CN114839662A - A Wide Range Gamma Dosimeter - Google Patents

Abstract

The invention provides a wide-range gamma dosimeter, comprising a detection module, a collection and analysis module for collecting and analyzing the electrical pulse signal output by the detection module, and a data collecting and distributing module for human-computer interaction and data sharing. The detection module includes a scintillator detector and a readout circuit, and the acquisition and analysis module includes a conditioning circuit, an AD converter, and an FPGA (Field Programmable Logic Gate Array). The wide-range gamma dosimeter cooperates with AD conversion by using FPGA. The device enables the scintillator detector to work in single-pulse mode and current mode, expands the measurement range of gamma dose rate, and can obtain gamma energy spectrum in single-pulse mode.

Description

A Wide Range Gamma Dosimeter

technical field

The invention belongs to the technical field of ionizing radiation detection. Specifically related to a wide-range gamma dosimeter

Background technique

Gamma dose rate meters are widely used in radiation monitoring, special workplaces in the nuclear industry, nuclear medicine, nuclear security and other fields. Warning, to provide radiation safety guarantee for relevant practitioners.

The dose conversion methods used in the existing gamma dose rate meter mainly include count rate conversion method, G(E) function method, and current method. Among them, when the count rate conversion method is applied to inorganic scintillators, the dose rate obtained by the count rate conversion will have a large error due to the higher energy response at the low energy end, and in the high ambient dose rate, the measurement will be caused by the accumulation of detector pulse signals. The deviation increases; the G(E) function method uses the full gamma energy spectrum information for dose rate conversion, and the conversion accuracy is the best, but the detector pulse signal is seriously accumulated in the high environmental dose rate, so the accurate gamma energy spectrum cannot be obtained. As a result, this method fails; the working conditions of the above two methods are that the detector is in single-pulse mode; although the current method can cooperate with the detector to work in the current mode in a high dose rate environment, it will be due to the detection sensitivity in low dose rate places. Deficiencies lead to increased errors.

Existing various gamma dosimeters often use a single detector because they can only work in single pulse mode or current mode, resulting in a narrow coverage of dose rate range, especially inorganic scintillator detectors are usually used as ambient gamma dosimeters. The equipment for measuring horse dose rate may lead to wrong judgment in emergencies because the dose rate range cannot be covered. Under this background, the wide-range gamma dosimeter is of great significance to the gamma dose rate meter.

Applicants are unaware of prior art solutions in the aforementioned field, providing a wide range gamma dosimeter for enabling measurements over a wide range of gamma dose rates.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the above-mentioned defects or deficiencies in the prior art, and provide a wide-range gamma dosimeter, in order to realize the control of the measuring instrument in a single probe mode, so that the scintillator detector can be operated in a single pulse mode and a current mode. Work under the gamma dose rate meter to widen the range.

The purpose of the present invention is achieved as follows: it is composed of a detection module, a collection and analysis module, and a data collection and distribution module. The composition and functions of each part are as follows:

The detection module includes a scintillator detector and a readout circuit; the scintillator detector is composed of a scintillator and a photoelectric conversion device, and the scintillator generates optical photons by interacting with incident gamma rays to cause a radiation-induced photon effect; The light-receiving surface of the optoelectronic replacement device is coupled with the scintillator to convert optical photons into electrical pulse signals; the readout circuit is connected to the photoelectric conversion device of the scintillator detector, and is used to convert the current output by the scintillator detector. The pulse signal is converted into a voltage pulse signal.

The acquisition and analysis module includes a conditioning circuit, an AD converter, and an FPGA; the conditioning circuit is connected to the readout circuit of the detection module, and is used for conditioning the voltage pulse signal output by the readout circuit to a voltage range adapted by the AD converter; The AD converter is used to convert the analog signal input by the conditioning circuit to the AD converter into a digital signal; the FPGA is used to monitor the nuclear pulse digital signal data stream of the AD conversion in real time and set the corresponding pulse integration time according to the type of scintillator detector. window, the FPGA integrates the voltage signal within the time window and outputs the integrated value.

The data collection and distribution module is connected with the acquisition and analysis module, and includes a single-chip microcomputer, a USB and wireless communication module, and peripherals; the single-chip microcomputer is used for secondary processing of the nuclear pulse integral data output by the acquisition and analysis module to obtain the gamma dose rate of the radiation field, Gamma cumulative dose, gamma energy spectrum information, and control other components of the data collection and distribution module.

Preferably, the scintillator is an inorganic scintillator.

