Neutron fluence response calibration method based on neutron generator reference radiation field

Abstract

The application relates to the technical field of data calibration, in particular to a neutron fluence response calibration method based on a neutron generator reference radiation field, which comprises the following steps: collecting, by a neutron detector and a neutron generator, the count rate, the neutron fluence rate and the data of each kind of environmental parameter around the reference radiation field at each time in each monitoring period; regarding each monitoring period and a plurality of monitoring periods before the monitoring period as each historical period; determining the measurement error degree of each historical period; obtaining the measurement interference degree of each kind of environmental parameter under each monitoring period; calculating the scattering interference degree of each kind of environmental parameter under each monitoring period, obtaining the calibration count rate and performing real-time calibration on the neutron fluence response. The application can quantize the interference influence of different environmental factors on the measurement result of the neutron detector through dynamic environmental changes, calibrate the measurement result of the neutron detector in real time and improve the measurement accuracy of the neutron fluence response.

Description

Technical Field

[0001] This application relates to the field of data calibration technology, specifically to a neutron fluence response calibration method based on a neutron generator reference radiation field. Background Technology

[0002] A neutron generator is a compact accelerator device that produces neutrons through nuclear reactions. It is widely used in medicine, materials analysis, and the nuclear industry for neutron generation. A neutron detector is an instrument used to monitor and measure neutrons. To ensure the detection accuracy of the neutron detector meets requirements, it needs to be calibrated according to the neutron response characteristics. This calibration allows the detector to accurately measure the neutron flux, improving the reliability and consistency of measurement results and ensuring the safety and effectiveness of neutron-related applications.

[0003] The reference radiation field, serving as a crucial benchmark for neutron detector calibration, is a specific radiation field used to calibrate and measure neutron fluence. Existing neutron reference radiation fields, established based on isotopic radioactive sources, while covering a wide energy range, do not adequately consider the impact of various environmental factors on neutron fluence measurements during actual calibration. For example, environmental factors can alter the molecular density in air, leading to increased elastic scattering of neutrons and a decrease in neutron beam intensity, resulting in errors in neutron detector measurements. Furthermore, the scattering interference from different environmental factors varies, causing deviations in neutron detector calibration results. This makes them unable to adapt to dynamic environmental changes, affecting the accuracy of neutron detector measurement calibration and resulting in low accuracy in neutron fluence response measurements. Summary of the Invention

[0004] To address the aforementioned technical issues, a neutron fluence response calibration method based on a neutron generator reference radiation field is provided to resolve existing problems.

[0005] The solution to the technical problem presented in this application is to provide a neutron fluence response calibration method based on a neutron generator reference radiation field, comprising the following steps:

[0006] The count rate, neutron fluence rate, and data of each environmental parameter around the reference radiation field at each moment in each monitoring cycle are collected by the neutron detector and neutron generator.

[0007] Each monitoring cycle and the multiple monitoring cycles preceding it are recorded as historical cycles. The dispersion of the count rate, the correlation between the count rate and the neutron flux rate, and the differences in the changing trends between the count rate and the neutron flux rate within each historical cycle are analyzed to determine the measurement error of each historical cycle.

[0008] The measurement error of all historical periods is clustered, and the dispersion of the average level of data in different historical periods within each cluster under each environmental parameter is analyzed, as well as the correlation between the average level of data of each environmental parameter in different historical periods and the measurement error, so as to obtain the measurement interference of each environmental parameter under each monitoring period.

[0009] Based on the correlation between the data and the count rate of each environmental parameter at all times in each historical period, and the difference between the data and the measurement interference, all historical periods are filtered to obtain each significant period.

[0010] By analyzing the deviations of data for each environmental parameter in different significant periods and the deviations in the count rate, the scattering interference degree of each environmental parameter in each monitoring period is calculated. The count rate at each moment in the next monitoring period is then calibrated to obtain the calibrated count rate at each moment in the next monitoring period, thereby performing real-time calibration of the neutron fluence response.

[0011] Preferably, the environmental parameters include temperature, humidity, and air pressure.

