CN105759302A - System and method for uniformity measurement of large-area radioactive source - Google Patents

Abstract

The invention belongs to the technical field of radioactive measurement, and discloses a system and method for the uniformity measurement of a large-area radioactive source. The system comprises a uniformity measurer, a porous shielding body, and a fixed support. The porous shielding body is provided with a plurality of through holes for radioactive measurement, wherein the thickness of the porous shielding body is greater than the radiation range of a measured radionuclide, and the size of the porous shielding body is not less than the area of the active region of the radioactive source. The size of a probe of a semiconductor detector is matched with the size of the through holes on the porous shielding body, so the probe can carry out the measurement of alpha or beta radionuclides. The fixed support is located above the porous shielding body, and the center of the fixed support is provided with a duct, wherein the periphery of the duct is provided with a supporting baffle plate. The method can employs the system, and selects a proper measurement time for the measurement of a large-area source. The system and method are high in measurement efficiency, is good in adaptability, is low in cost, and can be used for the uniformity measurement of the radioactive source with the area being greater than 1000 square centimeters.

Description

A kind of System and method for measured for large area Uniformity of Radioactive Source

Technical field

The invention belongs to radiometry technical field, be specifically related to a kind of System and method for measured for large area Uniformity of Radioactive Source.

Background technology

The existing system and method measured for large area Uniformity of Radioactive Source has following two:

One be vertification regulation " JJG788-92 α, β standard flat source " provides for 150cm²The uniformity measurement of big surface source recommends method, and it is that to adopt pore radius be 1.36cm, area is 6cm²Band window template totally three pieces, every piece of template only opens a hole, and the position of opening of three pieces of templates is different, and the final position, hole measured is uniformly distributed on the diagonal of active region.Before measurement, plane source is placed in the detector (flow-gas proportional counter) of slin emissivity standard set-up, its active region overlying cover strip window template, by the particle counting rate that measurement window is launched, calculates the uniformity obtaining big surface source with standard deviation.Code also illustrating, the available scintillation counter through calibration replaces flow-gas proportional counter measurement, except requiring to keep template window relative to the identical geometrical condition of scintillation counter detection window, does not provide other and specifically describe.

The second is the device that Chen Zhi ability etc. describes the mounted measurement Uniformity of Radioactive Source of a kind of Medical coating, detector adopts the proportional counter windowed in side, is placed in a big shielded box with measurement bracket, and proportional counter is placed in the bottom of big shielded box, under the panel of measurement bracket, window is upwards.During measurement, radioactive source is put on the panel of measurement bracket or is put on limit bundle plate, and there is downwards individual collimator the middle position of panel.For adapting to different requirements, have the measurement bracket of 2 kinds of differing heights, be separately furnished with three blocks of limit bundle aluminium sheets, open a limit beam hole between two parties.During use, can select on demand with the suitable limit bundle plate limitting beam hole, and be covered on the panel of support.What concrete example provided is active region planar dimension is the uniformity measurements in β source of 20mm × 20mm, and during measurement, source faces down, and often surveys a point, and source is a mobile limit beam hole diametral distance on aluminum limit bundle plate, and 16 points are surveyed in each source altogether.

For first method, have a disadvantage in that when measuring with flow-gas proportional counter, owing to a hole once can only be measured, except needs more tape swapping window template, transposition measurement is required for switch panel every time, more tape swapping window template, the gas long period is to remove the electronegative gas entered in detector simultaneously, until counting rate starts formal measurement after stable equilibrium, (20～30) min is generally about needed to measure a position, 9 positions are measured by (3～4.5) consuming time h by vertification regulation requirement, and waste a large amount of argon methane gas, time-consuming, require great effort and relatively costly.This is also that active region is only 150cm²Big surface source, make 1000cm if changed²Big surface source, due to perforated area can not geometric ratio amplify, hole bit quantity certainly will be increased, measurement time, air consumption, cost etc. will be multiplied.

For second method, owing to proportional counter and measurement bracket are placed in a big shielded box, report was only used as the measurement in skin plaster device β source at that time, had no report later.The statement of this method is concrete not, do not provide overall instrumentation plan, measurement bracket and limit beam hole size do not provide yet and only illustrate that concrete example is to measure activity to be of a size of the β source of 20mm × 20mm, deduction should be the radioactive source being suitable for measuring less area, but it is measured the concrete arrangement mode of hole when position and how to position (underlapped to ensure between Kong Yukong) and also do not report.If being used for measuring active area up to 1000cm²Big surface source, the size making whole shield is become huge, operates increasingly complex.

Accordingly, it would be desirable to seek a kind of measurement efficiency height and area can be suitable for greatly to 1000cm²Uniformity of Radioactive Source measure system and method.

