JP3535045B2 - Device for determining gamma-ray incident direction from trajectory image of recoil electrons by MSGC - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to relates to a γ-ray incident direction determined TeiSo location from the trajectory image of the recoil electrons by MSGC (Micro Strip Gas chamber).

[0002]

2. Description of the Related Art γ rays (γ rays here are 100 keV
1MeV) is the electromagnetic wave with the highest energy, and it has a very high straightness like light and has excellent permeability of substances more than X-rays. By using isotope nuclei that generate rays, as a tracer for observing migration of substances in a living body, chemistry,
It is used in many fields including biology, medicine, and pharmacy.

In the medical field, in particular, γ-ray-based image diagnosis is currently used for a number of diagnoses such as cancer and tumor. The applicable organs are the brain, heart, lungs, liver,
It is widely used in most fields such as cardiovascular and bone.
Many use radioactive isotopes that emit gamma rays around 140 keV, and capture these gamma rays with a gamma ray detector that limits the direction in which they can be detected by a collimator to obtain an image.

Investigations using γ rays have also been attempted in biological and industrial applications.

On the other hand, in nuclear power utilizing nuclear reactions, γ rays must be shielded because they are dangerous.
Contamination can be investigated by looking for lines.

As described above, γ-rays in the energy range are indispensable for the current state-of-the-art technology, and it can be said that the improvement and improvement of the detection method has a great influence not only on science but also on industry.

In the field where the detection of γ-rays is required, the energy of the γ-rays is determined according to the purpose of the detection, the spectral analysis for determining the substance that has emitted the γ-rays, and the direction of the source
Furthermore, it is necessary to detect the image with γ rays. In the former, various scintillation crystals have been developed and many devices are used.

On the other hand, γ-rays have almost no reflection or refraction phenomena such as light or X-rays, and an optical method cannot be applied, so that it is almost impossible to take an image.

[0009]

However, in the use of γ-rays in the above-mentioned conventional medical field, the position resolution is determined by the size of the collimator, and the collimator itself creates background gamma-rays to increase noise. Will end up. Therefore, the detection is such that a shadow is visible rather than an image, and it is almost impossible to obtain a three-dimensional image. Moreover, as a practical matter, the diagnosis can not be used only a small fraction of the γ-rays entering the collimator, requires absolutely strong dose to take the entire image, as a result have increased radiation exposure of the patient It was

[0010] Recently, PET (Pos) has been used as a decisive factor for early detection of very early cancer that cannot be detected by other tests.
(itron Emission Tomography)
A method using has appeared. PET is an excellent detector that can obtain a high resolution of several millimeters and a three-dimensional image by capturing 2γ rays that are generated simultaneously from positron and electron annihilation. However, the equipment is very expensive, and an accelerator for making special isotopes is also required, and the reality is that there are only about 20 units nationwide.

Apart from this, there is also a method for determining the γ-ray incident direction using the double Compton effect, but the efficiency is still very poor. This will not be described here.

As described above, without using a collimator, γ
If the direction of arrival of the ray can be detected, a highly efficient and highly accurate γ-ray direction detector, which is unprecedented, can be obtained. The target γ of 100 keV to 1 MeV
The interactions that a line causes with ordinary matter are mainly the photoelectric effect and the Compton effect. In both cases, recoil electrons are generated in the substance as a result of this action. The direction of this recoil electron has a certain probability distribution with respect to the direction of the incident γ ray, and its energy is constant in the photoelectric effect and has a value corresponding to the recoil angle in the Compton effect.

Table 1 summarizes the scattering angle and energy of recoil electrons in each effect.

[0014]

[Table 1] From this table, it can be seen that if the direction and energy of recoil electrons generated by incident γ-rays in a substance can be measured, the incident direction can be determined by only a few events of γ-rays.

[0015] The present invention is, in view of the above situation, without the use of collimators, quickly, reliably γ-ray incident direction decision from the trajectory image of the recoil electrons by MSGC capable of determining the γ-ray incident direction an object of the present invention is to provide the equipment.

