JP6301745B2 - Muon trajectory detector and muon trajectory detection method - Google Patents

Description

  Embodiments described herein relate generally to a muon trajectory detection technique for detecting a flight trajectory of a cosmic ray muon.

  As a technique for imaging the inside of a structure, a technique for observing a muon reaching the ground surface and seeing through the inside is known. This technique has been suitably used for large-sized things that are difficult to enter, such as volcanoes or pyramids.

  As a method for seeing through the inside of a structure using a muon, there are known a transmission method for measuring the attenuation of a muon particle bundle and a scattering method for measuring a muon's Coulomb multiple scattering angle. As a scattering method, a displacement method for measuring the displacement of a locus due to Coulomb multiple scattering is also known.

  In the muon fluoroscopy technique, a muon trajectory detector is externally provided on a structure to be fluoroscopically targeted. The detector detects the flight trajectory of muon and analyzes the trajectory, thereby imaging the inside of the structure.

A general muon locus detector is configured by arranging a plurality of drift tubes filled with drift gas in multiple layers.
The drift tube has an anode wire at its center. When charged particles such as muons pass through the drift tube, the gas enclosed inside is ionized to generate electrons. When the generated electrons reach the anode wire, the passage of the muon is detected.

  The drift radius (distance from the anode wire) can be converted from the drift time until the electrons reach the anode wire, and the passing position can be measured with an accuracy less than the size of the detector. Become.

JP 2012-501450 A

  By the way, in order to derive a muon flight trajectory using a muon detector capable of detecting a muon passage position, it is necessary to measure detection signals generated simultaneously by a plurality of detectors within a certain time as one detection event. There is.

  However, since muon detectors are sensitive not only to muons but also to radiation such as gamma rays, detection signals based on gamma rays and detection signals based on muons are mixed in a high radiation environment. It was difficult to accurately measure the detection event.

  The present invention has been made in view of such circumstances, and even in a high radiation environment, a muon trajectory that can accurately detect a detection event by the same muon and derive a flight trajectory of the muon. It aims to provide detection technology.

In the muon trajectory detector according to the embodiment of the present invention, the detection signal is measured based on a detection signal output by detecting the passage of the muon by any one of a plurality of muon detectors arranged in at least three layers. A measurement start control unit to be started by the measurement unit, and after the start of measurement, if the detection signal is not output within the set reset time, the measurement is reset, and if it is output, detection by the same muon is performed. A measurement end control unit that causes the measurement unit to perform measurement of the detection signal during a gate time set to identify as an event, and the measurement measured within the gate time for each of the detection events equipped with a trajectory deriving section for deriving a flight trajectory of the muons from each of passing positions the muons detector, which has been calculated based on the detection signal The reset time, when one of the muons incident on each of the muons detector is set based on the detected time difference in the detection signals of the muon detector, it is characterized.

In the muon locus detection method according to the embodiment of the present invention, the detection signal is measured based on a detection signal output by detecting the passage of a muon from any of a plurality of muon detectors arranged in at least three layers. When the detection signal is not output within the set reset time after the start of the measurement, the measurement is reset if the detection signal is not output within the set reset time. Measuring the detection signal during the gate time set to perform measurement within the gate time for each of the detection events identified based on the gate time; The muon flight trajectory is derived from the passing positions of the muon detectors obtained based on the detected signals. Viewed including the steps, wherein the reset time, wherein when one of the muons incident on each of the muons detector is set based on the detected time difference in the detection signals of the muon detector, that And

  The embodiment of the present invention provides a muon trajectory detection technique that can accurately detect a detection event caused by the same muon and derive a flight trajectory of the muon even in a high radiation environment.

