Neutron detector

Abstract

The invention is suitable for the field of radiation detection, and provides a neutron detector. Comprising a proportional counter tube, a signal amplifying and shaping module connected with the signal output end of the proportional counter tube, a first pulse counting module connected with the signal amplifying and shaping module, a signal integral quantization module connected with the ground signal output end of the proportional counter tube, and a second pulse counting module connected with the signal integral quantization module, the processor is respectively connected with the first pulse counting module and the second pulse counting module, and the prompting module, the storage module and the communication module are respectively connected with the processor. According to the invention, the effect of zoning measurement of 2nSv / h-1000mSv / h is realized, the linearity of full-range measurement is ensured by the zoning measurement technology, and the neutron dose with a relatively wide range is measured by one proportional counter tube.

Description

Technical Field

[0001] The invention belongs to the field of radiation detection, and in particular relates to a neutron detector. Background Art

[0002] Neutron detectors are devices that detect neutrons by using charged particles generated by the interaction of neutrons with boron or uranium to ionize gases or activate materials themselves after neutron irradiation. Neutron detectors are widely used in reactor nuclear power measurement, core neutron injection rate distribution measurement, or accelerator site and environmental area dose measurement.

[0003] The existing technology usually uses proportional counters (such as BF3 proportional counters or HE3 proportional counters, etc.) to measure the neutron dose in the accelerator environment and the local neutron dose. A neutron hitting the proportional counter will generate a pulse. Since the pulse has a pulse width, the actual measured pulse width is between 10-200us. If the pulse width is 10us, the value measured by the proportional counter (based on actual experience, assuming that the F factor is 0.2nSv / h) corresponds to a maximum measured dose of 72mSv / h. Based on the limitations of the physical properties of the proportional counter, the technology of using a proportional counter for pulse counting to measure neutron dose generally does not exceed a maximum dose of 100mSv / h, and the measurement range is limited to 2nSv / h-100mSv / h.

[0004] However, the actual demand for large-dose field measurement is far more than 100mSv / h. The currently known accelerator environment requires dose measurement of more than 500mSv / h. The neutron detectors currently on the market mostly measure in the range of 2nSv / h-100mSv / h. For measurements of neutron doses exceeding 100mSv / h, crystal technology or ultra-high-speed data acquisition and analysis technology can be used. However, products with a large range of neutron doses exceeding 100mSv / h generally cannot take into account small-dose measurements (2nSv / h-10uSv / h). In addition, in the case of large-dose measurements, the small-dose measurement accuracy is not enough. Summary of the invention

[0005] The object of the present invention is to provide a neutron detector, aiming to solve the problem of how to take into account both small-dose measurement and large-dose measurement to achieve measurement of neutron doses in a wider range.

[0006] The present invention provides a neutron detector, comprising a proportional counting tube, a signal amplifying and shaping module connected to a signal output end of the proportional counting tube, a first pulse counting module connected to the signal amplifying and shaping module, a signal integral quantizing module connected to a ground signal output end of the proportional counting tube, a second pulse counting module connected to the signal integral quantizing module, a processor connected to the first pulse counting module and the second pulse counting module respectively, and a prompting module, a storage module and a communication module connected to the processor respectively; The signal amplification and shaping module amplifies the pulse signal output from the signal output end of the proportional counter tube. After regularizing the amplified pulse signal higher than the first preset threshold voltage, a pulse signal is formed and output to the first pulse counting module; The signal integration and quantization module integrates the current output from the ground signal output end of the proportional counter tube and quantizes it into a pulse signal, which is then output to the second pulse counting module; The first pulse counting module and the second pulse counting module count the pulse signal and transmit the number of pulses to the processor; The processor obtains the radiation dose rate of neutrons based on the number of pulses obtained by the first pulse counting module and the second pulse counting module and the corresponding relationship between the number of pulses and the radiation dose rate.

[0007] Further, the signal amplification and shaping module includes an amplification triode, a first voltage comparator, and a first logic control circuit connected in sequence; the signal amplification and shaping module also includes a first positive power supply, a first negative power supply, and a second positive power supply. The first positive power supply and the first negative power supply are respectively electrically connected to the amplification triode and the first voltage comparator; the amplification triode is connected to the signal output end of the proportional counter tube; the first logic control circuit is also connected to the first pulse counting module; the second positive power supply is respectively connected to the first logic control circuit and the first positive power supply.