[0016]

In order to achieve the above object, the present invention provides [1] a γ-ray incident direction determining device from a recoil electron trajectory image by MSGC, which comprises a drift electrode serving as a window. A gas package, a long drift region having a plurality of field wires arranged in the gas package, a capillary plate arranged in the gas package, an MSGC substrate part arranged in the gas package, and data. A collector system for ionizing the gas in the detection region by recoil electrons in the gas package, the electrons drifting along a drift electric field tuned to be perpendicular to the detection surface and being an intermediate amplifier. A two-dimensional electrode that reaches the capillary plate, is gas-amplified, and drifts the amplified electron to the MSGC substrate part It generates a signal, in which this is so located in each high speed time nanosecond order is recorded by the data acquisition system.

[2] A device for determining the γ-ray incident direction from a recoil electron trajectory image by MSGC, which comprises a drift electrode serving as a window, a gas package, and a plurality of field wires arranged in the gas package. A long drift region having, a photodetector arranged beside the long drift region arranged in the gas package, a capillary plate arranged in the gas package, and an MSGC substrate arranged in the gas package. And a data acquisition system, the recoil electrons in the gas package ionize the gas in the detection region, and the γ-rays are photoelectrically converted in the gas.
In order to determine the instant of time when the Compton effect is caused, the photodetector captures the light generated by the ionized gas, and the electrons drift along a drift electric field adjusted to be perpendicular to the detection surface, After reaching the capillary plate, which is an intermediate amplifier, and gas-amplified, the amplified electrons are drifted to the MSGC substrate part, and a signal is generated by a two-dimensional electrode, which is a high-speed time of nanosecond order by the data acquisition system. The position is recorded for each.

[3] MSG according to the above [ 1 ] or [ 2 ]
In γ-ray incident direction determining device from the trajectory image of the recoil electrons by C, the gas package is obtained so as to be filled with a gas based on Xe.

[0019] [4] In the above [3] γ-ray incident direction determining device from the trajectory image of the recoil electron by MSGC according, the gas package is one which is adapted to permit adjustment of the pressure of Xe.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

In the conventional detector, it was impossible to determine the direction and energy of the recoil electron tracks of tens of keV to hundreds of keV generated by γ-rays in the substance. However, it is considered that this can be achieved by using a two-dimensional microstrip gas chamber (MSGC) and a pipeline data processing circuit for MSGC which are being put to practical use in the group of the present inventors in recent years. Note that the description of this MSGC is omitted here. If necessary, JP-A-10-
See 300856, Japanese Patent Publication No. 2843319 and the like. This MSGC seems to be clear from these publications as well.
The substrate (substrate), anode strip, cathode
Base substrate made of trip and ceramic, back strike
MSGC substrate part consisting of lip, drift plate and this
Gas channel filled between the drift plate and the MSGC substrate
It consists of a bar.

FIG. 1 is a diagram showing the principle of two-dimensional readout of a charged particle trajectory using time information according to the present invention.

In this figure, 1 is MSGC, 2 is a drift electrode, 3 is a drift electric field (E electric field), 4 is a gas atmosphere, 5 is a detector, 6 is a detection signal by the detector 5 , and 7 is an electron cloud. .

As shown in this figure, the MSGC 1 detects the position by drifting the electron cloud 7 generated in the gas atmosphere 4 in the detection region to the electrode by the drift electric field 3 and further performing gas amplification. . Here, electronic cloud 7
Is a linear one caused by fast charged particles, the electron cloud 7 drifts to the electrodes while maintaining its shape, and the signal 6 appears one after another at the position corresponding to the shape of the electron cloud 7. Become.

That is, in the conventional MSGC and high-speed data acquisition system, the first three-dimensional trajectory of the high-speed charged particles can be obtained by continuously recording the signal position and the detection time.

A method of capturing a three-dimensional trajectory of a charged particle by a similar method is used in the field of high energy physics for observing particles of several MeV or more (Time).
Projection Chamber (TPC) is M
With SGC, it is possible to accurately observe even low-energy electrons (tens of keV) whose track is about several millimeters.

