CN117607941A - Energy spectrum-dose conversion method based on digital multichannel spectrometer - Google Patents
Energy spectrum-dose conversion method based on digital multichannel spectrometer Download PDFInfo
- Publication number
- CN117607941A CN117607941A CN202311603040.0A CN202311603040A CN117607941A CN 117607941 A CN117607941 A CN 117607941A CN 202311603040 A CN202311603040 A CN 202311603040A CN 117607941 A CN117607941 A CN 117607941A
- Authority
- CN
- China
- Prior art keywords
- rate
- energy spectrum
- dose
- spec
- count rate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000001228 spectrum Methods 0.000 title claims abstract description 83
- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 17
- 238000005259 measurement Methods 0.000 claims abstract description 14
- 238000012937 correction Methods 0.000 claims abstract description 13
- 238000004364 calculation method Methods 0.000 claims abstract description 9
- 238000010521 absorption reaction Methods 0.000 claims abstract description 7
- HJBWJAPEBGSQPR-UHFFFAOYSA-N DMCA Natural products COC1=CC=C(C=CC(O)=O)C=C1OC HJBWJAPEBGSQPR-UHFFFAOYSA-N 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 4
- 238000004458 analytical method Methods 0.000 description 5
- 230000005855 radiation Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000001550 time effect Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 239000002689 soil Substances 0.000 description 2
- 229910014323 Lanthanum(III) bromide Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000005251 gamma ray Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- XKUYOJZZLGFZTC-UHFFFAOYSA-K lanthanum(iii) bromide Chemical compound Br[La](Br)Br XKUYOJZZLGFZTC-UHFFFAOYSA-K 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000010183 spectrum analysis Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/36—Measuring spectral distribution of X-rays or of nuclear radiation spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T7/00—Details of radiation-measuring instruments
- G01T7/005—Details of radiation-measuring instruments calibration techniques
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- High Energy & Nuclear Physics (AREA)
- Molecular Biology (AREA)
- Measurement Of Radiation (AREA)
Abstract
The invention discloses an energy spectrum-dose conversion method based on a digital multichannel spectrometer, which comprises the following steps: 1) Collecting gamma energy spectrum of radionuclide, the collected energy spectrum is Spec out The corresponding output count rate is N; 2) Calculation of the Spectrum Spec out An output count rate N of (2); 3) According to the energy spectrum Spec out And an output count rate N for the input energy spectrum Spec in Performing correction calculation to obtain an approximate spectrum Spec 'of the input energy spectrum' in : 4) According to the approximate energy spectrum Spec' in And combining an energy spectrum-dose conversion model, and calculating to obtain the air absorption dose D. The invention can correct the counting rate loss generated by gamma energy spectrum and improve the accuracy of dose rate measurement.
Description
Technical Field
The invention relates to the field of gamma energy spectrum analysis of nuclear detection technology, in particular to an energy spectrum-dose conversion method based on a digital multichannel spectrometer.
Background
A digital multichannel spectrometer (Digital Multichannel Analyzer, DMCA) can be used to evaluate radiation pollution in the environment and calculate the air gamma absorption dose rate. The currently common dose rate measurement methods include a total count rate method, a Beck formula method, an energy spectrum-dose conversion method and the like; among these methods, the total count rate method is to calculate the dose rate by adding counts in the full spectral range, and the method has the energy response problem; the Beck formula method is to convert the activity concentration of U, th and K in the soil or rock into the air absorption dosage rate at the position 1 meter away from the ground, the method does not consider the nuclide distribution state in the soil, and the measurement accuracy is limited; according to the energy spectrum-dose conversion method, different dose rate conversion weights are given to the counts corresponding to each channel address of the gamma energy spectrum by introducing a G (E) function, and then the counts and the weights are subjected to weighted integration to obtain the air absorption dose rate, so that the problem caused by energy response of a spectrometer system can be solved, and the gamma dose rate can be accurately calculated.
