CN101666881B - Large-sized artificial nuclide plane source calibration device and gamma ray spectrometer calibration method thereof - Google Patents

Abstract

The invention provides a large-sized artificial nuclide plane source calibration device and an optimized calibration method for calibrating a machine-mounted/vehicle-mounted gamma ray spectrometer by using the device. In the device, the design that eight isosceles trapezoids are combined to form a regular hexagon plane source realizes the conversion of a limited plane source into an unlimited (saturated) plane source through gapless joint; a rigid supporting plate structure ensures the planarity of the plane source; the uniform mesh distribution on filter paper and the use of quantitative liquid filler for filling raw liquid ensure the design activity of the plane source and the uniformity of activity distribution; the sealing of the plane source by adhesive resin ensures that source spots are free from damages and the long-term stability of the activity of the plane source; and the establishment of an angle response model provides a feasible technical evidence for the reduction of detection workload in a follow-up detection process, and the calibration method can be used to calculate a calibration factor when no obvious change occurs in the angle response model.

Description

The method of large-sized artificial nucleic plane source calibrating installation and calibration gamma energy spectrometer thereof

Technical field

The present invention relates to nuclear and radiation environment monitoring and metering field, be specifically related to a kind of artificial nucleic plane source calibrating installation.

Background technology

The collimation technique method of airborne/large-scale gamma energy spectrometer monitoring artificial radionuclide such as vehicle-mounted, because of nature can't find natural calibration field, how use in the past some source calibrations and (or) " compare at the scene afterwards " carry out calibrating mode.After having an accident such as USSR (Union of Soviet Socialist Republics) Chernobyl Plant in 1986, when Sweden uses airborne mode (aerial survey) and carries out emergency monitoring in the scope of native country, promptly adopted the calibration steps of on-the-spot comparison that airborne gamma energy spectrometer is calibrated.

Point source calibration large-scale gamma energy spectrometer is only applicable to load the object that the loading body of energy spectrometer can hover aloft, like helicopter.For fixed wing aircrafts such as China Y12 commonly used, Y5, the relative detector area of the terrain clearance when parking state on ground is too little, and the homogeneity of the radiation field that the gamma-rays of radioactive point source radiation forms is difficult to satisfy the physical dimension of big detector.There is significant angular response in large-scale NaI (T1) detector to gamma-rays; Closely there is significant difference in point source to the angle distribution contribution of large-scale NaI (T1) detector and the plane angle distribution contribution of artificial radionuclide of actual monitoring, and the uncertainty of calibration result is restive.

On-the-spot comparison calibration is only applicable to the emergency monitoring after nuclear accident has taken place.Can not satisfy the prior calibration requirements of daily monitoring and emergency monitoring.

Summary of the invention

The object of the present invention is to provide even, the permanent stable large-sized artificial nucleic plane source calibrating installation of a kind of radioactivity, and use this device and calibrate the optimization calibration steps of airborne/vehicle-mounted gamma energy spectrometer, thereby reduced follow-up calibration operation amount.

Its summary of the invention is following:

A kind of large-sized artificial nucleic plane source calibrating installation; Comprise movably flat bogie and be tiled in the plane source above the dolly; It is characterized in that: plane source is that 60 ° isosceles trapezoid facet source is spliced by 8 base angles; Each isosceles trapezoid facet source comprises that the edge is provided with the supporting plate of barrier structure, is stained with the filter paper of the source liquid that instiled on the supporting plate, and the filter paper upper strata encapsulates with tackifying resin.

A kind of above-mentioned large-sized artificial nucleic plane source calibrating installation, wherein, described isosceles trapezoid facet source adopts following steps to be made:

(1) using rigid material to be processed into base angle that the edge has a barrier structure is 60 ° isosceles trapezoid supporting plate;

(2) on isosceles trapezoid filter paper, draw grid;

(3) filter paper is cut into the shape that is complementary with the thermoplastic instrument;

(4) use dropping source liquid on the filter paper of control amount charger after cutting out;

(5) treat that filter paper dries after, stick thermoplastic envelope film, carry out the thermoplastic envelope, form the source sheet;

(6) in advance splint upper surface is coated with one deck thinly with tackifying resin again, the source sheet is bonded on the supporting plate, after the drying, on the sheet of source, pour into a mould tackifying resin, dry naturally.