Further, the recoil electron energy can be known from the length of the trajectory (or the deposit energy detectable by MSGC). In order to obtain the original γ-ray incident direction from these information, the following steps need to be performed.

(1) Identification of Physical Element Process that Causes Recoil Electrons As described above, there are two processes in which recoil electrons caused by γ-rays of 1 MeV or less are photoelectric effect and Compton effect. In the photoelectric effect, the kinetic energy E _{out of} recoil electrons is limited to a constant value E _in −W regardless of the moving direction of electrons, because all the energy E _in of incident γ rays is absorbed. Here, W is the binding energy of electrons generated by the photoelectric effect.

On the other hand, the Compton effect is considered to be quasi-elastic scattering of photons and electrons, and the kinetic energy of recoil electrons depends on the scattering direction, but this energy is smaller than that due to the photoelectric effect.

Therefore, it can be said that the energy of recoil electrons may be used to distinguish between these two elementary processes. If the gamma rays to be detected are emitted from a certain nuclide,
Since the energy is known, the electron energy due to the photoelectric effect always has a constant value. So if anything lower than this energy is observed, it is the Compton effect.

(2) Estimation of candidates for the incident direction of incident γ-rays (in the case of photoelectric effect) The differential cross-section due to the scattering angle of electrons generated by the photoelectric effect is given by the angle θ between the incident γ-rays and scattered electrons. It is known that Here, β is the ratio of the initial velocity of recoil electrons to the speed of light. When the energy of the incident γ-rays is sufficiently small with respect to the electron mass (511 keV), photoelectrons are emitted in a direction almost perpendicular to the incident γ-rays, but as the incident energy becomes higher, the electron emission direction is changed by the relativistic effect. It is biased forward.

The electron generation directions at several energies of 50 keV to 800 keV are shown in FIG.

The azimuth angle distribution of the scattered electrons depends on the degree of polarization of the incident γ rays, but assuming that there is no polarization, the azimuth angle distribution is exactly the same.

Therefore, as shown in FIG. 3, from the observed trajectory of recoil electrons, the direction on the cone corresponding to FIG. 2 (correctly, a certain probability distribution centered on the cone) is It becomes a candidate for the incident direction. In FIG. 3, 8 is an electronic track and 9 is an incident γ-ray candidate cone.

(3) Estimation of the incident direction of incident γ-rays (in the case of Compton effect) When the trajectory of recoil electrons is due to the Compton effect, the incident direction of γ-rays with energy E _in and recoil electrons The relational expression of the formed angle θ and the electron energy E _out is as follows.

[0036] Here, mc ² is the rest mass of the electron. That is,
If the incident γ-ray and the recoil electron energy are known, this equation can be solved for θ, and the incident direction of the γ-ray is on the cone in the angle θ direction (see Fig. 3) with the trajectory of the recoil electron as the axis. Become a candidate.

(4) Determination of Incident Direction of γ-Ray by Observation of Recoil Electrons of Multiple Events According to the above method, from the observation of a single recoil electron, the arrival direction of the original γ-ray is greatly limited in space. Can be given, so multiple γ's coming from the same direction
By observing the recoil electrons caused by the line incidence, the incidence direction can be determined from the overlap of the candidates for the γ-ray incidence direction obtained from the respective recoil electrons. When the incident direction is uniquely determined by overlapping the cones, at least three events of γ-ray incidence are required. In addition, even when γ-rays arrive from multiple directions, it is possible to determine the incident direction by processing the superposition of cones calculated from the observed recoil electrons on a computer. (See Figure 4). In FIG. 4, A is a γ-ray incident direction obtained from a plurality of events, and B is a γ-ray incident direction candidate obtained from one recoil electron.

According to this method, a collimator for capturing γ-rays is unnecessary, and a detector having a large detection area can be used, so that the solid angle of the detector with respect to the radiation source is dramatically increased, and high efficiency γ is achieved. It is considered that a line direction detector can be realized.

Next, a concrete example will be described.

As the γ-ray direction detector, there are a case where a source which is relatively distant from the detector and a case where a source which is close to the detector are examined.