[0008] Further, the signal integration and quantization module includes an operational amplifier integration circuit, a second voltage comparator, and a second logic control circuit connected in sequence. The control end of the second logic control circuit is also connected to the operational amplifier integration circuit. The integration and quantization module also includes a third positive power supply, a third negative power supply, a fourth positive power supply, and a fourth negative power supply. The third positive power supply and the third negative power supply are respectively electrically connected to the operational amplifier integration circuit and the second voltage comparator; the operational amplifier integration circuit is connected to the ground signal output end of the proportional counter tube; the second logic control circuit is also connected to the second pulse counting module; the fourth positive power supply is respectively connected to the second logic control circuit and the third positive power supply; the fourth negative power supply is respectively connected to the second logic control circuit and the third negative power supply.

[0009] Further, a discharge circuit is also connected between the second logic control circuit and the operational amplifier integration circuit. The discharge circuit is triggered by the second logic control circuit to perform an instantaneous discharge on the operational amplifier integration circuit once, so that the operational amplifier integration circuit returns to its initial state for re-integration, thereby quantizing the ground signal into a pulse signal and finally outputting it to the second pulse counting module.

[0010] In the present invention, the positive and negative outputs of the proportional counter are respectively introduced into two different circuits. The first circuit is as follows: the signal output terminal of the proportional counter is sequentially connected to a signal amplification and shaping module and a first pulse counting module to measure the neutron dose in the range of 2 nSv / h - 100 mSv / h. The measurement principle of this circuit is to use the proportional pulse counting characteristic of the proportional counter to measure the neutron dose. The second circuit is as follows: the ground signal output terminal of the proportional counter is sequentially connected to a signal integration and quantization module and a second pulse counting module to measure the neutron dose in the range of 1 mSv / h - 1000 mSv / h. The measurement principle of this circuit is to use the ionization chamber characteristic of the proportional counter to measure the neutron dose. Thus, the effect of partitioning the measurement of 2 nSv / h - 1000 mSv / h is achieved. The partitioning measurement technology ensures the linearity of the full-range measurement and realizes the measurement of the neutron dose in a relatively wide range by a single proportional counter. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic diagram of the neutron detector provided by an embodiment of the present invention.

[0012] Figure 2 is a schematic diagram of the signal amplification and shaping module provided by an embodiment of the present invention.

[0013] Figure 3 is a schematic diagram of the signal integration and quantization module provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0015] In order to illustrate the technical solutions described in the present invention, the following will be described through specific embodiments.

[0016] Please refer to Figure 1 , this application provides a neutron detector, including a proportional counter 11, a signal amplification and shaping module 12 connected to the signal output terminal of the proportional counter 11, a first pulse counting module 13 connected to the signal amplification and shaping module 12, a signal integration and quantization module 14 connected to the ground signal output terminal of the proportional counter 11, a second pulse counting module 15 connected to the signal integration and quantization module 14, a processor 16 respectively connected to the first pulse counting module 13 and the second pulse counting module 15, and a prompt module 17, a storage module 18 and a communication module 19 respectively connected to the processor 16; The signal amplification and shaping module 12 amplifies the pulse signal output from the signal output end of the proportional counter tube, and after regularizing the amplified pulse signal higher than the first preset threshold voltage, forms a pulse signal and outputs it to the first pulse counting module 13; The signal integration and quantization module 14 integrates the current output from the ground signal output end of the proportional counter tube, and quantizes it into a pulse signal and outputs it to the second pulse counting module 15; The first pulse counting module 13 and the second pulse counting module 15 count the pulse signals, and transmit the number of pulses to the processor; The processor obtains the radiation dose rate of neutrons according to the number of pulses obtained by the first pulse counting module 13 and the second pulse counting module 15 and the corresponding relationship between the number of pulses and the radiation dose rate.

[0017] The specific formula is D = f * p / 1000, where D is the radiation dose rate, the unit is uSv / h, which is the dose per hour, f is the F factor, the unit is nSv / P; p is the number of pulses, the unit is P.

[0018] In the embodiment of the present application, the prompt module 17 may include a display module and / or an audio playback module, which is used to prompt the radiation dose rate of neutrons.

[0019] The storage module 18 is used to store the radiation dose rate of neutrons. The communication module 19 is used to send the radiation dose rate of neutrons to the user or the server.

