CN113484897A - Device and method for measuring Po-218 mobility and neutralization rate by electrostatic collection method - Google Patents
Device and method for measuring Po-218 mobility and neutralization rate by electrostatic collection method Download PDFInfo
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- CN113484897A CN113484897A CN202110680858.7A CN202110680858A CN113484897A CN 113484897 A CN113484897 A CN 113484897A CN 202110680858 A CN202110680858 A CN 202110680858A CN 113484897 A CN113484897 A CN 113484897A
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Abstract
The device and the method for measuring the Po-218 mobility and the neutralization rate by using the electrostatic collection method are disclosed, and the measuring device comprises a measuring box, a radon chamber, a pump and a high-voltage module. The measuring box is a rectangular box body, a first connector and a second connector are respectively arranged on two corresponding side walls of the box body, a panel and a bottom plate of the box body are both conductive metal plates, and a circular semiconductor detector is arranged on the panel. The first joint of the measuring box is connected with the first joint of the radon chamber, the second joint of the measuring box is connected with one end of the pump, the other end of the pump is connected with the second joint of the radon chamber, the panel of the measuring box is connected with the negative electrode of the high-voltage module, and the bottom plate of the measuring box is connected with the positive electrode of the high-voltage module. During measurement, the high-voltage module is opened, a cylindrical uniform electrostatic field is formed between the circular semiconductor detector and the bottom plate, the positively charged Po-218 is collected on the surface of the circular semiconductor detector, the Po-218 collection efficiency under different voltages is obtained, and then the Po-218 neutralization rate can be obtained by fitting the collection efficiency
And mobility
The value of (c).
Description
Technical Field
The invention relates to a nuclear radiation measurement technology, in particular to a device and a method for measuring the migration rate and the neutralization rate of radon daughter Po-218 in air by adopting an electrostatic collection method.
Background
Po-218(RaA) is formed by decay of radon and is also radioactive, producing internal radiation to the human respiratory system after inhalation. Therefore, the physical and chemical properties of the daughter are very important for understanding the behavior of the daughter in the indoor air. Po-218 produced after decay of radon was found to be 88% positively charged ions. The collection efficiency of a static charge radon meter for positively charged Po-218 depends on the mobility and neutralization of the Po-218 ions, which is a function of their size and charge. The removal of radon daughter by electrostatic deposition has been proposed as a means of reducing the level of radioactivity in the air of working and living environments. For this reason, how to accurately measure the mobility and neutralization rate of the radon daughter Po-218 during the drift of the electric field is a challenging task, and a device for measuring the mobility and neutralization rate of Po-218 needs to be specially designed and manufactured, and the mobility and neutralization rate of newly generated Po-218 ions can be measured under the condition of determined carrier gas neutralization and controlled humidity.
Disclosure of Invention
It is an object of the present invention to overcome the above-mentioned disadvantages of the prior art and to provide an apparatus and method for measuring Po-218 mobility and neutralization rate using electrostatic collection.
The technical scheme of the invention is as follows: the device for measuring the Po-218 mobility and the neutralization rate by the electrostatic collection method comprises a measuring box, a radon chamber, a pump, a high-pressure module, a first regulating valve and a second regulating valve.
The measuring box is a rectangular box body, a measuring cavity is arranged in the box body, and the length, the width and the height of the measuring cavity are respectively L1、L2、L3The side walls around the box body are made of plastic materials, the two corresponding side walls of the box body are respectively provided with a first connector and a second connector, the panel and the bottom plate of the box body are both conductive metal plates, and the panel is provided with a circular semiconductor detector with the radius of R.
The first joint of measuring case passes through the pipeline and is connected with the one end of first governing valve, and the other end of first governing valve passes through the pipeline and is connected with the first articulate of radon room, and the second of measuring case connects the one end of passing through pipeline and second governing valve and is connected, and the other end of second governing valve passes through the pipeline and is connected with the one end of pump, and the other end of pump passes through the pipeline and is connected with the second articulate of radon room to form a gas circuit between the first joint of measuring case and second joint.
The panel of the measuring box is connected with the negative electrode of the high-voltage module through a wire, and the bottom plate of the measuring box is connected with the positive electrode of the high-voltage module through a wire. When the high-voltage module is opened, a uniform parallel electric field can be formed between the panel and the bottom plate in the measuring cavity of the measuring box.
During measurement, the round semiconductor detector is connected with a measuring instrument.