The former is for examining only the direction of incident γ-rays to the detector, and is considered to be very useful in the field of radiation safety control (detection of leakage of radiation and investigation of activation site of radioactive waste). .

In the latter case, since the solid angle of the detector with respect to the radiation source becomes large, it can be expected that the spatial position of the low-capacity radioactive substance can be specified. Therefore, the latter can be used in combination with a medical radioactive tracer. Therefore, it is thought that it will be possible to carry out medical treatment that is far easier to handle and less dangerous than before, with high accuracy.

Since the embodiments of the γ-ray direction detector for long distance and the one for short distance are slightly different, each will be described.

FIG. 5 shows an MSGC showing a first embodiment of the present invention.
FIG. 3 is a schematic diagram of a γ-ray incident direction determination device from a recoil electron trajectory image by FIG. 1, showing the structure of a long-distance detector.

In this figure, 10 is a γ-ray arrival direction detecting device, 11 is a drift electrode (window), 12 is a gas package, 12A is a gas package side wall, 13 is a field wire (electric field structure line), 14 is a capillary plate, 1
5 is a long drift region, 16 is a MSGC substrate part (MSG
C main body) , 20 is a data collection system.

Here, the long drift region 1 is formed on the MSGC substrate 16 with the intermediate amplifier (capillary plate 14 ).
5 is provided. Since the linearity of the electric field is important in this long drift region 15, a field wire (electric field adjusting electrode) 13 for correcting the drift electric field is stretched around the periphery. The inside of the γ-ray arrival direction detection device 10 is filled with a gas based on Xe to improve the detection efficiency for γ-rays. The field wire 13 is stretched around the gas package side wall 12A. That is, the inside of the gas package 12 is hollow and receives γ rays.

Further, the portion enclosing this gas is a pressure vessel, and the internal gas pressure can be increased according to the needs of the energy and efficiency of the γ rays to be detected. There is. The recoil electrons ionize the gas in the detection region, and among them, the electrons drift along a drift electric field adjusted so as to be perpendicular to the detection surface, reach the capillary plate 14 which is an intermediate amplifier, and are gas-amplified. .

The further amplified electrons are the MSGC substrate 1
Drift to 6 and generate signals at two-dimensional electrodes spaced 200μ apart, which are recorded by the data acquisition system 20 every 50-100 ns position. The drift velocity of electrons at 1 atm and room temperature in xenon gas is
Since the electric field is about 2 cm / μsec when the electric field is 300 V / cm, in this case, three-dimensional recoil electron trajectories are obtained at intervals of 1 mm in the depth direction of the detector by collecting data every 50 nsec. Data corresponding to the structure will be obtained.

Here, it should be noted that in the case of the MSGC substrate portion having such a long drift region 15, positive ions generated by electron avalanche that occurs in the vicinity of the electrodes flow into the drift layer, and a gas package made of an insulator is formed. Side wall 1
Since it has the property of adhering to 2A and causing charge-up to distort the electric field, the capillary plate 14 installed on the MSGC substrate part 16 absorbs all the positive ions formed in the lower part by the electrode of the capillary plate 14. , This effect can be eliminated. for that reason,
The device of the present invention does not distort the electric field even in a strong radiation environment for a long time, and can accurately measure the γ-ray incident direction.

FIG. 6 shows an MSGC showing a second embodiment of the present invention.
FIG. 3 is a schematic diagram of a γ-ray incident direction determination device from a recoil electron trajectory image according to FIG. 1, showing the structure of a short-distance detector.

In the γ-ray direction detector for short distances, when obtaining a three-dimensional image of recoil electrons, it is necessary information as to which position (depth) in the detector it occurred. This information is obtained from the time when drift electrons are generated, that is, the arrival time of γ-rays and the time difference when the drift electrons reach the MSGC substrate unit 16.

