CN113985469A - Standard radon chamber222Rn concentration automatic constant value measurement system and method - Google Patents
Standard radon chamber222Rn concentration automatic constant value measurement system and method Download PDFInfo
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- 238000005259 measurement Methods 0.000 title claims abstract description 131
- 229910052704 radon Inorganic materials 0.000 title claims abstract description 71
- SYUHGPGVQRZVTB-UHFFFAOYSA-N radon atom Chemical compound [Rn] SYUHGPGVQRZVTB-UHFFFAOYSA-N 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000012545 processing Methods 0.000 claims abstract description 75
- CEMVIMZLAJHAHH-UHFFFAOYSA-N [Th].[Rn] Chemical compound [Th].[Rn] CEMVIMZLAJHAHH-UHFFFAOYSA-N 0.000 claims abstract description 31
- 238000013500 data storage Methods 0.000 claims abstract description 25
- 238000004891 communication Methods 0.000 claims description 39
- 238000005070 sampling Methods 0.000 claims description 18
- 238000004364 calculation method Methods 0.000 claims description 7
- 230000002285 radioactive effect Effects 0.000 claims description 7
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- 238000012216 screening Methods 0.000 claims description 3
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Abstract
Standard radon chamber222Rn concentration automatic constant value measurement system and method relates to metering device technical field. Standard radon chamber222The Rn concentration automatic constant value measuring system comprises a spherical scintillation chamber, a radon-thorium analyzer, a radon concentration automatic constant value calibrator and a PC (personal computer). The automatic radon concentration value-fixing calibrator comprises a high-voltage power supply, a low-voltage power supply, a signal amplifier, a single-channel pulse amplitude analyzer and an FPGA signal measurement processing module. The PC comprises a self-checking module, a background measuring module, a sample measuring module, a data storage module and a display. Standard radon chamber222Rn concentration automatic value setting method applied to standard radon chamber222An Rn concentration automatic constant value measurement system comprises the following steps: 1, self-checking the counting function of an FPGA signal measurement processing module; 2, measuring the background counting rate; 3, measuring222And (3) Rn concentration. The invention can realize standard radon chamber222Rn concentration is automatically set, so that the calibration process of the radon concentration measuring instrument is simpler, more convenient and more intelligent.
Description
Technical Field
The invention relates to the technical field of metering devices, in particular to a standard radon chamber222An automatic constant value measurement system and method for Rn concentration.
Background
The standard radon chamber is a standard device for magnitude transmission and experimental research, is mainly applied to verification, calibration and test of a radon concentration measuring instrument, and has great application value in the fields of radiation protection, radioactive environment protection, radon prospecting, earthquake prediction and the like. Accurately measuring in standard radon chambers222Rn concentration: (222Rn concentration fixed value) has important significance for detecting, calibrating and testing a radon concentration measuring instrument, and meanwhile, a standard radon chamber222Method for automatically setting Rn concentration in air222The accurate measurement of the Rn concentration has important reference value.
Ambient air as commonly used at present222The standard Rn concentration measuring method comprises a scintillation chamber method, a track etching method, an activated carbon box method and a double-filter-membrane method, wherein the scintillation chamber method is also a standard radon chamber method222And (3) an automatic Rn concentration setting method. The measuring device corresponding to the scintillation chamber method consists of a scintillation bottle, a scintillation detector, a high-voltage power supply and an electronic analysis recording unit. The electronic analysis recording unit can adopt a calibrator to measure counting and also can adopt a multichannel pulse amplitude analyzer to measure an energy spectrum. Scintillation chamber method based on calibrator measurement and counting222The Rn concentration fixed value process needs to calculate the net counting rate of the sample, and the numerical value needs to be measured for many times to average due to the requirement of radioactivity statistical characteristics.