[0012] Preferably, determining the measurement error degree for each historical period includes:

[0013] Calculate the degree of dispersion of the count rate at all times within each historical period, and denote it as the first degree of dispersion;

[0014] Calculate the correlation between the count rate and the neutron fluence rate at all times within each historical period, denoted as the first correlation degree, and perform a positive mapping on the first correlation degree;

[0015] Analyze the difference between the linear trend of the count rate and the linear trend of the neutron fluence rate in each historical period, and calculate the linear deviation; calculate the product of the linear deviation and the first dispersion.

[0016] The measurement error is the ratio between the product value and the result of the positive mapping.

[0017] Preferably, the calculation of linear deviation includes: performing linear fitting on the count rate and neutron flux rate at all times within each historical period, calculating the slope of the fitted line and denoting it as the first slope and the second slope; and denoting the difference between the first slope and the second slope as the linear deviation.

[0018] Preferably, obtaining the measurement interference degree of each environmental parameter in each monitoring cycle includes:

[0019] Calculate the average value of each environmental parameter at all times within each historical period; calculate the dispersion of the average value of each environmental parameter within each cluster for all historical periods, denoted as intra-cluster volatility;

[0020] Calculate the coefficient of variation of the intra-cluster volatility for all clusters under each environmental parameter;

[0021] The correlation between the average value of all historical periods for each environmental parameter and the measurement error degree is calculated and denoted as the second correlation degree.

[0022] The measured interference degree is the normalized result of the product of the second correlation degree and the coefficient of variation.

[0023] Preferably, the process for obtaining each significant period is as follows:

[0024] The correlation between the data and the count rate of each environmental parameter at all times in each historical period is calculated and denoted as the third correlation. The difference between the third correlation and the measurement interference is calculated and used as the discrimination coefficient for each historical period under each environmental parameter.

[0025] The historical periods corresponding to the discriminant coefficient being greater than or equal to 0 are denoted as significant periods.

[0026] Preferably, the calculation of the scattering interference degree of each environmental parameter in each monitoring cycle includes:

[0027] Select the historical period corresponding to the minimum measurement error before each monitoring period and record it as the standard reference period; analyze the distribution of the count rate within the standard reference period and the distribution of data for each environmental parameter within the standard reference period to determine the standard count rate and the standard value corresponding to each environmental parameter;

[0028] Calculate the difference between the count rate at each time point within each significant period and the standard count rate, and record it as the first difference;

[0029] Calculate the difference between the data of each environmental parameter at each time point in each significant period and the standard value, and record it as the second difference;

[0030] The average of the ratios of the first difference to the second difference for each environmental parameter at all times within each significant period is denoted as the interference coefficient.

[0031] The scattering interference degree is the average of the interference coefficients for all significant periods under each environmental parameter.

[0032] Preferably, determining the standard count rate and the standard value corresponding to each environmental parameter includes: calculating the mode of the count rate at all times within the standard reference period, which is denoted as the standard count rate; and calculating the mode of the data for each environmental parameter at all times within the standard reference period, which is denoted as the standard value.

[0033] Preferably, obtaining the calibration count rate at each time point within the next monitoring cycle includes:

[0034] The calibrated count rate λ of the r-th environmental parameter at time t within the (q+1)-th monitoring period. r,q+1,t The calculation formula is: Among them, J q+1,t Let j be the count rate before calibration at time t within the (q+1)th monitoring period. q+1,t Let h0 be the data of the r-th environmental parameter at time t within the (q+1)-th monitoring period, and let G be the standard value corresponding to the r-th environmental parameter. r,q Let r be the scattering interference degree of the r-th environmental parameter in the q-th monitoring period;

[0035] The average of the calibrated count rates of all environmental parameters at each time point in the next monitoring cycle is taken as the calibrated count rate at each time point in the next monitoring cycle.

[0036] Preferably, the real-time calibration of the neutron flux response includes: using the ratio of the calibration count rate to the neutron flux rate as the calibrated neutron flux response at each moment in the next monitoring cycle.

