Portable radiation monitor

Abstract

The invention provides a portable radiation monitor (1) which comprises a pulse radiation field detector (10) for detecting X / gamma rays of pulse radiation, a continuous radiation field detector (20) for detecting X / gamma rays of continuous radiation, a preamplifier (31), a main amplifier (32), a signal processor (40) and a display screen (50), the pulse radiation field detector (10) is formed by coupling an inorganic scintillator and a photodiode, and the continuous radiation field detector (20) is formed by coupling an organic scintillator and a silicon photomultiplier. According to the invention, a plurality of composite detectors are adopted, and continuous, short-time and pulse radiation measurement is realized. A small-size scintillator is coupled with a photodiode or a silicon photomultiplier to serve as a detector, high-voltage power supply is not needed, the overall power consumption of the device is reduced, the size of the device is reduced, and the device is convenient to carry.

Description

Technical Field

[0001] The present invention relates to the field of nuclear radiation measurement technology, and in particular to a portable radiation monitor which can meet the radiation detection requirements of various places or environments and is suitable for monitoring X / gamma rays. Background Art

[0002] With the development of science and technology and the expansion of human activities, radiation issues are attracting more and more attention. Radiation measuring instruments have the function of monitoring radiation doses. They can quickly and accurately detect radiation dose rates in different environments, help people understand the radiation level in the environment in a timely manner, indicate the safety of environmental radiation, and effectively prevent and control radiation hazards.

[0003] At present, the mainstream radiation measuring instruments are mainly divided into two categories: one is the pulse counting detector, and the other is the current ionization chamber type detector. The disadvantage of the pulse counting detector is that the energy response performance is average, and energy compensation for different radiation fields is required when designing the dose rate meter. The disadvantage of the current ionization chamber detection is that the time constant is large, the signal acquisition time is long, the response time performance is poor, and the accuracy and stability are poor.

[0004] In addition, depending on the location or environment of the radiation, characteristics such as the amount of radiation and the radiation loading time are different. According to the time characteristics of radiation loading, radiation can be divided into pulse radiation and continuous radiation. Pulse radiation: high-energy radiation released in the form of pulses in a very short time, such as X-rays, gamma rays, etc., which have the characteristics of high instantaneous intensity, short duration and wide frequency range. For example, pulse radiation produced by nuclear explosions, X-ray photography commonly used in radiological diagnosis (pulse width is mostly in the ms level), and X-rays produced by medical linear accelerators (pulse width is in the μs level). Continuous radiation: radiation that occurs continuously over a certain period of time. Generally, its state is relatively stable, for example, continuous irradiation of sealed radioactive sources, X-ray fluoroscopy in medical examinations, etc.

[0005] Existing radiation measuring instruments are difficult to meet the radiation detection needs in various places or environments. Summary of the invention

[0006] In order to solve the technical problems existing in current radiation measuring instruments, the present invention proposes a portable radiation monitor that can meet the radiation detection needs of various places and can complete continuous, short-time and pulse radiation measurements.

[0007] In order to achieve the above object, the present invention includes the following technical solutions.

[0008] A portable radiation monitor comprises: a pulse radiation field detector for detecting pulsed X / γ rays; a continuous radiation field detector for detecting continuous X / γ rays; a preamplifier and a main amplifier for amplifying the output signals of the pulse radiation field detector and the continuous radiation field detector; a signal processor for processing the signal output by the main amplifier; and a display screen for displaying the radiation amount, wherein the pulse radiation field detector is constructed by coupling an inorganic scintillator with a photodiode, and the continuous radiation field detector is constructed by coupling an organic scintillator with a silicon photomultiplier tube, the waveform signals output by the pulse radiation field detector and the continuous radiation field detector are respectively input to the corresponding preamplifier and main amplifier, the amplified waveform signal output from the main amplifier is input to the signal processor, the signal processor samples the waveform signal using a high-speed ADC, and performs signal processing on the sampled waveform signals of the pulse radiation field detector and the waveform signal of the continuous radiation field detector to obtain radiation intensity measurement values.

[0009] Preferably, the pulse radiation field detector includes a low-range pulse radiation field detector and a high-range pulse radiation field detector, wherein the low-range pulse radiation field detector adopts a method of coupling a thicker CsI (Tl) scintillator with a silicon photodiode, and the high-range pulse radiation field detector adopts a method of coupling a thinner CsI (Tl) scintillator with a silicon photodiode, and the continuous radiation field detector includes a low-range continuous radiation field detector and a high-range continuous radiation field detector, wherein the low-range continuous radiation field detector adopts a method of coupling a thicker plastic scintillator with a silicon photomultiplier tube, and the high-range continuous radiation field detector adopts a method of coupling a thinner plastic scintillator with a silicon photomultiplier tube.