Therefore, the structure of the detector for short distance is not limited to that for long distance, and ionized gas is generated in order to determine the moment when the γ-ray causes the photoelectric / Compton effect in the gas. A high-speed photodetector 17 (a detector capable of capturing one photon with an accuracy of a few nanoseconds such as a photoelectron image multiplier) for capturing the light (scintillation) is arranged beside the drift region. The trigger signal generated from this photodetector 17 is also sent to the data acquisition system 20. The rest of the configuration is the same as that of the first embodiment, so the description is omitted here.

Furthermore, in common with long distance and short distance, 1M
In order to measure the energy when observing γ-rays near eV, there is a case in which a magnetic field can be applied to the detection region if necessary.

FIG. 7 is a block diagram of a data collection system for MSGC showing an embodiment of the present invention.

In this figure, the MSGC data collection system 20 includes an encoder system 21, a memory module 22, a clock 23, and a counter (time stamp).
24 and a computer system 25. 16
Is an MSGC substrate part , 17 is a photodetector, and 26 is a trigger signal.

As shown in FIG. 7, the structure is basically the same as that of the conventional high-speed data acquisition system for imaging, but the accuracy of time recording for capturing the three-dimensional structure of the trajectory is improved. There is. In other words, when two-dimensional coordinates are obtained with a conventional two-dimensional strip detector, the track formed by particles with a speed close to the speed of light becomes an event, and the conventional gate is opened to hit between them. It was impossible to capture by the method of recording the position of the strip. The way to solve this is to attach a circuit to each pixel as a row of pixels called a position direction strip called a pad, and record the hit pad and the remaining direction strip hit, and its time. For the first time, it was possible to capture the entire track by capturing the three-dimensional position of the particle track on each strip. This is TPC (Time Project)
Ion Chamber). Read the analog signal from both ends of the unidirectional strip without using other pads,
JE to get the position of particle track on its strip
There is a method called T-Chamber. In the case of TPC, the number of circuits increases in proportion to the area. Also, JE
In the case of T-Chamber, the position resolution is poor and an ADC circuit for converting many analog signals is required.

The high speed data acquisition system 20 for imaging of the present invention synchronizes the signals from each strip with a high speed clock 23. That is, a hit of each strip within one clock 23 is one event. Electrons that drift from ordinary particle tracks bring about microsecond variations, so a clock of about 10 MHz
When data is obtained by using, the track is easily recorded as data of continuous points of about 10 points in one track. This system uses perimeter rather than detector area,
In other words, since it increases only by the square root of the area and does not require any analog processing, it is possible to process a large number of events in a small size. That is, in the conventional data acquisition system, data acquisition is performed at a 10 MHz clock, and time recording is performed every 10 clocks at the maximum (1 μsec resolution), whereas the high speed data acquisition system 20 for imaging according to the present invention. Then, the time for each clock 23 is recorded. Further, the timing of the trigger signal 26 from the photodetector 17 can also be recorded as data in the short distance system.

The data acquired by the data acquisition system 20 can be directly acquired by the computer system 25, from which the direction of the incident γ-ray will be calculated. The energy can be measured from the trajectory of the recoil electron in the space, its emission direction, and its length. Regarding the energy, in the case of γ-ray incident with high energy near 1 MeV, many recoil electron trajectories may not fit within the detector. In this case, therefore, a magnetic field is applied to the detection area to trace the electron trajectories. The energy of recoil electrons can be obtained by observing the curvature that bends. Once these values are obtained, the direction of the incident γ-ray can be determined from the locus of several events, as described above.

For short distances, the distance to the radiation source can also be specified by a method similar to triangulation using the difference in the position of the locus in the detector. Further, even when observing a radiation source at a long distance, the spatial position of the radiation source can be similarly detected by the triangulation method by using a plurality of detectors. It is considered that these calculations can be performed almost instantly by using a current computer, and it is also possible to record and display the incident direction of γ rays in real time.

Next, the result of the operation test will be described.

Since the structure is often common to the conventional MSGC, the basic phenomenon has been observed using the conventional MSGC.

FIG. 8 shows an image obtained when the MSGC was operated for 10 seconds with nothing incident on it.

