JPH07218643A - Incident position detector for radiation - Google Patents

Abstract

PURPOSE:To provide an incident position detector for radiation in which the detection sensitivity is enhanced while simplifying the structure at cathode section. CONSTITUTION:In the incident position detector 1 for radiation, an incident position read-out circuit is connected through a delay line 3 with an anode section 4 comprising a plurality of anode needles 41 arranged while being insulated electrically. The radiation detecting position is read out at the anode section 4. Consequently, the cathode section 5 is simplified in structure. Alternatively, the body case 2 itself is constituted as the cathode section surrounding the anode section 4. This constitution enhances the charge collecting capacity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation incident position detecting device used when analyzing a crystal structure of a substance by utilizing a diffraction phenomenon of radiation.

[0002]

2. Description of the Related Art In order to analyze a microscopic crystal structure of a substance, radiation diffraction measurement using radiation such as X-ray has been conventionally performed. In this radiation diffraction measurement, a substance is irradiated with radiation, and the diffracted or scattered radiation at this time is detected around the substance. A device such as a goniometer is known as a device used for this type of radiation diffraction measurement.

For example, in the radiation incident position detecting device disclosed in Japanese Patent Laid-Open No. 59-157944, an anode portion and a cathode portion which are spaced apart from and opposed to each other are arranged in a cavity of a main body case having a radiation incident window. , Operates as an ionization chamber or proportional counter. Further, the main body case has a shape curved in an arc shape in order to detect the diffracted X-rays and scattered X-rays radially emitted from the substance.

A high voltage is applied between the anode part and the cathode part when detecting the incident position of the diffracted or scattered X-ray. This high voltage is applied to form an electric field that collects and amplifies the charge generated by the X-rays that are incident into the cavity of the body case through the radiation entrance window. Further, the incident position of the radiation is detected as an induced charge appearing on the delay line connected to the cathode.

[0005]

By the way, there is a demand for improving the radiation detection sensitivity in the radiation incident position detecting device. Therefore, Japanese Patent Application No. 4 filed earlier by the applicant of the present application
No. 205447 proposes a radiation incident position detection device capable of improving detection sensitivity. The proposed radiation incident position detection device is composed of an anode part in which a plurality of anode needles having sharp tips are arranged. Since this anode needle can improve the electric field strength near the sharp tip, the detection sensitivity can be improved as a result.

However, in the above-mentioned proposed radiation incident position detecting device, the anode part is divided into a plurality of anode needles, and the cathode part is divided into a plurality of strip-shaped cathode plates with an insulator interposed therebetween. However, there is a problem in that the structure is complicated. The present invention has been made to solve the above problems, and an object of the present invention is to provide a radiation incident position detection device that can simplify the structure and improve the radiation detection sensitivity.

[0007]

In order to achieve such an object, the present invention is a radiation incident position detecting device for detecting the incident position of radiation, which is arranged in an electrically insulated state from each other. An anode part composed of a plurality of anode needles,
A cathode part to which a voltage is applied between the anode part, a delay line in which the plurality of anode needles are electrically connected in parallel, and a radiation incident position reading means connected to the delay line,
It is characterized by having.

Further, the present invention is characterized in that the cathode portion is formed in a shape surrounding the periphery of the plurality of anode needles.

[0009]

In the radiation incident position detecting device of the present invention, instead of the detection at the cathode portion, the radiation incident position is detected by a plurality of anode needles constituting the anode portion. Therefore,
Since the electric field strength near the anode needle can be improved in the anode part, the radiation detection sensitivity can be improved as in the device of the above-mentioned application. Moreover, since it is not necessary to divide the cathode portion into a plurality of cathode plates and to interpose an insulator between the cathode plates, the structure of the entire device can be simplified in comparison with the device of the above-mentioned application.

Further, according to the present invention, in the above-mentioned radiation incident position detecting device, since the charges can be collected from around the anode needle, the charge collecting efficiency can be improved and the detection sensitivity can be further improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show an example of the main configuration of the radiation incident position detecting device of the present invention.