The block diagram of the muon locus detector which concerns on 1st Embodiment. An arrangement example of a muon passage detector when a scintillator detector is used as the muon detector. An arrangement example of a muon passage detector when a drift tube is used as a muon detector. (A) Timing chart showing the relationship between the gate time and the detection signal by muon when the gate time is fixed, and (B) When the detection signal due to gamma rays is output when the gate time is fixed. The timing chart which shows the relationship between the gate time and the detection signal by muon. The timing chart which shows the relationship between the gate time which concerns on this embodiment, and the detection signal by muon. (A) Explanatory drawing which shows an example of the detection event by muon, (B) Explanatory drawing which shows an example of the detection event other than muons, such as a gamma ray. The block diagram of the noise removal part applied to this embodiment. The block diagram which shows the modification of the noise removal part applied to this embodiment. The flowchart which shows operation | movement of the muon locus detector which concerns on 1st Embodiment. The block diagram of the muon locus detector which concerns on 2nd Embodiment. The figure explaining the method of collation by a pattern matching evaluation part. The flowchart which shows operation | movement of the muon locus detector which concerns on 2nd Embodiment.

Hereinafter, this embodiment is described based on an accompanying drawing.
As shown in FIG. 1, the muon locus detector 10 according to the first embodiment is configured such that any of a plurality of muon detectors arranged in a plurality of layers (preferably at least three layers) detects the passage of a muon. A measurement start control unit 14 that causes the measurement unit 12 to start measurement of the detection signal based on the output detection signal, and resets the measurement when the detection signal is not output within the set reset time after the measurement starts. A measurement end control unit 15 that causes the measurement unit 12 to perform measurement of a detection signal during a gate time set to be identified as a detection event by the same muon when output, and for each detection event The trajectory deriving unit 20 derives the flight trajectory of the muon from the passing positions of the muon detectors obtained based on the detection signal measured within the gate time. , And a.

  The muon passage detection unit 11 is configured by arranging a plurality of muon detectors capable of detecting muons and arranging them in a plurality of layers, preferably at least three layers. Here, one layer of muon detectors refers to a group of muon detectors each composed of a row of a plurality of muon detectors arranged in parallel to each other.

  Each of the muon detectors outputs a detection signal when the passage of the muon is detected. This detection signal includes information necessary for specifying the passing position of the muon in the detector, such as a detector number for mutually identifying the muon detectors and detected time information.

  As a muon detector, the scintillator material that emits light by muon is elongated, and a scintillator detector that detects optical signals and ionized gas are enclosed inside, and electrons ionized from the gas by muon are detected as electrical signals. Examples include a drift tube. Thus, since each muon detector has a shape extending in the longitudinal direction, one layer of the muon detector is formed by a group of a plurality of muon detectors arranged in parallel in a direction orthogonal to the longitudinal direction. It is configured in a planar shape.

  FIG. 2 shows an arrangement example of the muon passage detector 11 when scintillator detectors (21a, 21b) are used as the muon detector.

  A scintillator detector 21a, each extending in the Y direction as a longitudinal direction, and a plurality of scintillator detectors 21b arranged in parallel in the X direction, and a scintillator detector 21b, each extending in the X direction as a longitudinal direction and arranged in parallel in the Y direction. Each is arranged in three layers. This makes it possible to obtain the muon passage positions in the X and Y directions.

  FIG. 3 shows an arrangement example of the muon passage detection unit 11 when the drift tube (22a, 22b) is applied to the muon detector.

  6 layers of drift tubes 22a each extending in the Y direction as a longitudinal direction and plurally arranged in parallel in the X direction, and drifts each extending in the Y direction as a longitudinal direction and drifting in the Y direction. The tube 22b is arranged in a total of 12 layers including 6 layers. Thus, by stacking the drift tubes 22 in combination, the muon trajectory can be detected three-dimensionally.

  2 and 3, an example is shown in which three or six muon detectors are arranged in the X direction and the Y direction, respectively, but in this embodiment, at least two layers (multiple layers) of muon detection are shown. The present invention can be applied to the muon trajectory detector 10 or the muon trajectory detection method including the device.

  The measurement unit 12 measures the detection signal output from the muon passage detection unit 11. The start and end of the measurement are controlled by switching the gate signal set in the measurement unit 12. Measurement is performed when the gate signal is ON, while measurement is not performed when the gate signal is OFF.