Generally, 1 per cm ² on the ground
About 0 ^-2 μ particles are pouring in, but in this figure,
What can be seen as the locus is clearly observed. With the current data acquisition system, it is not possible to accurately record the time sequence of the obtained point sequence, but since the data acquisition is performed with a 10 MHz clock, each point is obtained every 100 nsec. (C in Fig. 8
See).

Here, since the electron density generated by recoil electrons due to γ rays is much larger than the density of ionized electrons generated by passage of μ particles originating from cosmic rays, at least the trajectory of μ particles can be seen. The fact that γ-ray recoil electrons could be easily observed as well.

In this MSGC, the drift region has a thickness of 5
mm and the electric field applied here is about 200 V /
cm, data collection is 100 ns, gas composition is xenon 7
Since it was 0%: ethane 30%, the trajectory of μ particles penetrating this drift region appears as a sequence of 5 to 6 points. This is evidence that MSGC operates as TPC, and the trajectory of charged particles is 1 mm in the depth direction.
It is obtained in units, indicating that a three-dimensional particle trajectory is recorded.

As described above, the apparatus of the present invention has the above-mentioned P
A three-dimensional position resolution equal to or higher than ET can be obtained for a single γ-ray generation source in this energy range, and a large solid angle of 2π steradian (2π str: almost hemispherical region) is obtained. Also, since no collimator is required, the background is drastically reduced. Therefore, for example, the position resolution of the above PET while the radiation exposure of the patient to less than one conventional 100 minutes. Before use of the medical field, it is possible to obtain the temporal resolution in a single gamma-ray source.

Also, for the detection of 2 gamma ray decay, this device can detect recoil electrons (most of which are 200 keV or less, which can be perfectly captured by this device) generated by Compton scattering from 500 keV. The position can be detected with the same accuracy. In the case of medical use, since the energy of gamma rays is known, the direction of gamma rays can be obtained only from the direction and energy of electrons as described above. That is, only one gamma ray needs to be detected. Also, due to the large solid angle, the detection efficiency is also improved several hundred times. If you want to increase the sensitivity, place a scintillator plate detector (not necessary to be a pixel) for simultaneous measurement on the opposite side of the detector in order to reduce noise, and use 2 gamma ray events for simultaneous measurement and energy measurement. Can be identified.

In this way, the conventional concept of gamma ray diagnosis is renewed, and the ability close to that of X-ray CT can be obtained.

Next, biological / industrial use will be described.

In this field of application, as with medical applications, isotope-based tracer flow can be examined in real-time and in real-time for movements far away from the detector. For example, the movement of the tracer can be usually detected in a place where the amount of substance can transmit gamma rays to some extent, such as the place of reaction in the reaction furnace, the degree of progress, and the degree of diffusion.

Further, this detector is for obtaining the angle of gamma ray, and the closer to the detector, the higher the position resolution. Therefore, the distance between the radiation source and the detector can be made small in a small animal used in biology, medicine, and medicine, which improves the position resolution and enables the position determination of a site even for a small animal.

[0072] In addition, the nuclear-related, confirmation of a wide range of pollution situation of the previous work, such as confirmation of the radiation exposure of the entire human body after work, there is no way other than to check the entire area in a conventional Sabemeta, also confidence takes time What was low was greatly improved in terms of both quality and time.

The present invention can also be applied to a two-dimensional gas proportional coefficient device having an electrode interval of 1 mm or less.

The present invention is not limited to the above embodiments, but various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0075]

As described in detail above, according to the present invention, the following effects can be achieved.

(1) The γ-ray incident direction can be determined quickly and reliably without using a collimator.

(2) It is also possible to record and display the incident direction of γ-rays in real time.

(3) By filling with xenon gas, the detection efficiency for γ-rays can be improved.

(4) By adjusting the pressure of the xenon gas, it is possible to further improve the detection efficiency for γ rays.

[Brief description of drawings]

FIG. 1 is a diagram showing the principle of two-dimensional readout of a charged particle trajectory using time information according to the present invention.

FIG. 2 is a diagram showing directions of recoil electrons generated by the photoelectric effect of the present invention.

FIG. 3 is a diagram showing candidates for an incident γ-ray direction obtained from a recoil electron trajectory of the present invention.