A kind of optimization calibration steps of using the airborne/vehicle-mounted gamma energy spectrometer of above-mentioned large-sized artificial nucleic plane source calibration is characterized in that this method adopts following steps to carry out successively:

(1) on the level ground, draw one with onesize just hexagonal of the described plane source of claim 1, draw onesize regular hexagon, formation first lap regular hexagon respectively while being with six of this regular hexagons; In that with the polygonal outer side edges of new formation to be that the limit is drawn respectively onesize just hexagonal, form the second circle regular hexagon, draw successively, till meeting the demands;

(2) the large-sized artificial nucleic plane source calibrating installation described in the claim 1 is moved to respectively on the regular hexagon position of each drafting, write down respectively gamma energy spectrometer to plane source in each locational response count rate;

(3) according to accumulated counts rate computing formula

$N_{\mathrm{cn}}=N_{00}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=0}{\overset{6n-1}{\mathrm{\Σ}}}{N}_{\mathrm{ij}}=N_{00}+6\·\underset{i=1}{\overset{n}{\mathrm{\Σ}}}n\·\stackrel{\‾}{N_i}$

Calculate the measured count rates sum N of plane source contribution within each circle _Cn, wherein, N ₀₀Be the gamma energy spectrometer counting rate that high h place produces on the perpendicular line of crossing large-scale plane source center, N _IjBe the counting rate of plane source in i circle j position generation, Average counter rate for each plane source generation of i circle;

(4) be ordinate with

; The blade diameter length ratio of every circle is to mark a little on the coordinate system of horizontal ordinate; Carry out the Trendline match, utilize least square method to obtain average counter rate function curve

$\stackrel{\‾}{N_i}=B\·X_i^C$

Wherein, B and C are fitting coefficient, X _iBe blade diameter length ratio;

(5) according to formula

$N_{\mathrm{mn}}=N_{00}+\underset{j=0}{\overset{5}{\mathrm{\Σ}}}{N}_{1j}+6\·N_{00}\·\underset{i=2}{\overset{n}{\mathrm{\Σ}}}i\·B{\·X}_i^C$

Prediction draws the counting rate sum N of plane source contribution on each calibrating point position within the n circle _Mn, wherein, N _1jBe the counting rate that gamma energy spectrometer produces the 1st each plane source of circle, X _iBe blade diameter length ratio;

(6) calculate relative deviation $\mathrm{\δ}=\frac{N_{\mathrm{Mn}}-N_{\mathrm{Cn}}}{N_{c\mathrm{Max}}}\×100\%,$ Wherein, N _CmaxThe counting rate sum that on all plane sources within the great circle, produces for gamma energy spectrometer.

Remarkable result of the present invention is: be combined to form the design of regular hexagon plane source by 8 isosceles trapezoids, can realize that the finite plane source converts unlimited (saturated) plane source into through the splicing of no gap; The structure that can large-scale plane source be regarded as a circle circle, thus the optimization calibration steps of using among the present invention carries out the calibration of airborne/vehicle-mounted gamma energy spectrometer; The rigid tray structure has guaranteed the planarity of plane source; On filter paper, evenly arrange net, use control amount charger to drip source liquid, guaranteed the design activity of plane source and the homogeneity that activity distributes; Plane source has guaranteed the injury-free permanent stability with the plane source radiation activity of source spot with tackifying resin sealing; Set up the angular response model, feasible technical basis is provided, and when the angular response model does not have significant change, can utilize this calibration steps to calculate calibration factor for reducing the calibration operation amount in the follow-up verification process.

Description of drawings

Fig. 1 large-sized artificial nucleic plane source calibrating installation structural representation;

Fig. 2 plane source structural representation;

Fig. 3 supporting plate vertical view (a) and side view (b);

Fig. 4 filter paper piecemeal synoptic diagram;

Fig. 5 detector and face source relative position synoptic diagram;

Fig. 6 draws plane source shift position synoptic diagram;

Fig. 7 ¹³⁷The Cs plane source is examined and determine the angular response matched curve of airborne GRS16 gamma spectrometer.

Among the figure: 1. isosceles trapezoid plane source 2. flat bogies 3. universal wheels 4. tackifying resins 5. filter paper 6. supporting plates 7. regular hexagon plane sources 8. cabins 9. gamma energy spectrometers.

Embodiment

As depicted in figs. 1 and 2; A kind of large-sized artificial nucleic plane source calibrating installation; Comprise movably flat bogie and be tiled in the plane source above the dolly, it is characterized in that: plane source is that 60 ° isosceles trapezoid facet source is spliced by 8 base angles, and each isosceles trapezoid facet source comprises that the edge has barrier rib structure supporting plate; Be stained with the filter paper of the source liquid that instiled on the supporting plate, the filter paper upper strata encapsulates with tackifying resin.