The scintillation chamber method has the following disadvantages: 1.automatic cyclic measurement after automatic sampling cannot be realized, the automation degree is low, and the repeated measurement times of operators are more; 2. each time, manually setting measurement time, starting a counting start measurement button, waiting for measurement, and needing an operator to watch in the whole process during the measurement process; 3. the measured counting value can only be displayed immediately after the measurement is finished, and the counting value needs to be manually recorded by an operator and then calculated222Rn concentration; 4. the storage of intermediate and final result related data cannot be performed.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a standard radon chamber222Rn concentration automatic constant value measuring system and method, which solves the problem of the prior standard radon chamber222The scintillation chamber method for Rn concentration fixed value has lower automation degree, does not realize unattended operation,222Rn concentration needs to be calculated manually, and data cannot be stored automatically.
The technical scheme of the invention is as follows: standard radon chamber222The Rn concentration automatic constant value measuring system comprises a spherical scintillation chamber, an FD-125 radon-thorium analyzer, an radon concentration automatic constant value calibrator and a PC (personal computer);
the spherical scintillation chamber is used for sampling radioactive gas in the standard radon chamber, and is provided with a sampling tube;
the radon-thorium analyzer is used for detecting the sampling gas in the spherical scintillation chamber and is provided with a low voltage line interface, a high voltage line interface and a signal line interface;
the radon concentration automatic-fixed value calibrator comprises a high-voltage power supply, a low-voltage power supply, a signal amplifier, a single-channel pulse amplitude analyzer and an FPGA signal measurement processing module; the high-voltage power supply is electrically connected with a high-voltage wire interface of the radon-thorium analyzer, and a high-voltage adjusting potentiometer is arranged on the high-voltage power supply; the low-voltage power supply is respectively and electrically connected with the signal amplifier, the single-channel pulse amplitude analyzer and the FPGA signal measurement processing module; the signal input end of the signal amplifier is in communication connection with a signal line interface of the radon-thorium analyzer, and the signal output end of the signal amplifier is in communication connection with the signal input end of the single-channel pulse amplitude analyzer; the signal output end of the single-channel pulse amplitude analyzer is in communication connection with the FPGA signal measurement processing module, and a single-channel threshold value adjusting potentiometer is arranged on the single-channel pulse amplitude analyzer; and a counting module for counting the digital logic pulses is arranged in the FPGA signal measurement processing module.
The PC is in communication connection with the FPGA signal measurement processing module; the PC comprises a self-checking module, a background measuring module, a sample measuring module, a data storage module and a display; the self-checking module is used for self-checking the counting function of the FPGA signal measurement processing module; the background measuring module is used for calculating the counting rate of radioactive alpha particles in the sampling pipe which is not sampled; the sample measuring module being arranged to count the interior of the scintillation chamber after sampling222Rn concentration; the self-checking module is respectively in communication connection with the FPGA signal measurement processing module, the data storage module and the display; the background measurement module is respectively in communication connection with the FPGA signal measurement processing module, the data storage module and the display; the sample measuring module is respectively in communication connection with the FPGA signal measuring and processing module, the data storage module and the display; the data storage module is respectively in communication connection with the self-checking module, the background measuring module and the sample measuring module; the display is respectively in communication connection with the self-checking module, the background measuring module and the sample measuring module.
The further technical scheme of the invention is as follows: the automatic radon concentration value calibrator also comprises a display screen; the display screen is electrically connected with the high-voltage power supply and is used for displaying the voltage of the high-voltage power supply.
The invention further adopts the technical scheme that: the voltage output range of the high-voltage power supply is continuously adjustable from 0V to-1500V, and the high-voltage power supply comprises a voltage control module for adjusting output voltage; the low-voltage power supply comprises a +/-5V output power supply and a +/-12V output power supply, wherein the-5V output power supply supplies power to a voltage control module of the high-voltage power supply, the +5V output power supply supplies power to the single-channel pulse amplitude analyzer and the FPGA signal measurement processing module, and the +/-12V output power supply supplies power to the signal amplifier.
