JP2005061892A - Pressure vessel system for radiation detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein a very fine signal pulse output from a radiation sensor element is required to be output attenuated through a large number of series resistance lines, corresponding to the number of detection wires or the number of strips in the sensor element, in order to obtain detection position information of a radiation and wherein lowering in the S/N ratio cannot be avoided, the problem wherein the pulse width is widened as a result that a fine current pulse output from the sensor element is required to be sufficiently integrated at several microseconds of time constant by an amplifying circuit in order to reduce a pulse crest value fluctuations and wherein quick measurement, i.e. a wide dynamic range cannot be realized, and the like, in a conventional resistance attenuation system position detecting type radiation sensor. <P>SOLUTION: This multidimensional position detecting type radiation detector, requiring a pressure vessel using an ionization gas, has a structure for transmitting fine and high-speed electrical signal pulses output in several tens or more of multichannels, from an individually mounted multidimensional radiation detecting element to a multichannel amplifying board via a pressure boundary, without attenuation or delays. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention is used for radiation measurement such as X-rays, comma rays, and neutron imaging that requires high-speed response performance, a wide measurement range and high position detection resolution in structural analysis experiments of materials using X-rays or neutron scattering, for example. The present invention relates to a pressure vessel system for a one-dimensional or two-dimensional radiation detector.

In an imaging sensor using a gas converter for measuring X-rays or neutrons, the primary energy obtained from them is usually very small as 3 × 10 ⁻¹⁵ coulomb [C] or less, but the primary energy is increased to improve the position detection resolution. In the original position detection type radiation detector, the position of each minute output signal having 10 channels or more per unit length of 1 [cm], and in the two-dimensional position detection type radiation detector, 20 channels or more per unit area of 1 [cm ² ]. Amplification and processing are required without degrading information accuracy. Conventional multi-dimensional position detection type radiation detectors include the following.

(1) A one-dimensional multi-wire proportional counter (MWPC) type radiation sensor element in which a very thin metal wire having a diameter of about 20 [μm] is stretched at intervals of several millimeters, and each signal line output is an X-axis signal, or the above-mentioned In a two-dimensional multi-wire proportional counter (MWPC) type radiation sensor element having a structure in which a signal line is extended in a direction orthogonal to a metal line and the signal output is a Y-axis signal, the X-axis signal or X and X of these sensors For both Y-axis signals, one end of the signal line stretched side by side in the pressure vessel is connected to a large electric resistance of the same value between each signal line, and both ends of the series resistor string arranged in large numbers. using the principle of proportional to the distance to between the output from the second signal position attenuation of pulse peak value has occurred in the signal from the second signal to the outside of the pressure vessel through a coaxial feedthrough Resistance attenuation type position detection type radiation sensor for measuring out.

(2) In the above resistance attenuation type position detection type radiation sensor, instead of a large electric resistance of the same value connected between the signal lines, a pulse delay element that works to delay the propagation of the signal pulse in time Using the principle that the delay time difference of two signal pulses from both ends of the delay element array arranged in large numbers is proportional to the distance from the position where the signal is generated to the output, the two signals are coaxially fed through . A pulse-delayed position-detection type radiation sensor that is led out of the pressure vessel and measured.

  The above resistance attenuation type position detection type radiation sensor and pulse delay type position detection type radiation sensor are examples in which the MWPC type radiation sensor is used, but the MWPC type radiation sensor element is a microstrip gas counter (MSGC) type radiation. There is a two-dimensional position detection type radiation sensor or the like replaced with a sensor element or a micropixel gas counter (MPGC) type radiation sensor element.

  The microstrip gas counter (MSGC) type radiation sensor element has an anode strip having a width of about 10 [μm] on an insulating substrate surface and an anode strip sandwiched between both sides through an insulating gap of about 50 [μm]. A large number of electrode pairs on which cathode strips having a width of about 100 [μm] are arranged, and on the back side, back strips having the same width as the cathode strips are arranged at the same pitch as the positive electrodes on the surface in the direction orthogonal to the anode strips, Each anode strip output is an X-axis signal, and each back strip output is a Y-axis signal.

 The micropixel gas counter (MPGC) type radiation sensor element has a large number of positive electrode wires arranged at intervals of several hundreds [μm] on the back surface of an insulating substrate, and positive electrode wires in the length direction of the positive electrodes. A cylindrical metal stud pin having a diameter of 50 [μm] or less that penetrates the insulating substrate at intervals of several hundreds [μm] is formed on the insulating substrate portion in contact with the surface, and is orthogonal to the positive electrode line right above the stud pin on the surface. A negative electrode line is arranged in the direction, and a donut-shaped insulation gap of about 100 [μm] width is provided concentrically with the stud pin at a portion where the negative electrode line and the stud pin overlap, and each positive electrode line output is an X-axis signal, Each negative electrode line output is a Y-axis signal.