[0037] This application has at least the following beneficial effects:

[0038] This application determines the measurement error degree of each historical period by analyzing the fluctuation of the count rate and the correlation between the count rate and the neutron flux rate. Its advantage lies in considering the interference experienced by the neutron detector during the measurement process and assessing the degree of deviation of the neutron detector in the neutron flux measurement process. It then clusters the historical periods based on the measurement error degree to obtain the measurement interference degree of each environmental parameter in each monitoring period. This is beneficial because it reflects the overall interference degree of changes in environmental factors around the neutron reference radiation field on the measurement error when the measurement error is consistent, thus enabling the selection of historical periods with more significant influence (i.e., obtaining significant periods). Secondly, it calculates the scattering interference degree of each environmental parameter in each monitoring period. Its advantage lies in considering the significant interference. The deviations of environmental parameters and count rates within a period are analyzed to reflect the interference caused by different environmental parameters on the measurement results. This assesses the differences in scattering interference from different environmental parameters on the radiation field, allowing for subsequent correction and calibration of the measurement results based on the scattering interference caused by each environmental parameter. This enables dynamic data calibration based on environmental changes. By analyzing the scattering interference of each environmental parameter, the count rate at each moment in the next monitoring period is calibrated to obtain the calibrated count rate for each moment in the next monitoring period. This real-time calibration of the neutron fluence response is beneficial because it quantifies the interference impact of different environmental factors on the neutron detector's measurement results through dynamic environmental changes, thereby enabling real-time calibration of the neutron detector's measurement results and improving the accuracy of neutron fluence response measurements. Attached Figure Description

[0039] The neutron fluence response calibration method based on the neutron generator reference radiation field of this application will be further described in detail below with reference to the accompanying drawings.

[0040] Figure 1 A flowchart illustrating the steps of a neutron fluence response calibration method based on a neutron generator reference radiation field, provided for embodiments of this application.

[0041] Figure 2 A flowchart illustrating the steps of a method for obtaining the measurement interference level of each environmental parameter in each monitoring cycle, as provided in the embodiments of this application.

[0042] Figure 3 A flowchart illustrating the steps of the method for obtaining the scattering interference level of each environmental parameter in each monitoring cycle provided in this application embodiment. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the neutron fluence response calibration method based on a neutron generator reference radiation field proposed in this application will be further described in detail below with reference to the accompanying drawings and implementation examples. It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0045] Please see Figure 1 It illustrates a flowchart of a neutron fluence response calibration method based on a neutron generator reference radiation field according to an embodiment of this application. The method includes the following steps:

[0046] Step 1: Collect the count rate, neutron fluence rate, and data of each environmental parameter around the reference radiation field at each moment in each monitoring cycle using a neutron detector and a neutron generator.

[0047] Quasi-monoenergetic neutrons are generated by a miniaturized, electronically controlled neutron generator to establish a neutron reference radiation field. A smart sensor (in this embodiment, a long BF3 neutron detector) is fixed at the center of the neutron reference radiation field, with the detector perpendicularly aligned to the beam direction of the quasi-monoenergetic neutrons generated by the generator. The neutron generator and detector are activated. The neutron fluence is counted per unit time by the neutron detector and recorded as the count rate. The neutron fluence generated by the neutron generator per unit time is also recorded as the neutron fluence rate. Each unit time is defined as 1 second, thus obtaining the count rate and neutron fluence rate at each moment.

[0048] In the process of neutron detector measurement, background interference of gamma rays is eliminated by setting an appropriate discrimination threshold in advance. The discrimination threshold is set in the range of (0.5, 1). In this embodiment, the discrimination threshold is set to 0.8. As other implementation methods, implementers can set it according to the actual situation.

[0049] Secondly, the gas law is satisfied by the relationship between air pressure and the density of molecules in the air: ρ is the density of the gas, M is the molar mass of the molecules in the gas, R is the ideal gas constant with a value of 8.314, and T is the temperature. Therefore, the higher the air pressure, the higher the number density of molecules in the air per unit volume. When neutrons scatter with molecules in the air, a higher molecular number density leads to more scattering events, thus changing the direction and energy of the neutrons, directly affecting the measurement results of the neutron beam intensity and neutron fluence. Secondly, higher temperatures intensify the thermal motion of the gas per unit volume, leading to an increase in the kinetic energy of the molecules in the air, which can cause deviations in the measurement results of the neutron detector. Furthermore, higher humidity results in a higher water vapor content in the air, containing a large number of hydrogen atoms. The scattering cross-section between neutrons and hydrogen nuclei is larger, and water molecules become additional scatterers, causing changes in the energy distribution and direction of neutron motion. Additionally, fast neutrons collide with water vapor, reducing their energy and potentially being slowed down into thermal or hyperthermal neutrons, leading to deviations in the measurement results of the neutron detector. Therefore, taking into account the influence of environmental factors, temperature, humidity and air pressure in the environment surrounding the neutron reference radiation field are collected by temperature sensors, humidity sensors and air pressure sensors;