The further technical scheme of the invention is as follows: the standard radon chamber radon concentration automatic constant value measuring system also comprises a signal generator; and the signal output end of the signal generator is in communication connection with the FPGA signal measurement processing module.
The further technical scheme of the invention is as follows: the FPGA signal measurement processing module is provided with a counting interface A for counting the digital logic pulses sent by the signal generator, a counting interface B for counting the digital logic pulses sent by the single-channel pulse amplitude analyzer and a communication interface for connecting a PC.
The further technical scheme of the invention is as follows: the operation logic of the background measurement module refers to formula 1; equation 1: n isb＝NB/tb(ii) a In the formula 1, nbBackground count rate, NbFor background count, tbThe corresponding duration is counted for background.
The further technical scheme of the invention is as follows: the running logic of the sample measuring module refers to formula 2; equation 2: cRn＝KS·(NC/tC-Nb/tb)·eλT(ii) a In the formula 2, CRnIs composed of222Rn concentration value in Bq m-3，KSIs the scale factor of a spherical scintillation chamber, e is the base number of the natural logarithm, and lambda is222The decay constant of Rn, T is the waiting time, and N is taken to be 2.9-3.1 hCFor the sample counting, t, by the FPGA signal measurement processing moduleCThe samples were counted for the corresponding length of time.
The technical scheme of the invention is as follows: standard radon chamber222Rn concentration automatic value setting method applied to standard radon chamber222An Rn concentration automatic constant value measurement system comprises the following steps:
s01, counting function of the self-checking FPGA signal measurement processing module: a. firstly, a signal generator outputs a standard signal to an FPGA signal measurement processing module, then counting duration and counting times are preset on a self-checking module, the counting duration is longer than one time period of the standard signal, the counting times are at least three times, and then a counting starting signal is sent out by the self-checking module;
b. after the FPGA signal measurement processing module receives a counting starting signal through the communication interface, the standard signal is immediately counted, and after counting is finished, the FPGA signal measurement processing module transmits a counting value to the self-checking module through the communication interface;
c. after the self-checking module receives the counting value, counting rates are respectively calculated according to the counting duration and the counting value of each counting, and then the average counting rate is calculated; the self-checking module controls the display to display the average counting rate on one hand, and controls the data storage module to store the counting value and the counting rate on the other hand so as to facilitate subsequent reference;
d. an operator judges whether the counting function of the FPGA signal measurement processing module is normal according to the error between the actually measured counting rate and the frequency of the standard signal, and if the counting function is normal, the next step is carried out;
in this step, the standard signal is a square wave signal with fixed frequency;
in the step, the error between the actually measured counting rate and the frequency of the standard signal is in the range of 1%, which indicates that the counting function of the FPGA signal measurement processing module is normal;
s02, measuring background count rate: installing a spherical scintillation chamber which is not sampled from a standard radon chamber on a radon-thorium analyzer, starting the radon-thorium analyzer, a radon concentration automatic constant value calibrator and a PC (personal computer), amplifying a measurement signal of the radon-thorium analyzer through a signal amplifier, screening noise through a single-channel pulse amplitude analyzer, converting the signal into a digital logic pulse, counting the digital logic pulse through an FPGA (field programmable gate array) signal measurement processing module, transmitting a count value to a background measurement module through the FPGA signal measurement processing module, measuring a background counting rate through the background measurement module, displaying a calculation result through a display, and storing the calculation result into a data storage module;
in the step, the operation logic of the background measurement module refers to a formula 1; equation 1: n isb＝NB/tb(ii) a In the formula 1, nbBackground count rate, NbFor background count, tbCounting the corresponding time length for the background;
s03, measuring222Rn concentration: installing a spherical scintillation chamber sampled from a standard radon chamber on a radon-thorium analyzer, starting the radon-thorium analyzer, an automatic radon concentration fixed value calibrator and a PC (personal computer), amplifying a measurement signal of the radon-thorium analyzer through a signal amplifier, screening noise through a single-channel pulse amplitude analyzer, and converting the signal into a signalThe digital logic pulse is counted by the FPGA signal measurement processing module, the counting value is transmitted to the sample measurement module by the FPGA signal measurement processing module, and the sample measurement module calculates222The Rn concentration, the calculation result is displayed through a display and stored in a data storage module;
in this step, the operation logic of the sample measurement module refers to formula 2; equation 2: cRn＝KS·(NC/tC-Nb/tb)·eλT(ii) a In the formula 2, CRnIs composed of222Rn concentration value in Bq m-3，KSIs the scale factor of a spherical scintillation chamber, e is the base number of the natural logarithm, and lambda is222The decay constant of Rn, T is the waiting time, and N is taken to be 2.9-3.1 hCFor the sample counting, t, by the FPGA signal measurement processing moduleCThe samples were counted for the corresponding length of time.