[0010] Preferably, the inorganic scintillator used in the low-range pulse radiation field detector is a 10mm×10mm×10mm CsI (Tl) crystal, the inorganic scintillator used in the high-range pulse radiation field detector is a 10mm×10mm×1mm CsI (Tl) crystal, the organic scintillator used in the low-range continuous radiation field detector is a 10mm×10mm×10mm plastic scintillator, and the organic scintillator used in the high-range continuous radiation field detector is a 10mm×10mm×1.75mm plastic scintillator.

[0011] Preferably, the waveform signals detected by the low-range pulse radiation field detector, the high-range pulse radiation field detector, the low-range continuous radiation field detector and the high-range continuous radiation field detector are respectively input into four preamplifiers, wherein the preamplifiers include high-speed low-noise JFETs or high-bandwidth BJTs.

[0012] Preferably, the signal processor integrates the sampled waveform signal of the continuous radiation field detector to obtain the pulse amplitude of the waveform signal, and obtains the radiation intensity measurement value based on counting the waveform signal.

[0013] Preferably, the signal processor performs weighted compensation processing on the radiation intensity measurement value according to the pulse amplitude of the acquired waveform signal to improve the accuracy of the radiation intensity measurement value. In the weighted compensation processing, it is determined which amplitude range of multiple predetermined amplitude ranges the pulse amplitude of the waveform signal falls into, and when the radiation intensity measurement value is obtained based on the count of the waveform signal within the amplitude range, the count is weighted compensated using a weighting coefficient determined in advance for each of the multiple amplitude ranges.

[0014] Preferably, the signal processor integrates the sampled waveform signal of the pulse radiation field detector for a specified time to obtain an accumulated charge amount, and acquires a radiation intensity measurement value based on the accumulated charge amount.

[0015] Preferably, before the signal processor samples the waveform signal using a high-speed ADC, it first performs threshold discrimination processing on the waveform signal to filter out background noise of the circuit.

[0016] Preferably, at least in the pulse radiation field detector, an energy compensation sheet for homogenizing the radiation energy response is provided.

[0017] Effects of the Invention

[0018] The beneficial effects of the present invention are:

[0019] 1. Using a variety of composite detectors to achieve continuous, short-time and pulse radiation measurement.

[0020] 2. A small-volume scintillator coupled with a photodiode or silicon photomultiplier tube is used as a detector, which does not require a high-voltage power supply, reduces the overall power consumption of the device, reduces the size of the device, and is easy to carry.

[0021] 3. High-range detectors and low-range detectors are set up, and the radiation energy response is compensated for uniformity, which expands the energy response range of the equipment and can detect X-rays and gamma rays as low as 15keV. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a block diagram of the main structure of a portable radiation monitor according to one embodiment of the present invention.

[0023] Figure 2 FIG. 4 is a diagram showing the overall structure and signal flow of a portable radiation monitor according to an embodiment of the present invention.

[0024] Figure 3 FIG. 4 is an overall structural diagram of a portable radiation monitor according to an embodiment of the present invention.

[0025] Figure 4 for Figure 3 A partially enlarged cross-sectional view of a display screen of a portable radiation monitor is shown.

[0026] Figure 5 The figure shows the arrangement of detectors in a portable radiation monitor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The word "embodiment" used here as an "exemplary" does not necessarily mean that any embodiment described is superior to or better than other embodiments. Unless otherwise specified, the performance index tests in the embodiments of this application are performed using conventional test methods in the art. It should be understood that the terms described in this application are only used to describe specific implementation methods and are not used to limit the content disclosed in this application.

[0028] Unless otherwise specified, the technical and scientific terms used in this document have the same meanings as commonly understood by ordinary technicians in the technical field to which this application belongs; other experimental methods and technical means not specifically specified in this application refer to experimental methods and technical means commonly used by ordinary technicians in this field.

[0029] In this document, including the scope of the claims, transitional words such as "include", "comprising", "with", "having", "containing", "involving", "accommodating", etc. are understood to be open, that is, to mean "including but not limited to". Only the transitional words "consisting of" and "composed of" are closed transitional words.

[0030] In order to better illustrate the content of the present application, numerous specific details are provided in the specific examples below. It should be understood by those skilled in the art that the present application can also be implemented without certain specific details. In the embodiments, some methods, means, instruments, equipment, etc. well known to those skilled in the art are not described in detail in order to highlight the main purpose of the present application.

[0031] Under the premise of no conflict, the technical features disclosed in the embodiments of the present application can be arbitrarily combined, and the obtained technical solutions belong to the contents disclosed in the embodiments of the present application. It should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like mentioned in the present application indicate the orientation or position relationship based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the technical features and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention, unless it conflicts with the context. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance, unless it conflicts with the context.

[0032] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the scope of the claimed rights and the determined spirit and scope of the present invention, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

[0033] Specific implementation modes and embodiments of the present invention are described below with reference to the accompanying drawings.