The background art of the present invention further includes the following.
(1) A two-dimensional position detector based on the MWPC principle was fabricated for a small neutron scattering experiment. Sensitive area of the detector is 640x640mm ^2. In order to obtain the performance of neutron detection efficiency and high position resolution, and to minimize the parallax, the mixed gas was 190 kPa ³ He + 100 kPa CF ₄ and the sensitive volume was 30 mm thick. The maximum neutron count rate design of the detector is 10 ⁵ events / second. The calculated neutron detection efficiency was 60% with 2Å neutrons, and the measured neutron energy resolution in the anode grid was typically 20% (half width). The position of the neutron detected on the sensitive surface was determined using the wire-to-wire method (high resolution 5x5mm ² defined by wire coordinates). A 16-channel charge preamplifier / amplifier / comparator module has been developed that has a channel sensitivity of 0.1 V / fC, a noise line width of 0.4 fC, and channel-to-channel crosstalk of less than 5%. (Non-Patent Document 1).

(2) We have developed a two-dimensional microstrip gas chamber (MSGC) with a detection area of 5cm x 5cm using microchip module (MCM) technology. It has a 17 mm thin element substrate, a 254 anode with a 200 mm pitch and a 255 backstrip. The MSGC is mounted in a large pin grid array (PGA) package with over 500 pins. It makes it possible to easily connect a large amount of signals from the imaging MSGC combined with readout electronics. In this paper, we report on the ability of MSGC as an X-ray imaging detector to operate near an intense X-ray source. In order to obtain stable operation under high-intensity X-rays, it was found that a solution of about 20 mm element substrate and about 10 ¹⁵ W / square surface resistance was the solution. The surface resistance was controlled by coating the surface of the polyimide element substrate with organic titanium. This improvement, MSGC is activated about ¹⁰³ seconds stable under high count rate 10 ⁷ Hz / mm ^2. The MSGC also operated for several months under moderate-brightness X-rays from an X-ray generator. In this measurement, high-quality digital X-ray imaging having a resolution of about 60 mm RMS was achieved by using a simple reading method that only records the position of the hit electrode (Non-patent Document 2).

(3) The detector Micro Pixel Chamber (mu-PIC) using a novel gas was developed for imaging X-rays, gamma rays and charged particles. The mu-PIC is manufactured on the basis of a double-sided printed circuit board that can easily produce a large area detector. An operational test using a 0.4 mm pitch, 3 cm x 3 cm area mu-PIC was successfully performed. Gas gain and stability were measured in this test. In a five-day continuous operation test at a gas gain of 10 ³ , the anode-to-cathode discharge was not even reduced. Further, no decrease in gain was observed until X-ray irradiation with a luminance of 10 ⁷ cps / mm ² (Non-patent Document 3).
Author: Knott, -RB; Watt, -G .; Boldeman, -JW; Smith, -GC; et al. Title: A large 2D PSD for thermal neutron detector. -in-Physics-Research.-SectionA, -Accelerators, Spectrometers. Date of issue: (21 Jun 1997). Applicable page: v.392 (1-3). P.62-67 Author: Toru Tanimori; Atsuhiko Ochi; Seiji Minami, Tomofumi Naga. Title: Development of an imaging microstrip gas chamber with a 5cm x tcm area based on multi-chip module technology. Publication (book title): Nuclear-Instruments-and-Methods -in-Physics-Research.-Section-A 381 (1996). Date of acceptance: (6 May 1996). Applicable page: P.280-288 Author: Ochi Atsuhiko; Nagayoshi Tsutomu; Koishi Satoshi, Tanimori, -Toru; et al. Title: Development of micro pixel chamber.Nuclear-Instruments-and-Methods-in-Physics-Research.-Section-A, -Accelerators,- Spectrometers, -Detectors-and-Associated-Equipment (1 Feb 2002) v. 478 (1-2) Publication date: (1 Feb 2002). Corresponding page: p. 196-199