  The OR signal generation unit 13 is connected to the muon passage detection unit 11 and measures the establishment signal when a detection signal is output from any one of a plurality of muon detectors constituting the muon passage detection unit 11. Output to the start control unit 14.

  When the establishment signal is input from the OR signal generation unit 13, the measurement start control unit 14 switches the gate signal of the measurement unit 12 from OFF to ON, and causes the measurement unit 12 to start measuring the detection signal.

  The gate time setting unit 16 sets a gate time for identifying detection events due to the same muon.

  The gate time is set to the maximum time difference that can be detected from incident to emission when one muon enters the muon passage detector 11. When the drift tube is applied to the muon detector, the gate time is calculated and set based on the drift time (several hundred nsec to several μsec) from the moment when the muon is incident on the drift tube. Note that the gate time is appropriately changed according to the energy of the muon, the configuration and size of the muon passage detection unit 11, and the like.

  The reset time setting unit 17 sets a reset time for resetting the measurement when the detection signal is not continuously output. As the reset time, when one muon enters the muon passage detection unit 11, a maximum value or an average value of a distribution of detection time differences (time lag) in detection signals of the muon detectors is set. When the detection is simultaneously performed by a plurality of muon detectors such as a muon, the detection time difference in the detection signal of each muon detector is very short compared to the gate time.

  For example, when a structure in which six drift tubes having a diameter of 50 mm as shown in FIG. Time difference. Note that the reset time is appropriately changed according to the muon energy, the configuration and size of the muon passage detection unit 11, and the like, similarly to the gate time.

  The measurement end control unit 15 inputs the gate time and the reset time from the gate time setting unit 16 and the reset time setting unit 17, respectively.

  If the detection signal is not output from the muon passage detection unit 11 within the reset time after the measurement is started, the measurement end control unit 15 switches the gate signal of the measurement unit 12 from ON to OFF, so that the measurement unit 12 Reset the measurement.

  On the other hand, when the detection signal is output from the muon passage detection unit 11 within the reset time, the ON state of the gate signal is maintained, and the measurement signal is measured by the measurement unit 12 during the gate time. And when gate time passes, the gate signal of the measurement part 12 is switched from ON to OFF, and the measurement in the measurement part 12 is complete | finished.

  Here, the effect of providing the reset time will be specifically described with reference to a comparative example when the gate time is fixed without providing the reset time.

FIG. 4A shows a timing chart of the detection signal s _{1 to} s ₃ due to the passage of the gate signal and the muon when the gate time is fixed.

In the detection signal s ₁ is output timing, measurement is started the gate signal is switched to ON. Since the detection signals s ₂ and s ₃ due to the passage of the muon are detected without a time lag, the detection signals s _{1 to} s ₃ are measured within the gate time.

On the other hand, FIG. 4B shows the timing of the detection signals s _{1 to} s ₃ detected by the passage of the muon after the detection signal t ₁ due to the gate signal and gamma rays is detected when the gate time is fixed. A chart is shown.

In the detection signal t ₁ is output timing, measurement is started the gate signal is switched to ON. Then, after the time difference exists, the detection signals s _{1 to} s ₃ due to the passage of the muon are output, so that the gate signal is turned off during the measurement of the detection signal s _{2 and} the measurement ends. For this reason, the detection signals s _{1 to} s ₃ cannot be accurately measured within the gate time.

  As described above, when the gate time is fixed, if the measurement is started by the detection signal due to the gamma ray, the detection signal due to the passage of the muon may not be correctly measured within the gate time. If the detection signal detected by the passage of the muon cannot be accurately measured within the gate time, the muon trajectory cannot be derived.

FIG. 5 shows a timing chart of the gate signal and the detection signals s _{1 to} s ₃ due to the passage of the muon according to the present embodiment.

In the detection signal t ₁ is output timing, measurement is started the gate signal is switched to ON. After detection signal t ₁ by gamma rays is output, since the detection signal of the continuity within the reset time is not outputted, the gate signal is measured is switched to OFF is reset.