[0034] Figure 1 This is a block diagram showing the main structure of a portable radiation monitor 1 according to an embodiment of the present invention.

[0035] like Figure 1 As shown, a portable radiation monitor 1 according to an embodiment of the present invention includes a pulse radiation field detector 10 for detecting pulsed radiation X / γ rays; a continuous radiation field detector 20 for detecting continuous radiation X / γ rays; a preamplifier 31 and a main amplifier 32 for amplifying output signals of the pulse radiation field detector 10 and the continuous radiation field detector 20; a signal processor 40 for processing the signal output by the main amplifier 32; and a display screen 50 for displaying the radiation amount.

[0036] As described in detail below, the pulse radiation field detector 10 is constructed by coupling an inorganic scintillator with a photodiode, and the continuous radiation field detector 20 is constructed by coupling an organic scintillator with a silicon photomultiplier tube (SiPM photoelectric conversion device).

[0037] exist Figure 1In the figure, for the sake of simplicity, only one box is used to represent the preamplifier 31 and the main amplifier 32. However, the waveform signals output by the pulse radiation field detector 10 and the continuous radiation field detector 20 are respectively input to the corresponding preamplifier 31 and the main amplifier 32, and the amplified waveform signals output from the main amplifier 32 are input to the signal processor 40.

[0038] The signal processor 40 samples the waveform signal using a high-speed ADC (analog-to-digital converter), and performs signal processing on the sampled waveform signal of the pulse radiation field detector 10 and the waveform signal of the continuous radiation field detector 20 to obtain radiation intensity measurement values.

[0039] Preferably, the pulse radiation field detector 10 includes a low-range pulse radiation field detector 11 and a high-range pulse radiation field detector 12, and the continuous radiation field detector 20 includes a low-range continuous radiation field detector 21 and a high-range continuous radiation field detector 22. The low range mentioned here has a measurement range of approximately 0-0.5μSv / h. The high range mentioned here has a measurement range of approximately 0.5μSv / h-100Sv / h. The portable radiation monitor 1 of the present invention is provided with a high-range detector and a low-range detector, and as described below, the radiation energy response is uniformly compensated, which expands the energy response range of the device and can detect X-rays and gamma rays as low as 15keV.

[0040] Although in Figure 1 It is shown that the pulse radiation field detector 10 includes a low-range pulse radiation field detector 11 and a high-range pulse radiation field detector 12, and the continuous radiation field detector 20 includes a low-range continuous radiation field detector 21 and a high-range continuous radiation field detector 22, but it should be understood that it is only a preferred embodiment of the present invention. The portable radiation monitor 1 of the present invention can also be a pulse radiation field detector 10 and a continuous radiation field detector 20 each including only one detector. In this case, continuous, short-time and pulse radiation measurements can be achieved through a composite detector, and the structure of the radiation monitor can be simplified to reduce costs.

[0041] Preferably, the low-range pulse radiation field detector 11 adopts a method of coupling a thicker CsI (Tl) scintillator (thallium-doped cesium iodide scintillator) with a silicon photodiode, the high-range pulse radiation field detector 12 adopts a method of coupling a thinner CsI (Tl) scintillator with a silicon photodiode, the low-range continuous radiation field detector 21 adopts a method of coupling a thicker plastic scintillator with a silicon photomultiplier tube, and the high-range continuous radiation field detector 22 adopts a method of coupling a thinner plastic scintillator with a silicon photomultiplier tube.

[0042] The photodiode works in the current integration mode. The density of CsI crystal is relatively large and the ability of energy deposition is relatively strong. It can completely collect photons and increase the detection efficiency. Specifically, CsI crystal has a high light yield, a high density and a short luminescence decay time. Its spectral emission wavelength is at a maximum of 550nm, which can be well matched with PD photodiodes. It has a high detection efficiency for gamma rays and X-rays and a high energy resolution. Therefore, the coupling method of CsI (Tl) scintillator and silicon photodiode is suitable for use as a pulse radiation field detector 10. In addition, CsI crystal has the advantages of not being easy to deliquesce compared to NaI crystal, easy to process, and good uniformity.

[0043] The advantages of using a plastic scintillator coupled with a silicon photomultiplier tube as the continuous radiation field detector 20 are as follows: SiPM photoelectric conversion devices can work in pulse counting mode. In order to expand the energy response range of continuous radiation field measurement, a detector with a relatively low density is required, so that low-energy rays can be deposited as little as possible, so a plastic scintillator is selected.

