阅读说明：本技术 一种使用电子束改变淬灭状态的液闪测量方法 (Liquid flash measurement method for changing quenching state by using electron beam ) 是由 梁金胜 于 2019-11-21 设计创作，主要内容包括：本发明提供了一种使用电子束改变淬灭状态的测量方法,基于电子束对标准样品淬灭程度的影响,结合TDCR值原理,突破了对待测样品CMP的依赖,从TDCR值作为过渡,把标准样品的DPM和待测样品的DPM进行联系,并通过拟合度选择更优的拟合曲线,计算方法简单,该方法避免了对标准样品本身的操作,提高了测量精度。(The invention provides a measuring method for changing a quenching state by using an electron beam, which breaks through the dependence on the CMP of a sample to be measured based on the influence of the electron beam on the quenching degree of a standard sample and in combination with a TDCR value principle, takes the TDCR value as transition, connects the DPM of the standard sample with the DPM of the sample to be measured, selects a better fitting curve through the fitting degree, has a simple calculation method, avoids the operation on the standard sample and improves the measuring precision.)

1. A liquid flash measurement method for varying a degree of quenching using an electron beam, the measurement method comprising:

the method comprises the steps of firstly, establishing a quenching rule relation, placing a standard sample with known absolute decay variable DPM in unit time on a sample bearing unit, arranging an electron beam emission unit over the sample, closing the electron beam emission unit, obtaining an actual count CPM and a triple-double coincidence ratio TDCR value of the standard sample in unit time in the state through a photomultiplier, opening the electron beam emission unit, setting a voltage value V of the electron beam emission unit to an electron beam accelerating electric field, loading current I of a hot cathode, obtaining the actual count CPM and TDCR value of the standard sample in unit time in the state, changing the voltage value V of the electron beam accelerating electric field, keeping the loading current I of the hot cathode unchanged, obtaining different CPM values and TDCR values of the standard sample, obtaining at least 5 groups of data, keeping the voltage value V of the electron beam accelerating electric field unchanged, changing the loading current I of the hot cathode, obtaining different CPM values and TDCR values of the standard sample, and obtaining a plurality of groups of data;

step two, a measuring step, namely arranging a sample to be measured of unknown DPM on a sample bearing unit, keeping an electron beam emission unit closed, measuring a TDCR value and a CPM value, opening the electron beam emission unit, and respectively obtaining a plurality of groups of CPM values and TDCR value data by changing current and voltage according to the same adjusting mode of a standard sample;

step three, calculating, namely performing linear fitting on the two groups of data with the voltage and the current changed in the step one by respectively using the TDCR value and the corresponding CPM value to obtain a voltage value fitting curve and a current value fitting curve; and (3) respectively fitting the TDCR value and the CPM value of the two groups of data with the voltage and the current changed in the step (II) to calculate the fitting degree, if the fitting degree of the data obtained by changing the voltage value is high, substituting the TDCR value obtained by the sample to be detected under the condition that the electron beam emission unit is closed into the voltage value fitting curve obtained in the step (I) to obtain a corresponding CPM value, and multiplying the DPM value of the sample to be detected by the ratio of the CPM value to the CPM value of the known sample under the condition that the electron beam emission unit is closed by the DPM value of the known sample.

2. A liquid flash measurement method according to claim 1, characterized in that: the CPM values and TDCR values of the standard samples and the CPM values and TDCR values of the samples to be detected are at least about 5 groups of data.

Technical Field

The invention relates to the measurement of nuclear radiation or X-ray radiation, in particular to the measurement field of X-ray radiation, gamma-ray radiation, corpuscular radiation or cosmic radiation, in particular to the measurement of the radiation intensity of a scintillation detector of which a scintillator is liquid, and particularly relates to a liquid scintillation measurement method for changing the quenching state by using an electron beam.

Background

The liquid scintillation measurement (liquid scintillation for short) technology is an effective method for measuring low-energy beta rays developed in the early fifties of the twentieth century, and can also be used for detecting other nuclear radiation, such as alpha rays, neutrons, gamma rays and other radiation.