The radiation incident position detecting device 1 for analyzing the crystal structure of a substance using X-rays of the radiation is diffracted and scattered when the target (measurement substance) is irradiated with the X-rays generated by the X-ray irradiation device. Detect X-rays. As shown in FIGS. 1 and 2, the radiation incident position detecting device 1 is composed of a main body case 2, an anode part 4, a cathode part 5, a delay line 3, an incident position reading circuit 8 and a high voltage generation source 7. .

The body case 2 has an X-ray incident direction (see FIG. 1).
The cross section is formed in a U shape in a direction (y direction) intersecting with the middle and z directions, and has a cavity inside. Further, the main body case 2 has an X-ray entrance opening 21 and an X-ray entrance window 22 in a direction (z direction) that coincides with the direction in which diffracted or scattered X-rays enter. The inside of the cavity of the main body case 2 is hermetically sealed to the outside, and a PR gas (a mixed gas of argon-methane), which is a general working gas, is sealed in the cavity of the main body case 2 at a constant pressure.

The body case 2 has a curved structure having an arc shape centered on a target (measurement substance) not shown. That is, in the main body case 2, the distance between the target and the detection position of the X-ray diffracted or scattered from the target is set uniformly in the detection direction (x direction) of the incident X-ray.

The anode part 4 has an X-ray detection direction (x direction).
A plurality of anode needles 41 are arranged along the line. 1
The anode needle 41 of the book is composed of an anode needle body 42 and an insulator 43 that covers the anode needle body 42 except at least a tip portion 44 on one end side. Tip part 4 on one end side of the anode needle body 42
4 is located in the cavity of the main body case 2 and has a sharp shape. As a result, the anode needle body 42 can increase the electric field strength near the tip, and the X-ray detection sensitivity can be improved. The space between the anode needle bodies 42 of the anode needles 41 adjacent to each other is electrically insulated by the insulator 43 that covers the anode needle bodies 42. Anode needle body 42 of the anode needle 41
Are formed of, for example, stainless steel. The insulator 43 is formed of an insulating material such as a metal oxide film or a resin film, and has a film thickness of about 0.1 to 0.2 mm in order to prevent dielectric breakdown between the delay line 3 and the magnet wire 3C. Formed in thickness.

In the anode part 4, a plurality of anode needles 4 are provided.
The other end side of the anode needle body 42 of No. 1 passes through the resistor 6 respectively,
In addition, they are electrically connected in parallel and connected to a high voltage generation source (high voltage generation circuit) 7. The high voltage source 7 is the anode part 4
Between the anode needle 41 and the cathode portion 5 of the high voltage, for example, about 250
A high positive voltage of 0 V is applied, which generates an electric field in the cavity of the body case 2 for collecting and amplifying charges generated by X-rays.

The cathode portion 5 is arranged in the cavity of the main body case 2 at a position (the bottom surface of the main body case 2) facing the X-ray entrance window 22 and the anode portion 4. This cathode part 5
As will be described later, since the incident position of X-rays is detected at the anode part 4, the belt-shaped integral body extends along the X-ray detection direction (x direction) and along the curved surface inside the cavity of the main body case 2. Composed of structure. That is, the cathode part 5 is formed of a simple strip-shaped metal plate without the structure including a plurality of strip-shaped metal plates (cathode plate) and an insulator interposed between the metal plates. As will be described later, the cathode portion 5 can be formed in a shape surrounding the anode portion 4. For example, the body case 2 can also be used as the cathode part. The cathode part 5 generates an electric field due to a high voltage between the cathode part 5 and the anode part 4 as described above, and thus is basically grounded. The cathode part 5 is formed of a conductive metal material, for example, stainless steel material. The anode part 4
As shown in FIGS. 1 and 2, the plurality of anode needles 41 of
The delay line 3 is electrically connected to the outside of the main body case 2. The delay line 3 extends on the surface of the plurality of anode needle main bodies 42 along the arrangement direction of the plurality of anode needles 41 (toward the x direction which is the X-ray detection direction). The anode needle body 4 is provided between the delay line 3 and the plurality of anode needle bodies 42.
It is electrically insulated via an insulator 43 covering 2 That is, the plurality of anode needle bodies 42 and the magnet wires 3C of the delay line 3 are electrically capacitively coupled in parallel.