Preferably, the photoelectric conversion device is one of a photomultiplier tube and a silicon photomultiplier tube, and the spectral response wavelength range of the photoelectric conversion device coincides with the emission wavelength range of the scintillator.

Preferably, in order to ensure the charge integration-energy correlation of the signal, the readout circuit is composed of a current-type pre-circuit.

Preferably, the conditioning circuit is composed of an adjustable gain amplifying circuit and a single-ended to differential circuit. In order to realize the acquisition of the fast component of the nuclear pulse signal, the adjustable gain amplifying circuit is composed of a high-speed operational amplifier.

Preferably, the AD converter is of a differential input type.

Preferably, the FPGA sets a signal threshold by judging the electronic noise and the signal baseline, and the threshold is used to start the pulse integration time window.

Preferably, the single-chip microcomputer determines whether the instrument works in single-pulse mode or current mode by judging the number of integral values output by the FPGA per unit time. In the single-pulse mode, the single-chip microcomputer performs dose rate conversion and gamma energy spectrum drawing. Only the dose rate change is performed in the mode.

Preferably, the single-chip microcomputer can establish two-way communication with the host computer through USB and share the information of gamma dose rate, gamma cumulative dose, and gamma energy spectrum.

Preferably, the single-chip microcomputer can establish two-way communication with a device having the same wireless communication function through a wireless communication module and share the gamma dose rate, gamma cumulative dose, and gamma energy spectrum information.

Preferably, the wireless communication module is any one of a Bluetooth module, a ZigBee module, and a WiFi module.

Preferably, wherein the peripheral includes:

The control button is connected with the single-chip microcomputer and is used for controlling the working mode of the wide-range gamma dosimeter.

The display screen, connected with the single chip microcomputer, is used for displaying the gamma dose rate, the gamma cumulative dose and the gamma energy spectrogram.

An alarm, connected with the single chip microcomputer, is used to issue an alarm when the gamma dose rate or the gamma cumulative dose exceeds a preset threshold.

Preferably, the power supply module is connected to the detection module, the acquisition and analysis module, and the data collection and distribution module, and is used to supply power to the detection module, the collection and analysis module, and the data collection and distribution module.

Compared with the prior art, the beneficial effects of the present invention are: the wide-range gamma dosimeter of the present invention enables the scintillator detector to work in a single pulse by integrating the functions of the AD converter, the FPGA and the single-chip microcomputer with the modular design of each part. Mode and current mode, which expand the gamma dose rate measurement range of the scintillator detector, and can adjust the relative installation position of each module according to the actual working environment, which is highly practical.

Description of drawings

Fig. 1 is the structural block diagram of a kind of wide-range gamma dosimeter of the present invention;

Fig. 2 is the structural schematic diagram of the detection module of the present invention

Fig. 3 is a kind of structural schematic diagram of the present invention

Reference numerals: 1-detection module, 2-collection and analysis module, 3-data collection and distribution module, 4-power supply module, 5-scintillation detector, 6-readout circuit, 7-conditioning circuit, 8-AD changer , 9-FPGA, 10-MCU, 11-USB, 12-Wireless communication module, 13-Peripherals, 14-Scintillator, 15-Photoelectric replacement device, 16-Control buttons, 17-Display screen, 18-Alarm device, 19-optical glue, 20-optical reflection layer, 21-pin header, 22-stainless steel hollow pipe, 23-main box, 24-aluminum cylindrical box, 25-coaxial cable.

Detailed ways

The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

FIG. 1 shows a system structure block diagram of a wide-range gamma dosimeter according to a preferred embodiment of the present invention, including a detection module 1 , a collection and analysis module 2 , a wireless communication module 3 , and a power supply module 4 .

Referring to FIG. 2 , the detection module 1 includes a scintillator detector 5 and a readout circuit 6. The scintillator detector 5 is a closed whole, and its interior includes a scintillator 14 and a photoelectric replacement device 15. Connected by optical glue 19; an optical reflection layer 20 is arranged in the inner gap of the detection module; the readout circuit 6 is a current-type pre-circuit, packaged on a PCB, and connected to the signal output end of the scintillator detector 5 through pin headers 21 connected;

The acquisition and analysis module 2 is connected to the detection module 1, and the acquisition and analysis module 2 is packaged on a PCB, which includes a conditioning circuit 7, an AD converter 8, and an FPGA 9;

The data collection and distribution module 3 includes a single-chip microcomputer 10, a USB 11, a wireless communication module 12, and a peripheral device 13; the single-chip microcomputer 10 is connected to the FPGA 9 of the acquisition and analysis module 2; the peripheral device includes a control button 16, a display screen 17 , Alarm 18;

The power supply module 4 is connected to the detection module 1 , the acquisition and analysis module 2 and the data collection and distribution module, and is used to supply power to each module.