[0020] In the embodiment of the present application, the first pulse counting module 13 and the second pulse counting module 15 may adopt a programmable logic chip EPM3064A chip to count the pulse signals and convert them into parallel digital signals and transmit them to the processor. For example, the counting period is 1s, that is, the number of pulses within 1 second is calculated each time. After the counting is completed, it is sent to the processor and then re-counted.

[0021] The output current level of the proportional counter tube of the neutron detector is between fA and nA. The characteristic of this output current is that the fA-level current is very weak, and the fA-nA level range has a large span.

[0022] Based on this characteristic, the present application respectively introduces the positive and negative outputs of the proportional counter tube into two different circuits. The first circuit is: the signal output end of the proportional counter tube is sequentially connected to the signal amplification and shaping module and the first pulse counting module to measure the neutron dose in the range of 2 nSv / h - 100 mSv / h. The measurement principle of this circuit is to use the proportional pulse counting characteristic of the proportional counter tube to measure the neutron dose.

[0023] When a neutron strikes a proportional counter tube, a pulse count is generated, which is a characteristic of proportional pulse counting. When the number of strikes on the proportional counter tube is relatively small, the signal can be effectively recognized, and this circuit is used to measure the pulse count at this time.

[0024] The second path is: the ground signal output terminal of the proportional counter tube is sequentially connected to the signal integration quantization module and the second pulse counting module to measure the neutron dose in the range of 1 mSv / h - 1000 mSv / h. The measurement principle of this circuit is to use the ionization chamber characteristic of the proportional counter tube to measure the neutron dose. Thus, the effect of dividing the measurement of 2 nSv / h - 1000 mSv / h into zones is achieved. The zoning measurement technology ensures the linearity of the full-range measurement and realizes the measurement of a relatively wide range of neutron doses by a single proportional counter tube.

[0025] When the number of neutrons is very large, the pulse signals generated by striking the proportional counter tube will gather into continuous signals. At this time, the first path cannot be used for counting measurement. It is necessary to use the second path to integrate and measure the current. According to the principle of the ionization chamber, the positive and negative output currents generated after particles strike the proportional counter tube are a pair of positive and negative signals. In the case of a large dose, the signal output current of the proportional counter tube at this time is also in a certain proportional relationship with the number of neutron strikes, and the proportional relationship has not failed. Experimental data shows that the current signal of the neutron dose above 10 μSv / h can be effectively measured after integral measurement, and the measurement result is also in a linear proportional relationship with the number of neutron strikes.

[0026] Based on the above characteristics, this application performs current integration quantization on the ground signal of the proportional counter tube to achieve the measurement of the neutron dose in the range of 1 mSv / h - 1000 mSv / h.

[0027] Please refer to Figure 2 , the signal amplification and shaping module in this application includes an amplification triode 121, a first voltage comparator 122, and a first logic control circuit 123 that are sequentially electrically connected. The signal amplification and shaping module also includes a first positive power supply 124, a first negative power supply 125, and a second positive power supply 126. The first positive power supply 124 and the first negative power supply 125 are respectively electrically connected to the amplification triode 121 and the first voltage comparator 122; the amplification triode 121 is connected to the signal output terminal of the proportional counter tube 11; the first logic control circuit 123 is also connected to the first pulse counting module 13. The second positive power supply 126 is respectively connected to the first logic control circuit 123 and the first positive power supply 124; In the embodiment of the present application, the first logic control circuit 123 can adopt a programmable logic chip EPM3064A. The first positive power supply 124 can adopt a power supply chip L7805CV-5 to generate a +5V power supply. The second positive power supply 126 can adopt a power supply chip AMS1117-3.3 to generate a +3.3V power supply. The first negative power supply 125 can adopt a power supply chip L7905CV-5 to generate a -5V power supply. The first voltage comparator 122 adopts an LM393 integrated chip.

[0028] The working principle of the signal amplification and shaping module in the present application is as follows: The pulse signal output from the signal output end of the proportional counter tube is amplified by an amplification triode. The amplified pulse signal enters the first voltage comparator. After comparison by the first voltage comparator, the pulse signal with a voltage higher than the first preset threshold voltage is considered a valid neutron signal. After the pulse signal higher than the first preset threshold voltage passes through the first voltage comparator, the first voltage comparator outputs a high-level signal, which is output to the first logic control circuit. After being regularized by the first logic control circuit, a pulse signal is output to the first pulse counting module.

[0029] In the embodiment of the present application, the first preset threshold voltage can be 0.5V or other values determined according to actual experience.