However, in actual measurement, because interference of various factors causes limited measurement accuracy, the main influencing factor is influence of quenching, the quenching is of various types and comprises phase quenching, ionization quenching, concentration quenching, chemical quenching, color quenching and the like, so that the counting efficiency of a sample becomes low (CPM/DPM value becomes small, CPM represents the counting rate of a liquid flash measuring instrument to the sample per minute; DPM represents the absolute decay variable of the sample per minute, and the percentage of the two is called the counting efficiency of the sample). The known quenching correction method produced by various manufacturers in the prior art mainly comprises an internal standard method, an external standard method, an efficiency tracing method and the like, wherein no matter which method is adopted, an index capable of directly or indirectly representing the counting efficiency is essentially found, the index is measurable in a physical sense, when a sample is measured, the current counting efficiency can be known through the measurable index, so that the DPM can be calculated from the CPM measured value, the internal standard method belongs to a direct representation mode, but a specially configured liquid scintillation liquid is required, the external standard method must have a group of indexes related to the quenching degree and the counting efficiency to be fitted, and the indexes are obtained how, and need to be given through radioactive sources with different quenching degrees of known activities, and the method for giving the radioactive sources with different quenching degrees in the prior art generally comprises the following steps: 1) multiple bottles of samples of different degrees of quenching of known activity; 2) a bottle of sample with known activity is obtained by adding different amounts of quenching agent into the bottle continuously to obtain samples with different quenching degrees. Therefore, the calibration methods all need a relatively complicated quenching and correcting process, the correcting process takes a lot of time before the liquid flash measuring instrument is used, and needs relatively professional operation, and the property of the standard sample is easily changed due to improper operation, so that a great error of a result is caused.

Therefore, on the basis of the prior art, a technical team of the applicant researches a measuring method of the liquid flash measuring instrument through a large amount of material resources and manpower input (actually, three available schemes are researched, the application relates to one scheme, the other two schemes are filed in another scheme, each scheme is divided into main units, and the whole device and the method are arranged).

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a measuring method of a liquid flash measuring instrument for changing the quenching degree by using an electron beam, and mainly aims to provide a liquid flash measuring method which is simple to operate and high in measuring precision.

In order to achieve the purpose, the invention is realized by the following technical scheme:

the method is realized on the basis of a liquid flash measuring instrument and comprises a sample bearing unit, a driving unit, a measuring unit and a calculation control unit; the driving unit comprises a driving motor and a rotating platform, the sample bearing unit is arranged on the rotating platform, the whole sample bearing unit and one part of the rotating platform are arranged in a shell of the measuring unit, the other part of the rotating platform and the driving motor are arranged outside the shell of the measuring unit, the driving motor is used for driving the rotating platform to rotate so as to drive the sample bearing unit to rotate, at least three photomultiplier tubes are further arranged in the shell of the measuring unit, and an electron beam emitter is arranged at the same time, when a sample is placed on the sample bearing unit, the photomultiplier tubes and the electron beam emitter can surround the sample; the calculation control unit is connected with the photomultiplier, the electron beam emitter and the driving motor and is used for controlling the electron beam emitter to emit electrons, collecting measurement signals of the photomultiplier, calculating and controlling the driving motor to drive.

Furthermore, the electron beam emission unit is a thermal emission electron gun with a high-voltage accelerating electric field, the voltage value of the high-voltage accelerating electric field is 10-80KV, the hot cathode loading current range of the electron gun is 10-100mA, the diversion coefficient is larger than 0.2, and the cathode is composed of tungsten wires.

Further, when the photomultiplier and the electron beam emitter surround the specimen, the electron beam exit of the electron beam emitting unit is at a horizontal distance of less than 50cm from the specimen container.

The measuring method of the liquid flash measuring instrument comprises the following steps:

step one, establishing a quenching rule relation, namely placing a standard sample with known absolute decay variable DPM in unit time on a sample bearing unit, closing an electron beam emission unit, obtaining an actual count CPM and a triple-double coincidence ratio TDCR value in unit time of the standard sample in the state through a photomultiplier, opening the electron beam emission unit, setting a voltage value V of the electron beam emission unit to an electron beam accelerating electric field and a hot cathode loading current I, obtaining an actual count CPM and a TDCR value in unit time of the standard sample in the state, changing the voltage value V of the electron beam accelerating electric field, keeping the hot cathode loading current I unchanged, obtaining different CPM values and TDCR values of the standard sample, obtaining at least 5 groups of data, keeping the voltage value V of the electron beam accelerating electric field unchanged, changing the hot cathode loading current I, obtaining different CPM values and TDCR values of the standard sample, acquiring at least 5 groups of data;

step two, a measuring step, namely arranging a sample to be measured with unknown DPM on a sample bearing unit, keeping an electron beam emission unit closed, measuring a TDCR value and a CPM value, opening the electron beam emission unit, and respectively obtaining CPM value and TDCR value data of more than 5 groups by changing current and voltage according to the same adjusting mode of a standard sample;

step three, calculating, namely performing linear fitting on the two groups of data with the voltage and the current changed in the step one by respectively using the TDCR value and the corresponding CPM value to obtain a voltage value fitting curve and a current value fitting curve; and (3) respectively fitting the TDCR value and the CPM value of the two groups of data with the voltage and the current changed in the step (II) to calculate the fitting degree, if the fitting degree of the data obtained by changing the voltage value is high, substituting the TDCR value obtained by the sample to be detected under the condition that the electron beam emission unit is closed into the voltage value fitting curve obtained in the step (I) to obtain a corresponding CPM value, and multiplying the DPM value of the sample to be detected by the ratio of the CPM value to the CPM value of the known sample under the condition that the electron beam emission unit is closed by the DPM value of the known sample.

