CN201286192Y - Photoneutron conversion target and photoneutron X ray source - Google Patents
Photoneutron conversion target and photoneutron X ray source Download PDFInfo
- Publication number
- CN201286192Y CN201286192Y CNU2008201257287U CN200820125728U CN201286192Y CN 201286192 Y CN201286192 Y CN 201286192Y CN U2008201257287 U CNU2008201257287 U CN U2008201257287U CN 200820125728 U CN200820125728 U CN 200820125728U CN 201286192 Y CN201286192 Y CN 201286192Y
- Authority
- CN
- China
- Prior art keywords
- ray
- photoneutron
- conversion target
- main beam
- passage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 92
- 238000009826 distribution Methods 0.000 claims description 16
- 238000010894 electron beam technology Methods 0.000 claims description 11
- 230000000295 complement effect Effects 0.000 claims description 6
- 238000001514 detection method Methods 0.000 description 45
- 230000005251 gamma ray Effects 0.000 description 38
- 239000000463 material Substances 0.000 description 34
- 238000003384 imaging method Methods 0.000 description 29
- 239000013078 crystal Substances 0.000 description 19
- 238000000034 method Methods 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 8
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 5
- 229910052721 tungsten Inorganic materials 0.000 description 5
- 239000010937 tungsten Substances 0.000 description 5
- 239000004698 Polyethylene Substances 0.000 description 4
- 239000006096 absorbing agent Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002360 explosive Substances 0.000 description 4
- -1 polyethylene Polymers 0.000 description 4
- 229920000573 polyethylene Polymers 0.000 description 4
- 238000003491 array Methods 0.000 description 3
- 125000004429 atom Chemical group 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000033001 locomotion Effects 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 230000005855 radiation Effects 0.000 description 3
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910052770 Uranium Inorganic materials 0.000 description 2
- 238000000333 X-ray scattering Methods 0.000 description 2
- 229910052790 beryllium Inorganic materials 0.000 description 2
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- ZPUCINDJVBIVPJ-LJISPDSOSA-N cocaine Chemical compound O([C@H]1C[C@@H]2CC[C@@H](N2C)[C@H]1C(=O)OC)C(=O)C1=CC=CC=C1 ZPUCINDJVBIVPJ-LJISPDSOSA-N 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910001385 heavy metal Inorganic materials 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000012188 paraffin wax Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 2
- 230000005461 Bremsstrahlung Effects 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N Heavy water Chemical compound [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- GVGLGOZIDCSQPN-PVHGPHFFSA-N Heroin Chemical compound O([C@H]1[C@H](C=C[C@H]23)OC(C)=O)C4=C5[C@@]12CCN(C)[C@@H]3CC5=CC=C4OC(C)=O GVGLGOZIDCSQPN-PVHGPHFFSA-N 0.000 description 1
- 229910052778 Plutonium Inorganic materials 0.000 description 1
- 230000005856 abnormality Effects 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 210000000746 body region Anatomy 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 229960003920 cocaine Drugs 0.000 description 1
- 230000006854 communication Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229960002069 diamorphine Drugs 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 230000004992 fission Effects 0.000 description 1
- 230000005021 gait Effects 0.000 description 1
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011824 nuclear material Substances 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000013519 translation Methods 0.000 description 1
- PBYZMCDFOULPGH-UHFFFAOYSA-N tungstate Chemical compound [O-][W]([O-])(=O)=O PBYZMCDFOULPGH-UHFFFAOYSA-N 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Landscapes
- Analysing Materials By The Use Of Radiation (AREA)
Abstract
The utility model discloses a photoneutron conversion target and a photoneutron- X-ray source by using the same, used for simultaneously producing the photoneutron and the X-ray. The photoneutron- X-ray source includes an X-ray generator for producing the X-ray main beam; the photoneutron conversion target is bombarded by using the X-ray main beam to produce the photoneutron and has body and a channel limited by the body, the channel penetrates through the body; wherein the first X-ray beam in the X-ray main beam can penetrate through the channel without the reaction with the body, at the same time, the second X-ray beam in the X-ray main beam can enter the body and be reacted with the body to produce the photoneutron.
Description
Technical field
The utility model relates to the photoneutron conversion target, and this photoneutron conversion target is used to utilize X ray to produce photoneutron, and this photoneutron conversion target particularly can be used in the contraband detection system.
Background technology
At present, terrorism has constituted great threat to international and domestic society stable, and national governments all are being devoted to solve counterterrorism issues.And the detection technique of contraband such as explosive is the core of counterterrorism issues.
A kind of existing contraband detection technique is the x-ray imaging detection technique.The x-ray imaging detection technique is a kind of safety check technology of being used widely, on the airport, the railway station can see much the equipment based on the x-ray imaging detection technique.Because X ray mainly is to react with atomic nucleus electronics outward, to the as broad as long ability of nuclear characteristic, therefore utilizes X ray can only measure the density of object to be detected (mass thickness), and can't judge the element kind of object to be detected.In practice, when contraband mix with articles for daily use place and density refractory when distinguishing, utilize the x-ray imaging detection technique just to be difficult to find it.Though the x-ray imaging detection technique that some are novel, as: dual-energy x-ray, CT technology etc. increases on recognition capability, still can't overcome can not the recognition element kind inherent defect.
