CN105137471A - Low-energy [beta] nuclide surface pollution detection system and method capable of inhibiting [gamma] interference - Google Patents
Low-energy [beta] nuclide surface pollution detection system and method capable of inhibiting [gamma] interference Download PDFInfo
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- CN105137471A CN105137471A CN201510574776.9A CN201510574776A CN105137471A CN 105137471 A CN105137471 A CN 105137471A CN 201510574776 A CN201510574776 A CN 201510574776A CN 105137471 A CN105137471 A CN 105137471A
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Abstract
The invention provides a low-energy [beta] nuclide surface pollution detection system and method capable of inhibiting [gamma] interference, and the system and the method are used for solving the problem that a low-energy [beta] radionuclide surface pollution measuring system is liable to influenced by [gamma] interference. The detection system provided by the invention comprises a detector and a signal processing unit. The distance L2 between an anode filament plane of the detector and a cathode incident window is larger than the distance L1 between the anode filament plane to a cathode plane. Mixed gas of argon and methane serves as the working gas, and the working gas is introduced into the detector through a gas nozzle. The signal processing unit is used for carrying out waveform discrimination on pulse signals generated by low-energy [beta] nuclides. The background value of the detection system is lowered by about one magnitude, and the detection sensitivity is improved.
Description
Technical field
The invention belongs to radiation detection and protection field, be specifically related to a kind of suppress γ to disturb low-energy β nuclide surface contamination detection system and method.
Background technology
Producing or applying nuclear facilities and the laboratory of the low energy beta activity nucleic such as H-3, Ni-63, needing regularly to detect radioactive surface contamination's level.The Detection Techniques being applicable to the surface contamination of To Detect Lower Energy β nucleic (energy is less than 100keV) comprise ionization chamber, scintillator, proportional counter and PIN diode etc., in commercial cellular low-energy β nuclide pollution detection instrument, detector adopts the most general of the windowless proportional counter of flow gas, as the FlatFerret series of Overhoff company of the U.S., the JE series of China Engineering Physics Research Institute.It is high that the detector of this type has detection efficiency, working service low cost and other advantages.Energy due to β particle is continuous spectrum, γ photon has overlapping region with the electronic secondary power spectrum that detector effect produces with β particle spectrum, use the method for energy discrimination can not distinguish the energy gamma-rays electronic secondary overlapping with β power spectrum, therefore commercial higher based on the low energy beta detection system background of proportional counter, be easily subject to gamma-rays interference simultaneously.US Patent database discloses a key name and is called " Tritiummonitorwithimporovedgamma-raydiscrimination " (patent No.: 4,504,737) patent of invention, the temporal characteristics utilizing gaseous state tritoxide and gamma-rays to produce signal in detector is screened the two, and its measuring object be suitable for is gaseous state tritium.Disclosed in Chinese patent literature database, a patent of invention name is called " tritium surface contamination survey meter and tritium surface pollution monitoring method " (patent No.: CN100445764C), use the surface contamination of flow-gas proportional counter measurement of tritium, wherein do not comprise the function suppressing gamma-rays interference.Above-mentioned patent does not all relate to the method suppressing γ interference in low-energy β nuclide surface contamination detection.
Summary of the invention
The technical matters that the present invention will solve is to provide a kind of low-energy β nuclide surface contamination detection system suppressing γ to disturb, and another technical matters that the present invention will solve is to provide a kind of signal processing method of the low-energy β nuclide surface contamination detection system suppressing γ to disturb.
The low-energy β nuclide surface contamination detection system of suppression γ of the present invention interference, be made up of detector and signal processing unit, be characterized in, detector comprises cathode plane, valve, anodic wire plane, negative electrode entrance window; Signal processing unit comprises high-voltage capacitance; Low energy beta rays enters detector by described negative electrode entrance window, and the electronic secondary track that γ interference produces originates from described cathode plane; Described anodic wire plane is connected with signal processing unit by high-voltage capacitance; Working gas passes into detector by described valve; Described anodic wire plane and the distance L2 of negative electrode entrance window are greater than the distance L1 of anodic wire plane and cathode plane; The feature that described signal processing unit utilizes the low energy beta rays induced signal rise time to be greater than the γ interference electronic secondary track induced signal rise time carries out pulse examination.