Due to the electronic nature of the spectrometer system, it takes time to process the nuclear radiation events generated by the detection system, when the dose rate is too high, the intensity of the incoming radiation to the detector becomes high, and a large number of nuclear radiation events are generated in a short time, and the situation that the current pulse is not processed but the subsequent pulse has arrived, resulting in that the subsequent pulse is not processed, is called dead time effect. Due to the influence of dead time, the actual counting rate of the detector can generate a certain loss, the counting rate loss can reduce the counting of each channel of the acquired energy spectrum, so that the error in the calculation of the dosage rate is smaller, the application of the energy spectrum-dosage conversion method in the aspect of dosage rate measurement has a certain limitation, and therefore the counting rate loss generated by the gamma energy spectrum must be corrected, and the accuracy of dosage rate measurement is improved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide an energy spectrum-dose conversion method based on a digital multichannel spectrometer, which can correct the counting rate loss generated by gamma energy spectrum and improve the accuracy of dose rate measurement.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows: a method for energy spectrum-dose conversion based on a digital multichannel spectrometer, comprising the steps of:
1) The gamma energy spectrum of the radionuclide is acquired through a DMCA system, and the energy spectrum acquired at any time t is recorded as Spec out ,Spec out ＝{y 1 ,y 2 ,...y n -the corresponding output count rate is N;
2) Calculation of the Spectrum Spec out Output count rate N of (2):
3) According to the energy spectrum Spec out And an output count rate N for the input energy spectrum Spec in Performing correction calculation to obtain an approximate spectrum Spec 'of the input energy spectrum' in ：
Wherein: w (-Nτ) is the Lambert W function, τ is the dead time of a single pulse generation;
4) According to the approximate energy spectrum Spec' in Combining an energy spectrum-dose conversion model, and calculating to obtain an air absorption dose D:
wherein: n (E) is the input gamma energy spectrum, i.e. Spec' in The method comprises the steps of carrying out a first treatment on the surface of the G (E) is a dose rate weight of the address count corresponding to energy E, wherein:
wherein: k is the highest polynomial, A k Is the coefficient corresponding to the kth term of the polynomial.
Further, in step 3), the approximate energy spectrum Spec' in The correction process of (2) is as follows:
1) Respectively selecting the dose rate calibrated 60 Co and Co 137 Cs two radionuclides;
2) Respectively at 10 mu Gy.h -1 、30μGy·h -1 、50μGy·h -1 、80μGy·h -1 、100μGy·h -1 、300μGy·h -1 、500μGy·h -1 、800μGy·h -1 、1mGy·h -1 、2mGy·h -1 And 3 mGy.h -1 The energy spectrum is acquired for 1 minute under the standard dose rate point to obtain the corresponding actual measurement count rate N of the slow forming channel S Measured count rate N of rapid prototyping channel F ；
3) According to the actual measurement count rate N of the rapid forming channel F Calculating to obtain an input counting rate M:then calculating according to the input counting rate to obtain the corresponding energy spectrum correction coefficient +.>
4) By using the method that the dosage rate is 10 mu Gy.h -1 Measured count rate n of fast forming channel at F Deriving an ideal count rate M' at the remaining dose rate points;
5) Separately calculate 137 662keV of Cs and 60 the actual net count rate x of the corresponding characteristic peak of 1332keV of Co at each dose rate point is calculated by using an energy spectrum correction coefficient to obtain the actual net count rate x' =alpha x of the characteristic peak;
6) By using the method at the dose rate of 10 mu Gy.h -1 The measured net count rate at that point derives the ideal net count rate at the remaining dose rate points.
Compared with the prior art, the invention has the following advantages:
1. according to the invention, the analysis function of the input counting rate relative to the output counting rate is given by researching the dead time generation mode of the DMCA system, and the analysis function is utilized to correct the gamma and G (E) function, so that the dose rate error caused by the dead time effect is effectively overcome.
2. The method can lead the spectrometer system to have the dose rate of less than or equal to 2 mGy.h -1 In the range, the corrected energy spectrum input counting rate is consistent with the change trend of the ideal input counting rate along with the dosage rate, the relative inherent error of the dosage rate can be controlled within 9%, the counting rate loss generated by gamma energy spectrum can be corrected, and the accuracy of dosage rate measurement is improved.
Drawings
FIG. 1 is a schematic diagram of a conventional gas turbine 137 A change trend graph of the actual measured net count rate, the actual net count rate and the ideal net count rate of the characteristic peaks of the Cs nuclides with the dosage rate;
FIG. 2 is a schematic diagram of a conventional device 60 Actual measured net count rate, true net count rate and ideal net count rate of characteristic peaks of Co nuclides with dose rate.