Summary of the invention

(1) goal of the invention

Problem existing for prior art, the invention provides and a kind of measure that efficiency is high, the suitability is good, cost is low and can be used in area greatly to 1000cm²Uniformity of Radioactive Source measure system and method.

(2) technical scheme

In order to solve the problem existing for prior art, technical scheme provided by the invention is as follows:

A kind of system measured for large area Uniformity of Radioactive Source, this system includes uniformity measurement instrument, porous shield and fixed support, wherein uniformity measurement instrument includes semiconductor detector and controller, when large area Uniformity of Radioactive Source is measured, fixed support, porous shield are covered in above large area radioactive source in accordance with the order from top to bottom；Being provided with several on described porous shield for radiometric through hole, the thickness of porous shield is more than the range of tested radionuclide, and apparent size is not less than the active area of large area radioactive source to be measured, and material is rustless steel；The probe of semiconductor detector is circular, and its size adapts with the size of the through hole of setting on porous shield, it is possible to α or β nucleic is carried out automatic or manual measurement；Fixed support is positioned at above porous shield, and its center position is provided with a duct corresponding with the through hole arranged on porous shield, and the surrounding in this duct is provided with supporting baffle, and this baffle plate plays the effect supported and to radioactive shield around.

Preferably, the radius of through hole porous shield arranged is 1cm.

Preferably, the Kong Weiwei rice font of through hole porous shield arranged.

Utilizing the method that large area Uniformity of Radioactive Source is measured by said system, the method comprises the following steps:

1) species type according to tested large area radioactive source, the gear selecting semiconductor detector is that α or β measures shelves；

2) set the time, measure the background counting rate of this semiconductor detector；

3) active area according to large area radioactive source, selects apparent size to be not less than the porous shield of this active area, is placed on radioactive source to be measured；

4) selecting a room on certain angle on porous shield is position, initial measurement hole, fixed support is placed on this position, initial measurement hole, the duct of fixed support center position is directed at this position, initial measurement hole, then semiconductor-type detector is placed on support bracket fastened duct；

5) it is set according to the intensity of radioactive source the measurement time, by the activity measurement 4～6 times of position, initial measurement hole, records measurement data；

6) unload semiconductor-type detector, fixed support is translated on porous shield, make the duct of fixed support center position be directed at the position, next hole to survey, then semiconductor-type detector is placed on fixed support, until all Location measurement is complete；

7) calculate the average counter rate under position, each hole, calculate population mean simultaneously, and according to formula $\begin{array}{c}u=\frac{1}{\stackrel{\‾}{n}}\sqrt{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\frac{{\left(n_i-\stackrel{\‾}{n}\right)}^1}{m-1}}\\ \left(m\≥9\right)\end{array}$ Calculate uniformity.

(3) beneficial effect

Homogeneity measuring systems provided by the invention and method, have the advantages that

1. utilizing little probe semiconductor detector that large area Uniformity of Radioactive Source is detected, save the switch panel needed for proportional counter, gas ventilation is until the times such as balances, and without working gas, saved cost, work efficiency significantly improves.

2. system and method is only with taking one piece of porous shield, can solve the uniformity measurement problem of large area radioactive source；And in order to reflect large area Uniformity of Radioactive Source quality, the radius of measured hole and area are contracted to 1cm and 3cm further²。

3. the application eliminates shielded box, it is possible to not by the restriction of any area.This patent gives position, concrete hole layout simultaneously, and Kong Weiyu hole is not covered with between position, when changing Location measurement every time, only need to fixed support be moved to above corresponding hole site, make alignment Kong Wei center, fixed support center, put little probe semiconductor detector, easy and simple to handle.

Accompanying drawing explanation

Fig. 1 is that the large area Uniformity of Radioactive Source that the application provides measures system schematic；Wherein 1 is semiconductor-type detector；2. connecting line；3. controller；4. fixed support；5. porous shield；6. surveyed large area radioactive source；

Fig. 2 is active region is 1000cm²Porous shielding body opening position schematic diagram.

Detailed description of the invention

Below in conjunction with detailed description of the invention and Figure of description, the present invention is further elaborated.

Embodiment

A kind of system measured for large area Uniformity of Radioactive Source, this system includes uniformity measurement instrument, porous shield 5 and fixed support 4, wherein uniformity measurement instrument includes semiconductor detector 1 and controller 3, when large area Uniformity of Radioactive Source is measured, fixed support 4, porous shield 5 are covered in above large area radioactive source in accordance with the order from top to bottom；Being provided with several on described porous shield 5 for radiometric through hole, the thickness of porous shield 5 is more than the range of tested radionuclide, and size is not less than the active area of large area radioactive source to be measured, and material is rustless steel；The probe of semiconductor detector 1 is circular, and its size adapts with the size of the through hole of setting on porous shield 5, it is possible to α or β nucleic is measured；Fixed support 4 is positioned at above porous shield 5, and its center position is provided with a duct corresponding with the through hole arranged on porous shield 5, and the surrounding in this duct is provided with supporting baffle, and this baffle plate plays the effect supported and to radioactive shield around.The radius of the through hole arranged on porous shield is 1cm.The Kong Weiwei rice font of the through hole arranged on porous shield.