[0044] More preferably, the inorganic scintillator used in the low-range pulse radiation field detector 11 is a 10mm×10mm×10mm CsI (Tl) crystal, the inorganic scintillator used in the high-range pulse radiation field detector 12 is a 10mm×10mm×1mm CsI (Tl) crystal, the organic scintillator used in the low-range continuous radiation field detector 21 is a 10mm×10mm×10mm plastic scintillator, and the organic scintillator used in the high-range continuous radiation field detector 22 is a 10mm×10mm×1.75mm plastic scintillator. The above-mentioned scintillator is small in size, and different detection sensitivities can be achieved only by appropriately selecting its thickness, and is suitable for use in the portable radiation monitor 1. That is, a small-volume scintillator is coupled with a photodiode or a silicon photomultiplier tube as a detector, and no high-voltage power supply is required, which reduces the overall power consumption of the device, reduces the size of the device, and is easy to carry.

[0045] Preferably, the waveform signals detected by the low-range pulse radiation field detector 11, the high-range pulse radiation field detector 12, the low-range continuous radiation field detector 21 and the high-range continuous radiation field detector 22 are respectively input to four preamplifiers 31, wherein the preamplifier 31 includes a high-speed low-noise JFET (junction field effect transistor) or a high-bandwidth BJT (bipolar junction transistor). Such a structure has the characteristics of extremely low noise, faster time response speed, higher resolution, and wide output dynamic range. That is, the preamplifier 31 of the present device adopts an extremely sensitive analog circuit design, and the rise time of the pulse waveform that can be collected is 10ns.

[0046] Preferably, the signal processor 40 integrates the waveform signal of the sampled continuous radiation field detector 20 to obtain the pulse amplitude of the waveform signal, and obtains the radiation intensity measurement value based on the counting of the waveform signal. The waveform signal of the continuous radiation field detector 20 is a pulse signal with a very narrow width, and it is difficult to accurately measure its pulse amplitude. Integrating the waveform signal can accurately obtain the pulse amplitude of the entire signal. The continuous radiation field measurement is used to measure the number of pulses. The higher the frequency of the pulses, the greater the radiation dose of the continuous radiation field, and the greater the measured radiation intensity, that is, the dose rate.

[0047] The response of the radiation field detector to radiation of different energies is different. The response of different energies to the circuit is the amplitude of the pulse signal. The higher the energy, the greater the amplitude. In order to improve the accuracy of the radiation intensity measurement value, it is preferred that the signal processor 40 performs weighted compensation processing on the radiation intensity measurement value according to the pulse amplitude of the acquired waveform signal. In the weighted compensation processing, it is determined which amplitude range (which can be implemented in the circuit with 12 digital comparators) the pulse amplitude of the waveform signal falls into among the predetermined multiple amplitude ranges (for example, divided into 12 intervals), and when obtaining the radiation intensity measurement value based on the count of the waveform signal within the amplitude range, the count is weighted compensated using the weighting coefficient determined in advance for each amplitude range of the multiple amplitude ranges. The weighting coefficient can be determined in advance by experiments in a standard test field.

[0048] For a pulsed radiation field, the radiation intensity, i.e., the dose rate, can be calculated based on the amplitude of each pulse obtained by the pulsed radiation field detector 10. Preferably, the signal processor 40 integrates the waveform signal of the sampled pulsed radiation field detector 10 for a specified time to obtain the accumulated charge amount, and obtains the radiation intensity measurement value based on the accumulated charge amount.

[0049] Preferably, before the signal processor 40 samples the waveform signal using a high-speed ADC, it first performs threshold discrimination processing on the waveform signal to filter out background noise of the circuit and improve the accuracy of the radiation intensity measurement value.

[0050] Preferably, at least in the pulse radiation field detector 10, an energy compensation sheet for homogenizing the radiation energy response is provided. As mentioned above, the radiation field detector has different responses to radiation of different energies. For the waveform signal obtained by the continuous radiation field detector 20, the above-mentioned weighted compensation process can be used to correct the radiation intensity measurement value. For the pulse radiation field, the radiation intensity, i.e., the dose rate, is calculated based on the amplitude of each pulse obtained by the pulse radiation field detector 10, and it is not suitable to use the weighted compensation process.

[0051] To this end, at least for the pulse radiation field detector 10, a "physical compensation" method can be adopted, that is, an energy compensation sheet for uniformly compensating the radiation energy response is set on the detector. Specifically, the density of the shielding material can be calculated by mathematical modeling in advance according to the response of the detector under different energy rays, and then the energy compensation material, that is, the energy compensation sheet, can be made and covered on the detector to compensate for the energy response uniformly. The technology for designing and making the energy compensation sheet can adopt the technical solution disclosed in CN109839657B, for example.

[0052] Example

[0053] Refer to the following Figures 2 to 5 , illustrating an embodiment of the portable radiation monitor 1 of the present invention, which can complete continuous, short-time and pulse radiation measurements in order to meet the ionizing radiation detection needs of various locations.

[0054] Figure 2 FIG. 4 is a diagram showing the overall structure and signal flow of the portable radiation monitor 1 according to an embodiment of the present invention.