[0050] All collected data are normalized to obtain the count rate, neutron flux rate, temperature, humidity, and air pressure at each time point. Multiple time points are considered as a monitoring cycle to obtain the count rate and neutron flux rate at each time point within each monitoring cycle. Data for each environmental parameter at each time point within each monitoring cycle are also obtained, including temperature, humidity, and air pressure.

[0051] In this embodiment, the sensor's data acquisition time interval is 1 second, consistent with the data recording time interval of the neutron detector and neutron generator. Furthermore, the duration of one monitoring cycle is 10 minutes. As other implementation methods, the implementer can set these values ​​according to actual conditions. Normalization is performed using the maximum-minimum value normalization method, which is a well-known technique and will not be elaborated upon here. As other implementation methods, the implementer can use other methods from the prior art, such as the Z-score normalization method. This embodiment does not impose any special restrictions on this.

[0052] Thus, the count rate, neutron fluence rate, and data for each environmental parameter at each time point within each monitoring cycle are obtained.

[0053] Step 2: Record each monitoring cycle and the multiple monitoring cycles preceding it as historical cycles; analyze the dispersion of the count rate, the correlation between the count rate and the neutron flux rate, and the differences in the changing trends between the count rate and the neutron flux rate within each historical cycle to determine the measurement error of each historical cycle.

[0054] The process of measuring neutron fluence within a neutron reference radiation field is relatively straightforward. When the performance of the long BF3 neutron detector is ideal, the interference from gas scattering or scattering from the surrounding environment is minimal. In this case, the trend of neutron fluence data is mainly influenced by the characteristics of the neutron source itself and the radiation field. In a stable monoenergetic neutron reference radiation field, the neutron fluence rate is usually fixed, and the collected count rate should exhibit a stable linear trend. If the trend of the count rate fluctuates significantly, it indicates that the error caused by scattering interference from the surrounding environment through the neutron detector is greater. Secondly, if the measurement error of the neutron fluence by the neutron detector is small, there should be a strong proportional relationship between the count rate and the neutron fluence rate.

[0055] Based on the above analysis, the measurement error is calculated by analyzing the fluctuation of the count rate and the correlation between the count rate and the neutron fluence rate. Specifically:

[0056] Each monitoring cycle and the multiple monitoring cycles preceding it are recorded as each historical cycle;

[0057] In this embodiment, each monitoring cycle and the 30 monitoring cycles preceding it are recorded as each historical cycle. As for other implementation methods, the implementer can set them according to the actual situation.

[0058] Calculate the degree of dispersion of the count rate at all times within each historical period, and denote it as the first degree of dispersion;

[0059] In this embodiment, the degree of dispersion is measured by calculating the variance of the count rate at all times within each historical period. As other implementation methods, implementers may use other methods of the prior art, such as standard deviation, information entropy, etc. This embodiment does not impose any special restrictions on this.

[0060] It should be noted that the larger the first dispersion, the greater the fluctuation in the count rate trend when measuring the neutron fluence.

[0061] Calculate the correlation between the count rate and the neutron fluence rate at all times within each historical period, denoted as the first correlation degree, and perform a positive mapping on the first correlation degree;

[0062] In this embodiment, the correlation is measured by calculating the Spearman correlation coefficient between the count rate and the neutron fluence rate at all times within each historical period. The calculation of the Spearman correlation coefficient is a well-known technique and will not be elaborated here. As other implementation methods, implementers can use other methods of the prior art, such as the Pearson correlation coefficient, etc. This embodiment does not impose any special restrictions on this. It should be noted that the absolute value of the Spearman correlation coefficient is denoted as the first correlation degree. Secondly, the specific process of positive mapping is as follows: positive mapping is performed through an exponential function. Assuming the first correlation degree is denoted as R, the result of exp(R) is taken as the result of positive mapping, where exp() is an exponential function with the natural constant as the base.