X-ray and neutron imaging sensors used in structural analysis experiments of materials using X-rays or neutron scattering have extremely high position detection resolution of several hundreds [μm], a dynamic range of 5 digits or more, and a high signal-to-noise ratio (S / N) and high operational stability. In order to realize these, first, an extremely small signal pulse of 10 ⁻¹³ coulomb [C] or less output from a one-dimensional or two-dimensional radiation sensor element is transmitted to a pulse amplification amplifier circuit without being attenuated. The pulse signal width of the amplifier output is required to be several microseconds or less, and the time delay of two signals output from both ends of the signal line for position detection is required to be 0.5 [μs] or less. The

  In order to obtain the radiation detection position information in the conventional resistance attenuation type position detection type radiation sensor, the extremely small amount output from the sensor element is passed through a large number of series resistance arrays corresponding to the number of detection wires or strips of the radiation sensor element. It is necessary to attenuate and output the signal pulse, and the reduction in S / N is unavoidable. Further, in order to reduce the fluctuation of the pulse peak value, a minute current pulse output from the sensor element is several microseconds by an amplifier circuit. As a result of the necessity of sufficient integration with the time constant, the signal pulse width is widened, and there is a problem in high-speed measurement, that is, realization of a wide dynamic range.

  In order to obtain the detection position information of the radiation in the pulse delay type position detection type radiation sensor, the extremely small amount output from the sensor element through a large number of serial pulse delay element arrays corresponding to the number of detection wires or strips of the radiation sensor element. Output signal pulse must be output with a large delay. As a result, the rise of the signal pulse in accordance with the propagation distance of the output signal pulse is deteriorated, the position detection accuracy is lowered, and the signal is output from both ends of the signal line. Since a long time interval occurs between two signal pulses, it is difficult to achieve high-speed measurement, that is, to achieve a wide dynamic range. Furthermore, if the signal pulse is significantly delayed by a pulse delay element, the signal pulse wave height is attenuated. There were problems such as the inevitable decrease in S / N.

  The present invention is a multi-dimensional position detection type radiation detector that requires a pressure vessel using ionized gas, and a minute and high-speed electric signal output from the mounted multi-dimensional radiation detection element through several tens of channels. The present invention provides a pressure vessel system for a radiation detector having a structure in which pulses are directly transmitted to a multi-channel amplifier board through a pressure boundary without being individually attenuated and delayed.

  According to the present invention, each minute signal pulse output from each detection wire or strip of the radiation sensor element can be directly transmitted to the amplifier circuit through a multi-pin feedthrough provided in the detector pressure vessel. Attenuation is hardly generated and a high S / N is obtained, and the problems of the conventional resistance attenuation type position detection type radiation sensor and pulse delay type position detection type radiation sensor are solved.

  According to the present invention, each minute signal pulse output from each detection wire or strip of the radiation sensor element can be directly transmitted to the amplifier circuit through a multi-pin feedthrough provided in the detector pressure vessel. Can be directly amplified by the amplifier circuit as a high-speed current pulse, and each signal pulse can be digitized and position detection processing can be performed with a digital signal. As a result, the position detection accuracy can be greatly improved, and the speed can be increased. Provides a wide dynamic range.

  According to the present invention, each minute signal pulse output from each detection wire or strip of the radiation sensor element can be directly transmitted to the amplifier circuit through a multi-pin feedthrough provided in the detector pressure vessel. It is no longer necessary to incorporate a large number of resistance elements for signal pulse attenuation or a large number of pulse delay elements for signal pulse delay in the inside, and as a result, the pressure vessel can be greatly reduced in size and the thickness of the pressure vessel wall can be reduced. Therefore, an effect of reducing attenuation and scattering of the radiation to be measured at the pressure vessel entrance window, and an effect of eliminating the deterioration of the ionized gas due to the resistance element or the signal pulse delay are provided.

  The present invention eliminates the difficult task of connecting a large number of wires in a narrow pressure vessel by adopting a socket arrangement structure for connecting a multi-pin feedthrough in a pressure vessel and a one-dimensional or two-dimensional radiation sensor element. It provides effects such as easy mounting of the sensor element and easy replacement when the radiation sensor element fails.

  By adopting a socket arrangement structure for connecting the multi-pin feedthrough outside the pressure vessel and the amplifier circuit board or motherboard, the present invention can eliminate high-density wiring and prevent signal deterioration due to wiring. Provides the effect of enabling the exchange of

  In FIG. 1, the structure of the neutron imaging sensor using the pressure vessel system for radiation detectors of this invention is shown. 1 is a pressure vessel cap for a radiation detector, 1a is a neutron entrance window, 1b is neutron, 2 is a valve for gas mixture pressurization, 3 is a pressure vessel end flange, 3a is a metal gasket, 3b is a flange mounting bolt, 4 is a feed Ceramic board for through, 4a is a feedthrough pin arrangement, 5 is a two-dimensional position detection type radiation sensor element, 5a is a substrate for mounting a radiation sensor element, 5b is a drift plate, 6 is an amplifier circuit board, 6a is for connecting a feedthrough pin A through-hole arrangement is shown.