In this embodiment, the optical photons generated after the scintillator 14 is irradiated by gamma rays enter the photoelectric conversion device 15 under the guidance of the optical reflection layer and the optical glue to generate a current pulse signal, and the current pulse signal passes through the readout circuit 6. The voltage pulse signal is converted into a voltage pulse signal by the type pre-circuit circuit, and the magnitude of the voltage pulse signal is positively related to the energy E _γ of the incident gamma ray and the energy E _dep deposited in the scintillator 14 by the incident gamma ray, and E _dep is directly related to the scintillator. The absorbed dose D _s of 14 is positively correlated, and the absorbed dose D _s of scintillator 14 and air absorbed dose _Da can be expressed by the dose conversion formula:

D _s /D _a =(μ _en /ρ) _s /(μ _en /ρ) _a

In the formula, (μ _en /ρ) _s is the mass energy absorption coefficient of the scintillator, and (μ _en /ρ) _a is the mass energy absorption coefficient of the air. According to the above formula, the absorbed dose D _a of the air is positively correlated with the absorbed dose D _s of the scintillator 14 . Therefore, the information related to incident gamma ray energy related to the voltage pulse signal can be obtained by integrating a single voltage pulse signal, and the information related to the air absorbed dose per unit time can be obtained by integrating all the voltage pulse signals per unit time. The information can be calibrated to obtain the energy and air absorbed dose of the incident gamma rays. The above-mentioned voltage pulse signal enters the conditioning circuit 7, and is adjusted to the voltage range adapted by the AD converter 8 by the adjustable gain amplifier circuit in the conditioning circuit 7, and then converted into a differential signal by the single-ended to differential circuit in the conditioning circuit 7 to be suitable. With the input mode of the AD converter 8, the AD converter 8 digitizes the differential voltage pulse signal and transmits it to the FPGA 9, and the FPGA 9 compares the input data stream with the preset threshold one by one. Then record a time window and accumulate the signals in the time window to obtain the integral value, and transmit the recorded integral value to the single-chip microcomputer 10 one by one. The accumulation degree is judged. When the accumulation degree is lower than the preset value of the single-chip microcomputer 10, the scintillator detector 5 works in the single-pulse mode. All signal integral values in the time are accumulated to obtain the total signal integral value. When the accumulation degree is higher than the preset value of the single-chip microcomputer 10, the scintillator detector 5 works in the current mode, and the single-chip microcomputer 10 stops counting the integral value and the gamma energy spectrum but continues The total signal integral value is obtained by accumulating all signal integral values in a unit time, and the single chip 10 further brings the total signal integral value into the calibration fitting formula to obtain the gamma dose rate.

In this embodiment, the display content of the display screen 17 can be controlled by setting the control button 16, and the above-mentioned display content includes the gamma dose rate, the gamma cumulative dose, and the gamma energy spectrum. Further, the user can reset the gamma by pressing the button. Accumulated dose and set alarm value, when the gamma dose rate or the gamma cumulative dose exceeds the set alarm value, the alarm 18 will give an alarm.

In this embodiment, by setting the USB 11, the wide-range gamma dosimeter can establish two-way communication with the host computer in a wired manner and share the gamma dose rate, gamma cumulative dose and gamma energy spectrum information; by setting the wireless communication mode Group 12, the wide-range gamma dosimeter can establish two-way communication with devices with the same wireless communication function and share gamma dose rate, gamma cumulative dose and gamma energy spectrum information.

In some preferred manners, the scintillator is a 14-bit BGO scintillation crystal, a cylinder with a diameter of 25.4 mm and a length of 25.4 mm, and the photoelectric conversion device is a photomultiplier tube with a diameter of 25.4 mm and a length of 50 mm.

In some preferred manners, the AD converter is a 12-bit high-speed ADC with a sampling rate of 250Msps.

In some preferred manners, the structure of the wide-range gamma dosimeter is shown in FIG. 3 , the acquisition and analysis module 2 and the data collection and distribution module 3 are installed in the main box 23 , the detection module 1 is installed in an aluminum cylindrical box 24 , and the aluminum The cylindrical box 24 and the main box 23 are connected by a 1 m long stainless steel hollow pipe 22 .