  Since the detection signal due to the gamma ray depends only on the event rate, for example, even a high-rate event of 1 M (count / sec) is about one event per 1 usec. In other words, since it is unlikely that a detection signal due to gamma rays is output at short intervals, by providing a reset time, measurement can be reset when a detection signal due to gamma rays occurs.

Then, measurement is started by the gate is switched from OFF to ON when the detection signal s ₁ by the muon is output. Since the detection signal s ₂ due to the passage of the muon is detected within a time lag no reset time, measurement is performed until after the gate time without being reset. For this reason, the detection signals s _{1 to} s ₃ can be accurately measured within the gate time.

  As described above, the measurement is reset when the detection time is not output within the reset time without fixing the gate time. Thereby, the detection signal by the same muon can be accurately measured within the gate time without reducing the detection signal of the muon to be measured.

Returning to FIG. 1, the description will be continued.
After all the detection times in the muon passage detection unit 11 are completed, the measurement unit 12 organizes data as detection events by the same muon after detecting the detection signals detected within the same gate time, and the measurement data of each detection event is used as an event. It transmits to the extraction part 18.

  The event extraction unit 18 has a muon detector corresponding to a detection signal detected from each detection event transmitted from the measurement unit 12 in a predetermined layer or more, for example, two or more of the total number of layers. Is extracted as a detection event by muon.

  FIG. 6A shows an example in which the drift tubes 22 are arranged in six layers. In the detection event by the muon, the passage of muons is detected one by one in the drift tube 22 of each layer, and the drift tubes 22 are spread over the six layers. Are formed on a straight line. On the other hand, FIG. 6B shows a detection event other than a muon such as a gamma ray. In this case, the detection event is randomly detected by a small number of drift tubes 22.

  Therefore, when counted simultaneously by multiple layers of muon detectors, it means that there is a high possibility of a detection event due to muons.

  Further, when the muon detector is arranged in the A layer, when the detection probability of each layer is X and the gate time is 1 u (sec), the probability P detected in the B layer or more during 1 u (sec) is expressed by the following equation ( It is obtained in 1).

^{P = X B (1-X} ) A-B × A C B (1)
P: Probability P detected in layer B or higher
X: Detection probability of each layer A: Total number of layers B: Number of detected layers

  For example, the probability P detected in X = 0.2, A = 6, B = 4 layers or more is 2% or less. Therefore, since the probability of being simultaneously counted by the multi-layer muon detector is very low, it is possible to determine that it is due to the passage of the muon when simultaneously counted by the multi-layer muon detector.

  The event extraction unit 18 utilizes the property that when a muon passes, the muon detectors of a plurality of layers simultaneously count, and the muon detector corresponding to the detection signal is detected on a predetermined layer or higher. Extract by detecting event by.

  As a result, even if the reset time is set, event data other than the measurement target such as gamma rays may be generated, but these event data are excluded, and the detection event by muon is efficiently extracted. be able to.

  Further, the event extraction unit 18 obtains detector number patterns expected to pass corresponding to each of muon passage trajectories set in advance, and extracts only detected events that match the pattern, thereby performing muon processing. The detection event may be extracted.

  The noise removal unit 19 inputs a detection event from the event extraction unit 18. Then, from the detection signals in the detection event, using the detector number of the muon detector corresponding to the measured detection signal, signals detected due to other than the muon are excluded as noise signals.

  FIG. 7 shows a configuration diagram of the noise removing unit 19 applied to the present embodiment.

The noise removing unit 19 includes a first pattern recording unit 23 and a first removing unit 24.
The first pattern recording unit 23 stores a detection pattern of a detector number that is expected to pass corresponding to each of muon trajectories set in advance. In each detection pattern, one detector number is stored for each layer.

  The first removal unit 24 collates the detected detector number of the (measured) muon detector with the detection pattern stored in the first pattern recording unit 23. Then, a detection pattern that matches at least a predetermined condition, for example, at least two-thirds of the detected detector numbers, is selected.

  Then, detection signals corresponding to detector numbers not included in the selected detection pattern are excluded as noise signals in the detected detector numbers.