  FIG. 2 is an exploded view of the parts 5 and 5a of FIG. The through-hole array substrate is mounted on the feed-through pin of the pressure vessel end plate flange, and after each pin is attached halfway, the two-dimensional position detection type radiation sensor element is mounted on the through-hole array substrate. 5 is a two-dimensional position detection type radiation sensor element, 5a is a through-hole array substrate, 5c is a through-hole array, and 5d is a bonding pad.

  FIG. 3 is a cross-sectional view of the pressure vessel end plate of the radiation detector pressure vessel system shown in FIG. 1 using a two-dimensional position detection type radiation sensor element mounted on a multi-pin IC package, using parts made of sockets at both ends. It is the figure which showed the components structure in the case of mounting | wearing with the feedthrough pin arrangement | sequence of a flange. After the socket array component 7 is mounted on the feedthrough pin array 4a, the two-dimensional position detection type radiation sensor element 8 is mounted on the socket array component. Here, 3 is a pressure vessel end plate flange, 4a is a feedthrough pin arrangement, 7 is a socket arrangement component, and 8 is a two-dimensional position detection type radiation sensor element mounted on a multi-pin IC package.

  FIG. 4 shows a structure in which the amplifier circuit board 6 in FIG. 1 is replaced with the motherboard 9 with socket arrangement shown in FIG. 1 so that a large number of amplifier circuit boards can be mounted. The socket array 9a is attached to the feedthrough pin array protruding from the lower surface of the pressure vessel end panel flange 3 in FIG. 1, and the amplifier circuit board 10 is attached to each multi-pin connector provided on the mother board. 9 is a motherboard with a socket arrangement, 9a is a socket arrangement, 9b is a multi-pin connector, 10 is an amplifier circuit board, 10a is a multi-pin connector for signal input, 10b is an amplifier module, and 10c is a multi-pin connector for signal output.

  FIG. 5 is an external view of the completed pressure detector system for a radiation detector according to the invention. 1 is a pressure vessel cap for a radiation detector, 1a is a neutron entrance window, 1b is neutron, 2 is a valve for gas mixture pressurization, 3 is a pressure vessel end plate flange, 9 is a motherboard with a socket array, 10 is an amplifier circuit board, 10a is A multi-pin connector for signal input, 10b is an amplifier module, and 10c is a multi-pin connector for signal output.

  As an example, FIG. 1 shows a configuration when the present invention is applied to a neutron imaging sensor. In the neutron imaging sensor, a pressure vessel cap 1 for a radiation detector, a neutron entrance window 1a, a neutron 1b, a mixed gas pressurizing valve 2, a pressure vessel end plate flange 3, a metal gasket 3a, a flange mounting bolt 3b, and a feedthrough ceramic plate 4 , A feedthrough pin array 4, a two-dimensional position detection type radiation sensor element 5, a radiation sensor element mounting substrate 5a, a drift plate 5b, an amplifier circuit substrate 6, and a feedthrough pin connection through hole array 6a. In actual use, a two-dimensional position detection type radiation sensor element is mounted on the feedthrough pin protruding from the upper surface of the pressure vessel end plate flange, and the pressure vessel cap is attached to the pressure vessel end plate flange using a flange mounting bolt. To do. The amplifier circuit board is electrically connected by inserting the through-hole arrangement of the amplifier circuit board into the feedthrough pin protruding from the lower surface of the pressure vessel end plate flange. A mixed gas acting as a neutron converter and an ionized gas is pressurized from a mixed gas pressurizing valve, and a negative voltage is applied to the drift plate, and a positive and negative voltage is applied between the anode and the cathode of the radiation sensor element. In the measurement of neutrons, a group of electrons generated between the drift plate and the radiation sensor element due to neutron incidence is drifted to the surface of the radiation sensor element by the negative electric field generated by the drift plate, and electrons are generated in the strong electric field region near the radiation sensor element surface. The group is gas amplified and the electron cloud induces negative and positive micro electrical signal pulses at the anode and cathode, respectively. In the pressure vessel system for the radiation detector of the invention, since all the electrode lines of the radiation sensor element are directly connected to the amplifier circuit through the multi-pin feedthrough arrangement, the X-axis and Y-axis electrode lines can be connected from several to several tens. The induced minute electric signal pulses are input in parallel to the respective amplifier circuit systems, amplified and digitized, and then subjected to position detection signal processing.