[0055] exist Figure 2 In the portable radiation monitor 1 of the embodiment of the present invention shown, the portable radiation monitor 1 includes a pulse radiation field detector 10, a continuous radiation field detector 20, a signal processor (circuit board) 40, a housing assembly 100, 101, 102, 103, an MCU main control board 60, a lithium battery 61, a display screen 50 composed of OLED, an RS485 wired communication module 63, a LoRa wireless communication module 64, a membrane switch button 65, and a GPS / Beidou positioning module 66. However, the RS485 wired communication module 63, the LoRa wireless communication module 64, and the GPS / Beidou positioning module 66 are not components that must be possessed by the present invention. For example, the wired and wireless communication modules can be omitted when there is no need to communicate with an external device. When positioning is not required, the GPS / Beidou positioning module 66 can be omitted. The components such as the lithium battery 61, the display screen 50 composed of OLED, the membrane switch button 65, etc. can also be replaced by other corresponding components, which is obvious to those skilled in the art.

[0056] The pulse radiation field detector 10 adopts an inorganic scintillator and a photodiode (PD) coupling method, wherein the low-range pulse radiation field detector 11 adopts a 10mm×10mm×10mm CsI (Tl) crystal coupled with S3590-08 (silicon photodiode) of Hamamatsu, Japan, and the high-range pulse radiation field detector 12 adopts a 10mm×10mm×1mm CsI (Tl) crystal coupled with S3590-08 (silicon photodiode) of Hamamatsu, Japan.

[0057] The continuous radiation field detector 20 uses an organic scintillator coupled with a SiPM photoelectric conversion device, wherein the low-range continuous radiation field detector 21 uses a 10mm×10mm×10mm organic scintillator coupled with ON (ON Semiconductor) MicroFJ-60035SiPM, and the high-range continuous radiation field detector 22 uses a 10mm×10mm×1.75mm organic scintillator coupled with ON (ON Semiconductor) Micro FJ-60035SiPM. Each SiPM unit includes multiple avalanche photodiodes (APDs) operating in Geiger mode, each APD is a pixel, and after receiving a photon, it will output a charge pulse signal, and the sum of the charge output by all APDs is proportional to the total number of photons detected by the SiPM unit.

[0058] The electrical signals detected by the four detectors are respectively input to four preamplifiers 31, and the amplified four electrical signals are input to one main amplifier. The electrical signals detected by the four detectors of the portable radiation monitor 1 are input to the preamplifier 31, wherein the preamplifier 31 includes a high-speed low-noise JFET and a high-bandwidth BJT. Such a structure has the characteristics of extremely low noise, fast time response speed, high resolution, and wide output dynamic range.

[0059] The exponential pulse signal output by the preamplifier 31 is then input to the main amplifier for signal amplification, and becomes a pulse signal with a relatively strong amplitude. The frequency of the pulse signal corresponds to the intensity of the radiated photons.

[0060] The value of the radiation intensity monitored by the radiation monitor is the dose rate value, and the unit is uSv / h. The portable radiation monitor 1 of the present invention can automatically identify and measure the radiation intensity in two irradiation scenarios: pulse radiation and continuous radiation. Compared with the existing pulse radiation monitoring equipment that can only measure the radiation intensity, the portable radiation monitor 1 of the present invention can not only measure the intensity of the pulse radiation field, but also measure the frequency of the pulse. It can measure high-speed pulse fields of the 10ns level, and existing equipment cannot measure such high-speed radiation fields. The measurement range of the continuous field is large, and can measure 0.1uSv / h to 100Sv / h.

[0061] This device can check the 10nS pulse signal. In the analog circuit design, a relatively high sampling rate ADC is used. A 10ns signal is a 100MHz signal. This device uses a 500Mhz high-speed ADC to sample the signal, and adopts a dual-channel alternating sampling method to ensure the integrity of the 10ns signal collected. When the signal is input into the analog circuit and the signal is checked, the signal is immediately integrated to obtain the pulse amplitude of the entire signal. Because it is a dual-channel alternating sampling, not only the amplitude of the signal can be obtained, but also the number of signals can be accurately obtained.

[0062] The pulse signal enters the signal processor 40 for threshold discrimination, amplitude acquisition, signal compensation, etc. The threshold discrimination is mainly to filter out some background noise of the circuit and screen the effective detector signal and noise in the hardware circuit.

[0063] The radiation of different energies has different luminous intensities on the detector, and the amplitudes obtained through the photoelectric conversion circuit are also different. After the effective signal is identified by the threshold, it passes through the fast ADC circuit to obtain its corresponding amplitude.