Compared with the prior art, the invention has the following advantages:
the invention can realize standard radon chamber222Rn concentration is automatically set, so that the calibration process of the radon concentration measuring instrument is simpler, more convenient and more intelligent; the technical performance indexes of system resolution time, counting rate, counting capacity, timing time and the like are advanced; a power supply anti-interference circuit is arranged in the device, so that external interference signals can be inhibited; solves the problem of the prior standard radon chamber222The scintillation chamber method for Rn concentration constant value has the problems of low automation degree, complex operation steps and large calculation workload.
The invention is further described below with reference to the figures and examples.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention.
Description of the drawings: in the figure, the thin solid line connections between the components are power supply connections, and the dotted line connections are electrical signal connections.
Illustration of the drawings: a spherical scintillation chamber 1; a radon-thorium analyzer 2; a low voltage line interface 21; a high-voltage line interface 22; a signal line interface 23; a radon concentration automatic-setting calibrator 3; a high-voltage power supply 31; a low voltage power supply 32; a signal amplifier 33; a single-pass pulse amplitude analyzer 34; an FPGA signal measurement processing module 35; a display screen 36; a PC machine 4; a background measurement module 42; a sample measurement module 43; a data storage module 44; a self-test module 41; a display 45; a signal generator 5.
Detailed Description
Example 1:
as shown in FIG. 1, a standard radon chamber222The Rn concentration automatic definite value measuring system comprises a spherical scintillation chamber 1, an FD-125 radon-thorium analyzer 2, a radon concentration automatic definite value calibrator 3 and a PC 4.
The spherical scintillation chamber 1 is used for sampling radioactive gas in a standard radon chamber, and is provided with a sampling tube.
The radon-thorium analyzer 2 is used for detecting sampling gas in the spherical scintillation chamber, and is provided with a low-voltage line interface 21, a high-voltage line interface 22 and a signal line interface 23.
The radon concentration automatic-value-setting calibrator 3 comprises a high-voltage power supply 31, a low-voltage power supply 32, a signal amplifier 33, a single-channel pulse amplitude analyzer 34 and an FPGA signal measurement processing module 35. The high-voltage power supply 31 is electrically connected with the high-voltage wire interface 22 of the radon-thorium analyzer 2, and the high-voltage power supply 31 is provided with a high-voltage adjusting potentiometer. The low-voltage power supply 32 is electrically connected with the signal amplifier 33, the single-channel pulse amplitude analyzer 34 and the FPGA signal measurement processing module 35 respectively. The signal input end of the signal amplifier 33 is connected with the signal line interface 23 of the radon-thorium analyzer 2 in a communication mode, and the signal output end of the signal amplifier 33 is connected with the signal input end of the single-channel pulse amplitude analyzer 34 in a communication mode. The signal output end of the single-channel pulse amplitude analyzer 34 is in communication connection with the FPGA signal measurement processing module 35, and a single-channel threshold value adjusting potentiometer is arranged on the single-channel pulse amplitude analyzer 34. The FPGA signal measurement processing module 35 is internally provided with a counting module for counting digital logic pulses.