Utilizing the method that large area Uniformity of Radioactive Source is measured by said system, the method comprises the following steps:

1) species type according to tested large area radioactive source, the gear selecting semiconductor detector is that α or β measures shelves；

2) set the time, measure the background counting rate of this semiconductor detector；

3) active area according to large area radioactive source, selects apparent size to be not less than the porous shield of this active area, is placed on radioactive source to be measured；

4) room selected on porous shield on certain angle is position, initial measurement hole, fixed support is placed on this position, initial measurement hole, the duct of fixed support center position is directed at this position, initial measurement hole, then semiconductor-type detector is placed on support bracket fastened duct；

5) it is set according to the intensity of radioactive source the measurement time, by the activity measurement 4～6 times of position, initial measurement hole, records measurement data；

6) unload semiconductor-type detector, fixed support is translated on porous shield, make the duct of fixed support center position be directed at the position, next hole to survey, then semiconductor-type detector is placed on fixed support, until all Location measurement is complete；

7) calculate the average counter rate under position, each hole, calculate population mean simultaneously, and according to formula $\begin{array}{c}u=\frac{1}{\stackrel{\‾}{n}}\sqrt{\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\frac{{\left(n_i-\stackrel{\‾}{n}\right)}^1}{m-1}}\\ \left(m\≥9\right)\end{array}$ Calculate uniformity.

Utilize said system and method, respectively the 300cm to preparation²、600cm²And 1000cm²The large area of three kinds of different activities district areas²⁴¹Am and⁹⁰Sr-⁹⁰Y radioactive source has carried out uniformity measurement, and concrete outcome is in Table 1, wherein to 1000cm²Its porous of large area radioactive source shielding body opening position schematic diagram as shown in Figure 2.

The large area of table 1 different activities area²⁴¹Am and⁹⁰Sr-⁹⁰The uniformity measurements in Y plane source

Claims (4)

1. the system measured for large area Uniformity of Radioactive Source, it is characterized in that, this system includes uniformity measurement instrument, porous shield and fixed support, wherein uniformity measurement instrument includes semiconductor detector and controller, when large area Uniformity of Radioactive Source is measured, fixed support, porous shield are covered in above large area radioactive source in accordance with the order from top to bottom；Being provided with several on described porous shield for radiometric through hole, the thickness of porous shield is more than the range of tested radionuclide, and apparent size is not less than the active area of large area radioactive source to be measured, and material is rustless steel；The probe of semiconductor detector is circular, and its size adapts with the size of the through hole of setting on porous shield, it is possible to α or β nucleic is carried out automatic or manual measurement；Fixed support is positioned at above porous shield, and its center position is provided with a duct corresponding with the through hole arranged on porous shield, and the surrounding in this duct is provided with supporting baffle, and this baffle plate plays the effect supported and to radioactive shield around.

2. a kind of system measured for large area Uniformity of Radioactive Source according to claim 1, it is characterised in that the radius of the through hole arranged on described porous shield is 1cm.

3. a kind of system measured for large area Uniformity of Radioactive Source according to claim 1, it is characterised in that the Kong Weiwei rice font of the through hole arranged on described porous shield.

4. utilize the method that large area Uniformity of Radioactive Source is measured by said system, it is characterised in that the method comprises the following steps:

1) species type according to tested large area radioactive source, the gear selecting semiconductor detector is that α or β measures shelves；

2) set the time, measure the background counting rate of this semiconductor detector；

3) active area according to large area radioactive source, selects apparent size to be not less than the porous shield of this active area, is placed on radioactive source to be measured；

4) selecting a room on certain angle on porous shield is position, initial measurement hole, fixed support is placed on this position, initial measurement hole, the duct of fixed support center position is directed at this position, initial measurement hole, then semiconductor-type detector is placed on support bracket fastened duct；

5) it is set according to the intensity of radioactive source the measurement time, by the activity measurement 4～6 times of position, initial measurement hole, records measurement data；

6) unload semiconductor-type detector, fixed support is translated on porous shield, make the duct of fixed support center position be directed at the position, next hole to survey, then semiconductor-type detector is placed on fixed support, until all Location measurement is complete；

7) calculate the average counter rate under position, each hole, calculate population mean simultaneously, and according to formula

Calculate uniformity.