[0064] For the waveform signal acquired by the continuous radiation field detector 20, the count value is weighted and compensated according to the pulse amplitude of the acquired waveform signal to finally obtain the radiation intensity value. In the weighted compensation process, the pulse amplitude is divided into 12 intervals in advance, and it is determined which interval the pulse amplitude of the waveform signal falls into, and then the count value is weighted and compensated using the weighting coefficient determined in advance for each interval. A specific example of the weighting coefficient is as follows, where weighPre represents the weighting coefficient, and the numbers from 0 to 11 represent the 0th to 11th intervals.

[0065] weighPre[0]=0.0535; weighPre[1]=0.0746; weighPre[2]=0.0796;

[0066] weighPre[3]=0.1032; weighPre[4]=0.1272; weighPre[5]=0.1586; weighPre[6]=0.1839; weighPre[7 ]=0.1942; weightPre[8]=0.2053; weightPre[9]=0.2539; weightPre

[10] =0.2582; weightPre

[11] =0.2596.

[0067] The electronic components of the signal processor 40 are FPGA, high-speed amplifier, triode, high-precision resistor and capacitor, and the signal processor 40 includes a threshold voltage setting unit, an amplitude acquisition judgment unit and a pulse signal output unit. The threshold voltage setting unit sets the threshold voltage through the MCU main control board 60 according to the voltage value of the matching pulse processing circuit, and judges whether the amplified pulse signal voltage amplitude exceeds the threshold voltage through the amplitude acquisition judgment unit. If it exceeds, the MCU main control board 60 controls the sound, light and vibration alarm unit to issue an alarm message. If it does not exceed, the amplified signal outputs a pulse signal.

[0068] Each unit of the signal processor 40 is connected in parallel with a high-precision capacitor and a high-precision resistor. By connecting a resistor in parallel with the capacitor, a DC signal is blocked from passing through, while an AC pulse signal is allowed to pass through. This reduces the passing capacity of low-frequency signals and increases the passing capacity of high-frequency signals. The high-precision capacitors connected in parallel achieve bypass, decoupling, filtering and energy storage functions.

[0069] Among them, the MCU uses the STM32F103 series from STMicroelectronics, which has low power consumption, 3.3V power supply, rich enhanced I / O ports and bus peripherals, supports multiple communication protocols, and is equipped with multiple debugging and testing interfaces, which is convenient for developers to debug and test, and has a high cost performance.

[0070] The display screen 50 composed of OLED is connected to the MCU main control board by using a shielded FPC cable, and the membrane switch button 65 is also connected to the MCU main control board by using a shielded FPC cable.

[0071] RS485 wired communication module 63 uses Maxim Semiconductor's MAX3485E, which is powered by 3.3V and has a transmission rate of up to 12Mbps. It has enhanced electrostatic protection. All transmitter outputs and receiver inputs have +15kV protection and pass the IEC 1000-4-2 air discharge test; +8kV protection passes the IEC 1000-4-2 contact discharge test, and ±15kV protection passes the human body model test. In the design of the communication circuit, two-level protection is performed on both ends of 485A+ and 485B-, and a self-recovery insurance is added to automatically disconnect when the current is too large to protect the RS485 chip from damage; TVS tubes are added between 485A+ and 485B-, between 485A+ and GND, and between 485B- and GND to control the voltage and ensure that the voltage difference is within the working range of the chip.

[0072] The LoRa wireless communication module 64 and the GPS / Beidou positioning module 66 both use RS485 communication to exchange data with the MCU main control board. There are two openings on the upper left side of the back shell, which are used to connect the suction cup antenna of the LoRa wireless communication module 64 and the GPS / Beidou positioning antenna respectively, to improve the stability of communication, increase the transmission distance, and improve the anti-interference ability.

[0073] The portable radiation monitor 1 of the present invention is used to realize continuous, short-time and pulse radiation measurement with multiple composite detectors; a small-volume organic scintillator and SiPM coupling are used as detectors, and a PD photodiode is selected as a detector, so that no high-voltage power supply is required, the overall power consumption of the device is reduced, the device size is reduced, and it is easy to carry; a constant field and pulse field comprehensive energy compensation algorithm is adopted to expand the energy response range of the device, and X-rays and gamma rays as low as 15keV can be detected; an aluminum alloy shell of a certain thickness, a reasonable circuit board design and layout, and a complete shielding design are selected to improve the accuracy, reliability and anti-interference of the radiation measurement of the device.

[0074] Figure 3-Figure 5 The internal and external structures of the portable radiation monitor 1 of the present invention are shown.

[0075] The material of the housing 100 of the portable radiation monitor is 7075-T651 aluminum alloy with a thickness of 5 mm as a high-strength aluminum alloy, which is subjected to conductive oxidation treatment, and the outer surface of the housing 100 is evenly sprayed with an insulating paint with a thickness of 85 μm. As a result, the electric field inside the housing 100 is greatly reduced, effectively shielding electric field or electromagnetic field interference.