[0030] Please refer to Figure 3 , the signal integration and quantization module in the present application includes an operational amplifier integration circuit 141, a second voltage comparator 142, and a second logic control circuit 143 that are electrically connected in sequence. The control end of the second logic control circuit 143 is also connected to the operational amplifier integration circuit 141. The integration and quantization module further includes a third positive power supply 144, a third negative power supply 145, a fourth positive power supply 146, and a fourth negative power supply 147. The third positive power supply 144 and the third negative power supply 145 are both electrically connected to the operational amplifier integration circuit 141 and the second voltage comparator 142 respectively; the operational amplifier integration circuit 141 is connected to the ground signal output end of the proportional counter tube 11; the second logic control circuit 143 is also connected to the second pulse counting module 15; the fourth positive power supply 146 is connected to the second logic control circuit 143 and the third positive power supply 144 respectively; the fourth negative power supply 147 is connected to the second logic control circuit 143 and the third negative power supply 145 respectively; The working principle of the signal integration and quantization module in the present application is as follows: The operational amplifier integrating circuit integrates the current output from the ground signal output terminal of the proportional counter tube and converts it into a voltage signal. The voltage signal enters the second voltage comparator. If it is confirmed through comparison by the second voltage comparator that the voltage is higher than the second preset threshold voltage, the second voltage comparator outputs a high-level signal to the second logic control circuit, indicating that an integration is completed. At the same time, the second logic control circuit generates a pulse signal for the second pulse counting module. After receiving the high-level signal, the second logic control circuit outputs a low level to discharge the operational amplifier integrating circuit until it reaches the initial integration state, and then outputs a high level to stop the discharge. At this time, the operational amplifier integrating circuit starts to integrate again. This process repeats, quantifying the current output from the ground signal output terminal of the proportional counter tube into a pulse signal, which is finally output to the second pulse counting module.

[0031] In the embodiment of the present application, the current output from the ground signal output terminal is a pA-nA level current signal representing the neutron dose.

[0032] In the embodiment of the present application, the second voltage comparator uses an LM393 integrated chip.

[0033] In the embodiment of the present application, the second preset threshold voltage can be 2.5V or other values determined according to actual experience.

[0034] In the embodiment of the present application, the third positive power supply 144 can use an L7805CV-5 power supply chip to generate a +5V power supply. The third negative power supply 145 can use an L7905CV-5 power supply chip to generate a -5V power supply. The fourth positive power supply 146 can use an AMS1117-1.5 power supply chip to generate a +1.5V power supply. The fourth negative power supply 147 can use an ADP7182AUJZ-2.5 power supply chip to generate a -2.5V power supply.

[0035] In the embodiment of the present application, the operational amplifier integrating circuit 141 can use an integrating circuit built with the operational amplifier ADA4530-1ARZ to integrate the ground signal.

[0036] In the embodiment of the present application, a discharge circuit is also connected between the second logic control circuit 143 and the operational amplifier integrating circuit 141. The discharge circuit is triggered by the second logic control circuit 143 to perform an instantaneous discharge on the operational amplifier integrating circuit, so that the operational amplifier integrating circuit returns to the initial state for re-integration, thereby effectively quantifying the ground signal into a pulse signal, which is finally output to the second pulse counting module.

[0037] In the present invention, the positive and negative outputs of the proportional counter are respectively introduced into two different circuits. The first circuit is as follows: the signal output terminal of the proportional counter is sequentially connected to a signal amplification and shaping module and a first pulse counting module to measure the neutron dose in the range of 2 nSv / h - 100 mSv / h. The measurement principle of this circuit is to use the proportional pulse counting characteristic of the proportional counter to measure the neutron dose. The second circuit is as follows: the ground signal output terminal of the proportional counter is sequentially connected to a signal integration and quantization module and a second pulse counting module to measure the neutron dose in the range of 1 mSv / h - 1000 mSv / h. The measurement principle of this circuit is to use the ionization chamber characteristic of the proportional counter to measure the neutron dose. Thus, the effect of partitioning the measurement of 2 nSv / h - 1000 mSv / h is achieved. The partitioning measurement technique ensures the linearity of the full-range measurement and realizes the measurement of the neutron dose in a relatively wide range by a single proportional counter.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A neutron detector, characterized in that, It includes a proportional counter tube, a signal amplification and shaping module connected to the signal output end of the proportional counter tube, a first pulse counting module connected to the signal amplification and shaping module, a signal integration and quantization module connected to the ground signal output end of the proportional counter tube, a second pulse counting module connected to the signal integration and quantization module, a processor respectively connected to the first pulse counting module and the second pulse counting module, and a prompting module, a storage module and a communication module respectively connected to the processor; The signal amplification and shaping module amplifies the pulse signal output from the signal output end of the proportional counter tube, and after regularizing the amplified pulse signal higher than the first preset threshold voltage, forms a pulse signal and outputs it to the first pulse counting module; The signal integration and quantization module integrates the current output from the ground signal output end of the proportional counter tube, and quantizes it into a pulse signal and outputs it to the second pulse counting module; The first pulse counting module and the second pulse counting module count the pulse signal, and transmit the number of pulses to the processor; The processor obtains the radiation dose rate of neutrons according to the number of pulses obtained by the first pulse counting module and the second pulse counting module and the corresponding relationship between the number of pulses and the radiation dose rate.

