CN102109474A - Method and system for detecting defect of material based on electron pair effect - Google Patents
Method and system for detecting defect of material based on electron pair effect Download PDFInfo
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- CN102109474A CN102109474A CN2009102443605A CN200910244360A CN102109474A CN 102109474 A CN102109474 A CN 102109474A CN 2009102443605 A CN2009102443605 A CN 2009102443605A CN 200910244360 A CN200910244360 A CN 200910244360A CN 102109474 A CN102109474 A CN 102109474A
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Abstract
The invention discloses a method and a system for detecting the defect of a material based on an electron pair effect. The method comprises the following steps of: providing low-energy X-rays which can be subjected to the electron pair effect with the detected material; irradiating the detected material by using the low-energy X-rays to produce positive electrons in the detected material through the electron pair effect; measuring a gamma photon spectrum released due to annihilation of the positron electrons by using a gamma ray detector; and analyzing the gamma photon spectrum to judge whether the defect exists in the detected material or not. In the method, the internal defect of the detected material is detected by the positive electrons produced because the low-energy X-rays are subjected to the electron pair effect in the detected material, and the positive electrons are uniformly produced in the material, so microstructure information in the material can be uniformly brought out by 511keV gamma rays released after the annihilation of the positron electrons; in addition, the purchasing cost and using cost of the low-energy X-rays are lower, and the method and the system have a few protection requirements and are convenient to use on site.
Description
Technical field
The present invention relates generally to the technology of utilizing X ray that fault in material is detected, more specifically, relates to the method and system based on pair effect test material defective.
Background technology
The application of positron analytical technology more and more widely.Known, as the antiparticle of negatron, positron can be fallen into oblivion effect with the former after producing, and the process of annihilation and product thereof are very relevant with negatron characteristic in the material.By the gamma-rays angle association that to measure two energy expectation values of emitting after the life-span of positron in material, the positron-electron annihilation be 511keV, perhaps (mainly) because the 511keV gamma-rays full energy peak broadening that causes of negatron momentum, can study the architectural characteristic of material atomic layer time.
The present used radiographic source of positron analytical technology comes material is analyzed by the mode on positron irradiating object surface mainly from isotope source and accelerator.This mode can be measured small sample easily, can do the positron analysis to sample under the signal to noise ratio (S/N ratio) preferably.Yet because radiographic source separates with sample, positron need be injected sample from the surface, and the range of positron in sample is very little, so this mode can only be analyzed the part of the surface～mm thickness of material.
Now need a kind of method and corresponding detecting system that can detect the defective of material internal based on the positron analytical technology of pair effect.
Summary of the invention
One of purpose of the present invention provides a kind of method based on pair effect test material defective.This method may further comprise the steps: provide can with the low energy X ray of detected material generation pair effect; Shine described detected material with described low energy X ray, in described detected material, produce positron by pair effect; Utilize gamma ray detector to measure the γ photons spectrum of emitting owing to the annihilation of described positron; With analyze described γ photons spectrum to determine whether there is defective in the described detected material.The positron that this method utilizes low energy X ray to produce at detected material internal generation pair effect is realized the detection to detected material internal defect, because positron is to produce comparatively uniformly at material internal, the 511keV gamma-rays of emitting after the described positron annihilation can be taken the micromechanism information of material internal equably out of.And, than low-energy X-ray purchase, lower aspect the use cost, requirement of shelter is few, be convenient to on-the-spot the use.
As a preferred embodiment of this method, low energy X ray is the bremsstrahlung X ray that is lower than 7MeV.Like this, when detecting, needn't worry photoneutron problem (have only 2H, the photoneutron threshold value of minority nucleic such as 9Be is less than 7MeV) substantially.
Two of purpose of the present invention provides a kind of system based on pair effect test material defective, and it comprises: the low energy X ray generator, be used to provide can with detected material generation pair effect to produce the low energy X ray of positron; Gamma ray detector is used to measure the γ photons spectrum of emitting owing to the annihilation of positron; With the energy spectrum analysis device, be used to analyze described γ photons spectrum to determine whether described detected material exists defective.This system detects according to the defective of above-mentioned method based on pair effect test material defective to material internal, therefore has the benefit similar to said method.
Reach with reference to the accompanying drawings by reading following detailed description, other purposes of the present invention and advantage will become clearly.
Description of drawings
Fig. 1 is the synoptic diagram of the test material defective according to the present invention.
Embodiment
Fig. 1 has shown the schematic diagram of the most preferred embodiment of method and system of the present invention.As described in Figure, the electronics of the severals MeV that produced by electron accelerator is after bombarding tungsten target, meeting produce power value is lower than the bremsstrahlung X ray of 7MeV, these X ray process x-ray collimators (1) are the detected material of directive afterwards, pass through x-ray collimator (2) again and carry out the collimation second time, shine certain local location of detected material then.