Wherein the concrete manufacture craft of plane source is following:

As shown in Figure 3, can rigidity aluminium alloy supporting plate be processed into the base angle is that 60 ° upper base is 500mm, goes to the bottom to 1000mm, highly be the isosceles trapezoid supporting plate of 433mm, and the supporting plate base thickness can be 8mm, and the edge can be provided with and widely be the barrier rib of 6mm for 5mm, height;

Can evenly draw square net at the filter paper of three A3 breadths; Mesh shape can also be shapes such as rectangle, parallelogram; The foursquare grid length of side can be 5mm, 8mm or 10mm etc.; The shape of planning grid, size can guarantee that the homogeneity of plane source gets final product in a word, the filter paper of the good grid of cloth are cut to the rectangle of 420mm * 245mm; Diagonal angle wherein separately, in order to all the other two piece together an isosceles trapezoid filter paper, as shown in Figure 4; Repeat above step and prepare 8 whole filter paper that isosceles trapezoid is required;

With ¹³⁷The Cs plane source with ⁶⁰The Co plane source is an example, as ¹³⁷The activity concentration of Cs source liquid is 118.3kBq/g, ⁶⁰The activity concentration of Co source liquid is 269.0kBq/g, and the source liquid acidity can be 0.1mol/L, ¹³⁷Cs source liquid can drip with the micropipet examination, ⁶⁰Co source liquid can try to drip with the plastics kettle of weighing, and calculates the average weight of every source liquid and every source liquid forms the source spot on filter paper average area, prepares needed source liquid according to result of calculation, ¹³⁷Cs source liquid can use each point of micropipet to drip about 33 μ L solution, ⁶⁰Co source liquid can be with each the drop 13mg solution of plastics kettle of weighing, 1 grid a source liquid that instils at interval on filter paper;

After treating that filter paper dries, stick thermoplastic envelope film, end liner filter paper is carried out thermoplastic envelope formation source sheet, thermoplastic envelope film hem width is 5mm, and promptly the source sheet is than the big 5mm in filter paper edge;

Available epoxy is coated with one deck with the aluminium alloy splint upper surface in advance thinly from the plane of flow lacquer, and the source sheet is bonded on the supporting plate, and the epoxy resin of going up thick about 5mm more in the above coats with lacquer from plane of flow, dries naturally.

The optimization calibration steps of the airborne/vehicle-mounted gamma energy spectrometer of the artificial nucleic plane source of a kind of Application of Large calibrating installation calibration, our ratio juris is to set up airborne/vehicle-mounted gamma spectrometer to artificial nucleic ¹³⁷Cs with ⁶⁰The angular response of Co, promptly counting rate is with the mathematical model of blade diameter length ratio variation: Y=AX ^B, wherein, A, B are fitting coefficient; In follow-up calibrating; Take out an inspection and confirm that if angular response meets the represented Changing Pattern of this mathematical model, the illustrative system angular response does not have marked change; Can carry out the accumulated counts rate according to the angular response that the calibrating data referencing of central point and first lap is examined and determine first and calculate, and then calculate calibration factor.

As shown in Figure 5; The detector geometric center is calibrating height h to the vertical distance on ground; The plane source geometric center is the calibrating radius r to the horizontal range of detector geometric center; Definition blade diameter length ratio X is the ratio of r and h, and the definition gamma energy spectrometer is that gamma energy spectrometer is the ratio of 0 o'clock response count rate to the response count rate of plane source on the X blade diameter length ratio with X to the counting rate Y of plane source, and Y is called angular response with the variation of X.Gamma energy spectrometer is gone up omnibearing average response can be used mathematical model with the variation of search angle power (Y=AX to different search angles (blade diameter length ratio) ^B) rule simulates, the response trend of each energy window (the full energy peak counting rate of gamma-rays characteristic peak) consistent (seeing table 1), i.e. the average angle of different search angles response has good rule.This simplifies for examining and determine a position through the angular response rule of calibrating first in the follow-up calibrating, saves the calibration operation amount and lays a good foundation.

The practical implementation step of this method is following:

(1) as shown in Figure 6; On the level ground, draw one with onesize just hexagonal of plane source, draw onesize regular hexagon with six of this regular hexagons respectively while being, form the first lap regular hexagon; It is onesize just hexagonal to be with the polygonal outer side edges of new formation that the limit is drawn respectively; Form the second circle regular hexagon, draw successively, can draw 8 circle regular hexagons (general 8 enclose the source effect that can reach capacity);

(2) above-mentioned large-sized artificial nucleic plane source calibrating installation is moved to respectively on the regular hexagon position of each drafting, write down respectively gamma energy spectrometer to plane source in each locational response count rate;

(3) according to accumulated counts rate computing formula

$N_{\mathrm{cn}}=N_{00}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=0}{\overset{6n-1}{\mathrm{\Σ}}}{N}_{\mathrm{ij}}=N_{00}+6\·\underset{i=1}{\overset{n}{\mathrm{\Σ}}}n\·\stackrel{\‾}{N_i}$

Calculate the measured count rates sum N of plane source contribution within each circle _Cn, wherein, N ₀₀Be the gamma energy spectrometer counting rate that high h place produces on the perpendicular line of crossing large-scale plane source center, N _IjBe the counting rate of plane source in i circle j position generation, It is the average counter rate that each plane source of i circle produces;