Another kind of existing dangerous material detection technique is middle subclass detection technique.For middle subclass detection technique, neutron can react with the atomic nucleus of material, emits to have distinctive gamma-rays, according to gamma-ray power spectrum, then can judge the element kind of analyzed material.The defective of middle subclass detection technique is the imaging resolution that it is lower, preferably also can only reach the spatial resolution of 5cm * 5cm * 5cm at present, and this is far below the mm class resolution ratio of x-ray imaging.And independent neutron source costs an arm and a leg usually, and service time is limited, and the neutron intensity that is produced is not high.
Therefore, just wishing to have a kind of method and/or system can make up aforesaid x-ray imaging detection technique and middle subclass detection technique, with the high-resolution of acquisition x-ray imaging detection technique and these advantages of element recognition capability of middle subclass detection technique.U.S. Patent No. 5078952 discloses a kind of detecting system for explosive material that makes up multiple detection means, comprising x-ray imaging device and neutron detection device, to realize higher detection probability and lower rate of false alarm.And this United States Patent (USP) also discloses and will be associated with the data that obtained by the neutron detection device by the data that x-ray imaging device obtains, so that remedy the middle not high defective of subclass detection technique resolution with high-resolution radioscopic image.But, in this United States Patent (USP), having used x-ray source independent of each other and neutron source, its cost is higher.
It should be noted that a kind of mode that produces neutron is to bombard conversion target with X ray, and produce neutron from this conversion target, the neutron of Chan Shenging can be described as photoneutron like this.This neutron producing method provide in a source produce X ray and neutron the two may, this is than producing X ray respectively with two sources respectively and neutron will be saved cost.
A kind of system that utilizes photoneutron and x-ray imaging to come the detection and Identification contraband is disclosed in the open WO 98/55851 of international application.This system adopts the two-step mode to come work.Particularly, this system at first produces X-ray beam with the linear accelerator x-ray source, and tested object is detected with x-ray imaging, if do not note abnormalities, then allow tested object pass through, if then insert a photoneutron conversion target (beryllium) in the X-ray beam in discovery suspicion zone temporarily, producing photoneutron, and the characteristic gamma-rays of emitting according to photoneutron and material atom nuclear generation radiation capture reaction further detects the suspicion zone.This system only carries out the first step with X ray and detects because the restriction of the recognition capability of aforesaid x-ray imaging detection technique, so its have lower detection probability (probability of detection, PD).And, this system does not produce X ray and the photoneutron that is used to detect simultaneously, but in two steps, produce X ray and the photoneutron that is used to detect respectively, promptly, in a step, only produce X ray and do not produce photoneutron, and be to produce photoneutron with X ray in another step, but this X ray only is used to produce photoneutron and be not used in testing goal.Further, the photoneutron of its generation only is used to detect the suspicion zone of tested object, and is not used in tested object is totally detected.
A kind of method of carrying out material identification with fast neutron and X ray is disclosed in the applicant's Chinese patent application No.200510086764.8.Described a kind of method and apparatus that produces X ray and photoneutron simultaneously in this application, it will speed up X ray that device produces and is divided into two bundles, wherein a branch ofly is used to produce photoneutron.Yet in this application, for neutron, it is that the intensity of utilizing the photoneutron transmission to cross tested object detects, and is not the characteristic gamma-rays that utilizes neutron and checking matter precursor reactant to be emitted.And, in this application, in such detection mode,, need make usually to be spaced laterally apart certain distance between X-ray beam and the neutron beam in order to make the detection of X-ray beam and neutron beam not interfere with each other.
Above-mentioned application and patent all are incorporated herein by reference in full.
The utility model content
Photoneutron-x-ray source that the purpose of this utility model provides a kind of photoneutron conversion target and utilizes this photoneutron conversion target, it allows to produce simultaneously photoneutron and X ray.
According to an aspect of the present utility model, a kind of photoneutron conversion target is provided, be used to utilize the X ray main beam to bombard this photoneutron conversion target and produce photoneutron, the passage that this photoneutron conversion target has body and limited by this body, this passage run through described body;
Wherein, first X-ray beam in the described X ray main beam can pass this passage and not react with this body, and simultaneously, second X-ray beam in the described X ray main beam can enter in the described body, and reacts to produce photoneutron with this body.
According on the other hand of the present utility model, a kind of photoneutron-x-ray source is provided, be used for producing photoneutron and X ray simultaneously, comprising:
X ray generator is used to produce the X ray main beam;
The photoneutron conversion target, described X ray main beam can bombard this photoneutron conversion target and produce photoneutron, and the passage that this photoneutron conversion target has body and limited by this body, this passage run through described body;
Wherein, first X-ray beam in the described X ray main beam can pass this passage and not react with this body, and simultaneously, second X-ray beam in the described X ray main beam can enter in the described body, and reacts to produce photoneutron with this body.
In aspect above-mentioned two, described passage extends along the target axis of symmetry of described body.