Multiple reaction can take place with it in the X ray of injecting detected material, comprises photoelectric effect, Compton scattering, pair effect, Rayleigh scattering etc.When X ray and detected material generation pair effect, can produce positron and negatron.The positron that produces slows down in object to be detected, slowing down, when having some defective in the material, these positrons can be had slightly that electronegative defective attracts, and with negatron generation annihilation reaction there, emitting expectation value is the γ photon of 511keV.Because it is relevant with the momentum characteristic of negatron that the energy of γ photon departs from the degree of 511keV, and the momentum characteristic of negatron is relevant with the defect characteristics of material, therefore can realize the analysis to the fault in material characteristic by the analysis of these γ photon energies are distributed (being power spectrum).
In Fig. 1, adopt high purity germanium detector to come pair annihilation γ photons spectrum to measure.In order to realize that gamma spectrum is measured effectively, also need high purity germanium detector is freezed, this needs a refrigeration mechanism.In the present embodiment, refrigeration mechanism is a refrigeration machine.Certainly, in other embodiments, also can use Dewar container for liquefied nitrogen bottle or other refrigerating plants that detector is freezed.Detector also needs good shielding to stop the X ray by accelerator target point directive detector.In the front of detector, x-ray collimator (3) and (4) are set, to limit the detection direction of detector.
The photon of considering the directive detector not only has the annihilation photon of 511keV, and photon, the X ray after the photoelectric effect, the bremsstrahlung X ray after the photoelectric effect that Compton scattering has taken place arranged, therefore in order to improve this ratio of letter, increase ray hardened body before at x-ray collimator (4).The material of hardenite is generally selected the material of high atomic number, lead metal or contain plumbous material for example, and other metallic iron, copper, bismuth also are alternative materials.The thickness of hardenite is then determined by the situation of object to be detected.
In system of the present invention and since X ray collimated when the directive object to be detected be a beam, and detector its direction when measuring also collimated be a bundle, can form a point after these two bundles intersect.The 511keV annihilation photon that detector is measured can compose the fault in material information that has reflected this point.In order to realize the positron analysis to the material internal diverse location, native system comprises the mobile device of test sample and moving and whirligig of detector.By the mobile device of test sample, sample can two dimension translations, promptly move forward and backward and move up and down, and direction as shown in Figure 1.By moving and whirligig of detector, detector can be rotated and move forward and backward (i.e. the translation of a dimension), and direction also as shown in Figure 1.By such travel mechanism, just can utilize X-ray beam behind the collimation and the direction of measurement behind the collimation to come the three-dimensional position of sample is analyzed, obtain the defect characteristics of its inner each point.Because these move what adopt with whirligig all is prior art, therefore they is not carefully stated at this.
Detector links to each other with spectrometer system and computer system, with to detector measurement to the γ photons spectrum handle and analyze, whether have defective to determine material internal, and a degree of defective.
Though described exemplary embodiments of the present invention, should be understood that and the invention is not restricted to these embodiment, concerning the professional and technical personnel, various changes and modifications of the present invention can both realize, but these are all within the spirit and scope of claim of the present invention.
Claims (29)
1. method based on pair effect test material defective may further comprise the steps:
Provide can with the low energy X ray of detected material generation pair effect;
Shine described detected material with described low energy X ray, in described detected material, produce positron by pair effect;
Utilize gamma ray detector to measure the γ photons spectrum of emitting owing to the annihilation of described positron; With
Analyze described γ photons spectrum to determine whether there is defective in the described detected material.
2. method according to claim 1 is characterized in that: described method also comprises the step that moves described detected material.
3. method according to claim 1 is characterized in that: described method also comprises the step that moves and/or rotate gamma ray detector.
4. method according to claim 1 is characterized in that: the front of described gamma ray detector is provided with ray hardened body to improve this ratio of letter.
5. method according to claim 4 is characterized in that: described ray hardened body is selected from the material of high atomic number.
6. method according to claim 5 is characterized in that: described ray hardened body is by lead metal or contain plumbous material and make.
7. method according to claim 5 is characterized in that: described ray hardened body is made by the material that contains one of following metal: iron, copper, lead, bismuth.
8. method according to claim 1 is characterized in that: described low energy X ray is the bremsstrahlung X ray that is lower than 7MeV.
9. method according to claim 8 is characterized in that: described bremsstrahlung X ray produces by other electron bombard tungsten target of MeV level.
10. method according to claim 1 is characterized in that: described method also comprises the step that described low energy X ray is at least once collimated.
11. method according to claim 11 is characterized in that: described method comprises the step of described low energy X ray being carried out twice collimation.
12. method according to claim 1 is characterized in that: described method also comprises the step that γ photon ray is at least once collimated.
13. method according to claim 13 is characterized in that: described method comprises the step of described γ photon ray being carried out twice collimation.
14. method according to claim 14 is characterized in that: described method is included in the preceding step that this gamma-rays is hardened and shields of the described gamma-ray collimation second time.
15. method according to claim 1 is characterized in that: described method also is included as described gamma ray detector the detector shield is provided.
16. method according to claim 1 is characterized in that: described method also is included as described gamma ray detector cooling is provided.
17. method according to claim 1 is characterized in that: described gamma ray detector is a high purity germanium detector.
18. the system based on pair effect test material defective, it comprises:
The low energy X ray generator, be used to provide can with detected material generation pair effect to produce the low energy X ray of positron;
Gamma ray detector is used to measure the γ photons spectrum of emitting owing to the annihilation of positron; With
The energy spectrum analysis device is used to analyze described γ photons spectrum to determine whether described detected material exists defective.
19. system according to claim 18 is characterized in that: described system also comprises ray hardened body, and gamma-rays enters described gamma ray detector via this ray hardened body.
20. system according to claim 18 is characterized in that: also be provided with collimating apparatus between described gamma ray detector and the described ray hardened body.
21. system according to claim 18 is characterized in that: described system also comprises the device that moves and/or rotate described gamma ray detector.
22. system according to claim 18 is characterized in that: described system also comprises the device that moves described detected material.
23. system according to claim 18 is characterized in that: described system also comprises the detector shield of described gamma ray detector.
24. system according to claim 18 is characterized in that: described system also comprises the cooling device that is used to cool off described gamma ray detector.
25. system according to claim 24 is characterized in that: described cooling device is refrigeration machine or Dewar container for liquefied nitrogen bottle.
26. system according to claim 18 is characterized in that: described system comprises that also at least one is used to collimate the collimating apparatus of low energy X ray.
27. system according to claim 18 is characterized in that: described system comprises that also at least one is used to collimate gamma-ray collimating apparatus.
28. system according to claim 18 is characterized in that: described energy spectrum analysis device comprises spectrometer system.
29. system according to claim 18 is characterized in that: described low energy X ray generator comprises electron accelerator and tungsten target, and the electron bombard tungsten target of described electron accelerator generation MeV energy level is lower than the bremsstrahlung X ray of 7MeV with generation.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103687270A (en) * | 2012-09-19 | 2014-03-26 | 同方威视技术股份有限公司 | Accelerator |
| CN104754848A (en) * | 2013-12-30 | 2015-07-01 | 同方威视技术股份有限公司 | X-ray generating device and X-ray perspective imaging system having the device |
| CN110988628A (en) * | 2019-12-09 | 2020-04-10 | 西北核技术研究院 | Method for detecting insulating property of dielectric material by positron annihilation technology |
| CN111751396A (en) * | 2020-07-17 | 2020-10-09 | 北京唯实兴邦科技有限公司 | Method for detecting and analyzing damage and failure of microstructure of mechanical structural part |
| CN113687404A (en) * | 2021-08-19 | 2021-11-23 | 南京航空航天大学 | A kind of18F-labeled aerosolised positron imaging agent and preparation method thereof |
-
2009
- 2009-12-29 CN CN2009102443605A patent/CN102109474A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103687270A (en) * | 2012-09-19 | 2014-03-26 | 同方威视技术股份有限公司 | Accelerator |
| CN103687270B (en) * | 2012-09-19 | 2016-06-29 | 同方威视技术股份有限公司 | Accelerator installation |
| CN104754848A (en) * | 2013-12-30 | 2015-07-01 | 同方威视技术股份有限公司 | X-ray generating device and X-ray perspective imaging system having the device |
| CN104754848B (en) * | 2013-12-30 | 2017-12-08 | 同方威视技术股份有限公司 | X-ray generator and the radioscopy imaging system with the device |
| US10224170B2 (en) | 2013-12-30 | 2019-03-05 | Nuctech Company Limited | X-ray generating apparatus and X-ray fluoroscopyimaging system equipped with the same |
| CN110988628A (en) * | 2019-12-09 | 2020-04-10 | 西北核技术研究院 | Method for detecting insulating property of dielectric material by positron annihilation technology |
| CN111751396A (en) * | 2020-07-17 | 2020-10-09 | 北京唯实兴邦科技有限公司 | Method for detecting and analyzing damage and failure of microstructure of mechanical structural part |
| CN113687404A (en) * | 2021-08-19 | 2021-11-23 | 南京航空航天大学 | A kind of18F-labeled aerosolised positron imaging agent and preparation method thereof |
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Application publication date: 20110629 |