The further technical scheme of the invention is as follows: the device for measuring the Po-218 mobility and the neutralization rate by adopting the electrostatic collection method comprises a measuring process and a calculating process, and the specific operation process comprises the following steps:
A. the measurement process comprises the following steps:
under the condition of constant temperature and humidity, opening a first adjusting valve, a second adjusting valve and a pump, pumping air in a radon chamber into a measuring cavity of a measuring box, transmitting radon and daughters thereof in the radon chamber into the measuring cavity, mixing uniformly for a period of time, closing the first adjusting valve, the second adjusting valve and the pump of the adjusting valves, opening a high-voltage module, forming a uniform electrostatic field between a panel and a bottom plate in the measuring cavity of the measuring box, wherein a cylindrical uniform electrostatic field is formed between a circular semiconductor detector with the radius of R on the panel and the bottom plate, and collecting the positively charged Po-218 on the surface of the circular semiconductor detector under the action of the uniform electrostatic field.
Alpha particles generated by Po-218 decay enter a round semiconductor detector to generate electric pulses, an energy spectrum is formed by processing the electric pulses through a preamplifier and a multichannel analyzer, the number of pulses generated by Po-218 decay is obtained after the energy spectrum is identified, and the number of pulses N generated every second is recorded.
The number of pulses N indicates that the circular semiconductor detector detects N alpha particles generated by the decay of Po-218 per second.
And repeating the steps, and respectively recording the number of pulses generated by Po-218 per second under different voltages.
B. And (3) calculating:
when the voltage is U0And the distance between Po-218 of decay of a certain radon in the measuring cavity of the measuring box and the circular semiconductor detector is x, a cylindrical uniform electric field E is formed between the circular semiconductor detector in the measuring cavity and the bottom plate of the measuring box, and the E is a constant:
collection time t versus distance x of the initial position from the semiconductor detector:
where k is the mobility of Po-218.
When x is 0, t is 0, then c is 0
The collection efficiency formula is:
wherein VnIs the neutralization rate of the positively charged Po-218.
The radon chamber concentration is C, and the radon concentration in the measuring cavity is the same as the radon chamber concentration, namely, each cubic meter per second produces C Po-218, and the circular semiconductor detector with the radius of R and the measuring box bottom plate form a cylindrical electrostatic field, and the volume of the cylindrical electrostatic field is V. The total number of Po-218 generated in the cylindrical detection area is VC, and the collection efficiency of the circular semiconductor detector of the cylindrical detection area to the Po-218 is as follows:
where η is the detection efficiency of the circular semiconductor detector for alpha particles produced by the Po-218 decay collected on its surface.
Substituting equation (7) into equation (6) to calculate:
the collection efficiency of the circular semiconductor detector of the cylindrical detection area to Po-218 under different voltages is obtained through experiments, and the neutralization rate V of Po-218 can be obtained by fitting according to the formula (8)nAnd the value of the mobility k.
Compared with the prior art, the invention has the following characteristics:
the measuring device provided by the invention has a simple structure and is easy to operate, the accuracy of measuring the Po-218 mobility and the neutralization rate can be improved, and reference is provided for theoretically and accurately calculating the collection efficiency of Po-218 and accurately estimating the radon concentration.
The detailed structure of the present invention will be further described with reference to the accompanying drawings and the detailed description.
Drawings
FIG. 1 is a schematic structural diagram of an apparatus for measuring Po-218 mobility and neutralization rate by electrostatic collection provided by the present invention;
FIG. 2 is a schematic view of the structure of the measuring chamber;
fig. 3 is a cross-sectional view a-a of fig. 2.
Detailed Description
First embodiment, as shown in fig. 1-3, the apparatus for measuring Po-218 mobility and neutralization rate by electrostatic collection method comprises a measuring chamber 1, a radon chamber 2, a pump 3, a high voltage module 4, a first regulating valve 5 and a second regulating valve 6.
The measuring box 1 is a rectangular box body, a measuring cavity is arranged in the box body, and the length, the width and the height of the measuring cavity are respectively L1、L2、L3The side walls of the periphery of the box body are made of plastic materials, a first connector 1-4 and a second connector 1-5 are respectively arranged on two corresponding side walls of the box body, a panel 1-1 and a bottom plate 1-2 of the box body are both conductive metal plates, and a circular semiconductor detector 1-3 with the radius of R is arranged on the panel 1-1.
The first joint 1-4 of the measuring box 1 is connected with one end of a first adjusting valve 5 through a pipeline, the other end of the first adjusting valve 5 is connected with the first joint 2-1 of the radon chamber 2 through a pipeline, the second joint 1-5 of the measuring box 1 is connected with one end of a second adjusting valve 6 through a pipeline, the other end of the second adjusting valve 6 is connected with one end of a pump 3 through a pipeline, the other end of the pump 3 is connected with the second joint 2-2 of the radon chamber 2 through a pipeline, and therefore a gas loop is formed between the first joint 1-4 and the second joint 1-5 of the measuring box 1.
The panel 1-1 of the measuring box 1 is connected with the negative electrode of the high-voltage module 4 through a lead, and the bottom plate 1-2 of the measuring box 1 is connected with the positive electrode of the high-voltage module 4 through a lead. When the high-voltage module 4 is opened, a uniform parallel electric field can be formed between the panel 1-1 and the bottom plate 1-2 in the measuring cavity of the measuring box 1.