Detailed Description
The invention will be further described with reference to the drawings and examples.
Examples: an energy spectrum-dose conversion method based on a digital multichannel spectrometer comprises the following steps:
1) The gamma energy spectrum of the radionuclide is acquired through a DMCA system, and the energy spectrum acquired at any time t is recorded as Spec out ,Specout＝{y 1 ,y 2 ,.. Yn, the corresponding output count rate is N.
The counting rate (called as "real counting rate") of the input spectrometer system is influenced by dead time, so that a certain degree of counting rate loss exists in the actually output counting rate (called as "actually measured counting rate"), and each channel of the gamma energy spectrum is smaller than the actually measured counting rate. The dead time formula for the DMCA system is as follows:
N＝Me -Mτ ；
wherein: n is the measured count rate, M is the true count rate, τ is the dead time generated by a single pulse, typically the rise time plus the plateau time in trapezoidal shaping.
Performing equivalent transformation on the dead time model formula to obtain a multi-value relation of the real counting rate with respect to the actual counting rate:
wherein W (-nτ) is a Lambert W function, and the corresponding function value can be calculated by common simulation software such as Matlab.
2) Calculation of the Spectrum Spec out Output count rate N of (2):
3) According to the energy spectrum Spec out And an output count rate N for the input energy spectrum Spec in Performing correction calculation to obtain an approximate spectrum Spec 'of the input energy spectrum' in ：
In order to study the rule of counting rate loss distribution generated by the influence of the dose rate on each channel site in the gamma energy spectrum, the dose rate calibrated method is selected 137 Cs、 60 Co two radionuclides, equipped with 3.81cm x 3.81cm LaBr3 (Ce) detector and 1024 channels, each at standard dose rate of 5. Mu. Gy.h -1 、30μGy·h -1 、50μGy·h -1 、80μGy·h -1 、100μGy·h -1 、300μGy·h -1 、500μGy·h -1 、800μGy·h -1 1 minute spectra were acquired at each measurement point of (c).
Due to the radionuclide chosen for the experiment 137 Cs and Cs 60 Co characteristic gamma-ray energy is concentrated in 1.5MeV, in order to avoid the influence of large statistical fluctuation on experimental analysis in single site counting, the first 500 tracks of the 1024 tracks of energy spectrum corresponding to each dose rate point are divided into 5 tracks according to each 100 tracks, and then the proportion of the integral counting rate of each track to the total counting rate of the whole spectrum is calculated.
From the above experiment, under the condition of the same radionuclide, the input energy spectrum of any time t is recorded as Spec because the counting rate of each energy spectrum is irrelevant to the energy spectrum acquisition time in ＝{x 1 ,x 2 ,...x n -the corresponding input count rate is M; the output spectrum is recorded as Spec out ＝{y 1 ,y 2 ,...y n -the corresponding output count rate is N; there is a case where the number of the group,wherein: n represents the number of addresses, x i 、y i A count (1.ltoreq.i.ltoreq.n) representing the ith lane; thus:
then there are:
the method comprises the following steps:
wherein: w (-Nτ) is a Lambert W function, τ is the dead time of a single pulse generation.
4) According to the approximate energy spectrum Spec' in Combining an energy spectrum-dose conversion model, and calculating to obtain an air absorption dose D:
wherein: n (E) is the input gamma energy spectrum, i.e. Spec' in The method comprises the steps of carrying out a first treatment on the surface of the G (E) is a dose rate weight of the track address count corresponding to energy E, and the G (E) function is: and forming a gamma energy spectrum on the spectrometer system for the characteristic gamma rays with certain fixed dose rate, wherein the gamma dose rate value corresponding to one count of each energy spectrum is used as a G (E) function value of the track. Multiplying the counting rate of each channel of the gamma energy spectrum by the corresponding G (E) function value, and adding the results of each channel to obtain the gamma dose rate value of the measuring point. Wherein:
wherein: k is the highest polynomial, A k Is the coefficient corresponding to the kth term of the polynomial.
