KR100805887B1 - Automatic calibration system for measuring radioactivity sources - Google Patents

Abstract

An automatic calibration system for measuring radioactivity sources is provided to improve reliability of calibrating results represented by operation voltage and coefficient efficiency. An automatic calibration system for measuring radioactivity sources includes a detector(100), a gas supply device(110), a voltage supply device(120), a first amplifier(130), a wave height analyzer(150), a counter(160), and a control unit(170). The detector measures radioactivity of the sources. The gas supply device is connected to a gas supply pipe in the detector to supply a gas to the detector. The voltage supply device is connected to an anode ray of the detector. The first amplifier amplifies voltage signals of the anode ray and a cathode ray of the detector and outputs the signals as voltages in proportion to energy. The wave height analyzer outputs the voltage signals amplified in the first amplifier as predetermined pulses. The counter counts the pulse by being connected to the wave height analyzer. The control unit is connected to the gas supply device, the voltage supply device, the first amplifier, the wave height analyzer, and the counter respectively and controls operations thereof.

Description

Automatic calibration system for measuring radioactivity sources

1 is a cross-sectional view of the automated calibration device of the present inventors radioactivity measuring instrument,

2 is an internal cross-sectional view of a detector of the present invention;

3 is a state diagram of the movement of the source by the left and right cylinder of the source moving unit,

4 is a state of movement of the source by the upper and lower cylinder after the movement of FIG.

5 is a graph showing a counting ratio with respect to an applied voltage;

6 is a flowchart for obtaining an operating voltage;

7 shows a flowchart for obtaining counting efficiency.

<Description of the symbols for the main parts of the drawings>

10: housing 12: source support plate

20: anode wire 30: cathode wire

40: gas supply pipe 42: gas discharge pipe

50: source or sample 60: left and right cylinders

70: upper cylinder 100: detector

110: gas supply device 120: voltage supply

130: first amplifier 140: second amplifier

150: wave analyzer 160: counter

162: timer 170: control unit

The present invention relates to an automated calibration device for a radioactivity measuring instrument which automatically proceeds the entire process in measuring and analyzing and outputting an analysis content in using a reference for calibrating a radioactive source.

As a reference for calibrating a measuring instrument for radioactivity, a proportional counter is a device for measuring α and β radioactivity, and is referred to as a 2π proportional counter or a 4π proportional counter according to the shape of the detector.

As a method for calibrating a radioactivity measuring instrument using a reference instrument having a predetermined efficiency, first, the radioactivity of the calibration sample (source) of the radiometer is measured using the reference instrument. For example, if a result of producing a predetermined radioactive material and measuring its intensity is 100 Bq, the content is issued in a report in the name of the Institute of Standards and Science.

If a standard sample having a strength of 100 Bq is measured as a reference, and the measured result is 50 counts per second, then the efficiency of the reference standard will be 50%, which is also the certificate or standard of the Institute of Standards and Science. It is issued as a certificate in the name of the calibration laboratory.

The radioactivity of the radioactivity meter calibration sample is measured using a reference device that knows a predetermined measurement efficiency, and in the above example, the radioactivity of the radioactivity meter calibration sample is measured using a standard having a efficiency of 50%. If the count value, it can be seen that the actual radioactivity of the radiometer calibration sample is 400 Bq.

Through the measurement as described above it is possible to determine the actual radioactivity of the various calibration samples, it is possible to obtain the efficiency of the radiometer by comparing the sample having the value of the radioactivity with the value measured by the commonly used radiometer.

The calibration device used to calibrate the measuring instrument for radioactivity measurement, because in the process of measuring the radioactivity of the sample manually operating the replacement of the source, the flow of the counter gas, the supply of voltage, etc. Therefore, there was a problem that the accuracy of the measurement is lowered.

The present invention has been made to solve the above problems, an object of the present invention is to measure and analyze the radioactivity of a sample (source) using a reference device, the automatic calibration device of the radioactivity measuring instrument automated the whole process of outputting the results To provide.

As a means for achieving the above object, in the calibration device for calibration of the measuring instrument for radioactivity,

An apparatus for measuring radioactivity of a source, a housing 10, a cathode wire 20 penetrating the housing 10 to be connected to the outside, and a cathode ray 30 provided to form a cavity in the housing 10. A detector 100 composed of a gas supply pipe 40 and a gas discharge pipe 42;

A gas supply device 110 connected to the gas supply pipe 40 to supply gas to the detector 100;

A voltage supply unit 120 connected to the anode line 20 of the detector 100;

A first amplifier (130) for amplifying the voltage signals of the anode line (20) and the cathode line (30) of the detector (100) and outputting a voltage proportional to energy;

A crest analyzer 150 for outputting a voltage signal amplified by the first amplifier 130 in a constant pulse;

A counter (160) connected to the wave analyzer (150) to count the pulses; And

And a controller 170 connected to the gas supply device 110, the voltage supplier 120, the first amplifier 130, the wave height analyzer 150, and the counter 160 to control an operation thereof. Provided is an automated device for calibration of radiation.