During measurement, the round semiconductor detector 1-3 is connected with a measuring instrument.
The second embodiment adopts the device for measuring the Po-218 mobility and the neutralization rate by the electrostatic collection method as the first embodiment, and the method for measuring the Po-218 mobility and the neutralization rate by the electrostatic collection method comprises a measuring process and a calculating process, and the specific operation process is as follows:
A. the measurement process comprises the following steps:
under the condition of constant temperature and humidity, opening a first adjusting valve 5, a second adjusting valve 6 and a pump 3, pumping air in a radon chamber 2 into a measuring cavity of a measuring box 1 through the pump, transmitting radon and daughters thereof in the radon chamber 2 into the measuring cavity, mixing uniformly for a period of time, closing the first adjusting valve 5, the second adjusting valve 6 and the pump 3, opening a high-voltage module 4, and forming a uniform electrostatic field between a panel 1-1 and a bottom plate 1-2 in the measuring cavity of the measuring box 1, wherein a cylindrical uniform electrostatic field is formed between a circular semiconductor detector 1-3 with the radius of R on the panel 1-1 and the bottom plate 1-2, and Po-218 with positive electricity is collected on the surface of the circular semiconductor detector 1-3 under the action of the uniform electrostatic field.
Alpha particles generated by Po-218 decay enter the circular semiconductor detector 1-3 to generate electric pulses, an energy spectrum is formed by processing the electric pulses through a preamplifier and a multichannel analyzer, the number of pulses generated by Po-218 decay is obtained after the energy spectrum is identified, and the number of pulses N generated every second is recorded.
The number of pulses N indicates that the circular semiconductor detector 1-3 detects N alpha particles generated by the decay of Po-218 per second.
And repeating the steps, and respectively recording the number of pulses generated by Po-218 per second under different voltages.
B. And (3) calculating:
when the voltage is U0And the distance between the Po-218 of decay of a certain radon in the measurement cavity of the measurement box 1 and the circular semiconductor detector 1-3 is x, a cylindrical uniform electric field E is formed between the circular semiconductor detector 1-3 in the measurement cavity and the bottom plate 1-2 of the measurement box 1, and E is a constant:
collection time t versus distance x of the initial position from the semiconductor detector 1-3:
where k is the mobility of Po-218.
When x is 0, t is 0, then c is 0
The collection efficiency formula is:
wherein VnIs the neutralization rate of the positively charged Po-218.
The concentration of the radon chamber 2 is C, the concentration of radon in the measuring cavity is the same as that of the radon chamber 2, namely C Po-218 are generated every cubic meter per second, the circular semiconductor detector 1-3 with the radius of R and the bottom plate 1-2 of the measuring box 1 form a cylindrical electrostatic field, and the volume of the cylindrical electrostatic field is V. The total number of Po-218 generated in the cylindrical detection area is VC, and the collection efficiency of the circular semiconductor detectors 1-3 of the cylindrical detection area to the Po-218 is as follows:
where η is the detection efficiency of the circular semiconductor detector 1-3 for alpha particles produced by the decay of Po-218 collected on its surface.
Substituting equation (7) into equation (6) to calculate:
the collection efficiency of the circular semiconductor detectors 1-3 in the cylindrical detection regions to Po-218 under different voltages is obtained through experiments, and the Po-218 neutralization rate V can be obtained by fitting according to a formula (8)nAnd the value of the mobility k.
Claims (2)
1. The device for measuring the Po-218 mobility and the neutralization rate by the electrostatic collection method is characterized in that: the radon measuring device comprises a measuring box, a radon chamber, a pump, a high-pressure module, a first regulating valve and a second regulating valve;
the measuring box is a rectangular box body, a measuring cavity is arranged in the box body, and the length, the width and the height of the measuring cavity are respectively L1、L2、L3The side walls of the periphery of the box body are made of plastic materials, a first connector and a second connector are respectively arranged on two corresponding side walls of the box body, a panel and a bottom plate of the box body are both conductive metal plates, and a circular semiconductor detector with the radius of R is arranged on the panel;
the first joint of the measuring box is connected with one end of a first regulating valve through a pipeline, the other end of the first regulating valve is connected with the first joint of the radon chamber through a pipeline, the second joint of the measuring box is connected with one end of a second regulating valve through a pipeline, the other end of the second regulating valve is connected with one end of a pump through a pipeline, and the other end of the pump is connected with the second joint of the radon chamber through a pipeline, so that a gas loop is formed between the first joint and the second joint of the measuring box;
the panel of the measuring box is connected with the negative electrode of the high-voltage module through a wire, the bottom plate of the measuring box is connected with the positive electrode of the high-voltage module through a wire, and an even parallel electric field can be formed between the panel and the bottom plate in the measuring cavity of the measuring box in the state that the high-voltage module is opened.