Described working gas is argon gas and methane blended gas, and argon gas volume is more than or equal to 50%, and preferred version is argon gas volume is 90%.
The signal processing method of the low-energy β nuclide surface contamination detection system of suppression γ of the present invention interference, comprises the following steps:
A. draw induced current signal by described anodic wire plane, induced current signal comprises the electronic secondary track induced signal of low energy beta rays induced signal and γ interference generation;
B. carry out integration to the induced signal of step a and amplify producing pulse signal;
C. use lag line forming technique to carry out filtering to the pulse signal of step b shaping, produce the shaping pulse signal of filtering;
D. in the filtering of step c shaping pulse signal negative edge range value 90% place, a timing signal A is produced;
E. in the filtering of step c shaping pulse signal negative edge range value 10% place, a timing signal B is produced;
F. as timing signal B occurs after timing signal A end-of-pulsing, what namely think that detector exports is low energy beta rays signal, otherwise the electronic secondary track signal produced for γ interference;
G. record is given to low energy beta rays signal.
The signal processing method of the low-energy β nuclide surface contamination detection system of suppression γ of the present invention interference, the difference of output current time response in the detector utilizing the difference of the ionization path position of low energy β particle in detector and γ photon electronic secondary ionization path position in detector to cause, the signal that gamma-rays electronic secondary is corresponding can be removed, detector sample-out count about 1 order of magnitude can be reduced, be adapted at the stronger particular place of gamma radiation field and use.
Accompanying drawing explanation
Fig. 1 is the low-energy β nuclide surface contamination detection system structural representation of suppression γ of the present invention interference;
Fig. 2 is the hardware composition frame chart of the signal processing method of detection system of the present invention;
Fig. 3 is the signal processing flow figure of detection system of the present invention;
Fig. 4 is the rise time characteristic pattern that detection system of the present invention outputs signal different nucleic;
In figure, 1. detector 2. signal processing unit 3. cathode plane 4. γ disturbs electronic secondary track 5. valve 6. anodic wire plane 7. low energy beta rays 8. negative electrode entrance window 9. high-voltage capacitance produced.
Embodiment
Following examples only for illustration of the present invention, and are not limitation of the present invention.Without departing from the spirit and scope of the present invention, can also make a variety of changes, replace and modification, therefore equal technical scheme also belongs to category of the present invention to the personnel of relevant technical field.
embodiment 1
Fig. 1 is the low-energy β nuclide surface contamination detection system structural representation of suppression γ of the present invention interference, Fig. 2 is the signal processing system composition frame chart of detection system of the present invention, Fig. 3 is the signal processing flow figure of detection system of the present invention, Fig. 4 is the rise time characteristic pattern that detection system of the present invention outputs signal different nucleic.
Composition graphs 1-4 introduces low-energy β nuclide surface contamination detection system and the method for suppression γ of the present invention interference.As shown in Figure 1, the low-energy β nuclide surface contamination detection system of suppression γ of the present invention interference, be made up of detector 1 and signal processing unit 2, detector 1 has done further improvement to windowless flow-gas proportional counter, and detector 1 comprises cathode plane 3, valve 5, anodic wire plane 6, negative electrode entrance window 8; Signal processing unit 2 comprises high-voltage capacitance 9; Low energy beta rays 7 enters detector 1, γ by negative electrode entrance window 8 and disturbs the electronic secondary track 4 produced to originate from cathode plane 3; Anodic wire plane 6 is connected with signal processing unit 2 by high-voltage capacitance 9; Working gas passes into detector 1 by valve 5.Cathode plane 3 adopts oxygen-free copper to process, and surface is through cuing open light process.Negative electrode entrance window 8 adopts stainless (steel) wire to make, and negative electrode entrance window 8 and anodic wire plane 6 are 10mm apart from L2, and cathode plane 3 and anodic wire plane 6 are 6mm apart from L1.Anodic wire plane 6 is made up of 10 diameters, 25 μm of gold-plated tungsten wires, gold-plated tungsten wire spacing 5mm.Anodic wire plane 6 adds 1800V positive high voltage, adopts teflon insulation between anodic wire and negative electrode.Detector working gas adopts argon gas and methane blended gas, and argon gas volume is 90%.