In some preferred manners, the power module 4 includes an AC-DC circuit and a rechargeable lithium battery.

In summary, the present invention relates to a wide-range gamma dosimeter, including a detection module, a collection and analysis module for collecting and analyzing the electrical pulse signals output by the detection module, and a data collection and distribution module for human-computer interaction and data sharing. module. The detection module includes a scintillator detector and a readout circuit, the acquisition and analysis module includes a conditioning circuit, an AD converter, and an FPGA (Field Programmable Logic Gate Array). The device enables the scintillator detector to work in single-pulse mode and current mode, expands the measurement range of gamma dose rate, and can obtain gamma energy spectrum in single-pulse mode.

Claims (10)

1. A wide range gamma dosimeter characterized in that: the power supply module is connected with the detection module, the acquisition and analysis module and the data distribution module and supplies power to the detection module, the acquisition and analysis module and the data distribution module; the detection module comprises a scintillator detector and a reading circuit, wherein the reading circuit is connected with the scintillator detector and is used for converting a current pulse signal output by the scintillator detector into a voltage pulse signal; the acquisition and analysis module comprises a conditioning circuit, an AD converter and an FPGA, wherein the conditioning circuit is connected with a reading circuit of the detection module and is used for conditioning a voltage pulse signal output by the reading circuit to a voltage range adapted to the AD converter; the AD converter is used for converting the analog signal output by the conditioning circuit into a digital signal; the FPGA is used for monitoring digital signals of the AD converter, setting an integration time window, integrating voltage signals in the integration time window and outputting an integration value; the data collecting and distributing module is connected with the collecting and analyzing module and comprises a single chip microcomputer, a USB (universal serial bus), a wireless communication module and a peripheral, the single chip microcomputer determines whether the measuring instrument works in a single-pulse mode or a current mode by judging the number of the integrated values output by the FPGA in unit time, the single chip microcomputer performs dose rate conversion and simultaneously performs gamma energy spectrum drawing in the single-pulse mode, and only performs dose rate conversion in the current mode.

2. The wide-range gamma dosimeter of claim 1, wherein: the scintillator is an inorganic scintillator.

3. The wide-range gamma dosimeter of claim 1, wherein: the photoelectric conversion device is one of a photomultiplier tube and a silicon photomultiplier tube, and the spectral response wavelength range of the photoelectric conversion device coincides with the emission wavelength range of the scintillator.

4. The wide-range gamma dosimeter of claim 1, wherein: the reading circuit is composed of a current type front-end circuit.

5. The wide-range gamma dosimeter of claim 1, wherein: the conditioning circuit consists of an adjustable gain amplifying circuit and a single-end to differential circuit, and the adjustable gain amplifying circuit consists of a high-speed operational amplifier in order to realize the acquisition of the fast component of the nuclear pulse signal.

6. The wide-range gamma dosimeter of claim 1, wherein: the AD converter is of a differential input type.

7. The wide-range gamma dosimeter of claim 1, wherein: and the FPGA sets a signal threshold value through judging electronic noise and a signal baseline, and the threshold value is used for starting the pulse integration time window.

8. The wide-range gamma dosimeter of claim 1, wherein: the single chip microcomputer determines whether the instrument works in a single pulse mode or a current mode by judging the number of the integrated values output by the FPGA in unit time, the single chip microcomputer performs dose rate conversion and simultaneously performs gamma energy spectrum drawing in the single pulse mode, and only performs dose rate conversion in the current mode; the single chip microcomputer establishes two-way communication with an upper computer through a USB and shares gamma dose rate, gamma accumulated dose and gamma energy spectrum information; the single chip microcomputer can establish two-way communication with equipment with the same wireless communication function through the wireless communication module and share gamma dose rate, gamma accumulated dose and gamma energy spectrum information.

9. The wide-range gamma dosimeter of claim 1, wherein: the wireless communication module is any one of a Bluetooth module, a ZigBee module and a WiFi module.

10. The wide-range gamma dosimeter of claim 1, wherein: the peripheral comprises a control key, a display screen and an alarm; the control key is connected with the single chip microcomputer and used for controlling the working mode of the wide-range gamma dosimeter; the display screen is connected with the singlechip and is used for displaying the gamma dose rate, the gamma accumulated dose and the gamma energy spectrogram; the alarm is connected with the single chip microcomputer and used for giving an alarm when the gamma dose rate or the gamma accumulated dose exceeds a preset threshold value.

Images