Photoneutron conversion target of the present utility model and utilize the photoneutron-x-ray source of this photoneutron conversion target can produce photoneutron and X ray simultaneously.And this photoneutron conversion target and this photoneutron-x-ray source can be applied to any application scenario that needs photoneutron and X ray simultaneously, and do not limit to and the described occasion of the following examples.
Description of drawings
Fig. 1 shows the structural representation according to the photoneutron of an embodiment of the utility model-X ray contraband detection system;
Fig. 2 shows the amplification floor map of the photoneutron conversion target among Fig. 1, wherein shows the passage that is limited by this photoneutron conversion target;
Fig. 3 shows the end-view of the photoneutron conversion target among Fig. 2;
Fig. 4 shows a kind of improved gamma-ray detector.
Embodiment
Below with reference to accompanying drawing, typical specific embodiment of the present utility model is described in detail.Following examples are used to illustrate the utility model, but are not used for limiting scope of the present utility model.
With reference to example shown in Figure 1, tested object (for example sealing container 8) is arranged on the platform 19.Should be noted that this container 8 shows with cutaway view in Fig. 1, so that demonstrate the various goods 10 that wherein load, these goods 10 may comprise various materials, as metal 11, wooden unit 12 and explosive 13.This platform 19 is drawn by actuator 20, enters the surveyed area of detection system of the present utility model.This container 8 is generally made by corrugated steel and aluminium.Other container such as air container also can be done similar detection.
When the position transducer (not shown) detected container 8 and moves to the precalculated position, the x ray generator that this position transducer can trigger in the utility model system was started working.In one embodiment, this x ray generator comprises electron accelerator (not shown) and electric target 2.This unshowned electron accelerator produces the electron beam 1 of directive electric target 2.Electric target 2 normally is made of as tungsten, gold the higher material of atomic number, and electronics can be emitted X ray main beam 3 because of bremsstrahlung after being stopped by the atom of tungsten or gold.As hereinafter will as described in, will from this X ray main beam 3, tell first X-ray beam and second X-ray beam, wherein, first X-ray beam is used for x-ray imaging and detects, and second X-ray beam is used for neutron detection.In this article, x-ray imaging detects and is meant the tested object of X ray transmission, and detects the density information of tested object by the decay of detecting x-ray; Thereby neutron detection is meant the atom of neutron and the tested object release characteristic gamma-rays that reacts, and by surveying the element kind of information that this characteristic gamma-rays detects tested object.Should be noted in the discussion above that in the system and method in the utility model, utilize x-ray imaging to detect simultaneously and and neutron detection tested object is detected.
In Fig. 1, illustrate photoneutron conversion target 4 with broken section.X ray main beam 3 bombardment photoneutron conversion targets 4 obtain photoneutron 6, and utilize 6 pairs of containers of this photoneutron 8 to carry out neutron detection.Particularly, in this embodiment, this photoneutron conversion target 4 also is used for telling first X-ray beam and second X-ray beam from X ray main beam 3.
Photoneutron conversion target 4 among Fig. 1 amplifies in Fig. 2 and Fig. 3 and illustrates.As shown in Figure 2, this photoneutron conversion target 4 comprises body 401.In one embodiment, this body 401 is the elongated body that extends along the direction of propagation of X ray main beam 3, and it has first end 402 and the second end 403.Have the passage 404 that runs through this body 401 in this body 401, this passage 404 extends to the second end 403 from first end 402.Among the embodiment of this Fig. 2 and Fig. 3, this passage 404 forms the slit of fully extending in plane P (perpendicular to the paper of Fig. 2 and Fig. 3), so that this body 401 is divided into two parts that are separated from each other.Preferably, this passage 404 passes the symmetrical centre of this body 401, and is divided into the part of two symmetries.This passage 404 is limited between these two separating parts.When X ray main beam 3 during towards body 401 incidents of photoneutron conversion target 4, part X-ray beam 405 directly passes this photoneutron conversion target 4 via this passage 404, and with this photoneutron conversion target 4 any reaction does not take place, this part X-ray beam is restricted to first X-ray beam 405.Another part X-ray beam 406 enters in this body 401, and towards from first end 402 to the second end 403 direction propagate, and in communication process, react with the atomic nucleus of this photoneutron conversion target 4, thereby emit photoneutron, this part X-ray beam 406 is restricted to second X-ray beam 406.As can be seen, this passage 404 has in fact played the effect of beam splitter, is used for telling first X-ray beam and second X-ray beam from X ray main beam 3.In other unshowned embodiment, this passage 404 also can adopt other form, for example, this passage also can be with these body 401 separated into two parts, but form the through hole (not shown) that runs through this body 401, perhaps form other channel form that limits by body 401, can pass this body 401 as long as guarantee the fan-shaped x-ray beam that is used for x-ray imaging.
In order to make full use of from the X ray main beam 3 of electric target 2 outgoing, to improve the photoneutron output of this photoneutron conversion target 4, the shape of this photoneutron conversion target 4 can be designed to be complementary basically with the intensity distributions of X ray main beam 3, that is, make the big X ray of intensity can in the body 401 of photoneutron conversion target 4, propagate farther distance.With reference to figure 1 and Fig. 2, the X ray main beam 3 that comes out from electric target 2 has into axisymmetric intensity distributions usually, and its intensity distributions axis of symmetry is along the direction of electron beam 1, and the closer to this intensity distributions axis of symmetry, the intensity of X ray is big more usually.Correspondingly, under the situation of the passage 404 in ignoring this photoneutron conversion target 4, this photoneutron conversion target 4 can have axisymmetric shape generally and define a target axis of symmetry 409, and the distribution of the axial symmetry of the axisymmetric shape of this photoneutron conversion target and X ray main beam 3 is complementary basically.When this used, this target axis of symmetry 409 overlapped with the intensity distributions axis of symmetry of X ray main beam 3.Preferably, at least a portion of this photoneutron conversion target 4 is preferably towards the tapered portion of the second end 403 convergents, so that make photoneutron conversion target 4 have longer length in the place of more close this target axis of symmetry.In the embodiment shown in Figure 2, this photoneutron conversion target 4 comprises the tapered portion 408 of contiguous the second end 403 and the barrel portion 407 of contiguous first end 402, and this barrel portion 407 can be integrally formed with this tapered portion 408.This tapered portion 408 can end at the second end 403.This tapered portion 408 shown in Fig. 2 is a conical butt.This barrel portion 407 has common longitudinal center's axis with this tapered portion 408, and overlaps with this target axis of symmetry.In other embodiments, this tapered portion 408 also can be the taper of non-butt, perhaps convergent (for example with the curve mode convergent) otherwise.In further embodiments, this photoneutron conversion target 4 also can begin to taper to the second end 403 from first end 402.
Although the passage 404 that limited by photoneutron conversion target 4 has been shown in Fig. 1～Fig. 3 as beam splitter, but, persons of ordinary skill in the art may appreciate that the beam splitter that also can adopt other form, be used for telling first X-ray beam and second X-ray beam from X ray main beam 3.For example, can adopt disclosed binary channels shunting collimater in the applicant's Chinese patent application No.200510086764.8.This binary channels shunting collimater can be divided into X ray main beam 3 spaced two bundles, and the photoneutron conversion target is arranged on wherein a branch of propagation path to produce photoneutron.
Shall also be noted that this feature that this photoneutron conversion target 4 has a tapered portion is not limited to is used for the described occasion of the utility model embodiment.This feature also is applicable to any other occasion of using X-ray beam bombardment photoneutron conversion target and producing photoneutron, for example can be applicable in open WO 98/55851 of international application and the described occasion of Chinese patent application No.200510086764.8, to improve the output of photoneutron.In these other application scenarios, this photoneutron conversion target can be with or without the aforementioned channels as beam splitter.
Return Fig. 1, the common needs of choosing of the energy of electron beam 1 are considered the energy of needed X-ray beam and the material of photoneutron conversion target.Different according to type, detection speed and the Environmental security of object to be detected can select the X-ray beam of different-energy to penetrate.For the reason of safety and in order to save cost, should select as far as possible little energy usually.The energy of the electron beam 1 that unshowned electron accelerator produces can be in the scope of 1MeV～15MeV.The ideal material of photoneutron conversion target 4 should have less photoneutron reaction threshold value and bigger photoneutron reaction cross section, but these two is difficult to satisfy simultaneously.For the X ray of 1MeV～15MeV because its energy is high not enough, big for the cross section but the material that threshold value is also high the photoneutron yield lower, and beryllium (
9Be) or heavy water (D
2O) then be desirable material comparatively.
9The photoneutron reaction threshold value of Be only is 1.67MeV, D
2The threshold of reaction of D is 2.223MeV among the O.Enter the X ray main beam 3 of photoneutron conversion target 4 with wherein
9Be or
2Photoneutron reaction takes place in H, has emitted photoneutron 6.Because the power spectrum of X ray main beam 3 is continuous distribution, so the power spectrum of photoneutron 6 also is a continuous distribution.In addition, when can the produce power higher electron beam 1 of institute use electron accelerator, but this photoneutron conversion target 4 also can use the bigger material in the higher cross section of threshold value, as each isotope of tungsten (W) and each isotope of uranium (U).
In one embodiment, unshowned electron accelerator can produce electron beam 1 with characteristic frequency, and like this, 1 of this electron beam is after having the beam pulse 1. beam pulses 1 bombardment electric target 2 of this characteristic frequency, the X ray pulse 3 that produces same frequency.This characteristic frequency can determine according to the gait of march of detected container 8, for example can be in the scope of 10Hz～1000Hz.In one embodiment, this characteristic frequency can be 250Hz.The pulsewidth scope of this beam pulse 1 can be 1～10 μ s.
It should be noted that, the 34 generation 6 used times of photoneutron of bombardment photoneutron conversion targets of X ray main beam are lacked (usually less than 1 μ s) very much, therefore, we can say, in the utility model, it almost is that " simultaneously " produces that the photoneutron 6 that is used for carrying out neutron detection and X ray main beam 3 are used for first X-ray beam 405 that x-ray imaging detects, and so just allows to carry out simultaneously x-ray imaging and detects and neutron detection, and this obviously is different from the open WO 98/55851 of international application.