FIG. 4 is a diagram in which a direction in space represented by a cone of the present invention is replaced with a plane.

FIG. 5 is a schematic diagram of a long range γ-ray direction detecting MSGC according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram of a short-range γ-ray direction detection MSGC showing a second embodiment of the present invention.

FIG. 7 is a block diagram of a data collection system for MSGC showing an embodiment of the present invention.

FIG. 8 is a diagram showing a locus of muons captured by the MSGC for γ-ray direction detection of the present invention.

[Explanation of symbols]

1 MSGC 2,11 drift electrode (window) 3 drift electric field (E electric field) 4 gas atmosphere 5 detector 6 detection signal by detector 7 electron cloud 8 electron track 9 incident γ ray candidate cone A γ ray obtained from multiple events Incident direction B Candidate of γ-ray incident direction obtained from one recoil electron 10 γ-ray arrival direction detector 12 Gas package 12A Gas package side wall 13 Field wire (electric field structure line stretched around the side wall of gas package) 14 Capillary plate 15 long drift region 16 MSGC substrate part 17 photodetector 20 data acquisition system 21 encoder system 22 memory module 23 clock 24 counter (time stamp) 25 computer system 26 trigger signal

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP 10-300856 (JP, A) JP 62-225984 (JP, A) JP 62-5194 (JP, A) JP 62- 203079 (JP, A) Special table 9-508750 (JP, A) Special table 2001-516454 (JP, A) Special table 2001-508935 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01T 1/00

Claims (4)

(57) [Claims] 1. A device for determining a γ-ray incident direction from a trajectory image of recoil electrons by MSGC, comprising: (a) a drift electrode serving as a window; (b) a gas package; and (c) a gas package inside the gas package. A long drift region having a plurality of field wires arranged therein; (d) a capillary plate arranged in the gas package; (e) an MSGC substrate portion arranged in the gas package; (f) data collection. And (g) ionizing the gas in the detection region by recoil electrons in the gas package, of which electrons drift along a drift electric field adjusted to be perpendicular to the detection surface, and an intermediate amplifier Reaching the capillary plate, gas-amplified, and further the amplified electrons are drifted to the MSGC substrate part to generate a signal at a two-dimensional electrode. A device for determining a γ-ray incident direction from a recoil electron trajectory image by MSGC, characterized in that the position is recorded at every high-speed time of nanosecond order by the data collection system. 2. A device for determining a γ-ray incident direction from a recoil electron trajectory image by MSGC, comprising: (a) a drift electrode serving as a window; (b) a gas package; and (c) a gas package inside the gas package. A long drift region having a plurality of field wires arranged therein; (d) a photodetector arranged beside the long drift region arranged in the gas package; and (e) arranged in the gas package. A capillary plate; (f) an MSGC substrate part arranged in the gas package; and (g) a data acquisition system. (H) recoil electrons in the gas package ionize the gas in the detection region. In order to determine the moment when the γ-ray causes the photoelectric / Compton effect in the gas, the photodetector captures the light generated by the ionized gas, and the electron is detected on the detection surface. It drifts along a drift electric field adjusted to be vertical, reaches the capillary plate which is an intermediate amplifier, gas-amplifies, and further drifts the amplified electron to the MSGC substrate part, and outputs a signal at a two-dimensional electrode. It occurs, this Nanobyoo by the data acquisition system
An apparatus for determining a γ-ray incident direction from a recoil electron trajectory image by MSGC, which is characterized in that the position is recorded at each high-speed time of the radar. 3. A γ-ray incident direction determining device from the trajectory image of the recoil electron by MSGC according to claim 1 or 2, wherein the gas package by MSGC characterized in that it is filled with a gas based on Xe A device for determining the γ-ray incident direction from the recoil electron trajectory image. 4. The γ-ray incident direction determination device from the recoil electron trajectory image by the MSGC according to claim 3 , wherein the gas package is capable of adjusting the pressure of Xe. An apparatus for determining a γ-ray incident direction from a recoil electron trajectory image by MSGC.