A second amplifier (140) located between the first amplifier (130) and the crest analyzer (150) and amplifying the signal of the first amplifier (130) into a signal suitable for the counter (160). It is desirable to.

The controller 170 may process information on an operating voltage or counting efficiency based on the obtained data.

In addition, the control unit 170 may further include an output unit for outputting information on the operating voltage or the counting efficiency.

The housing 10 preferably further includes a door that can be opened and closed.

In addition, the door opening and closing operation unit is connected to the door to open and close the door further, and the door opening and closing operation unit is preferably controlled by the control unit 170.

A source moving unit for moving the source support plate on which the source is placed so that the source is located in the housing 10 is further included, and the source moving unit is preferably controlled by the controller 170.

In addition, the source moving unit left and right cylinder for moving the source support plate left and right; And an upper and lower cylinder configured to move the source support plate.

Hereinafter, with reference to the accompanying drawings looks at the structure of the automated calibration device of the present invention for measuring radioactivity measuring instruments and preferred embodiments using the same.

1 is a block diagram of an automated calibration apparatus of a radiation measuring instrument of the present invention, Figure 2 is a cross-sectional view showing the structure of the detector.

Hereinafter, although the detector is a hemispherical reference device, a 2π proportional counter will be described. However, the automated calibration device of the radiation measuring instrument of the present invention is not limited to the hemispherical detector.

Detector 100 for measuring the radiation of the source (sample) of the invention is provided so that the cavity is formed in the housing 10, the anode wire 20 connected to the outside through the housing 10, the housing 10 It consists of the cathode ray 30, the gas supply pipe 40 which introduces the gas used at the time of the radiation measurement of a source, and the gas discharge pipe 42.

The negative charge, which is the charge of the cathode ray 30 provided to form a cavity inside the detector 100, appears on the inner surface, the positive charge appears on the anode line 20 inside the detector, and the voltage supply to the anode line 20. High voltage is applied by 120.

The housing 10 is preferably formed to open and close the door so that the source can be placed inside the detector (100).

The door opening / closing operation unit is connected to the door to open and close the door so that the source 50 can be placed inside the detector, and is controlled by the controller 170.

The source moving unit operates the source support plate 12 such that the source 50 placed on the source support plate 12 is introduced into the detector 100 while the door of the housing 10 is open.

The source moving unit is preferably composed of the left and right cylinder 60 and the upper and lower cylinder 70, the left and right cylinder 60 is a source support plate 12 so that the source support plate 12, which the source is placed outside the detector, is located directly below the detector. To move the left and right, the upper and lower cylinder 70 is moved to the upper portion of the source support plate 12 located directly below the detector 100 by the left and right cylinder 60 to position the source inside the detector. The source moving unit is driven as described above according to the signal of the controller 170 so that the source can be placed at the inner center of the detector, and the operation of the source moving unit will be reversed when the source is replaced.

The gas supply device 110 serves to supply a counter gas in a predetermined amount through the gas supply pipe 40 connected to the inside of the detector, and is controlled by the controller 170. An inert gas, a methane gas, etc. are used as a counter gas. The counter gas serves to keep the internal environment of the detector constant before radioactivity measurement, and is supplied at a constant flow rate even during radioactivity measurement.

으로 전리작용이 일어난다. 이때 전자가 평균자유행정을 유도하는 사이에 다른 중성원자를 전리하기에 충분한 운동에너지를 얻을 수 있으므로 전자-이온쌍의 수는 급격히 증가되며, 이를 기체증폭이라고 한다. 양극선(20)에 인가되는 전압이 적당한 경우, 기체 증폭율은 대개 일정하며, 방사선에 의한 일차 이온쌍의 수와 기체증폭에 의해 발생된 최종 이온쌍의 수는 비례관계에 있게 된다.When radiation from the source passes through the counter gas, the counter gas becomes an electron-ion pair by ionization, and the electrons and ions flow in opposite directions, respectively. At this time, the electron-ion pairs are collected by the electric field caught between the electrodes to obtain an electrical signal. That is, when argon (Ar) gas is used as the counter gas,

Ionization occurs. The number of electron-ion pairs is rapidly increased because electrons can obtain sufficient kinetic energy to ionize other neutral atoms while inducing an average free stroke. This is called gas amplification. When the voltage applied to the anode line 20 is appropriate, the gas amplification rate is usually constant, and the number of primary ion pairs caused by radiation and the number of final ion pairs generated by gas amplification are in proportional relationship.