  Even when detection events due to muons are extracted, detection of signals outside the measurement target may not be prevented, but these signals can be excluded by the noise removal unit 19. As a result, the trajectory deriving unit 20 described later can derive the muon trajectory with high accuracy.

  FIG. 8 is a configuration diagram illustrating a modified example of the noise removing unit 19 applied to the present embodiment. Note that this modification can be applied to a drift tube having a position resolution equal to or larger than the size of the detector.

  The noise removal unit 19 includes a trajectory estimation unit 25, a position information calculation unit 26, and a second removal unit 27.

  The trajectory estimation unit 25 obtains an estimated muon trajectory based on the detected detector number of the muon detector. The trajectory estimation unit 25 obtains all straight lines estimated with the resolution of the muon detector. Then, the position information calculation unit 26 calculates the passing position of the muon detector for each of the obtained estimated trajectories.

  The second removal unit 27 compares the calculated passage position corresponding to each estimated trajectory with the muon detector passage position obtained based on the detection signal. Then, an estimated trajectory with the smallest deviation of the passing position is selected. Then, the detection signal of the muon detector that does not pass through the selected estimated locus is excluded as a noise signal.

  Even if it is close to the actual passing trajectory and is difficult to exclude as noise, by comparing the passing position information, a detection signal that is not a measurement target can be excluded as a noise signal.

  The trajectory derivation unit 20 inputs a detection event from the noise extraction unit. Then, for each detection event, a muon flight trajectory is derived from the passing position of each muon detector obtained based on the detection signal measured within the gate time, using numerical processing of fitting. The method for obtaining the passing position may be a method for obtaining in units of detector size, or a method for calculating from a difference in arrival time of signals obtained from the detector or a difference in signal amount.

  When the muon detectors arranged in the X direction and the muon detectors arranged in the Y direction are independent, the detection signals acquired within the same gate time are specified. Then, the XZ straight line and the YZ straight line are calculated by fitting with a linear function, and the three-dimensional position information and vector information are calculated from these values to derive the muon flight trajectory.

  FIG. 9 is a flowchart showing the operation of the muon locus detector 10 according to the first embodiment (see FIG. 1 as appropriate).

  The OR signal generation unit 13 outputs an establishment signal to the measurement start control unit 14 when a detection signal is output from any one of the muon detectors included in the muon passage detection unit 11 (S10).

  The measurement start control unit 14 switches the gate signal of the measurement unit 12 to ON when the establishment signal is input (S11). And the measurement part 12 starts the measurement of a detection signal (S12).

When there is no output of the detection signal within the reset time, the measurement start control unit 14 switches the gate signal of the measurement unit 12 to OFF and resets the measurement (S13: YES, S14).
On the other hand, when the detection signal is output within the reset time, the gate signal is maintained in the ON state, and the measurement of the detection signal is continued during the gate time (S13: NO, S15).

  The measurement end control unit 15 turns off the gate signal after the gate time has elapsed, and ends the measurement (S16: YES, S17).

  Then, the muon locus detector 10 repeats S10 to S17 until the total detection time ends (S18: NO). The measurement unit 12 transmits each detection event to the event extraction unit 18 after the end of the total detection time.

  The event extraction unit 18 extracts a detection event by the same muon from the detection events transmitted from the measurement unit 12 (S19).

  The noise removal unit 19 inputs a detection event from the event extraction unit 18, and excludes a signal detected as a cause other than a muon from detection signals in the detection event as noise (S20).

  The trajectory deriving unit 20 derives a muon flight trajectory from each passing position of each muon detector obtained based on the detection signal measured within the gate time for each detection event (S21).

  In this way, the gate time is not fixed, but if the detection signal is not output from the muon detector within the set reset time, the measurement is reset, so that the same even in a high radiation environment. It becomes possible to derive the muon's flight trajectory by accurately measuring the detection event by the muon.