Fig. 2 is the hardware composition frame chart of the signal processing method of detection system of the present invention, first integration is carried out by charge-sensitive preamplifier antianode silk induced current signal, integrating capacitor 1pF, type is filtered into before charge-sensitive by the shaping amplifier of lag line, time delay 1 μ s, enlargement factor 100.The shaping output signal of filtering is input to wave analyzer, and wave analyzer A, B two-way exports the initial sum end signal as time to amplitude converter, and time to amplitude converter is input to multichannel analyzer, is undertaken analyzing and record by multichannel analyzer.
Fig. 3 is the signal processing flow figure of detection system of the present invention, and step is:
A. draw induced current signal by anodic wire plane 6, induced current signal comprises electronic secondary track 4 induced signal of low energy beta rays 7 induced signal and γ interference generation;
B. carry out integration to the induced signal of step a and amplify producing pulse signal;
C. use lag line forming technique to carry out filtering to the pulse signal of step b shaping, produce the shaping pulse signal of filtering;
D. in the filtering of step c shaping pulse signal negative edge range value 90% place, a timing signal A is produced;
E. in the filtering of step c shaping pulse signal negative edge range value 10% place, a timing signal B is produced;
F. as timing signal B occurs after timing signal A end-of-pulsing, what namely think that detector exports is low energy beta rays 7 signal, otherwise electronic secondary track 4 signal produced for γ interference;
G. record is given to low energy beta rays 7 signal.
Fig. 4 is the rise time characteristic pattern that detection system of the present invention outputs signal different nucleic, use in figure "
" curve that indicates is
55fe signal elevating time, "
" curve that indicates is
226ra signal elevating time, "
" curve that indicates is
3the H signal rise time.As shown in Figure 4, the rise time of the pulse that low energy beta rays produces is greater than γ and disturbs nucleic to produce the rise time of pulse, and detection system identifies low energy beta rays thus.
embodiment 2
Low-energy β nuclide surface contamination detection system and the method for the suppression γ interference of the present embodiment are identical with embodiment 1, and main difference part is that the volume of argon gas in detector working gas is 50%.
Claims (4)
1. the low-energy β nuclide surface contamination detection system suppressing γ to disturb, be made up of detector (1) and signal processing unit (2), it is characterized in that, detector (1) comprises cathode plane (3), valve (5), anodic wire plane (6), negative electrode entrance window (8); Signal processing unit (2) comprises high-voltage capacitance (9); Low energy beta rays (7) enters detector (1) by described negative electrode entrance window (8), and the electronic secondary track (4) that γ interference produces originates from described cathode plane (3); Described anodic wire plane (6) is connected with signal processing unit (2) by high-voltage capacitance (9); Working gas passes into detector (1) by described valve (5); Described anodic wire plane (6) is greater than the distance L1 of anodic wire plane (6) and cathode plane (3) with the distance L2 of negative electrode entrance window (8); The feature that described signal processing unit (2) utilizes low energy beta rays (7) the induced signal rise time to be greater than γ interference electronic secondary track (4) the induced signal rise time carries out pulse examination.
2. the low-energy β nuclide surface contamination detection system of suppression γ according to claim 1 interference, it is characterized in that, described working gas is argon gas and methane blended gas, and the volume of argon gas is more than or equal to 50%.
