, the one or more trigger devices 70, 72 may be located in a position which corresponds to a position where the object 102 of which motion was detected will be located at a computed time based on the processed muon flux time series data.

Claims

Claims1 . A method of monitoring land traffic in an area, wherein the method comprises: positioning one or more muon detectors in and / or below the area; measuring muon flux time series data by the one or more muon detectors; processing the muon flux time series data to detect motion in the area; determining a motion detection result based on the processing; and causing detonation of one or more explosives based on the motion detection result.

2. The method of claim 1 , wherein at least one muon detector of the one or more muon detectors is contained in an auger, and wherein the positioning comprises drilling the auger containing the at least one muon detector into ground below the area.

3. The method of claim 1 or 2, wherein the method comprises positioning at least one of the one or more muon detectors to a depth of at least 0.5 meters, preferably at least 0.75 meters, most preferably at least 1 meter in the ground below the area.

4. The method of any preceding claim, wherein the one or more muon detectors comprise at least two muon detectors, and wherein the method comprises positioning the at least two muon detectors to a distance from each other.

5. The method of any preceding claim, wherein the area comprises at least a part of a natural formation, such as a field, a forest, a meadow, a marsh, a swamp, a shore, a riverbank, and / or a park.

6. The method of any preceding claim, wherein the area comprises at least a part of a manmade formation, such as a road, a railroad, a yard, a parking lot, a border zone, an airport, and / or a clearing.

7. The method of any preceding claim, wherein the one or more muon detectors are configured to measure the total muon flux and / or the angle of incidence of the detected muons, and wherein the muon flux time series data comprises a total muon flux data and / or an angle of incidence data of the detected muons.

8. The method of claim 7, wherein the processing comprises processing the angle of incidence data of the detected muons to determine information on a location of motion, a direction of motion, and / or a speed of motion.

9. The method of any preceding claim, wherein the processing comprises comparing the measured muon flux time series data to one or more detection thresholds, such as a velocity threshold and / or a density threshold, and if the one or more detection thresholds are met, determining a positive motion detection result.

10. The method of any preceding claim, the method further comprising transmitting the muon flux time series data to a processing device by at least one of the one or more muon detectors, receiving the muon flux time series data by the processing device, and performing the processing and determining the motion detection result by the processing device.11 . The method of claim 10, wherein the one or more muon detectors comprise at least two muon detectors, and wherein the method comprises receiving the muon flux time series data from the at least two muon detectors by the processing device, and the processing comprises combining, by the processing device, the muon flux time series data of the at least two muon detectors to determine the motion detection result.

12. A trigger system for monitoring land traffic in an area comprising: one or more muon detectors configured to be positioned in and / or below the area, and to measure muon flux time series data, and one or more processing devices configured to: detect motion in the area by processing the muon flux data, determine a motion detection result based on the processing, and cause detonation of one or more explosives based on the motion detection result.

13. The trigger system of claim 12, wherein the trigger system comprises the one or more explosives.

14. The trigger system of claim 12 or 13, wherein the trigger system comprises one or more augers that contain the one or more muon detectors.

15. The trigger system of any one of claims 12 to 14, wherein the one or more muon detectors are configured to measure the total muon flux and / or the angle of incidence of the detected muons.

16. The trigger system of any one of claims 12 to 15, wherein the one or more muon detectors are configured to transmit the muon flux time series data to the one or more processing devices, and the one or more processing devices are configured to transmit a trigger command to one or more trigger devices coupled to the one or more explosives to cause the detonation of the one or more explosives.

17. The trigger system of any one of claims 12 to 15, comprising a trigger device coupled to the one or more processing devices and configured to be coupled to the one or more explosives, wherein the trigger system is integrated to a single apparatus.

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