The voltage supplier 120 serves to supply a high voltage to the anode line 20 of the detector 100 and is controlled by the controller 170.

The first amplifier 130 receives and amplifies the signal obtained by collecting the electron-ion pair in the proportional counter and outputs a voltage proportional to the energy. The output value is stored in the controller 170 and applied to the crest analyzer 150. Preferably it is applied to the second amplifier 140.

The second amplifier 140 is positioned between the first amplifier 130 and the crest analyzer 150 to amplify a signal output from the first amplifier 130 into a signal suitable for the counter 160.

The crest analyzer 150 receives a Gaussian type signal having a predetermined magnitude as a voltage signal amplified by the first amplifier 130 or a voltage signal amplified through the second amplifier 140. Output in square pulse form with delay time and pulse width set by user.

The counter 160 counts the number of collected ions by using the square pulses of the wave analyzer 150 as an input, and the obtained data is stored in the controller 170.

Preferably, the timer 162 is attached to the counter 160 to set the time so that the counter counts the number of ions for a predetermined time, and is preferably controlled by the controller 170.

The controller 170 operates the door opening / closing operation unit, the source moving unit, and the gas supply device 110 to position the source at the center of the detector. In addition, the voltage supply unit 120, the first amplifier 130, the wave analyzer 150 and the counter to the numerical value applied to the counter 160 performs a function of controlling the overall. In addition, the control unit 170 serves to store data obtained in such a measurement environment as well as the above control of each means unit.

The output unit (not shown) serves to issue a report on the operating voltage and the counting efficiency processed by the radioactivity measuring instrument to be calibrated by using the automatic calibration device of the radiological measuring instrument which will be described below.

Hereinafter, referring to the accompanying drawings, a method of measuring operating voltage and counting efficiency using an automated calibration apparatus of the present invention for measuring radioactivity is as follows.

<Measuring voltage measurement>

The step of measuring the operating voltage is a step of stabilizing the calibration device by supplying power before measurement (S110), supplying the counting gas to create the internal environment of the proportional counter (S120), positioning a standard source (S130) In step S140, data for counting rate is obtained while applying voltage to increase at predetermined intervals, and operation S150 is obtained based on the obtained data.

In step S110 of stabilizing the calibration device, it is preferable to stabilize the device by supplying power to the detector for 2 to 3 hours before placing the standard source inside the detector.

Before positioning the standard source, it is preferable to provide a counter gas (S120) to create an internal environment of the detector. The counter gas is for removing air and moisture present in the detector, and simultaneously exhausts gas at a predetermined flow rate while maintaining the counter gas at a predetermined flow rate for a predetermined time.

Thereafter, in step S130 of positioning the standard source, the control unit 170 is operated to drive the door opening and closing operation unit and the source moving unit, thereby placing the standard source in the inner center of the detector.

In the step of measuring the counting rate with respect to the applied voltage (S140), the control unit 170 inputs the starting voltage, which is expected to start counting, the voltage value gradually increased, and the voltage at which the counting ends. In addition, it is desirable to set the number of measurements to measure several times for accuracy of measurement.

Thereafter, the radiation particles are detected while supplying the counter gas to obtain data on the applied voltage and the count rate. The count rate is expressed as the ratio of the number of ions counted in the counter 160 during the predetermined time in the timer 162. The obtained data may be represented as a change in counting rate with respect to an applied voltage as shown in FIG. 5. After the first flat area appears on the graph, the second stops the measurement when the flat area appears completely.

As an embodiment for measuring the operating voltage, in the step of supplying a counter gas to create an internal environment of the proportional counter, the flow rate of the counter gas is 10 cc / s to 100 cc / s, and the duration is about 10 to 20 minutes. Supply the counter gas. The starting voltage is set to 500 V, and the ending voltage is increased by 50 V step by step to be 2500 V. The measurement time of the section is 60 s, repeated five times. During the measurement, the counter gas is supplied at a constant 2 cc / s.

The counting rate according to the applied voltage of the present invention according to the measurement environment is as shown in the graph of FIG. The first flat slope is due to the alpha line, and the second flat slope is due to the alpha and beta lines.

In operation S150 of calculating the operating voltage, the operating voltage V may be obtained as shown in Equation 1 based on the obtained data.

In Equation 1, V ₁ is a voltage at the start point where the slope is first flat, and V ₂ is a voltage at the end point.

<Measurement method of counting efficiency>

Next, the method of measuring the counting efficiency is largely made by measuring the above-described series of steps while changing the source to a base radiation source, a standard source, and again a source radiation source.