[0063] It should be noted that the larger the first correlation, the stronger the correlation between the change in count rate and neutron fluence rate, reflecting that the measurement error of neutron fluence by the neutron detector is small. Through positive mapping, the influence of the first correlation is increased and the denominator is avoided to be 0 when calculating the ratio in the subsequent calculation.

[0064] Linear fitting was performed on the count rate and neutron fluence rate at all times within each historical period, and the slopes of the fitted lines were calculated and denoted as the first slope and the second slope, respectively.

[0065] In this embodiment, the least squares method is used for linear fitting. The least squares method is a well-known technique and will not be described in detail here. As other implementation methods, implementers can use other methods of the prior art, such as Hough transform, etc. This embodiment does not impose any special restrictions on this.

[0066] The difference between the first slope and the second slope is denoted as the linear deviation;

[0067] In this embodiment, the absolute value of the difference between the first slope and the second slope is denoted as the linear deviation.

[0068] It should be noted that the smaller the linear deviation, the more accurately the change in count rate can reflect the change in neutron flux rate, and the smaller the error encountered by the neutron detector when measuring the neutron flux.

[0069] Calculate the product of the linear deviation and the first dispersion, and use the ratio between the product and the result of the positive mapping as the measurement error degree for each historical period;

[0070] It should be noted that the larger the measurement error, the greater the interference the neutron detector experiences during the measurement process, the greater the error in the measured count rate, and the more necessary it is to strengthen subsequent calibration to eliminate the error.

[0071] Thus, the measurement error for each historical period is obtained.

[0072] Step 3: Cluster the measurement error of all historical periods, analyze the dispersion of the average level of data in different historical periods within each cluster for each environmental parameter, and the correlation between the average level of data of each environmental parameter in different historical periods and the measurement error, to obtain the measurement interference of each environmental parameter in each monitoring period.

[0073] Furthermore, the flowchart of the method for obtaining the measurement interference level of each environmental parameter in each monitoring cycle provided in this application embodiment is as follows: Figure 2 As shown.

[0074] Furthermore, during neutron detector calibration, scattering interference from the surrounding environment directly affects the calibration results. For example, if a neutron undergoes elastic scattering with molecules in the air, the neutron transfers some of its kinetic energy to the air molecules during the elastic collision, altering its own direction of motion and energy. This leads to beam intensity attenuation and directly affects the neutron fluence measurement results. Therefore, by analyzing the interference effects of complex environmental factors on the neutron reference radiation field and assessing the impact of environmental scattering, the scattering effects caused by the complex environment can be minimized, ensuring the accuracy of the calibration results.

[0075] Based on the above analysis, by clustering the measurement error degrees of all historical cycles, historical cycles with consistent error degrees are grouped into one category. Then, the data changes under different environmental parameters under the condition of consistent measurement error degrees are analyzed, specifically as follows:

[0076] The measurement error rates of all historical periods are clustered to obtain multiple clusters;

[0077] In this embodiment, the K-means clustering algorithm is used for clustering, and the number of clusters is determined by the elbow rule. The K-means clustering algorithm is a well-known technology and will not be described in detail here. As other implementation methods, implementers can use other methods of existing technology, such as the DBSCAN clustering algorithm, etc. This embodiment does not impose any special restrictions on this.

[0078] Calculate the average value of each environmental parameter across all time points in each historical period;

[0079] The degree of dispersion of the average value of each environmental parameter over all historical periods within each cluster is calculated and denoted as intra-cluster volatility.

[0080] In this embodiment, the degree of dispersion is measured by calculating the variance of the average value of each environmental parameter across all historical periods within each cluster. As an alternative implementation, the implementer may use other methods of the prior art, such as standard deviation, information entropy, etc., and this embodiment does not impose any special restrictions on this.

[0081] It should be noted that the intra-cluster variability reflects the fluctuations in air pressure, temperature, and humidity in the surrounding environment when the measurement error is relatively consistent. The greater the intra-cluster variability, the greater the change in these environmental parameters in the surrounding environment, but the change in measurement error is relatively consistent, thus reflecting that the interference of gas scattering on the neutron detector is relatively small.