Compared with the prior art, the invention has the advantages that:

1) the invention breaks through the conventional thought of the traditional design and provides a novel quenching degree correction and measurement mode, the traditional design thought is limited to the configuration of different standard quenching samples, the applicant's invention team researches how to influence the quenching degree of the standard sample through an external means based on the prior art, and the operation of the standard sample is avoided;

2) based on the influence of the electron beam on the quenching degree of the standard sample and in combination with the TDCR value principle, the method breaks through the CPM dependence on the sample to be detected, takes the TDCR value as transition, associates the DPM of the standard sample with the DPM of the sample to be detected, and is simple in calculation method;

3) the invention provides two sets of standard curve establishing modes based on different sensitivity of samples to be measured on electron beam energy and density, and although the errors of the two modes are in acceptable ranges, the invention further considers the measurement precision, selects a more applicable fitting curve by using the fitting degree, and can further improve the precision;

4) the rotatable sample platform can flexibly adjust the position of the sample as required, improves the flexibility of the system, and can carry out more sufficient influence on the quenching degree of the sample by rotating the sample when the electron gun is opened.

Drawings

Fig. 1 is a schematic structural diagram of a measuring unit and a calculation control unit of the present invention.

Fig. 2 is the whole structure of the liquid scintillation meter of the invention.

In the figure: 1. the device comprises a sample bearing unit 2, a driving unit 3, a rotating platform 4, a photomultiplier 5, an electron beam emitter 6, a measurement unit shell 7, a calculation control unit 8 and a user side.

Detailed Description

The present invention is further described with reference to the accompanying drawings, as mentioned in the background art, there are many ways to characterize the quenching degree, and how to suggest the relationship between the characterization parameters and the actual quenching degree by not changing the properties of the sample itself, such as the principle and calculation method of the TDCR value mentioned in the present invention and other commonly used characterization parameters (SCR, SIS, ESR, H value, etc.) not mentioned in the present invention are all in the prior art, the present invention takes TDCR as an example, and not only applies this value, but also other values can be applied, and DPM and CPM are fixed terms in the art and have their known meanings, and the abbreviation mentioned in the present invention is a known definition and will not be described in detail in the description of the present application.

With reference to fig. 1 and 2, the liquid flash measuring instrument of the present invention comprises a sample carrying unit (1), a driving unit (2), a measuring unit (4), and a calculation control unit (7); the driving unit (2) comprises a driving motor and a rotating platform (3), the sample bearing unit (1) is arranged on the rotating platform (3), the whole sample bearing unit (1) and one part of the rotating platform (3) are arranged in a shell (6) of the measuring unit, the other part of the rotating platform (3) and the driving motor are arranged outside the shell (6) of the measuring unit, the driving motor is used for driving the rotating platform (3) to rotate so as to drive the sample bearing unit (1) to rotate, at least three photomultiplier tubes (PM 1-PM 3) are further arranged in the shell (6) of the measuring unit, and an electron beam emitter (PFG) is also arranged, when a sample is placed on the sample bearing unit (1), the photomultiplier tubes (PM 1-PM 3) and the electron beam emitter (PFG) can surround the sample; the calculation control unit (7) is connected with the photomultiplier (PM 1-PM 3), the electron beam emitter (PFG) and the driving motor and is used for controlling the electron beam emitter to emit electrons, collecting the measurement signals of the photomultiplier, calculating and controlling the driving motor to drive.

The electron beam emission unit is a thermal emission electron gun with a high-voltage accelerating electric field, the voltage value of the high-voltage accelerating electric field is 10-80KV, the hot cathode loading current range of the electron gun is 10-100mA, the whole size is about the degree that the diversion coefficient is larger than 0.2, the cathode of the electron gun is made of tungsten wires, the electron gun does not need to be specially designed, commercially available industrial electron guns can be generally adapted, the invention is not particularly limited, and only the voltage and current ranges are met.