The PC 4 is in communication connection with the FPGA signal measurement processing module 35; the PC 4 comprises a self-test module 41, a background measuring module 42, a sample measuring module 43, a data storage module 44 and a display 45; the self-checking module 41 is used for self-checking the counting function of the FPGA signal measurement processing module 35; the background measurement module 42 is used for calculating the radioactive alpha particle counting rate inside the sampling pipe which is not sampled; the sample measuring module 43 is used for calculating radon concentration inside the sampling tube after sampling; the self-checking module 41 is respectively in communication connection with the FPGA signal measurement processing module 35, the data storage module 44 and the display 45; the background measuring module 42 is respectively in communication connection with the FPGA signal measuring and processing module 35, the data storage module 44 and the display 45; the sample measuring module 43 is respectively in communication connection with the FPGA signal measuring and processing module 35, the data storage module 44 and the display 45; the data storage module 44 is respectively in communication connection with the self-inspection module 41, the background measurement module 42 and the sample measurement module 43; display 45 is in communication with introspection module 41, background measurement module 42, and sample measurement module 43, respectively.
Preferably, the radon concentration automatic-value-setting calibrator further comprises a display screen 36; the display screen 36 is electrically connected to the high voltage power supply 31 and displays the voltage of the high voltage power supply 31.
Preferably, the FPGA signal measurement processing module 35 is provided with a counting interface a for counting the digital logic pulses sent by the signal generator, a counting interface B for counting the digital logic pulses sent by the single-channel pulse amplitude analyzer, and a communication interface for connecting a PC.
Preferably, the voltage output range of the high voltage power supply 31 is continuously adjustable from 0V to-1500V, and the high voltage power supply 31 includes a voltage control module for adjusting the output voltage. The low voltage power supply 32 comprises a +/-5V output power supply and a +/-12V output power supply, wherein the-5V output power supply supplies power for a voltage control module of the high voltage power supply 31, the +5V output power supply supplies power for the single-channel pulse amplitude analyzer 34 and the FPGA signal measurement processing module 35, and the +/-12V output power supply supplies power for the signal amplifier 33.
Preferably, the system for automatically measuring the radon concentration of the standard radon chamber further comprises a signal generator 5, and a signal output end of the signal generator 5 is in communication connection with the FPGA signal measurement processing module 35.
Preferably, the operating logic of the background measurement module 42 refers to equation 1; equation 1: n isb＝NB/tb(ii) a In the formula 1, nbBackground count rate, NbFor background counting (obtained by counting through an FPGA signal measurement processing module), tbThe corresponding duration is counted for background.
Preferably, the operating logic of the sample measurement module 43 is referenced to equation 2; equation 2: cRn＝KS·(NC/tC-Nb/tb)·eλT(ii) a In the formula 2, CRnIs composed of222Rn concentration value in Bq m-3，KSIs the scale factor of a spherical scintillation chamber, e is the base number of the natural logarithm, and lambda is222The decay constant of Rn, T is the waiting time, and N is taken to be 2.9-3.1 hCCounting the samples (obtained by counting through an FPGA signal measurement processing module), tCThe samples were counted for the corresponding length of time.
Standard radon chamber222Rn concentration automatic value setting method applied to standard radon chamber222An Rn concentration automatic constant value measurement system comprises the following steps:
s01, counting function of the self-checking FPGA signal measurement processing module:
a. firstly, the signal generator 5 outputs a standard signal to the FPGA signal measurement processing module 35, then, counting time and counting times are preset on the self-checking module 41, the counting time is longer than one time period of the standard signal, the counting times are at least three times, and then, the self-checking module 41 sends out a counting starting signal;
b. after receiving the start counting signal through the communication interface, the FPGA signal measurement processing module 35 immediately counts the standard signal, and after the counting is finished, the FPGA signal measurement processing module 35 transmits the count value to the self-checking module 41 through the communication interface;
c. after receiving the count value, the self-checking module 41 calculates the count rate according to the count duration and the count value of each count, and then calculates the average count rate; the self-test module 41 controls the display 45 to display the average counting rate on one hand, and controls the data storage module 44 to store the counting value and the counting rate on the other hand so as to facilitate subsequent reference;
d. and the operator judges whether the counting function of the FPGA signal measurement processing module 35 is normal or not according to the error between the actually measured counting rate and the frequency of the standard signal, and if the counting function is normal, the next step is carried out.