(4) be ordinate with

; The blade diameter length ratio of every circle is to mark a little on the coordinate system of horizontal ordinate; Carry out the Trendline match, utilize least square method to obtain average counter rate function curve

${\stackrel{\‾}{N}}_i=B\·X_i^C$

Wherein, B and C are fitting coefficient, X _iBe blade diameter length ratio;

(5) according to formula

$N_{\mathrm{mn}}=N_{00}+\underset{j=0}{\overset{5}{\mathrm{\Σ}}}{N}_{1j}+6\·N_{00}\·\underset{i=2}{\overset{n}{\mathrm{\Σ}}}i\·B{\·X}_i^C$

Prediction draws the counting rate sum N of plane source contribution on each calibrating point position within the n circle _Mn, wherein, N _1jBe the counting rate that gamma energy spectrometer produces the 1st each plane source of circle, X _iBe blade diameter length ratio;

(6) calculate relative deviation $\mathrm{\δ}=\frac{N_{\mathrm{Mn}}-N_{\mathrm{Cn}}}{N_{c\mathrm{Max}}}\×100\%,$ Wherein, N _CmaxThe counting rate sum that on all plane sources within the great circle, produces for gamma energy spectrometer.

Table 1 is that airborne GRS16 gamma spectrometer is right ¹³⁷Cs plane source and characteristic electron-volt are 1.1732MeV and 1.3325MeV's ⁶⁰The Co plane source is measured data and the contrast of angular response analog computation data under the Different Diameter height ratio.

Claims (1)

1. the optimization calibration steps of the airborne/vehicle-mounted gamma energy spectrometer of the artificial nucleic plane source calibration of an Application of Large; It is characterized in that: the large-sized artificial nucleic plane source calibrating installation that this method adopts comprises movably flat bogie and is tiled in the large-sized artificial nucleic plane source above the dolly; Said plane source is that 60 ° isosceles trapezoid facet source is spliced by 8 base angles; Each isosceles trapezoid facet source comprises that the edge is provided with the supporting plate of barrier structure; Be stained with the filter paper of the source liquid that instiled on the supporting plate, the filter paper upper strata encapsulates with tackifying resin;

This method adopts following steps to carry out successively:

(1) on the level ground, draw one with the onesize regular hexagon of said large-sized artificial nucleic plane source, draw onesize regular hexagon, formation first lap regular hexagon respectively while being with six of this regular hexagons; Be that onesize regular hexagon is drawn on the limit respectively with the orthohexagonal outer side edges of first lap again, form the second circle regular hexagon, draw successively, form the 8th circle regular hexagon until drawing;

(2) said large-sized artificial nucleic plane source calibrating installation is moved to respectively on the regular hexagon position of each drafting, write down respectively gamma energy spectrometer to said large-sized artificial nucleic plane source in each locational response count rate;

(3) according to accumulated counts rate computing formula

$N_{\mathrm{cn}}=N_{00}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\underset{j=0}{\overset{6n-1}{\mathrm{\Σ}}}{N}_{\mathrm{ij}}=N_{00}+6\·\underset{i=1}{\overset{n}{\mathrm{\Σ}}}n\·\stackrel{\‾}{N_i}$

Calculate the measured count rates sum N of said large-sized artificial nucleic plane source contribution within each circle _Cn, wherein, N ₀₀Be the gamma energy spectrometer counting rate that high h place produces on the perpendicular line of crossing said large-sized artificial nucleic plane source center, N _IjBe the counting rate of large-sized artificial nucleic plane source in i circle j position generation,

Average counter rate for each large-sized artificial nucleic plane source generation of i circle;

(4) be ordinate with

; The blade diameter length ratio of every circle is to mark a little on the coordinate system of horizontal ordinate; Carry out the Trendline match, utilize least square method to obtain average counter rate function curve

$\stackrel{\‾}{N_i}=B\·X_i^C$

Wherein, B and C are fitting coefficient, X _iBe blade diameter length ratio;

(5) according to formula

$N_{\mathrm{mn}}=N_{00}+\underset{j=0}{\overset{5}{\mathrm{\Σ}}}{N}_{1j}+6\·N_{00}\·\underset{i=2}{\overset{n}{\mathrm{\Σ}}}i\·B\·X_i^C$

Prediction draws the counting rate sum N of said large-sized artificial nucleic plane source contribution on each calibrating point position within the n circle _Mn, wherein, N _1jBe the counting rate that gamma energy spectrometer produces the 1st each large-sized artificial nucleic plane source of circle, X _iBe blade diameter length ratio;

(6) calculate relative deviation

Wherein, N _CmaxThe counting rate sum that on all large-sized artificial nucleic plane sources within the great circle, produces for gamma energy spectrometer.

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