First, before measuring the radioactivity of the radiation source for the base radiation, supplying power to the measuring device to stabilize (S210), supplying the counting gas to create an internal environment of the proportional counter (S220), for the base radiation to the detector Positioning the source (S230), by supplying the operating voltage (V) obtained above to the counter and supplying the counter gas to detect the radiation particles to obtain the data on the applied voltage and the counting rate (S240) _Find (m _b1 ).

After the measurement is finished, the controller 170 is operated to lower the voltage applied to the detector, and the door opening and closing operation unit and the source moving unit are operated to replace the source with a standard source. (S250) Then, S230 to S240 described above. Obtain the standard source modulus (m _S ) in the same way as (S260).

Subsequently, the controller 170 is operated again to lower the voltage applied to the detector, and the door opening and closing operation unit and the source moving unit are operated to replace the source with the base radiation source that previously measured the base radiation coefficient m _b1 . (S270)

Then, through the same process as above, the basis radiation coefficient (m _b2 ) is obtained.

From the above measured values, the actual modulus of the standard source can be calculated, and the counting efficiency can be obtained. (S290)

)은 [수학식 2]를 사용하여 산출할 수 있다.Actual yield

) Can be calculated using [Equation 2].

는 m_b1 과 m_b2의 평균값이다. Where τ represents a decomposition time,

The m _b1 And m _b2 .

In addition, the counting efficiency epsilon under predetermined measurement conditions can be calculated using Equation 3.

In the above Equation 3, A means the radioactivity of the standard source at the measurement time, and conversely, the radioactivity A may be calculated as shown in Equation 4 under a predetermined measurement condition.

Using the relationship of Equation 4, it can be used to calibrate the source, the process is the same as the measuring method of counting efficiency.

As described above, in the case of using the automated calibration device of the present inventors radioactivity measuring instrument, the entire process up to the process of measuring the radioactivity and analyzing and issuing the test report is made of an automated process, thereby facilitating the convenience of the calibration process. In addition, errors can be reduced in creating a measurement environment. Therefore, it is possible to obtain an effect that can improve the reliability in the calibration results shown by the operating voltage and counting efficiency.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be readily apparent to those skilled in the art that various other modifications and variations are possible without departing from the spirit and scope of the invention. Are all within the scope of the appended claims.

Claims (8)

In the calibration device for calibration of the measuring instrument for radioactivity, An apparatus for measuring radioactivity of a source, a housing 10, a cathode ray 20 penetrating the housing 10 to be connected to the outside, and a cathode ray 30 provided to form a cavity in the housing 10. A detector 100 composed of a gas supply pipe 40 and a gas discharge pipe 42; A gas supply device 110 connected to the gas supply pipe 40 to supply gas to the detector 100; A voltage supply unit 120 connected to the anode line 20 of the detector 100; A first amplifier (130) for amplifying the voltage signals of the anode line (20) and the cathode line (30) of the detector (100) and outputting a voltage proportional to energy; A crest analyzer 150 for outputting a voltage signal amplified by the first amplifier 130 in a constant pulse; A counter (160) connected to the wave analyzer (150) to count the pulses; And And a controller 170 connected to the gas supply device 110, the voltage supplier 120, the first amplifier 130, the wave height analyzer 150, and the counter 160 to control an operation thereof. Radioactivity calibration automation device, characterized in that. The method of claim 1, A second amplifier (140) located between the first amplifier (130) and the crest analyzer (150) and amplifying the signal of the first amplifier (130) into a signal suitable for the counter (160). Radioactivity calibration automation device, characterized in that. The method of claim 1, The control unit 170 is a radioactivity calibration automation device, characterized in that for processing information on the operating voltage or counting efficiency based on the obtained data. The method of claim 3, wherein And an output unit for outputting information on the operating voltage or the counting efficiency processed by the control unit 170. The method of claim 1, The housing (10) is a radioactive calibration automation device, characterized in that it further comprises a door that can be opened and closed. The method of claim 5, wherein And a door opening and closing operation part connected to the door to open and close the door, and The door opening and closing operation control unit for radioactivity calibration, characterized in that controlled by the control unit (170). The method of claim 1, Further comprising a source moving unit for moving the source support plate 12 in which the source is placed so that the source is located in the housing 10, and The source moving unit is a radioactive calibration automation device, characterized in that controlled by the control unit (170). The method of claim 7, wherein The source moving unit, Left and right cylinder 60 for moving the source support plate 12 left and right; And The upper and lower cylinders (70) to move the source support plate (12) Shanghai; automated device for calibration of radiation, characterized in that consisting of.

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