It is a figure which shows the structure of the neutron imaging sensor using the pressure vessel system for radiation detectors of this invention.

(Explanation of symbols)
1. Pressure detector cap for radiation detector, 1a. Neutron entrance window, 1b. Neutrons, 2. 2. Valve for gas mixture pressurization, Pressure vessel end flange, 3a. Metal gasket, 3b. 3. flange mounting bolts; Ceramic board for feedthrough, 4a. 4. Feedthrough pin arrangement; Two-dimensional position detection type radiation sensor element, 5a. Radiation sensor element mounting substrate, 5b. 5. drift plate; Amplifier circuit board, 6a. Through-hole arrangement for feed-through pin connection.
It is the figure which decomposed | disassembled and shown 5 and 5a components of FIG.

(Explanation of symbols)
5). Two-dimensional position detection type radiation sensor element, 5a. Through-hole array substrate, 5c. Through-hole arrangement, 5d. Bonding pad.
In the pressure vessel system for a radiation detector shown in FIG. 1, a two-dimensional position detection type radiation sensor element mounted on a multi-pin IC package is used to feed through a flange of a pressure vessel end plate using parts manufactured with a socket arrangement at both ends. It is the figure which showed the component structure in the case of mounting | wearing with a pin arrangement.

(Explanation of symbols)
3. Pressure vessel end flange, 4a. 6. Feedthrough pin arrangement, 7. Socket arrangement parts A two-dimensional position detection type radiation sensor element mounted on a multi-pin IC package.
1 shows a structure in which a large number of amplifier circuit boards can be mounted by replacing the amplifier circuit board (6) of FIG. 1 with a motherboard 9 with a socket arrangement shown in FIG.

(Explanation of symbols)
9. Motherboard with socket arrangement, 9a. Socket array, 9b. Multi-pin connector, 10. Amplifier circuit board, 10a. Multi-pin connector for signal input, 10b. Amplifier module, 10c. Multi-pin connector for signal output.
The external view which assembled and completed the pressure vessel system for radiation detectors of this invention is shown.

(Explanation of symbols)
1. Pressure detector cap for radiation detector, 1a. Neutron entrance window, 1b. Neutrons, 2. 2. Valve for gas mixture pressurization, 8. Pressure vessel end plate flange, 10. Motherboard with socket arrangement Amplifier circuit board, 10a. Multi-pin connector for signal input, 10b. Amplifier module, 10c. Multi-pin connector for signal output.

Claims (3)

  In a multidimensional position detection type radiation detector having a multichannel signal output of 20 channels or more that gives one-dimensional or two-dimensional position information using an ionizing gas for radiation detection at a high pressure above atmospheric pressure or a low pressure below atmospheric pressure, Ceramic insulation having a high density feedthrough with a minute pin spacing of 5 mm or less on at least one metal wall forming a pressure boundary of a cylindrical or box-type pressure vessel having one or more input ports for enclosing ionized gas The plate is mounted in an airtight and pressure-resistant structure, the multi-dimensional radiation sensor element is directly mounted on the high-density feedthrough pin protruding into the pressure vessel, and the high-density feedthrough pin protruding outside the other pressure vessel A multi-channel amplifier board is attached to each channel with position information from the radiation sensor element. Individually air signal pulse, through the pressure boundary, the radiation detector pressure vessel system of the structure to be transmitted to the amplifier board directly.   2. The pressure vessel for a radiation detector according to claim 1, wherein a pin socket component having an upper end made of a socket structure is brazed to each pin of the high density feedthrough protruding into the pressure vessel by a brazing method. Radiation with a structure attached to the top or bottom so that both the upper and lower ends are fitted with socket parts with a socket structure, and radiation sensor elements manufactured with a pinned package structure can be directly inserted into these pin socket arrays. Pressure vessel system for detector.   3. A pressure vessel for a radiation detector according to claim 1, wherein a socket arrangement that matches the pin shape arrangement is arranged on an electronic circuit printed board for each pin of the high-density feedthrough that protrudes outside the pressure vessel. For a radiation detector characterized by a structure in which a multichannel signal from a multidimensional radiation detector is amplified by a group of amplifier circuits on an electronic circuit printed circuit board, which is fitted into a high-density feedthrough pin array outside the pressure vessel Pressure vessel system.

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