In this step, the standard signal is a square wave signal with fixed frequency.
In this step, the error between the actually measured count rate and the frequency of the standard signal is within the range of 1%, which indicates that the counting function of the FPGA signal measurement processing module 35 is normal.
S02, measuring background count rate: a spherical scintillation chamber which is not sampled from a standard radon chamber is installed on a radon-thorium analyzer 2, the radon-thorium analyzer 2 is started, a radon concentration automatic constant value calibrator and a PC are started, a measurement signal of the radon-thorium analyzer 2 is amplified through a signal amplifier 33, noise discrimination is performed through a single-channel pulse amplitude analyzer 34, the signal is converted into a digital logic pulse, the digital logic pulse is counted through an FPGA signal measurement processing module 35, then the FPGA signal measurement processing module 35 transmits the counting value to a background measurement module 42, a background counting rate is measured through the background measurement module 42, and a calculation result is displayed through a display and stored in a data storage module 44.
In the step, the operation logic of the background measurement module refers to a formula 1; equation 1: n isb＝NB/tb(ii) a In the formula 1, nbBackground count rate, NbFor background counting (obtained by counting through an FPGA signal measurement processing module), tbThe corresponding duration is counted for background.
S03, measuring222Rn concentration: installing a spherical scintillation chamber sampled from a standard radon chamber on a radon-thorium analyzer 2, starting the radon-thorium analyzer 2, a radon concentration automatic constant value calibrator and a PC (personal computer), amplifying a measurement signal of the radon-thorium analyzer 2 through a signal amplifier 33, discriminating noise through a single-channel pulse amplitude analyzer 34, converting the signal into a digital logic pulse, counting the digital logic pulse through an FPGA (field programmable gate array) signal measurement processing module 35, transmitting a count value to a sample measurement module 43 through the FPGA signal measurement processing module 35, and calculating by the sample measurement module 43222Rn concentration, the calculation result is displayed through a display and stored in the data storage module 44.
In this step, the operation logic of the sample measurement module 43 refers to formula 2; equation 2: cRn＝KS·(NC/tC-Nb/tb)·eλT(ii) a In the formula 2, CRnIs composed of222Rn concentration value in Bq m-3，KSIs the scale factor of a spherical scintillation chamber, e is the base number of the natural logarithm, and lambda is222The decay constant of Rn, T is the waiting time, and N is taken to be 2.9-3.1 hCCounting the samples (obtained by counting through an FPGA signal measurement processing module), tCThe samples were counted for the corresponding length of time.
Claims (8)
1. Standard radon chamber222Rn concentration automatic definite value measurement system, characterized by: comprises a spherical scintillation chamber, an FD-125 radon-thorium analyzer, an automatic radon concentration fixed value calibrator and a PC (personal computer);
the spherical scintillation chamber is used for sampling radioactive gas in the standard radon chamber, and is provided with a sampling tube;
the radon-thorium analyzer is used for detecting the sampling gas in the spherical scintillation chamber and is provided with a low voltage line interface, a high voltage line interface and a signal line interface;
the radon concentration automatic-fixed value calibrator comprises a high-voltage power supply, a low-voltage power supply, a signal amplifier, a single-channel pulse amplitude analyzer and an FPGA signal measurement processing module; the high-voltage power supply is electrically connected with a high-voltage wire interface of the radon-thorium analyzer, and a high-voltage adjusting potentiometer is arranged on the high-voltage power supply; the low-voltage power supply is respectively and electrically connected with the signal amplifier, the single-channel pulse amplitude analyzer and the FPGA signal measurement processing module; the signal input end of the signal amplifier is in communication connection with a signal line interface of the radon-thorium analyzer, and the signal output end of the signal amplifier is in communication connection with the signal input end of the single-channel pulse amplitude analyzer; the signal output end of the single-channel pulse amplitude analyzer is in communication connection with the FPGA signal measurement processing module, and a single-channel threshold value adjusting potentiometer is arranged on the single-channel pulse amplitude analyzer; and a counting module for counting the digital logic pulses is arranged in the FPGA signal measurement processing module.