(Second Embodiment)
FIG. 10 is a configuration diagram showing a second embodiment of the muon locus detector 10 according to the present invention. In addition, about the structure and part corresponding to 1st Embodiment, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The measurement start control unit 14 includes a second pattern recording unit 28, a data recording unit 29, and a pattern match evaluation unit 30.

  The second pattern recording unit 28 stores a detection pattern of a detector number that is expected to pass corresponding to each of muon trajectories set in advance. In each detection pattern, one detector number is stored for each layer. Further, a configuration in which two to three detector numbers for each layer are set in consideration of a minute displacement during the flight of the muon may be adopted.

  The pattern matching evaluation unit 30 collates the detector number corresponding to the detection signal sequentially output from the muon passage detection unit 11 with the detection pattern recorded in the second pattern recording unit 28. Then, when a predetermined condition is met, for example, when two or more of the total number of layers are met, the gate signal is switched to ON, and the measurement unit 12 starts measurement of the detection signal.

  The data recording unit 29 temporarily records a detection signal output from the muon detector and collated by the pattern matching evaluation unit 30. As a result of the collation by the pattern matching evaluation unit 30, if the predetermined condition is not met, the recorded data relating to the detection signal is deleted.

  The measurement unit 12 performs measurement during the gate time. After the measurement is completed, the detection signal temporarily recorded in the data recording unit 29 and the measured detection signal are combined into a detection event by the same muon.

FIG. 11 is a diagram for explaining a collation method by the pattern matching evaluation unit 30.
In the second pattern recording unit 28, detection patterns of detector numbers (ch) corresponding to respective muon trajectories assumed in advance are stored in separate memories.

  The pattern matching evaluation unit 30 receives the detection signal output from the muon passage detection unit 11 and collates the detector number corresponding to this detection signal with the detection pattern stored in the second pattern recording unit 28.

  Then, the pattern matching evaluation unit 30 sequentially collates the detection signals output from the muon passage detection unit 11 and matches the detection pattern with a predetermined condition or more (for example, more than two-thirds of the total number of layers). In this case, the gate signal of the measurement unit 12 is switched to ON so that the measurement unit 12 starts measuring the detection signal.

  As a result, even if a plurality of detection signals not included in the preset detection pattern are input, the gate signal is not turned on and measurement is not started. Since the gate signal is turned on only when the detection pattern matches a predetermined condition or more, the measurement is not started by a signal other than the measurement target such as gamma rays.

  FIG. 12 is a flowchart showing the operation of the muon locus detector 10 according to the second embodiment (see FIG. 2 as appropriate).

  The pattern matching evaluation unit inputs detection signals sequentially output from the muon passage detection unit 11 (S30). The data recording unit 29 temporarily records the detection signal output from the muon passage detection unit 11 (S31).

  Then, the pattern match evaluation unit 30 collates the detector number of the detection signal with the detection pattern recorded in the second pattern recording unit 28. Then, when the conditions are met under a predetermined condition or more, the gate signal is switched ON (S32: YES, S33). The pattern matching evaluation unit 30 causes the measurement unit 12 to start measuring the detection signal (S34).

  And the measurement part 12 continues the measurement of a detection signal during gate time (S35). The measurement end control unit 15 turns off the gate signal after the elapse of the gate time and ends the measurement (S36: YES, S37).

  The measurement unit 12 performs measurement during the gate time. After the measurement is completed, the detection signal temporarily recorded in the data recording unit 29 and the measured detection signal are combined to form a detection event by the same muon (S38).

  Then, the muon locus detector 10 repeats S10 to S17 until the total detection time ends (S39: NO). The measurement unit 12 transmits each detection event to the event extraction unit 18 after the end of the total detection time.

  The event extraction unit 18 extracts a detection event by the same muon from each detection event transmitted from the measurement unit 12 (S40).

  The noise removal unit 19 inputs a detection event from the event extraction unit 18 and excludes a signal detected as a cause other than a muon from detection signals in the detection event as noise (S41).

  The trajectory deriving unit 20 derives a muon flight trajectory from each passing position of each muon detector obtained based on the detection signal measured within the gate time for each detection event (S42).