As an example, referring to FIGS. 1 and 2, the approximate energy spectrum Spec 'in the present method' in The correction process of (2) is as follows:
1) Respectively selecting the dose rate calibrated 60 Co and Co 137 Cs two radionuclides;
2) Respectively at 10 mu Gy.h -1 、30μGy·h -1 、50μGy·h -1 、80μGy·h -1 、100μGy·h -1 、300μGy·h -1 、500μGy·h -1 、800μGy·h -1 、1mGy·h -1 、2mGy·h -1 And 3 mGy.h -1 The energy spectrum is acquired for 1 minute under the standard dose rate point to obtain the corresponding actual measurement count rate N of the slow forming channel S Measured count rate N of rapid prototyping channel F ；
3) According to the actual measurement count rate N of the rapid forming channel F Calculating to obtain an input counting rate M:then calculating according to the input counting rate to obtain the corresponding energy spectrum correction coefficient +.>
4) By using the method that the dosage rate is 10 mu Gy.h -1 Measured count rate n of fast forming channel at F Deriving an ideal count rate M' at the remaining dose rate points;
5) Separately calculate 137 662keV of Cs and 60 the actual net count rate x of the corresponding characteristic peak of 1332keV of Co at each dose rate point is calculated by using an energy spectrum correction coefficient to obtain the actual net count rate x' =alpha x of the characteristic peak;
6) By using the method at the dose rate of 10 mu Gy.h -1 The measured net count rate at that point derives the ideal net count rate at the remaining dose rate points.
The energy spectrum-dose conversion method can effectively approximate the corrected input counting rate to the ideal input counting rate, and can ensure that the dose rate calculated by using the G (E) function method is less than or equal to 2 mGy.h -1 The relative inherent error in the range is controlled within 9%.
According to the invention, the analysis function of the input counting rate relative to the output counting rate is given by researching the dead time generation mode of the DMCA system, and the analysis function is utilized to correct the gamma and G (E) function, so that the dose rate error caused by the dead time effect is effectively overcome. Adopts the bookThe method can lead the spectrometer system to have the dose rate of less than or equal to 2 mGy.h -1 In the range, the corrected energy spectrum input counting rate is consistent with the change trend of the ideal input counting rate along with the dosage rate, the relative inherent error of the dosage rate can be controlled within 9%, the counting rate loss generated by gamma energy spectrum can be corrected, and the accuracy of dosage rate measurement is improved.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the technical solution, and those skilled in the art should understand that modifications and equivalents may be made to the technical solution of the present invention without departing from the spirit and scope of the present invention, and all such modifications and equivalents are included in the scope of the claims.
Claims (2)
1. A method for energy spectrum-dose conversion based on a digital multichannel spectrometer, comprising the steps of:
1) The gamma energy spectrum of the radionuclide is acquired through a DMCA system, and the energy spectrum acquired at any time t is recorded as Spec out ,Spec out ＝{y 1 ,y 2 ,…y n -the corresponding output count rate is N;
2) Calculation of the Spectrum Spec out Output count rate N of (2):
3) According to the energy spectrum Spec out And an output count rate N for the input energy spectrum Spec in Performing correction calculation to obtain an approximate spectrum Spec 'of the input energy spectrum' in ：
Wherein: w (-Nτ) is the Lambert W function, τ is the dead time of a single pulse generation;
4) According to the approximate energy spectrum Spec' in Combining an energy spectrum-dose conversion model, and calculating to obtain an air absorption dose D:
wherein: n (E) is the input gamma energy spectrum, i.e. Spec' in The method comprises the steps of carrying out a first treatment on the surface of the G (E) is a dose rate weight of the address count corresponding to energy E, wherein:
wherein: k is the highest polynomial, A k Is the coefficient corresponding to the kth term of the polynomial.