2. The neutron detector according to claim 1, characterized in that, The specific formula of the corresponding relationship between the number of pulses and the radiation dose rate is D = f * p / 1000, where D is the radiation dose rate, the unit is μSv / h, which is the dose per hour, f is the F factor, the unit is nSv / P; p is the number of pulses, and the unit is P.

3. The neutron detector according to claim 1, wherein The first pulse counting module and the second pulse counting module use a programmable logic chip EPM3064A chip to count the pulse signal and convert it into a parallel digital signal and transmit it to the processor.

4. The neutron detector according to claim 1, characterized in that, The signal amplification and shaping module includes an amplification triode, a first voltage comparator and a first logic control circuit connected in sequence; the signal amplification and shaping module also includes a first positive power supply, a first negative power supply and a second positive power supply. The first positive power supply and the first negative power supply are respectively electrically connected to the amplification triode and the first voltage comparator; the amplification triode is connected to the signal output end of the proportional counter tube; the first logic control circuit is also connected to the first pulse counting module; the second positive power supply is respectively connected to the first logic control circuit and the first positive power supply.

5. The neutron detector according to claim 4, characterized in that, The first logic control circuit uses a programmable logic chip EPM3064A chip, the first positive power supply uses a power chip L7805CV-5 to generate a +5V power supply, the second positive power supply uses a power chip AMS1117-3.3 to generate a +3.3V power supply, the first negative power supply uses a power chip L7905CV-5 to generate a -5V power supply, and the first voltage comparator uses an LM393 integrated chip.

6. The neutron detector according to claim 1, characterized in that, The signal integration quantization module includes an operational amplifier integration circuit, a second voltage comparator, and a second logic control circuit that are electrically connected in sequence. The control terminal of the second logic control circuit is also connected to the operational amplifier integration circuit. The integration quantization module further includes a third positive power supply, a third negative power supply, a fourth positive power supply, and a fourth negative power supply. The third positive power supply and the third negative power supply are both electrically connected to the operational amplifier integration circuit and the second voltage comparator respectively; the operational amplifier integration circuit is connected to the ground signal output terminal of the proportional counter tube; the second logic control circuit is also connected to the second pulse counting module; the fourth positive power supply is connected to the second logic control circuit and the third positive power supply respectively; the fourth negative power supply is connected to the second logic control circuit and the third negative power supply respectively.

7. The neutron detector according to claim 6, wherein, The second voltage comparator uses an LM393 integrated chip.

8. The neutron detector according to claim 6, wherein The third positive power supply uses a power supply chip of L7805CV-5 to generate a +5V power supply, the third negative power supply uses a power supply chip of L7905CV-5 to generate a -5V power supply, the fourth positive power supply uses a power supply chip of AMS1117-1.5 to generate a +1.5V power supply, and the fourth negative power supply uses a power supply chip of ADP7182AUJZ-2.5 to generate a -2.5V power supply.

9. The neutron detector according to claim 6, wherein The operational amplifier integration circuit uses an integration circuit built with an operational amplifier ADA4530-1ARZ to integrate the ground signal.

10. The neutron detector according to claim 6, wherein, A discharge circuit is also connected between the second logic control circuit and the operational amplifier integration circuit. The discharge circuit is triggered by the second logic control circuit to perform an instantaneous discharge on the operational amplifier integration circuit once, so that the operational amplifier integration circuit is restored to the initial state for re-integration, thereby quantifying the ground signal into a pulse signal and finally outputting it to the second pulse counting module.

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