  In this way, the measurement is started by opening the gate and starting the measurement only when part of it matches the pre-set patterned trajectory information, and the measurement is started by turning on the gate with a signal not to be measured such as gamma rays. It can be suppressed. As a result, it is possible to accurately measure the detection event by the same muon and derive the flight trajectory of the muon.

  The radiation measurement unit 31 is a detector that is provided in the vicinity of the muon passage detection unit 11 and measures the intensity of radiation around the muon passage detection unit 11. The radiation measurement unit 31 may use any radiation detector as long as it is a detector having sensitivity to gamma rays and the like other than muons.

  According to the present embodiment, it is possible to reduce the influence of an event caused by gamma rays or other radiation not to be measured. However, since the muon flux falling from space is not so large, accurate measurement often takes time.

  For this reason, if the radiation dose in the measurement environment changes suddenly during measurement, this embodiment may not be able to cope with it. In this case, the reliability of the trajectory calculated by the muon trajectory detector 10 is lowered.

  The radiation measurement unit 31 outputs and displays an error on the trajectory deriving unit 20 when confirming a dose exceeding the application range of the present embodiment. As a result, muon trajectory detection is executed only in a highly reliable environment.

  According to the muon trajectory detector of each embodiment described above, the gate time is not fixed, but when the detection signal is not output from the muon detector within the set reset time, by resetting the measurement, Even under a high radiation environment, it is possible to accurately measure the detection event by the same muon and derive the flight trajectory of the muon.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof. The components of the muon trajectory detector can also be realized by a computer processor.

DESCRIPTION OF SYMBOLS 10 Muon locus detector 11 Muon passage detection part 12 Measurement part 13 OR signal generation part 14 Measurement start control part 15 Measurement end control part 16 Gate time setting part 17 Reset time setting part 18 Event extraction part 19 Noise removal part 20 Trajectory derivation part 21 (21a, 21b) Scintillator detector 22 (22a, 22b) Drift tube 23 First pattern recording unit 24 First removal unit 25 Trajectory estimation unit 26 Position information calculation unit 27 Second removal unit 28 Second pattern recording unit 29 Data Recording unit 30 Pattern match evaluation unit 31 Radiation measurement unit

Claims (11)