The PC is in communication connection with the FPGA signal measurement processing module; the PC comprises a self-checking module, a background measuring module, a sample measuring module, a data storage module and a display; the self-checking module is used for self-checking the counting function of the FPGA signal measurement processing module; the background measuring module is used for calculating the counting rate of radioactive alpha particles in the sampling pipe which is not sampled; the sample measuring module is used for calculating radon concentration in the sampling tube after sampling; the self-checking module is respectively in communication connection with the FPGA signal measurement processing module, the data storage module and the display; the background measurement module is respectively in communication connection with the FPGA signal measurement processing module, the data storage module and the display; the sample measuring module is respectively in communication connection with the FPGA signal measuring and processing module, the data storage module and the display; the data storage module is respectively in communication connection with the self-checking module, the background measuring module and the sample measuring module; the display is respectively in communication connection with the self-checking module, the background measuring module and the sample measuring module.
2. The standard radon chamber of claim 1222Rn concentration automatic definite value measurement system, characterized by: the automatic radon concentration value calibrator also comprises a display screen; the display screen is electrically connected with the high-voltage power supply and is used for displaying the voltage of the high-voltage power supply.
3. A standard radon chamber as claimed in claim 1 or 2222Rn concentration automatic definite value measurement system, characterized by: the voltage output range of the high-voltage power supply is continuously adjustable from 0V to-1500V, and the high-voltage power supply comprises a voltage control module for adjusting output voltage; the low-voltage power supply comprises a +/-5V output power supply and a +/-12V output power supply, wherein the-5V output power supply supplies power to a voltage control module of the high-voltage power supply, the +5V output power supply supplies power to the single-channel pulse amplitude analyzer and the FPGA signal measurement processing module, and the +/-12V output power supply supplies power to the signal amplifier.
4. Standard radon chamber as in claim 3222Rn concentration automatic definite value measurement system, characterized by: the standard radon chamber radon concentration automatic constant value measuring system also comprises a signal generator; and the signal output end of the signal generator is in communication connection with the FPGA signal measurement processing module.
5. Standard radon chamber as in claim 4222Rn concentration automatic constant value measuring system, characterized in that: the FPGA signal measurement processing module is provided with a counting interface A for counting the digital logic pulses sent by the signal generator, a counting interface B for counting the digital logic pulses sent by the single-channel pulse amplitude analyzer and a communication interface for connecting a PC.
6. Standard radon chamber as in claim 5222Rn concentration automatic definite value measurement system, characterized by: the operation logic of the background measurement module refers to formula 1; equation 1: n isb＝NB/tb(ii) a In the formula 1, nbBackground count rate, NbFor background count, tbThe corresponding duration is counted for background.
7. The standard radon chamber of claim 6222Rn concentration automatic definite value measurement system, characterized by: the running logic of the sample measuring module refers to formula 2; equation 2: cRn＝KS·(NC/tC-Nb/tb)·eλT(ii) a In the formula 2, CRnIs composed of222Rn concentration value in Bq m-3，KSIs the scale factor of a spherical scintillation chamber, e is the base number of the natural logarithm, and lambda is222The decay constant of Rn, T is the waiting time, and N is taken to be 2.9-3.1 hCFor counting samples, tCThe samples were counted for the corresponding length of time.