When the photomultiplier and the electron beam emitter surround the sample, the horizontal distance between the electron beam outlet of the electron beam emitting unit and the sample container is less than 50cm, because the shell is in normal atmosphere, the influence degree on the sample is small when the distance is larger than the distance according to experiments, the effect is not good, circuits such as amplification and conformity of the photomultiplier are also known in the prior art, and the invention does not make special requirements.

The invention also relates to a quenching correction unit of the liquid flash measuring instrument, which belongs to a part of a calculation control unit of the liquid flash measuring instrument and comprises the following components:

an electron beam emission control unit for controlling the opening and closing of the electron beam emission unit and capable of adjusting the voltage and current of the electron beam accelerating electric field;

a quenching data collection unit capable of acquiring and calculating a relevant signal value, acquiring an actual count CPM of the sample per unit time and calculating a TDCR value when the electron beam emission unit is controlled to be turned off or on;

the fitting correction unit is used for carrying out linear fitting on the CPM value and the TDCR value in the quenching data collection unit to obtain a fitting curve and calculating the fitting degree;

the logic judgment unit is used for judging the fitting degree of the CPM value and the TDCR value actually measured by the sample to be measured and selecting a corresponding fitting curve from the fitting curves of the standard sample;

and the calculating unit is used for substituting the TDCR value of the sample to be detected, which is not influenced by the electron beam emission unit, into the corresponding fitting curve to obtain a corrected CPM value, calculating the ratio of the CPM value to the CPM value of the known sample, which is not influenced by the electron beam emission unit, multiplying the DPM value of the known sample by the ratio to obtain the DPM value of the sample to be detected, and outputting the DPM value to a user.

Furthermore, the electron beam emission control unit can control the voltage value range of the high-voltage accelerating electric field to be 10-80KV, and the hot cathode loading current range of the electron gun to be 10-100 mA.

The functional units can be integrated in a computer and realized through conventional logic, calculation, storage and other units of the computer, or respectively realized through respectively setting corresponding upper computer functional units, and can be set according to specific requirements, and the two setting methods do not substantially influence the concept of the invention and are not particularly limited.

The invention also relates to a measuring method of the liquid flash measuring instrument, which comprises the following steps:

step one, establishing a quenching rule relation, namely placing a standard sample with known absolute decay variable DPM in unit time on a sample bearing unit, closing an electron beam emission unit, obtaining an actual count CPM and a triple-double coincidence ratio TDCR value in unit time of the standard sample in the state through a photomultiplier, opening the electron beam emission unit, setting a voltage value V of the electron beam emission unit to an electron beam accelerating electric field and a hot cathode loading current I, obtaining an actual count CPM and a TDCR value in unit time of the standard sample in the state, changing the voltage value V of the electron beam accelerating electric field, keeping the hot cathode loading current I unchanged, obtaining different CPM values and TDCR values of the standard sample, obtaining at least 5 groups of data, keeping the voltage value V of the electron beam accelerating electric field unchanged, changing the hot cathode loading current I, obtaining different CPM values and TDCR values of the standard sample, acquiring at least 5 groups of data;

step two, a measuring step, namely arranging a sample to be measured with unknown DPM on a sample bearing unit, keeping an electron beam emission unit closed, measuring a TDCR value and a CPM value, opening the electron beam emission unit, and respectively obtaining CPM value and TDCR value data of more than 5 groups by changing current and voltage according to the same adjusting mode of a standard sample;

step three, calculating, namely performing linear fitting on the two groups of data with the voltage and the current changed in the step one by respectively using the TDCR value and the corresponding CPM value to obtain a voltage value fitting curve and a current value fitting curve; and (3) respectively fitting the TDCR value and the CPM value of the two groups of data with the voltage and the current changed in the step (II) to calculate the fitting degree, if the fitting degree of the data obtained by changing the voltage value is high, substituting the TDCR value obtained by the sample to be detected under the condition that the electron beam emission unit is closed into the voltage value fitting curve obtained in the step (I) to obtain a corresponding CPM value, and multiplying the DPM value of the sample to be detected by the ratio of the CPM value to the CPM value of the known sample under the condition that the electron beam emission unit is closed by the DPM value of the known sample.

In order to verify the effect of the invention, the following comparison method is designed:

the comparison method is to measure the standard solution by the traditional method and the method of the invention respectively, the standard value of the used standard solution is 525700 times/minute, the standard solution is used if necessary, the standard deviation of the result obtained by measuring 10 groups of data by the traditional method is between plus or minus 0.55-0.72%, the deviation between the measured average value and the standard value is about 0.85%, the standard deviation of the method of the invention is less than 0.3%, and the deviation between the average value and the standard value is less than 0.36%.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the appended claims.