2. The method for measuring Po-218 mobility and neutralization by electrostatic trapping using the apparatus for measuring Po-218 mobility and neutralization according to claim 1, wherein: the method comprises a measurement process and a calculation process, and the specific operation process is as follows:
A. the measurement process comprises the following steps:
under the condition of constant temperature and humidity, opening a first adjusting valve, a second adjusting valve and a pump, pumping air in a radon chamber into a measuring cavity of a measuring box, transmitting radon and daughters thereof in the radon chamber into the measuring cavity, mixing uniformly for a period of time, closing the first adjusting valve, the second adjusting valve and the pump of the adjusting valves, opening a high-voltage module, forming a uniform electrostatic field between a panel and a bottom plate in the measuring cavity of the measuring box, wherein a cylindrical uniform electrostatic field is formed between a circular semiconductor detector with the radius of R on the panel and the bottom plate, and collecting the positively charged Po-218 on the surface of the circular semiconductor detector under the action of the uniform electrostatic field.
Alpha particles generated by Po-218 decay enter a round semiconductor detector to generate electric pulses, an energy spectrum is formed by processing the electric pulses through a preamplifier and a multichannel analyzer, the number of pulses generated by Po-218 decay is obtained after the energy spectrum is identified, and the number of pulses N generated every second is recorded.
The number of pulses N indicates that the circular semiconductor detector detects N alpha particles generated by the decay of Po-218 per second.
Repeating the steps, and respectively recording the pulse number generated by Po-218 per second under different voltages;
B. and (3) calculating:
when the voltage is U0And the distance between Po-218 of decay of a certain radon in the measuring cavity of the measuring box and the circular semiconductor detector is x, a cylindrical uniform electric field E is formed between the circular semiconductor detector in the measuring cavity and the bottom plate of the measuring box, and the E is a constant:
collection time t versus distance x of the initial position from the semiconductor detector:
where k is the mobility of Po-218.
When x is 0, t is 0, then c is 0
The collection efficiency formula is:
wherein VnIs the neutralization rate of the positively charged Po-218.
The radon chamber concentration is C, and the radon concentration in the measuring cavity is the same as the radon chamber concentration, namely, each cubic meter per second produces C Po-218, and the circular semiconductor detector with the radius of R and the measuring box bottom plate form a cylindrical electrostatic field, and the volume of the cylindrical electrostatic field is V. The total number of Po-218 generated in the cylindrical detection area is VC, and the collection efficiency of the circular semiconductor detector of the cylindrical detection area to the Po-218 is as follows:
where η is the detection efficiency of the circular semiconductor detector for alpha particles produced by the Po-218 decay collected on its surface.
Substituting equation (7) into equation (6) to calculate:
the collection efficiency of the circular semiconductor detector of the cylindrical detection area to Po-218 under different voltages is obtained through experiments, and the neutralization rate V of Po-218 can be obtained by fitting according to the formula (8)nAnd the value of the mobility k.
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5999275A (en) * | 1982-11-27 | 1984-06-07 | Univ Nagoya | Apparatus for measuring radon concentration |
| CN102299378A (en) * | 2011-07-21 | 2011-12-28 | 北京大学 | Composite polymer electrolyte for lithium ion secondary battery and preparation method thereof |
| CN109254314A (en) * | 2018-11-15 | 2019-01-22 | 衡阳师范学院 | Annular electrode improves positively charged218The measurement chamber and method of Po collection efficiency |
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- 2021-07-27 CN CN202110680858.7A patent/CN113484897B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5999275A (en) * | 1982-11-27 | 1984-06-07 | Univ Nagoya | Apparatus for measuring radon concentration |
| CN102299378A (en) * | 2011-07-21 | 2011-12-28 | 北京大学 | Composite polymer electrolyte for lithium ion secondary battery and preparation method thereof |
| CN109254314A (en) * | 2018-11-15 | 2019-01-22 | 衡阳师范学院 | Annular electrode improves positively charged218The measurement chamber and method of Po collection efficiency |
Non-Patent Citations (2)
| Title |
|---|
| P PAGELKOPF ET AL.: "Neutralisation rate and the fraction of the positive 218Po-clusters in air", 《ATMOSPHERIC ENVIRONMENT》 * |
| 马文荣 等: "218Po正离子的中和动力学研究现状", 《中国核科学技术进展报告（第二卷）》 * |
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Application publication date: 20211008 Assignee: Xiangtan Sanxing Instrument Co.,Ltd. Assignor: Hengyang Normal University Contract record no.: X2023980041584 Denomination of invention: Device and method for measuring the mobility and neutralization rate of Po-218 using electrostatic collection method Granted publication date: 20220812 License type: Common License Record date: 20230912 |