8. Standard radon chamber222Rn concentration automatic value-setting method applied to standard radon chamber in claim 7222Rn concentration automatic constant value measurement system, characterized by, the step is as follows:
s01, counting function of the self-checking FPGA signal measurement processing module:
a. firstly, a signal generator outputs a standard signal to an FPGA signal measurement processing module, then counting duration and counting times are preset on a self-checking module, the counting duration is longer than one time period of the standard signal, the counting times are at least three times, and then a counting starting signal is sent out by the self-checking module;
b. after the FPGA signal measurement processing module receives a counting starting signal through the communication interface, the standard signal is immediately counted, and after counting is finished, the FPGA signal measurement processing module transmits a counting value to the self-checking module through the communication interface;
c. after the self-checking module receives the counting value, counting rates are respectively calculated according to the counting duration and the counting value of each counting, and then the average counting rate is calculated; the self-checking module controls the display to display the average counting rate on one hand, and controls the data storage module to store the counting value and the counting rate on the other hand so as to facilitate subsequent reference;
d. an operator judges whether the counting function of the FPGA signal measurement processing module is normal according to the error between the actually measured counting rate and the frequency of the standard signal, and if the counting function is normal, the next step is carried out;
in this step, the standard signal is a square wave signal with fixed frequency;
in the step, the error between the actually measured counting rate and the frequency of the standard signal is in the range of 1%, which indicates that the counting function of the FPGA signal measurement processing module is normal;
s02, measuring background count rate: installing a spherical scintillation chamber which is not sampled from a standard radon chamber on a radon-thorium analyzer, starting the radon-thorium analyzer, a radon concentration automatic constant value calibrator and a PC (personal computer), amplifying a measurement signal of the radon-thorium analyzer through a signal amplifier, screening noise through a single-channel pulse amplitude analyzer, converting the signal into a digital logic pulse, counting the digital logic pulse through an FPGA (field programmable gate array) signal measurement processing module, transmitting a counting value to a background measurement module through the FPGA signal measurement processing module, and measuring a background counting rate through the background measurement module;
in the step, the operation logic of the background measurement module refers to a formula 1; equation 1: n isb＝NB/tb(ii) a In the formula 1, nbBackground count rate, NbFor background count, tbCounting the corresponding time length for the background;
s03, measuring222Rn concentration: installing the spherical scintillation chamber sampled from the standard radon chamber on a radon-thorium analyzer, and starting radonThe system comprises a thorium analyzer, an automatic radon concentration fixed value calibrator and a PC (personal computer), wherein a measurement signal of the radon-thorium analyzer is amplified through a signal amplifier, then a single-channel pulse amplitude analyzer is used for noise discrimination, the signal is converted into digital logic pulse, then the digital logic pulse is counted through an FPGA (field programmable gate array) signal measurement processing module, then the FPGA signal measurement processing module transmits a counting value to a sample measurement module, and the sample measurement module calculates the counting value222The Rn concentration, the calculation result is displayed through a display and stored in a data storage module;
in this step, the operation logic of the sample measurement module refers to formula 2; equation 2: cRn＝KS·(NC/tC-Nb/tb)·eλT(ii) a In the formula 2, CRnIs composed of222Rn concentration value in Bq m-3，KSIs the scale factor of a spherical scintillation chamber, e is the base number of the natural logarithm, and lambda is222The decay constant of Rn, T is the waiting time, and N is taken to be 2.9-3.1 hCFor counting samples, tCThe samples were counted for the corresponding length of time.
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| 张玉琴: "如何正确使用定标器", 核电子学与探测技术, no. 2, 31 December 1981 (1981-12-31), pages 63 - 64 * |
| 金晓峰: "基于FPGA氡浓度自动定值定标器设计与研究", 中国优秀硕士学位论文全文数据库 工程科技II辑, no. 4, 15 April 2016 (2016-04-15), pages 5 - 25 * |
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