[0076] The portable radiation monitor is a rectangular parallelepiped structure, and the main structural parts include the front panel 101, the rear shell 102, the battery cover 103, etc. The external interface is uniformly arranged on the upper left side of the rear shell. There are five opening positions on the shell 100, which are:

[0077] Figure 4 The screen opening is shown, and the screen surface is covered with a transparent metal film, which is tightly attached to the inside of the housing 100 and is sealed with a conductive adhesive. A 5mm thick aluminum alloy shielding cover is added to the inside of the screen to provide a second layer of protection.

[0078] Figure 3 , Figure 5 The two SMA (Sub Miniature version A) antenna openings 104 and one aviation plug opening 105 are shown. These three components are metal components. The housing 100 is assembled using an internal welding process to weld the connector and the housing 100 together. They are each equipped with a metal sealing cap. When the response function is not working, assembling the shielding cap can better ensure the shielding performance.

[0079] Figure 3 The battery cover 103 shown is made of metal, and has the same material and thickness as the outer shell 100, and adopts a trapezoidal structure. The battery compartment is made of aluminum, with a wall thickness of 2 mm and a bottom thickness of 3 mm, and the bottom thickness is the same as the thickness of the outer shell 100. The battery cover 103 is tightly fitted with the outer shell 100, and the internal battery compartment provides an additional shielding for the internal circuit part. The electrodes of the battery compartment are welded to the board to achieve a completely sealed effect.

[0080] The circuit board (PCBA) inside the portable radiation monitor 1 of this embodiment adopts a partial shielding solution, that is, a shielding cover is added to protect the relatively sensitive circuit units inside the housing 100; the shielding cover is formed by bending and stamping aluminum plates and has a seamless structure. The device display screen uses transparent metal shielding materials, which can effectively resist electromagnetic shielding and ensure high-definition display effects. Figure 5 As shown, the pulse radiation field detector 10 and the continuous radiation field detector 20 are placed in independent mounting grooves respectively and packaged with, for example, 0.03 mm aluminum foil material, so as to effectively resist electromagnetic interference and ensure the accuracy and reliability of pulse radiation field measurement.

[0081] In the portable radiation monitor 1 of this embodiment, grounding is the most effective method to suppress interference. The voltage at two points on the power ground line is a very serious interference to the signal level, so the power ground line cannot be used as a signal ground line. Decoupling capacitors are added to reduce the power common impedance coupling interference between power units on the same power line. Each unit on the signal ground line adopts a single-point grounding, and the overlap of the device signal ground line and the system signal ground line cannot destroy the single-point grounding of the system.

[0082] In order to better achieve isolation and ensure stable working performance, this system is divided into three areas.

[0083] (1) External ground PGND. PGND and internal ground are isolated. PGND is connected to the shell, and the shell is equipped with a grounding point and a grounding wire.

[0084] (2) Digital ground GND, GND provides a reference point for parts related to digital circuits, mainly including MCU control circuits, LCD display circuits, wired and wireless communication circuits, key interaction circuits, and Beidou positioning circuits.

[0085] (3) Analog ground AGND: AGND provides a reference point for parts related to analog circuits, mainly including detector working circuits, signal processing analog front-end circuits, and signal shaping amplifier circuits.

[0086] Among them, the analog ground and the digital ground are grounded at a single point, and the single-point connection uses a magnetic bead, which can suppress the high-frequency interference between the two ground planes while ensuring the equipotential of the two ground planes.

[0087] In the portable radiation monitor 1 of this embodiment, the circuit board (PCB) is designed with a 6-layer board topology structure, with the top and bottom layers being ground layers and the inner 4 layers being signal layers, which can effectively suppress the interference and crosstalk of space radiation on the signal line.

[0088] The portable radiation monitor 1 includes 4 circuit units, namely, a main controller processing unit, a detector signal processing unit, a display unit, and a positioning communication unit. The 4 unit modules are arranged separately, especially the detector signal processing unit is shielded and isolated from the other units, so that the part that is relatively susceptible to interference can be protected in space.

[0089] In terms of device selection, components that can reduce noise and suppress electromagnetic interference are preferred. The capacitors and inductors use EMc (electromagnetic compatibility) suppression devices produced by TDK. The power chip uses the LDO (low dropout linear regulator) chip produced by ADI (Analog Devices) with high common-mode power rejection ratio. No switching power chip is used, which not only ensures low power noise but also avoids space and board-level crosstalk generated by the switching power supply, as well as some harmonic interference. The main control chip selects a chip with a low main frequency while ensuring performance.

[0090] From the perspective of PCB device layout and routing, inductive devices should reserve a good grounding discharge path; the combination of high and low capacitance values ​​of capacitive devices can provide a discharge loop for noise in the entire frequency band; in terms of routing: the copper film line should have rounded or beveled corners at the bends, and the two adjacent layers of routing should be perpendicular, oblique or curved to avoid parallel routing, reduce parasitic coupling, thicken the ground wire so that it can pass three times the allowable current on the printed circuit board, and be grounded nearby to avoid the formation of a circular ground loop.