2. The method of claim 1, wherein in step 3), the spectrum Spec 'is approximated' in The correction process of (2) is as follows:
1) Respectively selecting the dose rate calibrated 60 Co and Co 137 Cs two radionuclides;
2) Respectively at 10 mu Gy.h -1 、30μGy·h -1 、50μGy·h -1 、80μGy·h -1 、100μGy·h -1 、300μGy·h -1 、500μGy·h -1 、800μGy·h -1 、1mGy·h -1 、2mGy·h -1 And 3 mGy.h -1 The energy spectrum is acquired for 1 minute under the standard dose rate point to obtain the corresponding actual measurement count rate N of the slow forming channel S Measured count rate N of rapid prototyping channel F ；
3) According to the actual measurement count rate N of the rapid forming channel F Calculating to obtain an input counting rate M:then calculating according to the input counting rate to obtain the corresponding energy spectrum correction coefficient +.>
4) By using the method that the dosage rate is 10 mu Gy.h -1 Measured count rate n of fast forming channel at F Deriving an ideal count rate M' at the remaining dose rate points;
5) Separately calculate 137 662keV of Cs and 60 the actual net count rate x of the corresponding characteristic peak of 1332keV of Co at each dose rate point is calculated by using an energy spectrum correction coefficient to obtain the actual net count rate x' =alpha x of the characteristic peak;
6) By using the method at the dose rate of 10 mu Gy.h -1 The measured net count rate at that point derives the ideal net count rate at the remaining dose rate points.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311603040.0A CN117607941A (en) | 2023-11-28 | 2023-11-28 | Energy spectrum-dose conversion method based on digital multichannel spectrometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311603040.0A CN117607941A (en) | 2023-11-28 | 2023-11-28 | Energy spectrum-dose conversion method based on digital multichannel spectrometer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117607941A true CN117607941A (en) | 2024-02-27 |
Family
ID=89951141
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311603040.0A Pending CN117607941A (en) | 2023-11-28 | 2023-11-28 | Energy spectrum-dose conversion method based on digital multichannel spectrometer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117607941A (en) |
-
2023
- 2023-11-28 CN CN202311603040.0A patent/CN117607941A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107907901B (en) | Method and system for measuring neutron and gamma energy spectrum and dosage of nuclear power station | |
| US9910167B2 (en) | Method for digitalizing scintillation pulse | |
| CN110941007B (en) | Nuclear energy spectrum processing method and device | |
| Honzátko et al. | Facility and method for studying two-step γ cascades in thermal neutron capture | |
| CN111045072B (en) | Be applicable to CeBr 3 Gamma energy spectrum iteration spectrum solving method of detector | |
| CN108646284B (en) | Gamma-spectrum combined detection system and gamma-spectrum measurement method | |
| CN116381772A (en) | Real-time energy response correction method, system and terminal for dose rate meter | |
| CN202177701U (en) | Device for extracting scintillation pulse information | |
| CN113466913A (en) | Mixed radiation field dosage measuring system based on liquid scintillator detector | |
| Koehler et al. | Spin measurements for Sm 147+ n resonances: Further evidence for nonstatistical effects | |
| CN117607941A (en) | Energy spectrum-dose conversion method based on digital multichannel spectrometer | |
| CN107238856B (en) | Method for determining neutron average energy of high-flux deuterium-tritium neutron generator | |
| CN114694863B (en) | Method for calculating multiple groups of slow-release photon yields by using fission yield and decay data | |
| CN112649835B (en) | Single-nuclide air absorption dose rate measurement method based on numerical integration | |
| CN115420226A (en) | Ray action position positioning device and method based on pulse width | |
| Marseguerra et al. | Use of the MCNP-Polimi code for time-correlation safeguards measurements | |
| Zhu et al. | Design and performance of an wide-range real-time NFM system using higher order Campbell mode | |
| CN113536679A (en) | Point source dosage rate correction method based on artificial neural network | |
| TW201040570A (en) | Method and apparatus of all function environmental gamma radiation monitor | |
| Ding et al. | A Calculation Software for 4πβ–γ Coincidence Counting | |
| CN114236601A (en) | Low air kerma rate measuring method based on proportional counter type secondary standard device | |
| Cao et al. | Monte Carlo Studies of the Neutron Detector Dead Time Effects on Pulsed Neutron Experiments | |
| CN105353399A (en) | Alpha/beta ray gas-flow type proportional counter high-voltage working point rapid measuring method | |
| Liu et al. | Study of dead time estimation method based on pulse interval distribution | |
| Yoshihara | Investigation of the energy resolution of high purity germanium detectors using trapezoidal filtering |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |