CN102109605A - Method for measuring energy of accelerator - Google Patents
Method for measuring energy of accelerator Download PDFInfo
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- CN102109605A CN102109605A CN2009102437727A CN200910243772A CN102109605A CN 102109605 A CN102109605 A CN 102109605A CN 2009102437727 A CN2009102437727 A CN 2009102437727A CN 200910243772 A CN200910243772 A CN 200910243772A CN 102109605 A CN102109605 A CN 102109605A
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Abstract
The invention discloses a method for measuring the energy of an accelerator, comprising the following steps: a measuring step for measuring a measurement curve that an attenuation multiple of an X ray from an accelerator is changed along with the thickness of a shielding material; and a comparing step for comparing the measurement curve with a reference curve to determine the energy of the X ray from the accelerator. The method can accurately judge the actual energy of the X ray beam from the electronic accelerator. The method is not limited from the restriction condition of the accelerator, and has the characteristics of low cost, simple operation, vivid data, high precision and small error caused by artificial factor. The method is not only suitable for the quality control of the production, debugging and check of the accelerator in the nuclear technology but also capable of guiding the operator to debug the accelerator precisely.
Description
Technical field
The present invention relates to a kind of method of measuring accelerator energy, especially for the mensuration of the X ray energy of accelerator generation in the Application of Nuclear Technology field.
Background technology
In the Application of Nuclear Technology field, determine that the energy of the X-ray beam that accelerator is launched is extremely important, in the energy test of industrial accelerator, measuring method commonly used is a steel half-value layer method, that is: at present
Select a fixed position at the accelerator beam direction, the perpendicular fasciculus flow path direction is placed the steel plate of some same thickness respectively, detector is placed on the position near steel plate, the serial ratio of detector signal did not fit to curve when the signal by the detector of measured X ray after through different effectively steel plate thickness did not add any steel plate relatively, extrapolate corresponding steel plate half value thickness again by curve, half-value layer is meant that original X-ray beam dose rate decays to two/for the moment thickness of required certain material (as steel plate), compare with a cover half-value layer reference data (as the table E13 in the U.S. NCRP51 report) then, remove to judge the accelerator energy that produces X ray by comparison half-value layer value.
There are many shortcomings in said method:
1, the reference frame of judgement energy is more rough: only use half-value layer more rough as energy criterion, because same energy-ray can be hardened in shielding material, have first, a plurality of half-value layer numerical value such as when second and balance, half-value layer is not unique, but corresponding scope, therefore there is the overlapping region in the corresponding half-value layer scope of ray that is more or less the same of energy and is difficult to distinguish, and promptly the energy resolving power is undesirable.For example: when the steel half-value layer that measures was 23mm, this method was difficult to be judged as 4MV or the accelerator of 6MV.
2, this method is mainly derived from the data that provide under the medical accelerator wide beam condition as the reference data of energy judgement, for the industrial accelerator under fan-shaped narrow beam, the little launched field condition and not exclusively suitable.
3, because this method is overall more spacious, in test, strict demand is proposed parameters such as geometric layout, and in fact when detector during near shielding slab small variable in distance can will bring bigger influence to measurement result.
Summary of the invention
The purpose of this invention is to provide another kind can more accurate measurement with judge the different limit bundle conditions that electron accelerator produces under the X ray ENERGY METHOD.
According to an aspect of the present invention, the invention provides a kind of method of measuring accelerator energy, this method comprises the steps: measuring process: the attenuation multiple of the X ray that the measurement accelerator sends is with the measurement curve of shielding material variation in thickness, comparison step: the measurement curve and the reference curve that will record compare, and determine the energy of the X ray that accelerator sends thus.
This method is not subjected to accelerator limit bundle condition restriction, and cost is low, simple to operate, data are directly perceived, precision is high, the error of being brought by human factor is very little, not only can be widely used in the quality control in the production, debugging, examination of all kinds of accelerators in the Application of Nuclear Technology field, but also can the guiding work personnel carry out the accurate debugging of accelerator.
Description of drawings
Fig. 1 covers the normative reference KD curve (shielding material: steel) that snap gauge is intended 2.5～4MV accelerator of software for calculation acquisition for utilizing;
Fig. 2 is a KD curve method energy measurement method synoptic diagram;
Fig. 3 is according to KD curve method testing scheme synoptic diagram provided by the invention;
Fig. 4 is the reference KD curve of cone-beam 5.0-7.5MV accelerator according to an embodiment of the invention.
Fig. 5-9 is according to the several embodiments of the present invention measurement result.
Figure 10 is a synoptic diagram, shows the variation tendency of 3MV accelerator energy with the electron gun high voltage adjusting, and accelerator energy raises with the electron gun high pressure and reduces, and the energy variation scope is about 0.8MV.
Figure 11 is a synoptic diagram, shows the variation tendency of 3MV accelerator energy with the magnetron pulse Current Regulation, and accelerator energy raises with the magnetron pulse electric current, and the energy variation scope is about 0.3MV.
Embodiment
Following examples are used to illustrate the present invention, but are not used for limiting the scope of the invention.
The method of measuring accelerator energy according to an embodiment of the invention comprises: measuring process: the attenuation multiple of the X ray that the measurement accelerator sends is with the measurement curve of shielding material variation in thickness, and comparison step: the measurement curve and the reference curve that will record compare, and determine the energy of the X ray that accelerator sends thus.
The attenuation multiple of X ray is with the measurement curve of shielding material variation in thickness, i.e. KD curve is the attenuation multiple change curve after X ray passes through the shielding material of different-thickness.Here shielding material can comprise various inorganic and organic materials such as tungsten, steel, lead, aluminium, water, crystal.
At first calculate with covering snap gauge plan software for calculation (for example GEANT 4), it is the reference KD curve of 0.5MV that the present invention has only provided (1.0-12) MV energy bite according to application need.As shown in Figure 1, (2.5～4MV) KD curve, corresponding respectively energy are the KD attenuation characteristic of X ray in the steel shielding material of coming out by slit behind 2.5MV, 3.0MV, 3.5MV and the 4.0MV accelerator electronic target to provide the portion of energy section among Fig. 1.
Here adopt Geant4 process simulation monoenergetic electrons to practice shooting, obtain forward direction 5 degree then with interior power spectrum, as the power spectrum of each energy, the angle that obtains X ray simultaneously distributes.Wherein target material and size can be determined according to the concrete parameter of accelerator.Table 1 is pairing target material and a size in this method analog computation.
Pairing target material of the various energy of table 1 and size
| Energy (MV) | Target thickness (mm) | Target diameter (mm) | Target material |
| 1.0-1.5 | 1.0 | 5.0 | Tungsten |
| 2.0-4.0 | 2.0 | 5.0 | Tungsten |
| 4.5-12.0 | 2.5 | 5.0 | Tungsten |
(1) obtains curve with reference to KD
Set up illiteracy snap gauge type by testing scheme shown in Figure 3, analogy model comprises four parts: source item, solid structure, geometric arrangement, dosage statistics.Wherein the solid structure mainly is made up of accelerator shielding structure, steel plate and ground three parts, and its light plate thickness and variation provide according to testing scheme, and simulation ground is to consider to have concrete ground area scattering situation in the test.In the accelerator structure, the outlet shielding is the principal element that influences the result, therefore need carry out analog computation according to different outlet shielding construction models.Fig. 4 has provided the analog computation KD reference curve of 5-7.5MV conical outlet accelerator.
Being provided with of analog prober, should use detector active region size to be consistent with actual measurement, for example Unidos ionization chamber probe detection face size is: (5mm * the 20mm of W * H).The physical quantity of statistics is an energy deposition, requires the statistics photon number at least more than 1000.
(2) set up testing scheme
Set up a cover experiment test scheme, main consideration shielding steel plate size, steel plate variable thickness, relative geometry are put problems such as distance, consider that simultaneously testing scheme is simple and convenient in implementation process, the measuring error that causes is as far as possible little, guarantees that with reference to KD curve and measurement KD curve be to obtain under the same terms.Through taking all factors into consideration fully and comparing, we obtain more excellent testing scheme, as shown in Figure 3.In the scheme
■ select the length of side be square body in (20～100) cm scope as shielding steel plate 4, thickness does not wait from 0～20cm;
■ dose fluctuations monitoring detector 3, the variation of monitoring accelerator output dose is used for revising the influence of accelerator dose fluctuations to measurement result in real time; It is placed on the accelerator outlet main beam, and promptly on 0 of the X ray degree directional ray 8, in a single day the position is determined just to maintain static, and finishes until whole test job;
The layout of ■ relative geometry position also is the key factor that influences measurement result.
In the measuring process, accelerator target spot 1 and dose detector 5 position relative fixed, spacing L remains on (1.0～2.0) m scope, and guarantees that detector 5 is on the accelerating tube axis, promptly on 0 of the X ray degree directional ray 8;
The distance of the surface 9 of shielding steel plate 4 (perpendicular to the plane of the paper of Fig. 3) and dose detector 5 is greater than 20cm;
0 degree directional ray 8 of surface 9 and the X ray of shielding steel plate 4 keeps vertical, and the center line of shielding steel plate 4 (being the center line of thickness direction or the normal of surperficial 9 center) is spent directional ray 8 with 0 of X ray and overlapped;
As shown in Figure 3, during test, shielding steel plate 4 is placed on the testing jig 6, and this testing jig 6 is placed on the ground 7;
(3) test concrete grammar
The first step: do not add shielding steel plate 4, directly read the reading D of dose detector 5
0Reading D with dose fluctuations monitoring detector 3
0m
Second step: adding a thickness in distance target spot 1L-D position is d
1 Shielding steel plate 4, obtain the reading D of dose detector 5 and dose fluctuations monitoring detector 3 respectively
1And D
1m
The 3rd step: increase progressively the thickness of shielding steel plate 4 respectively, record the dose value D of one group of correspondence respectively by dose detector 5 and dose fluctuations monitoring detector 3
2, D
3, D
4And D
2m, D
3m, D
4m
The 4th step: by formula K
i=(D
0/ D
i) (D
Im/ D
0m) calculate corresponding a certain thickness d
iThe attenuation multiple K of steel plate
i, curve plotting in EXCEL table then, and provide the measuring error line, attenuation multiple K is with the change curve of steel plate thickness D as shown in Figure 2, the measurement KD curve map of promptly corresponding a certain energy accelerator.
Little in dose fluctuations, accuracy requirement is not high or satisfied actual situation about requiring under, can be without dose fluctuations monitoring detector 3, this moment K
i=D
0/ D
i
Utilize among the present invention and cover card program (as GEANT 4) when carrying out analog computation, can obtain the normative reference KD curve of corresponding certain shielding material decay of accelerator X ray of a cover different-energy fully according to accelerator geometry to be measured, shielding material, detector and this several solid positioned opposite situations; Carry out actinometry according to the geometrical solution of simulate given fully then, directly obtain one group and measure the KD data, curve plotting in EXCEL table then, and provide the measuring error line, the normative reference curve that obtains with above illiteracy card compares and simple analysis again, just can judge the actual energy of the X-ray beam that this electron accelerator launches more exactly.
Adopt the KD curve method, judge the method for accelerator energy by measuring the attenuation change characteristic (KD variation relation) of X-ray beam in shielding material that the different-energy electron accelerator launches, can be applied to the X ray energy measurement that the electron accelerator under the various limit bundle conditions is launched.This method cost is low, simple to operate, data are directly perceived, precision is high, the error of being brought by human factor is very little, not only can be widely used in the quality control in the production, debugging, examination of all kinds of accelerators in the Application of Nuclear Technology field, but also can differentiate the subtle change of accelerator energy, thereby the guiding work personnel carry out the accurate debugging of accelerator.
Shown in Fig. 5-9, adopt method provided by the invention, the narrow beam accelerator that energy is nominally 2.5MV, 3.0MV, 4.0MV, 6.0MV, 9.0MV carries out the energy test result respectively, and shielding material adopts steel plate.
Fig. 5 is that a station symbol claims 2.5MV accelerator energy measurement result, the actual 2.6MV that is judged as; Fig. 6 is that a station symbol claims 3.0MV accelerator energy measurement result, the actual 3.0MV that is judged as; Fig. 7 is that a station symbol claims 4.0MV accelerator energy measurement result, the actual 4.9MV that is judged as; Fig. 8 is that a station symbol claims 6.0MV accelerator energy measurement result, and reality only reaches 6.2MV; Fig. 9 is that a station symbol claims 9.0MV accelerator energy measurement result, the actual 9.0MV that is judged as.
Accelerator is by regulating energy and the dosage that its electron gun high pressure and magnetron pulse electric current can change its output X ray.Therefore use the inventive method and implement the variation tendency of monitoring accelerator energy, as shown in Figure 10 and Figure 11 with electron gun high pressure and magnetron pulse electric current.
Figure 10 is a synoptic diagram, shows the variation tendency of 3MV accelerator energy with the electron gun high voltage adjusting, and accelerator energy raises with the electron gun high pressure and reduces, and the energy variation scope is about 0.8MV;
Figure 11 is a synoptic diagram, shows the variation tendency of 3MV accelerator energy with the magnetron pulse Current Regulation, and accelerator energy raises with the magnetron pulse electric current, and the energy variation scope is about 0.3MV.
In the foregoing description, only having provided the 1.0-12MV energy bite as required is the reference KD curve of 0.5MV, actual in application need, covers card and can also continue the expend energy scope.Require the statistics photon number at least more than 1000 when in addition, the dosage in covering the calculating of snap gauge plan is added up.
The variation of the real-time monitoring accelerator output dose of dose fluctuations monitoring detector is used for revising the influence of accelerator dose fluctuations to measurement result; In the measuring process, it is placed on the accelerator outlet main beam, promptly on 0 of the X ray degree directional ray 8, the position is in case determine just to maintain static.
In the above-mentioned experiment test scheme, accelerator target spot and dose detector position relative fixed, spacing L can remain on 0.5～12.0m, in the scope of preferred 1.0～2.5m; Shielding steel plate outside surface can be greater than 10cm apart from dose detector.
The above results shows, measuring method of the present invention can not only simply and exactly be measured accelerator energy, as produce, debugging and the quality control checked and accepted, but also can differentiate the subtle change of accelerator energy, thereby the guiding work personnel carry out the accurate debugging of accelerator.
In the above-described embodiments, adopt illiteracy card program to obtain reference curve,, also can obtain reference curve by measuring, perhaps adopt alternate manner well known in the art to obtain reference curve with the accelerator of known parameters as selection by analog computation.
Claims (12)
1. a method of measuring accelerator energy comprises the steps:
Measuring process: measure the measurement curve of the attenuation multiple of the X ray that accelerator sends with the shielding material variation in thickness,
Comparison step: the measurement curve and the reference curve that will record compare, and determine the energy of the X ray that accelerator sends thus.
2. the method for measurement accelerator energy according to claim 1, wherein
Reference curve obtains in the following way: by utilize covering the card program X ray that the accelerator of different-energy sends is carried out analog computation, the attenuation multiple of X ray of accelerator of obtaining different-energy is with the calculated curve of shielding material variation in thickness, and this calculated curve is as reference curve.
3. the method for measurement accelerator energy according to claim 1, described measuring process comprises:
Shielding material never, promptly the thickness of shielding material is zero, beginning increases the thickness of shielding material successively, and measures the dosage of the X ray that does not have shielding material and pass the dosage of X ray of the shielding material of different-thickness.
4. the method for measurement accelerator energy according to claim 1, described measuring process comprises:
Shielding material never, the thickness that is shielding material is zero, beginning increases the thickness of shielding material successively, and measure the dosage of the X ray do not have shielding material and pass the dosage of X ray of the shielding material of different-thickness, and measure directly the dosage of the X ray that sends from accelerator simultaneously, by the dosage of the X ray that directly sends from accelerator, revise the dosage of the X ray of the shielding material that passes different-thickness that records.
5. the method for measurement accelerator energy according to claim 1, wherein shielding material is that the length of side is the plate of the general square shape in 20～100cm scope.
6. the method for measurement accelerator energy according to claim 1, wherein in measuring process, the target spot of accelerator and the spacing that is used between the dose detector of measured X roentgen dose X are 0.5～12.0m.
7. the method for measurement accelerator energy according to claim 1, wherein in measuring process, the target spot of accelerator and the spacing that is used between the dose detector of measured X roentgen dose X are 1.0～2.5m.
8. according to the method for claim 6 or 7 described measurement accelerator energies, wherein in measuring process, the spacing between described dose detector and the described shielding material is greater than 10cm.
9. according to the method for claim 6 or 7 described measurement accelerator energies, wherein in measuring process, the spacing between described dose detector and the described shielding material is greater than 20cm.
10. the method for measurement accelerator energy according to claim 1, wherein in measuring process, the dose detector that is used for the measured X roentgen dose X roughly is in 0 degree directional ray of X ray.
11. the method for measurement accelerator energy according to claim 5,0 degree directional ray almost parallel of the normal to a surface direction of wherein said plate and X ray.
12. the method for measurement accelerator energy according to claim 11, the normal of the center on the surface of wherein said plate roughly overlaps with 0 degree directional ray of X ray.
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| CN102109605B CN102109605B (en) | 2013-06-26 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103185891A (en) * | 2011-12-30 | 2013-07-03 | 同方威视技术股份有限公司 | Accurate measurement device for accelerator ray bundles |
| CN104459754A (en) * | 2014-12-18 | 2015-03-25 | 清华大学 | Online measurement method of X-ray energy of accelerator of container inspection system |
| CN112485821A (en) * | 2020-11-19 | 2021-03-12 | 上海束能辐照技术有限公司 | Method for rapidly measuring beam energy of electron accelerator |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5012498A (en) * | 1988-01-25 | 1991-04-30 | Commissariat A L'energie Atomique | X-ray tomography device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5434417A (en) * | 1993-11-05 | 1995-07-18 | The Regents Of The University Of California | High resolution energy-sensitive digital X-ray |
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2009
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5012498A (en) * | 1988-01-25 | 1991-04-30 | Commissariat A L'energie Atomique | X-ray tomography device |
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103185891A (en) * | 2011-12-30 | 2013-07-03 | 同方威视技术股份有限公司 | Accurate measurement device for accelerator ray bundles |
| CN103645494A (en) * | 2011-12-30 | 2014-03-19 | 同方威视技术股份有限公司 | Method for measuring ray beam energy of accelerator |
| CN103645494B (en) * | 2011-12-30 | 2016-04-06 | 同方威视技术股份有限公司 | Measure the method for the energy of accelerator beam |
| CN103185891B (en) * | 2011-12-30 | 2016-06-08 | 同方威视技术股份有限公司 | The accurate metering facility of accelerator bundle of rays |
| CN104459754A (en) * | 2014-12-18 | 2015-03-25 | 清华大学 | Online measurement method of X-ray energy of accelerator of container inspection system |
| US10031261B2 (en) | 2014-12-18 | 2018-07-24 | Tsinghua University | Method for measuring X-ray energy of an accelerator in an inspection system |
| CN108594285A (en) * | 2014-12-18 | 2018-09-28 | 清华大学 | A kind of On-line Measuring Method of container check system accelerator X-ray energy |
| CN112485821A (en) * | 2020-11-19 | 2021-03-12 | 上海束能辐照技术有限公司 | Method for rapidly measuring beam energy of electron accelerator |
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| CN102109605B (en) | 2013-06-26 |
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Effective date of registration: 20190320 Address after: 101500 No. 18 Garden Road, Miyun Economic Development Zone, Beijing Co-patentee after: Nuctech Company Limited Patentee after: Tongfang Weishi Technology (Beijing) Co., Ltd. Address before: 100084 Beijing city Haidian District Shuangqing Road with Party building A block 2 layer Patentee before: Nuctech Company Limited |
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