[0082] Calculate the coefficient of variation of the intra-cluster volatility for all clusters under each environmental parameter;

[0083] It should be noted that the calculation of the coefficient of variation is a well-known technique and will not be elaborated here. The coefficient of variation reflects the overall interference of changes in the environmental parameter in the surrounding environment on the neutron fluence measurement process. The smaller the coefficient of variation, the higher the average level of the environmental parameter as a whole, and the smaller the difference between different clusters, indicating that the change of the environmental parameter is relatively stable. Therefore, the smaller the average interference of the environmental parameter, and the more consistent the interference of gas scattering under different interference errors in the neutron fluence measurement process, the smaller the interference of gas scattering on the neutron fluence measurement.

[0084] Secondly, changes in environmental parameters affect changes in measurement error. Therefore, we analyze the correlation between the average level of each environmental parameter in different historical periods and the measurement error, and calculate the measurement interference degree using the coefficient of variation. Specifically:

[0085] The correlation between the average value of all historical periods for each environmental parameter and the measurement error degree is calculated and denoted as the second correlation degree.

[0086] In this embodiment, the correlation is measured by the Spearman correlation coefficient between the average value of all historical periods for each environmental parameter and the measurement error. The calculation of the Spearman correlation coefficient is a well-known technique and will not be described in detail here. As other implementation methods, implementers may use other methods of the prior art, such as the Pearson correlation coefficient. This embodiment does not impose any special restrictions on this. It should be noted that the absolute value of the Spearman correlation coefficient is denoted as the second correlation degree.

[0087] The normalized result of the product of the second correlation and the coefficient of variation is used as the measurement interference degree of each environmental parameter in each monitoring period;

[0088] In this embodiment, the sigmoid function is used for normalization. The sigmoid function is a well-known technique and will not be described in detail here. As other implementation methods, implementers can use other methods of the prior art, such as the softmax function. This embodiment does not impose any special restrictions on this.

[0089] It should be noted that the second correlation reflects the degree to which the measurement error of the neutron detector responds to changes in environmental parameters, such as air pressure. Taking air pressure as an example, the smaller the second correlation, the less the measurement error changes with the average air pressure, thus reflecting the smaller the interference caused by air pressure on the measurement of neutron flux. The measurement interference reflects the overall impact of changes in environmental factors around the neutron reference radiation field on the measurement error when the neutron detector is used for measurement in the neutron reference radiation field. The larger the measurement interference, the greater the impact of changes in surrounding environmental factors on the measurement error. That is, gas scattering causes greater interference during the measurement process, and therefore, it is more necessary to strengthen the calibration of the neutron detector's measurement results based on the degree of change in such environmental parameters.

[0090] Thus, the measurement interference degree of each environmental parameter in each monitoring cycle is obtained.

[0091] Step 4: Based on the correlation between the data and count rate of each environmental parameter at all times in each historical period and the difference between the data and the measurement interference, all historical periods are filtered to obtain each significant period; by analyzing the deviation of the data and the count rate of each environmental parameter in different significant periods, the scattering interference of each environmental parameter in each monitoring period is calculated, and the count rate at each time in the next monitoring period is calibrated to obtain the calibrated count rate at each time in the next monitoring period, thereby calibrating the neutron fluence response in real time.

[0092] The flowchart of the method for obtaining the scattering interference degree of each environmental parameter in each monitoring cycle provided in the embodiments of this application is as follows: Figure 3 As shown.

[0093] Furthermore, based on the measurement error rate, the historical period with the smallest error is selected, and the changes in environmental parameters between the historical period with the smallest error and the other historical periods are analyzed, specifically as follows:

[0094] Select the historical period corresponding to the minimum measurement error before each monitoring period and record it as the standard reference period;

[0095] The mode of the count rate at all times within the statistical standard reference period is denoted as the standard count rate; the mode of the data for each environmental parameter at all times within the stated standard reference period is denoted as the standard value.