Photoneutron 6 is isotropic when producing in photoneutron conversion target 4, and therefore only some photoneutron can the detected container 8 of directive.Because in the photoneutron conversion target 4
9Be and
2H has bigger scattering section to neutron, and therefore, the photoneutron 6 that penetrates photoneutron target 4 can (promptly incide the direction of photoneutron conversion target 4) generally backward to be launched in contrast to X ray main beam 3.In order to improve the efficient that photoneutron 6 arrives detected container 8, can the neutron relfector (not shown) be set in the back of photoneutron target 4 (being adjacent to the first end 402 of photoneutron target 4).This neutron relfector is used to reflect the photoneutron 6 that deviates from these tested container 8 motions, makes it towards these tested container 8 motions.
With reference to figure 1 and Fig. 2, x-ray collimator 5 is arranged on first X-ray beam 405 and arrives on tested object 8 propagation path before, so that these first X-ray beam, 405 collimations are the plane fladellum.This x-ray collimator 5 preferably is arranged to the second end 403 of the body 402 of contiguous this photoneutron conversion target 4, and aims at passage 404.Like this, first X-ray beam 405 passes after this photoneutron conversion target 4 via passage 404, is collimated by x-ray collimator 5, to form plane fladellum 7.X ray outside this fladellum 7 will be shielded by x-ray collimator 5, can reduce the influence of X ray to neutron detection (gamma-ray detector especially hereinafter described) like this.
The neutron detection that the x-ray imaging that carries out with 405 pairs of containers of first X-ray beam 8 detects and uses 6 pairs of containers of photoneutron 8 of being produced by second beam 406 to carry out will be described respectively below.Should be known in that x-ray imaging detects and neutron detection itself is respectively well known to those of ordinary skill in the art.Yet in the utility model, because (the almost simultaneously in other words) generation simultaneously of first X-ray beam 405 and photoneutron 6, therefore, the beam x-ray imaging detects and neutron detection can be carried out simultaneously.
At first describing x-ray imaging detects.With reference to figure 1, X ray fladellum 7 (that is, the first collimated X-ray beam 405) the detected container 8 of directive, the goods 10 that is loaded in the container 8 can be decayed to this fladellum 7.Measure the X ray that these are attenuated by the X ray sniffer, this X ray sniffer can be the X-ray detector array 15 that comprises a plurality of X-ray detectors.Material the attenuation multiple of X ray has reflected from electric target 2 to X-ray detector array 15 on the line of corresponding X-ray detector is to the absorbability of X ray, the material density that is loaded in its size and the container 8 and form relevant.Utilize X-ray detector array 15 can realize two-dimensional x-ray imaging to container 8.Detector in this X-ray detector array 15 can be gas ionization chamber, cadmium tungstate crystal, CsI crystal, also can be the detector of other type.As previously mentioned, electron beam 1 is with some characteristic frequency bombardment electric targets 2, thus the X ray pulse that produces same frequency.For each X ray pulse, detector 15 arrays can obtain the one dimension image about certain section of container.Along with actuator 20 traction containers 8 advance, just constituted two-dimensional transmission image about container by a plurality of one dimension images that repeatedly measure.
Description and x-ray imaging detect the neutron detection of carrying out simultaneously now.After photoneutron conversion target 4 generation photoneutrons 6, tested container 8 will be washed in the photoneutron field.Photoneutron 6 is injected after the detected container 8, the off-energy by scattering (non-resilient and elastic scattering).There is no need before photoneutron 6 enters tested container 8, photoneutron 6 to be collimated, because it can permeate in scattering process in the quite wide zone.Photoneutron 6 is a fast neutron when producing, and just becomes slow neutron then in the time of several μ s.Afterwards, the energy of photoneutron 6 enters distinguishing of thermal neutron.The time interval of photoneutron 6 from the fast neutron to the thermal neutron generally is about 1ms.Thermal neutron finally can disappear, and the method for disappearance has two kinds: absorbed by material, perhaps escape.The life period of thermal neutron in the space is 1ms～30ms.Capture reaction also can take place in neutron when fast neutron and slow neutron can be distinguished, but the cross section is very little, when the neutron energy reduces, because the movement velocity relation of being inversely proportional to of its capture cross and neutron, so rise rapidly in the cross section.Because electron accelerator is with the work of continuous impulse mode, therefore the thermal neutron field between the different pulses can superpose.For example, when the mode that is about 250Hz, pulsewidth 5 μ s with frequency when electron accelerator is worked, finally the neutron field that forms in the space will be that a frequency is that 250Hz, pulsewidth are the fast neutron pulse of 5 μ s, be superimposed upon on the thermal neutron field of an approximately constant.
Thermal neutron can be emitted and has distinctive gamma-rays after material generation radiation capture reaction, for example
1H and neutron reaction can be emitted the feature gamma-rays of 2.223MeV,
14N and neutron reaction can be emitted the feature gamma-rays of 10.835MeV,
17Cl and neutron reaction can be emitted the feature gamma-rays of 6.12MeV.By to these features gamma-ray measurement can judge element kind in the object to be detected.Different materials in the container 8 can be emitted different feature gamma-rays under the irradiation of neutron.According to the difference of gamma spectrum, can analyze the type of this material.For example, if in container, find the signal of a large amount of N and H element, so just might there be explosive and " fertilizer bomb "; If found the gamma-rays of a large amount of Cl, then just might find drugs such as heroin and cocaine (they are being transported secretly with muriatic form usually).In addition, capture the fission neutron that is produced by photoneutron, also can check nuclear material (as uranium and plutonium) by measuring.
Measurement to the gamma-rays power spectrum is finished by the gamma-ray detection device, this gamma-ray detection device can be one or more gamma-ray detector arrays 14, each gamma-ray detector array 14 comprises a plurality of gamma-ray detectors, and is arranged to receive this characteristic gamma-rays.And as shown in Figure 1, when comprising a plurality of gamma-ray detector array 14, they can be arranged in the both sides of the travel path of container 8.And gamma-ray detector array 14 can be arranged to away from these X-ray detector array 15 certain distances, just departs from this X ray fladellum 7 (first X-ray beam) certain distance, so that this first X-ray beam minimizes the influence of gamma-ray detector.For each gamma-ray detector array,, then obtain the Two dimensional Distribution information of the element kind be concerned about by analyzing its gamma spectrum signal.
The kind that gamma-ray detector can be selected is more, as: NaI (T1), BGO, HPGe, LaBr
3Deng.
Used two types detector in the utility model: X-ray detector and gamma-ray detector, these two kinds of detector operation are in the environment of X ray, neutron and gamma-rays coexistence.It is very strong with respect to neutron and gamma-rays that two kinds of rays may form interference, particularly X ray mutually, so it might constitute the gamma spectrum of gamma-ray detection and disturbs.Therefore, for gamma detector, be necessary very much X ray and neutron ray are shielded.
Fig. 4 shows a kind of improved gamma-ray detector, and wherein, NaI crystal 22 and photomultiplier 23 have constituted the main body of this detector.This NaI crystal 22 have be used to receive gamma-ray front end face 30, with this front end face 30 back end opposite faces 31 and peripheral surface 32.When gamma-rays was injected NaI crystal 22, photoelectric effect, Compton scattering or pair effect can take place.The γ photon consigns to secondary electron with energy, and ionization takes place in crystal secondary electron, and the electron-hole pair that ionization produces will produce fluorescence.Fluorescent photon is got photoelectron on the photocathode of photomultiplier 23.Photoelectron is doubled by photomultiplier subsequently, forms voltage signal by preceding discharge road.For the shielding to X ray and neutron is provided to NaI crystal 22.Gamma-ray detector shown in Figure 4 also comprises neutron shielding material 28, and this neutron shielding material 28 has surrounded the peripheral surface 32 of this NaI crystal 22 at least, and exposes the front end face 30 of this NaI crystal 22.Preferably, this neutron shielding material 28 has also surrounded the rear end face 31 of this NaI crystal 22.This neutron shielding material 28 generally is made of the material that is rich in H, all is the material that is suitable for such as paraffin, polyethylene, water.Consider structure and fire protection requirement, generally select polyethylene.H atom pair neutron in the neutron shielding material 28 has very big scattering section, can reflected neutron, and promptly the energy of neutron is reduced and absorb.But neutron shielding material 28 with neutron generation radiation capture after can emit 2.223MeV feature H gamma-rays, the γ signal that this feature H gamma-rays will will be measured detector constitutes and disturbs.Therefore, in the inboard of neutron shielding material 28, this gamma-ray detector also comprises X/ gamma ray shielding body 26, and this X/ gamma ray shielding body 26 surrounds the peripheral surface of this detector crystal at least, and exposes the front end face 30 of this NaI crystal 22.Preferably, this X/ gamma ray shielding body 26 has also surrounded the rear end face 31 of this NaI crystal 22.The gamma-rays that X/ gamma ray shielding body 26 not only can intercept neutrons shielding material 28 be emitted when reacting with neutron, can also shield most X ray and scattered ray thereof, make gamma-ray detector can be in the normal operational environment from electric target 2.The material of this X/ gamma ray shielding body 26 is an atomic number more than or equal to 74 heavy metal, for example plumbous Pb or tungsten W.In the place ahead of gamma detector crystal 22, the front end face 30 facing to NaI crystal 22 also is provided with neutron absorber 27.With neutron shielding material 28 require differently, neutron absorber 27 is not only wanted can intercept neutrons, and the gamma-rays that can not emit the 2.223MeV of H.Neutron absorber 27 can be by paraffin or polyethylene and the boron with high-strength thermal neutron absorbability
10The B material constitutes (as containing boron polyethylene), and this makes H no longer include chance and emits the γ photon.In order to make gamma-ray detector only measure the detected material body region in its place ahead, and the signal (as the γ counting background of N in X ray scattering, the air) that other direction is come is lost interest in, this gamma-ray detector also comprises collimater 29.This collimater 29 is located at the place ahead of NaI crystal 22 and neutron absorber 27, the γ background that the X ray scattering background, neutron that is used for masking surrounding space produces in the material around.This collimater 29 comprises the through hole of aiming at the front end face 30 of NaI crystal, this through hole defines a bearing of trend, be used for only allowing basically entering this NaI crystal, thereby the gamma-rays that will survey is collimated along this bearing of trend and via the X/ gamma-rays that this through hole arrives this front end face.The diameter of this through hole can be identical with the diameter of NaI crystal 22, and length can be determined according to needed collimation effect, generally select the length range of 5～30cm.These collimater 29 common available atomic numbers are more than or equal to 74 heavy metal (for example plumbous Pb or tungsten W) or be made of a steel.
In addition, although it is not shown in the drawings, can also provide the time gate control circuit for this gamma-ray detector, be used to control the Measuring Time of gamma-ray detector, make the Measuring Time of gamma-ray detector avoid the spill time of the X-ray beam that x ray generator produced in the utility model system, can further suppress the interference of X ray like this gamma-ray detector.
According to signal, just can carry out x-ray imaging and neutron imaging to tested container 8 respectively, so that obtain radioscopic image and middle subimage from X-ray detector array 15 and gamma-ray detector array 14.Return Fig. 1, in system of the present utility model, x-ray imaging signal processing circuit 17 receives the signal from X-ray detector array 15, and it is handled to obtain radioscopic image.Gamma-rays signal processing circuit 18 receives the voltage signal from gamma-ray detector array 14, and analyzes gamma spectrum, thereby obtains comprising subimage in the two dimension of two-dimentional element distributed intelligence of tested object.Subimage combines with the two-dimensional x-ray images that is obtained in this two dimension, realizes identification and discovery to contraband in the container.
Consider when object to be detected is detected, because the X-ray detector array is different with the riding position of gamma-ray detector array, make object to be detected in the process of advancing, radioscopic image and middle subimage can not obtain simultaneously, and the difference of between each gamma-ray detector array because position, the middle subimage that obtains also is different.For radioscopic image and middle subimage are merged,, adopted following way to realize the contraband inspection better:
For different gamma-ray detector arrays, because their distance relation is determined, therefore the relation of the position between their the middle subimage also is definite, for the middle subimage that successively obtains, respectively their positions are adjusted, can be so that be in the common middle subimage that forms the distribution of width of cloth reflection element of the gamma-ray detector array at diverse location place.
For radioscopic image and middle subimage, its spatial relation is also determined, middle subimage and/or radioscopic image can be carried out translation and be merged into a sub-picture, the point corresponding to the object to be detected same position in feasible middle subimage and the radioscopic image overlaps fully.Like this, for the image after merging, wherein every bit has all comprised the element distributed intelligence and the density information of object to be detected.In system of the present utility model, can adopt an image to merge the device (not shown) and realize above-mentioned position adjustment, so that radioscopic image and middle subimage are incorporated in the sub-picture to radioscopic image and middle subimage.Like this, the operator only need observe element distributed intelligence and the density information that a sub-picture just can obtain object to be detected, so that the suspicious contraband in the tested object is carried out relatively accurate location.
Though described exemplary embodiments of the present utility model, should be understood that the utility model is not limited to these embodiment, concerning the professional and technical personnel, various changes and modifications of the present utility model can both realize, but these are all within the spirit and scope of the utility model claim.
Claims (23)
1. photoneutron conversion target is used to utilize the X ray main beam to bombard this photoneutron conversion target and produces photoneutron, it is characterized in that the passage that this photoneutron conversion target has body and limited by this body, this passage run through described body;
Wherein, first X-ray beam in the described X ray main beam can pass this passage and not react with this body, and simultaneously, second X-ray beam in the described X ray main beam can enter in the described body, and reacts to produce photoneutron with this body.
2. photoneutron conversion target according to claim 1 is characterized in that, described body is the elongated body that extends along the direction of propagation of X ray main beam, and this body has first end and the second end; And
The bearing of trend of described passage is identical with the direction of propagation of described X ray main beam.
3. photoneutron conversion target according to claim 2 is characterized in that, the shaped design of the body of described photoneutron conversion target becomes and the intensity distributions of described X ray main beam is complementary basically.
4. photoneutron conversion target according to claim 3 is characterized in that, the intensity distributions of described X ray main beam is that axial symmetry distributes, and it defines an intensity distributions axis of symmetry;
The described body configuration of described photoneutron conversion target becomes to become axisymmetric shape about a target axis of symmetry, and the axial symmetry of the axisymmetric shape of described photoneutron conversion target and described X ray main beam distributes and is complementary basically.
5. according to claim 3 or 4 described photoneutron conversion targets, it is characterized in that at least a portion of described body is a tapered portion, this tapered portion is towards described the second end convergent.
6. photoneutron conversion target according to claim 5 is characterized in that described tapered portion ends at described the second end.
7. photoneutron conversion target according to claim 6 is characterized in that, described tapered portion is taper or frustoconical.
8. photoneutron conversion target according to claim 5 is characterized in that described body also comprises barrel portion, the contiguous described the second end of described tapered portion, the contiguous described first end of described barrel portion.
9. photoneutron conversion target according to claim 4 is characterized in that, described passage extends along the target axis of symmetry of described body.