The delay line 3 includes a plastic core 3A,
It is composed of a capacitor electrode 3B, a magnet wire 3C and a phase compensation plate 3D. The magnet wire 3C is wound around the plastic core 3A in a coil shape. As the magnet wire 3C, for example, a copper wire on the surface of which an insulating coating is formed (so-called enamel wire) is used. The capacitor electrode 3B is formed between one surface of the plastic core 3A and the magnet wire 3C, and forms a capacitance between the electrode 3B and the magnet wire 3C. The capacitor electrode 3B is formed of, for example, a copper plate. The phase compensation plate 3D is formed by interposing the capacitor electrode 3B and the magnet wire 3C on one surface of the plastic core 3A, and can reduce delay time fluctuation due to frequency fluctuation and improve delay characteristics.

The magnet wire 3C of the delay line 3 is
It is coupled to the incident position readout circuit 8 shown in FIG. The incident position reading circuit 8 includes a preamplifier (PA) 81, a waveform shaping amplifier (A) 82, a wave height discriminator (D) 83, a delay circuit (T) 84, a time-wave height converter (TAC) 85 and a multiplex. It is composed of a wave height analyzer (MCA) 86.

The preamplifier 81 is a magnet wire 3C.
Are arranged at one end and the other end of the
And signal amplification. The waveform shaping amplifier 82 shapes the waveform and amplitude of the signal for the next timing circuit.
The wave height discriminator 83 selects a signal having an amplitude equal to or higher than a certain value, and always rises at a constant timing (regardless of the signal amplitude) at the time of signal input, which is convenient for the processing of the time-wave height converter 85 in the next stage. Outputs a fast digital pulse.

The delay circuit 84 transmits both systems between one end of the magnet wire 3C and the time-to-peak converter 85 and the other end of the magnet wire 3C to the time-to-peak converter 85. A time difference is generated in the signal.

The time-wave height converter 85 proportionally converts the time difference between the digital pulses appearing in the above two systems into the amplitude of the pulse and outputs it. The multiple pulse height analyzer 86 stores the input pulse in a memory position (memory location) according to the amplitude of the pulse.
channel) and display a histogram of amplitude information of a large number of pulses.

Next, a specific method for detecting the X-ray incident position of the radiation incident position detecting apparatus 1 thus constructed will be described with reference to FIG.

First, in the radiation incident position detection device 1, the effective length of the anode part 4 arranged in the main body case 2 in the X-ray detection direction is L, and the delay time of the magnet wire 3C covering the effective range is Td. . That is, the delay time per unit effective length is calculated by Td / L. Further, the incident position of the X-ray is x.

The X-rays incident on the incident position x excite the PR gas in the cavity of the main body case 2 to generate electric charges. This electric charge causes a pulse to be generated at the anode needle 41 at the corresponding position of the anode part 4 at the incident position x. This pulse is the anode needle 4
Magnet wire 3 of delay line 3 from 1 by capacitive coupling
The pulse transmitted to C is transmitted to the magnet wire 3
It is transmitted to both ends a and b of C. The time Ta when the pulse is transmitted to one end a of the magnet wire 3C and the time Tb when the pulse is transmitted to the other end b can be expressed by the following equation.

Ta = (L−x) · Td / L Tb = x · Td / L Here, based on the time when the pulse arrives at one end a, the time difference Tdiff between both ends a and b is expressed by the following equation. Can be represented.

Tdiff = Tb−Ta = 2 · x · Td / L−Td Since the delay time Td and the effective length L are constants, the time difference Tdiff
Can be expressed by a linear function of the incident position x. By measuring this time difference, the position where the X-ray is actually incident can be obtained. However, the time difference Tdiff is x <L /
Since it becomes negative when it is 2, it is inconvenient for measurement. Therefore, the delay time Td is set to the other side (system on the other end b side) so that the pulse on the side (one end a side) which is the reference of the time difference Tdiff always precedes.
A delay circuit 84 having a larger delay time is inserted.