3. the low-energy β nuclide surface contamination detection system of suppression γ according to claim 2 interference, it is characterized in that, the volume of argon gas is 90%.
4. for the signal processing method of detection system according to claim 1, it is characterized in that, described signal processing method comprises the following steps:
A. draw induced current signal by described anodic wire plane (6), induced current signal comprises electronic secondary track (4) induced signal of low energy beta rays (7) induced signal and γ interference generation;
B. carry out integration to the induced signal of step a and amplify producing pulse signal;
C. use lag line forming technique to carry out filtering to the pulse signal of step b shaping, produce the shaping pulse signal of filtering;
D. in the filtering of step c shaping pulse signal negative edge range value 90% place, a timing signal A is produced;
E. in the filtering of step c shaping pulse signal negative edge range value 10% place, a timing signal B is produced;
F. as timing signal B occurs after timing signal A end-of-pulsing, what namely think that detector exports is low energy beta rays (7) signal, otherwise electronic secondary track (4) signal produced for γ interference;
G. record is given to low energy beta rays (7) signal.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107144869A (en) * | 2017-06-19 | 2017-09-08 | 中广核久源（成都）科技有限公司 | A kind of tritium surface contamination survey meter |
| CN107367752A (en) * | 2017-07-28 | 2017-11-21 | 成都理工大学 | Measure the horizontal device of ventilation filter frame radiative |
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| US4317038A (en) * | 1980-03-24 | 1982-02-23 | Agence Nationale De Valorisation De La Recherche | Device for determining the spatial distribution of radiation |
| US4504737A (en) * | 1982-10-21 | 1985-03-12 | The United States Of America As Represented By The United States Department Of Energy | Tritium monitor with improved gamma-ray discrimination |
| US5604783A (en) * | 1995-03-03 | 1997-02-18 | Charpak; Georges | Medical imaging devices using low-dose X or gamma ionizing radiation |
| US5627377A (en) * | 1995-09-07 | 1997-05-06 | Santa Barbara Research Center | Single carrier-type solid-state radiation detector device |
| CN102928864A (en) * | 2012-11-01 | 2013-02-13 | 成都理工大学 | Method and system for measuring gas tritium based on multi-wire proportional chamber |
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2015
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US4317038A (en) * | 1980-03-24 | 1982-02-23 | Agence Nationale De Valorisation De La Recherche | Device for determining the spatial distribution of radiation |
| US4504737A (en) * | 1982-10-21 | 1985-03-12 | The United States Of America As Represented By The United States Department Of Energy | Tritium monitor with improved gamma-ray discrimination |
| US5604783A (en) * | 1995-03-03 | 1997-02-18 | Charpak; Georges | Medical imaging devices using low-dose X or gamma ionizing radiation |
| US5627377A (en) * | 1995-09-07 | 1997-05-06 | Santa Barbara Research Center | Single carrier-type solid-state radiation detector device |
| CN102928864A (en) * | 2012-11-01 | 2013-02-13 | 成都理工大学 | Method and system for measuring gas tritium based on multi-wire proportional chamber |
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| TAKAHIKO AOYAMA ET AL.: "A new type of tritium-in-air monitor for fusion reactors", 《FUSION ENGINEERING AND DESIGN》 * |
| 刘秀喜 等: "《高纯气体的性质、制造和应用》", 30 June 1997, 电子工业出版社 * |
| 吕宁 等: "大面积薄窗流气式正比计数器工作电压设置研究", 《核电子学与探测技术》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107144869A (en) * | 2017-06-19 | 2017-09-08 | 中广核久源（成都）科技有限公司 | A kind of tritium surface contamination survey meter |
| CN107367752A (en) * | 2017-07-28 | 2017-11-21 | 成都理工大学 | Measure the horizontal device of ventilation filter frame radiative |
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