A measurement start control unit that causes the measurement unit to start measurement of the detection signal based on a detection signal that is output by detecting the passage of the muon by any of a plurality of muon detectors arranged in at least three layers ;
After the start of measurement, if the detection signal is not output within the set reset time, the measurement is reset, and if it is output, the gate time is set to identify the same detection event by the muon. A measurement end control unit that causes the measurement unit to perform measurement of the detection signal,
For each of the detection event, provided with a locus deriving unit that derives the flight trajectory of the muons from said measured muons detector each passing position obtained on the basis of the detection signal within the gate time ,
The reset time is set based on a detection time difference in the detection signal of each muon detector when one of the muons enters each of the muon detectors.
Muon trajectory detector characterized by that. Further comprising an OR signal generation unit that outputs an establishment signal to the measurement start control unit when the detection signal is output from any one of the muon detectors,
The muon locus detector according to claim 1, wherein the measurement start control unit causes the measurement unit to start measuring the detection signal when the establishment signal is input.   The event detection part which extracts the said detection event from which the said muon detector corresponding to the said detection signal is detected in the predetermined layer or more from the said detection event is provided. Muon trajectory detector described in 1.   A noise removing unit for excluding the detection signal detected as a cause other than the muon from the detection signal in the detection event using a detector number of the muon detector corresponding to the measured detection signal. The muon locus detector according to any one of claims 1 to 3, further comprising: The noise removing unit
A first pattern recording unit for storing the detector numbers corresponding to the muon trajectories set in advance as detection patterns;
The detection number corresponding to the detector number not included in the detection pattern that matches the detection number of the detected muon detector and the detection pattern and is not included in the detection pattern that matches with a predetermined condition or more is excluded. The muon locus detector according to claim 4, further comprising: 1 exclusion unit. The noise removing unit
A trajectory estimation unit for obtaining an estimated trajectory of the muon from the detector number of the detected muon detector;
A position information calculation unit for calculating the passing position of the muon detector for each of the estimated trajectories;
The calculated passing position is compared with the passing position based on the detected detection signal to obtain the estimated trajectory with the smallest deviation, and the detection corresponding to the detector number that does not pass through the estimated trajectory The muon locus detector according to claim 4, further comprising a second excluding unit that excludes the signal. A measurement start control unit that causes the measurement unit to start measurement of the detection signal based on a detection signal output by detecting the passage of the muon by any of the plurality of muon detectors arranged in a plurality of layers;
After the start of measurement, if the detection signal is not output within the set reset time, the measurement is reset, and if it is output, the gate time is set to identify the same detection event by the muon. A measurement end control unit that causes the measurement unit to perform measurement of the detection signal,
A trajectory deriving unit for deriving a flight trajectory of the muon from the passing position of each of the muon detectors determined based on the detection signal measured within the gate time for each of the detection events;
A noise removing unit for excluding the detection signal detected as a cause other than the muon from the detection signal in the detection event using a detector number of the muon detector corresponding to the measured detection signal. And comprising
The noise removing unit
A trajectory estimation unit for obtaining an estimated trajectory of the muon from the detector number of the detected muon detector;
A position information calculation unit for calculating the passing position of the muon detector for each of the estimated trajectories;
The calculated passing position is compared with the passing position based on the detected detection signal to obtain the estimated trajectory with the smallest deviation, and the detection corresponding to the detector number that does not pass through the estimated trajectory A muon locus detector, comprising: a second excluding unit that excludes a signal. The measurement start control unit
A second pattern recording unit for storing a detection pattern of a detector number of the muon detector corresponding to each of the muon trajectories set in advance;
A data recording unit for temporarily recording the detection signal output from the muon detector;
A pattern matching evaluation unit that sequentially checks the detection number corresponding to the detection signal to be output and the detection pattern, and causes the measurement unit to start measuring the detection signal when they match at a predetermined condition or higher, Having
The said measurement part makes the said detection event by the same said muon combining the said detection signal temporarily recorded on the data recording part, and the said detection signal measured. muon trajectories detector according to any one of 7. Wherein provided in the vicinity of muon detectors, muon trajectories as claimed in any one of claims 8, characterized by further comprising a radiation measuring unit which measures the radiation intensity of the periphery of the muons detector Detector. A step of causing the measurement unit to start measurement of the detection signal based on a detection signal output by detecting the passage of a muon by any of a plurality of muon detectors arranged in at least three layers ;
After the start of measurement, if the detection signal is not output within the set reset time, the measurement is reset, and if it is output, the gate time is set to identify the same detection event by the muon. During which the measurement unit performs the measurement of the detection signal;
For each of the detection events identified based on the gate time, the flight trajectory of the muon is derived from the passing position of each of the muon detectors determined based on the detection signal measured within the gate time. the method comprising the steps of, only including,
The reset time is set based on a detection time difference in the detection signal of each muon detector when one of the muons enters each of the muon detectors.
A muon trajectory detection method characterized by the above. A step of causing the measurement unit to start measurement of the detection signal based on a detection signal output by detecting and outputting the passage of a muon by a plurality of muon detectors arranged in a plurality of layers;
After the start of measurement, if the detection signal is not output within the set reset time, the measurement is reset, and if it is output, the gate time is set to identify the same detection event by the muon. During which the measurement unit performs the measurement of the detection signal;
For each of the detection events identified based on the gate time, the flight trajectory of the muon is derived from the passing position of each of the muon detectors determined based on the detection signal measured within the gate time. And steps to
Obtaining an estimated trajectory of the muon from the detector number of the muon detector corresponding to the detection signal in the detection event;
Calculating the passing position of the muon detector for each of the estimated trajectories;
The calculated passing position is compared with the passing position based on the detected detection signal to obtain the estimated trajectory with the smallest deviation, and the detection corresponding to the detector number that does not pass through the estimated trajectory And a step of excluding the signal.

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