The time difference Tdiff is measured by the time-wave height converter 85 and the multiple wave height analyzer 86. That is,
The time difference Tdiff of pulse transmission in the two systems is time −
The pulse height is converted by the wave height converter 85, and this pulse is A / D converted by the multiple wave height analyzer 86. The converted digital pulse is stored in different memory channels for each wave height value. Then, the actual incident position of the X-ray is displayed as a histogram on the display of the multiple wave height analyzer 86. The time difference Tdiff may be directly converted into a digital pulse.

As described above, in the radiation incident position detecting device 1 of this embodiment, the anode portion 4 composed of a plurality of anode needles 41 and the magnet wire 3C are capacitively coupled to each other, and the magnet wire 3C is used. Is the incident position readout circuit 8
It is connected to the. That is, instead of the cathode portion 5, the charge according to the X-ray incident position is generated by the plurality of anode needles 4 of the anode portion 4.
Obtained from 1. The cathode part 5 exclusively forms an electric field for collecting and amplifying charges. Therefore, in the anode part 4, the electric field strength near the anode needle 41 can be improved, so that the radiation detection sensitivity can be improved and the structure of the cathode part 5 can be simplified.

FIG. 3 shows a modification of the radiation incident position detecting device 1.

The radiation incident position detection device 1 detects the incident position of X-rays in the anode part 4 as in the above-mentioned example. The anode part 4 is composed of a plurality of anode needles 41, and the other ends of the plurality of anode needle bodies 42 are electrically connected in parallel to each other by the magnet wire 3
Connected directly to C. The magnet wire 3C is connected to the incident position reading circuit 8. In addition, the high voltage source 7
(Not shown) is connected to the cathode portion 5, and a negative high voltage is applied to the cathode portion 5.

FIG. 4 shows another modification of the radiation incident position detecting device 1.

In the radiation incident position detecting device 1, the body case 2 and the X-ray entrance window 22 are made of a conductive material (metal material) instead of the cathode portion 5, and the body case 2 and the X-ray entrance window are formed. A cathode part is constituted by 22. That is, the cathode portion is configured to surround the entire periphery of the anode portion 4, especially the anode needle 41.

In the radiation incident position detecting device 1 thus constructed, the cathode portion (main body case 2 and X-ray incident window 22) is arranged around the anode portion 4 as a center, so that the electric field is spread over the entire area of the case. Can be formed. Further, the radiation incident position detection device 1 can improve the charge collection ability.

The present invention is not limited to the above-described embodiment, but various modifications can be made without departing from the scope of the invention. For example, the present invention is not limited to a main body case having a curved structure, but can be applied to a radiation incident position detection device configured by a main body case having a so-called linear structure. Further, the present invention can be applied to a detection device for radiation other than X-rays.

[0037]

As described above, according to the present invention,
In the radiation incident position detection device, the radiation detection sensitivity can be improved and the structure can be simplified.

Further, according to the present invention, the radiation detection sensitivity can be further improved.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional perspective view of a radiation incident position detection device of the present invention.

FIG. 2 is a block configuration diagram of the radiation incident position detection device.

FIG. 3 is a partial configuration diagram of a radiation incident position detection device of a modified example of the invention.

FIG. 4 is a partial cross-sectional perspective view of a radiation incident position detection device according to a modified example of the present invention.

[Explanation of symbols]

 1 Radiation incident position detector 2 Main body case 3 Delay line 3C Magnet wire 4 Anode part 41 Anode needle 42 Anode needle body 43 Insulator 44 Tip part 5 Cathode part 7 High voltage source 8 Incident position readout circuit

Claims (2)

[Claims] 1. A radiation incident position detecting device for detecting the incident position of radiation, wherein an anode part composed of a plurality of anode needles arranged in an electrically insulated state from each other and the anode part are provided. A cathode section to which a voltage is applied; a delay line in which the plurality of anode needles are electrically connected in parallel; and a radiation incident position reading unit connected to the delay line. Radiation incident position detector. 2. The radiation incident position detecting device according to claim 1, wherein the cathode portion has a shape surrounding the periphery of the plurality of anode needles.