10. a photoneutron-x-ray source is used for producing photoneutron and X ray simultaneously, it is characterized in that described photoneutron-x-ray source comprises:
X ray generator is used to produce the X ray main beam;
The photoneutron conversion target, described X ray main beam can bombard this photoneutron conversion target and produce photoneutron, and the passage that this photoneutron conversion target has body and limited by this body, this passage run through described body;
Wherein, first X-ray beam in the described X ray main beam can pass this passage and not react with this body, and simultaneously, second X-ray beam in the described X ray main beam can enter in the described body, and reacts to produce photoneutron with this body.
11. photoneutron-x-ray source according to claim 10 is characterized in that, described body is the elongated body that extends along the direction of propagation of X ray main beam, and this body has first end and the second end; And
The bearing of trend of described passage is identical with the direction of propagation of described X ray main beam.
12. photoneutron-x-ray source according to claim 11 is characterized in that, the shaped design of the body of described photoneutron conversion target becomes and the intensity distributions of described X ray main beam is complementary basically.
13. photoneutron-x-ray source according to claim 12 is characterized in that, the intensity distributions of described X ray main beam is that axial symmetry distributes, and it defines an intensity distributions axis of symmetry;
The described body configuration of described photoneutron conversion target becomes to become axisymmetric shape about a target axis of symmetry, and the axial symmetry of the axisymmetric shape of described photoneutron conversion target and described X ray main beam distributes and is complementary basically.
14., it is characterized in that at least a portion of described body is a tapered portion according to claim 12 or 13 described photoneutron-x-ray sources, this tapered portion is towards described the second end convergent.
15. photoneutron-x-ray source according to claim 14 is characterized in that, described tapered portion ends at described the second end.
16. photoneutron-x-ray source according to claim 15 is characterized in that, described tapered portion is taper or frustoconical.
17. photoneutron-x-ray source according to claim 14 is characterized in that, described body also comprises barrel portion, the contiguous described the second end of described tapered portion, the contiguous described first end of described barrel portion.
18. photoneutron-x-ray source according to claim 13 is characterized in that, described passage extends along the target axis of symmetry of described body.
19. photoneutron-x-ray source according to claim 10 is characterized in that, the described X ray main beam that described x ray generator produces is the X ray pulse with characteristic frequency.
20. photoneutron-x-ray source according to claim 10 is characterized in that, described x ray generator comprises:
Electron accelerator is used to produce electron beam; With
Electric target, described this electric target of electron beam directive is to produce described X ray main beam.
21. photoneutron-x-ray source according to claim 20 is characterized in that, described electron beam is the beam pulse with characteristic frequency.
22. photoneutron-x-ray source according to claim 10 is characterized in that, also comprises x-ray collimator, described x-ray collimator is arranged to and described channel alignment, is used for described first X-ray beam collimation through described passage is the plane fladellum.
23. photoneutron-x-ray source according to claim 10 is characterized in that, also comprises neutron relfector, is used to reflect the photoneutron that moves along the direction opposite with the direction of propagation of described X ray main beam.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008201257287U CN201286192Y (en) | 2008-06-19 | 2008-06-19 | Photoneutron conversion target and photoneutron X ray source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008201257287U CN201286192Y (en) | 2008-06-19 | 2008-06-19 | Photoneutron conversion target and photoneutron X ray source |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201286192Y true CN201286192Y (en) | 2009-08-05 |
Family
ID=40951157
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNU2008201257287U Expired - Lifetime CN201286192Y (en) | 2008-06-19 | 2008-06-19 | Photoneutron conversion target and photoneutron X ray source |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201286192Y (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101330795B (en) * | 2007-06-21 | 2011-03-30 | 清华大学 | Photoneutron conversion target and photoneutron-X ray source |
| WO2011079488A1 (en) * | 2009-12-29 | 2011-07-07 | 同方威视技术股份有限公司 | Method for imaging object by menas of photoneutron transmission and detector array |
-
2008
- 2008-06-19 CN CNU2008201257287U patent/CN201286192Y/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101330795B (en) * | 2007-06-21 | 2011-03-30 | 清华大学 | Photoneutron conversion target and photoneutron-X ray source |
| WO2011079488A1 (en) * | 2009-12-29 | 2011-07-07 | 同方威视技术股份有限公司 | Method for imaging object by menas of photoneutron transmission and detector array |
| US8841627B2 (en) | 2009-12-29 | 2014-09-23 | Nuctech Company Limited | Method for imaging object using photoneutron transmission and detector arrays using the same |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101330795B (en) | Photoneutron conversion target and photoneutron-X ray source | |
| US9207195B2 (en) | High-energy X-ray-spectroscopy-based inspection system and methods to determine the atomic number of materials | |
| US7453987B1 (en) | Method and system for high energy, low radiation power X-ray imaging of the contents of a target | |
| US7405409B2 (en) | Neutron irradiative methods and systems | |
| CN101581679B (en) | Method and system for detecting special nuclear material | |
| US10816679B2 (en) | Staggered detector array for locating radioactive sources | |
| CN201286191Y (en) | Optical neutron converting target | |
| Jones et al. | Photofission-based, nuclear material detection: technology demonstration | |
| CN201286192Y (en) | Photoneutron conversion target and photoneutron X ray source | |
| CN211123312U (en) | Special nuclear material detection device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20090805 Effective date of abandoning: 20080619 |