[0091] Through the above structure, the portable radiation monitor of the present invention can effectively shield electric field, magnetic field or electromagnetic field interference.

[0092] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

[0093] The technical solutions disclosed in the present invention and the technical details disclosed in the embodiments are merely illustrative of the inventive concept of the present invention and do not constitute a limitation on the technical solutions of the present invention. Any conventional changes, substitutions or combinations of the technical details disclosed in the embodiments of the present invention have the same inventive concept as the present invention and are within the scope of protection claimed by the present invention.

Claims

1. A portable radiation monitor, characterized in that: include: Pulsed radiation field detectors for detecting pulsed X / gamma rays; Continuous radiation field detector for detecting continuous radiation X / gamma rays; A preamplifier and a main amplifier for amplifying output signals of the pulse radiation field detector and the continuous radiation field detector; a signal processor for processing the signal output by the main amplifier; and a display screen for displaying the radiation amount, The pulse radiation field detector is formed by coupling an inorganic scintillator with a photodiode. The continuous radiation field detector is formed by coupling an organic scintillator with a silicon photomultiplier tube. The waveform signals output by the pulse radiation field detector and the continuous radiation field detector are respectively input to the corresponding preamplifier and main amplifier, and the amplified waveform signals output by the main amplifier are input to the signal processor. The signal processor samples the waveform signal using a high-speed ADC, and performs signal processing on the sampled waveform signal of the pulse radiation field detector and the waveform signal of the continuous radiation field detector to obtain radiation intensity measurement values.

2. The portable radiation monitor according to claim 1, characterized in that: The pulse radiation field detector includes a low-range pulse radiation field detector and a high-range pulse radiation field detector. The low-range pulse radiation field detector uses a thicker CsI (Tl) scintillator coupled with a silicon photodiode, and the high-range pulse radiation field detector uses a thinner CsI (Tl) scintillator coupled with a silicon photodiode. The continuous radiation field detector includes a low-range continuous radiation field detector and a high-range continuous radiation field detector. The low-range continuous radiation field detector uses a plastic scintillator with a relatively large thickness coupled to a silicon photomultiplier tube, and the high-range continuous radiation field detector uses a plastic scintillator with a relatively small thickness coupled to a silicon photomultiplier tube.

3. The portable radiation monitor according to claim 2, characterized in that: The inorganic scintillator used in the low-range pulse radiation field detector is a 10mm×10mm×10mm CsI(Tl) crystal, and the inorganic scintillator used in the high-range pulse radiation field detector is a 10mm×10mm×1mm CsI(Tl) crystal. The organic scintillator used in the low-range continuous radiation field detector is a plastic scintillator of 10mm×10mm×10mm, and the organic scintillator used in the high-range continuous radiation field detector is a plastic scintillator of 10mm×10mm×1.75mm.

4. The portable radiation monitor according to claim 2 or 3, characterized in that: The waveform signals detected by the low-range pulse radiation field detector, the high-range pulse radiation field detector, the low-range continuous radiation field detector and the high-range continuous radiation field detector are respectively input into four preamplifiers, wherein the preamplifiers include high-speed low-noise JFETs or high-bandwidth BJTs.

5. The portable radiation monitor according to any one of claims 1 to 4, characterized in that: The signal processor integrates the sampled waveform signal of the continuous radiation field detector to obtain the pulse amplitude of the waveform signal, and obtains the radiation intensity measurement value based on the counting of the waveform signal.

6. The portable radiation monitor according to claim 5, characterized in that: The signal processor performs weighted compensation processing on the radiation intensity measurement value according to the pulse amplitude of the acquired waveform signal to improve the accuracy of the radiation intensity measurement value. In the weighted compensation processing, it is determined which amplitude range of multiple amplitude ranges determined in advance the pulse amplitude of the waveform signal falls into, and when the radiation intensity measurement value is obtained based on the count of the waveform signal within the amplitude range, the count is weighted compensated using the weighting coefficient determined in advance for each of the multiple amplitude ranges.

7. The portable radiation monitor according to any one of claims 1 to 6, characterized in that: The signal processor integrates the sampled waveform signal of the pulse radiation field detector for a specified time to obtain an accumulated charge amount, and acquires a radiation intensity measurement value based on the accumulated charge amount.

8. The portable radiation monitor according to any one of claims 1 to 7, characterized in that: Before the signal processor samples the waveform signal using the high-speed ADC, it first performs threshold discrimination processing on the waveform signal to filter out the background noise of the circuit.

9. The portable radiation monitor according to any one of claims 1 to 8, characterized in that: At least in the pulse radiation field detector, an energy compensation sheet is provided for homogenizing the radiation energy response.

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