[0096] It should be noted that, when the environmental parameter is air pressure, the mode of the air pressure at all times within the standard reference period is recorded as the standard value corresponding to the air pressure; when the environmental parameter is temperature, the mode of the temperature at all times within the standard reference period is recorded as the standard value corresponding to the temperature; and when the environmental parameter is humidity, the mode of the humidity at all times within the standard reference period is recorded as the standard value corresponding to the humidity.

[0097] The correlation between the data of each environmental parameter and the count rate at all times in each historical period is calculated and denoted as the third correlation degree.

[0098] In this embodiment, the correlation is measured by calculating the Spearman correlation coefficient between the data and the count rate at all times within each historical period for each environmental parameter. The calculation of the Spearman correlation coefficient is a well-known technique and will not be elaborated upon here. As other implementation methods, the implementer may use other methods from the prior art, such as the Pearson correlation coefficient, etc., and this embodiment does not impose any special restrictions on this. It should be noted that the absolute value of the Spearman correlation coefficient is denoted as the third correlation degree. For the environmental parameter of air pressure, the correlation between air pressure and the count rate at all times within each historical period is calculated; for the environmental parameter of temperature, the correlation between temperature and the count rate at all times within each historical period is calculated; and for the environmental parameter of humidity, the correlation between humidity and the count rate at all times within each historical period is calculated.

[0099] It should be noted that the greater the third correlation, the higher the degree of coordinated change between the count rate and the environmental parameter, and the greater the influence of the environmental parameter on the count rate during this historical period.

[0100] The difference between the third correlation degree and the measurement interference degree is calculated and used as the discrimination coefficient for each historical period under each environmental parameter;

[0101] The historical periods corresponding to the discriminant coefficient being greater than or equal to 0 are selected and denoted as each significant period;

[0102] It should be noted that the discriminant coefficient is used to assess whether the degree of interference in a single historical period is greater than the overall degree of interference. If the discriminant coefficient is greater than or equal to 0, it indicates that the count rate is significantly affected by interference in this historical period.

[0103] Calculate the difference between the count rate at each time point within each significant period and the standard count rate, and record it as the first difference;

[0104] Calculate the difference between the data of each environmental parameter at each time point in each significant period and the standard value, and record it as the second difference;

[0105] The average of the ratios of the first difference to the second difference for each environmental parameter at all times within each significant period is denoted as the interference coefficient.

[0106] The mean of the interference coefficients of each environmental parameter over all significant periods is taken as the scattering interference degree of each environmental parameter in each monitoring period.

[0107] In this embodiment, taking the r-th environmental parameter in the q-th monitoring period as an example, the formula for calculating its scattering interference degree is:

[0108]

[0109] Among them, G q,r J represents the scattering interference degree of the r-th environmental parameter in the q-th monitoring period. x,y Let J0 be the count rate at time y within the x-th significant period, and h be the standard count rate. x,y Let h0 be the data at time y within the x-th significant period under the r-th environmental parameter, h0 be the standard value corresponding to the r-th environmental parameter, M be the number of all significant periods, and N be the number of all times within the x-th significant period.

[0110] It should be noted that when the second difference is 0, the ratio of the first difference to the second difference is set to 0. The ratio of the first difference to the second difference reflects the impact of a unit change in the data of each environmental parameter on the count rate. If the discrimination coefficient at each moment in all significant periods is less than 0, the value of M is 30. The larger the absolute value of the scattering interference, the greater the interference to the count rate when the data of that environmental parameter changes by a unit, and the more necessary it is to strengthen the calibration to eliminate the interference.

[0111] Furthermore, based on the aforementioned scattering interference level, the count rate at each time point in the next monitoring cycle is corrected, specifically as follows:

[0112]

[0113] Where, λ r,q+1,tLet J be the count rate calibrated for the r-th environmental parameter at time t within the (q+1)-th monitoring period. q+1,t h is the count rate before calibration at time t within the (q+1)th monitoring period. q+1,t Let h0 be the data of the r-th environmental parameter at time t within the (q+1)-th monitoring period, and let G be the standard value corresponding to the r-th environmental parameter. r,q Let represent the scattering interference degree of the r-th environmental parameter during the q-th monitoring period.

[0114] It should be noted that, therefore, in this embodiment, for the three environmental parameters corresponding to air pressure, temperature and humidity, the calibrated count rate at time t in the (q+1)th monitoring period when affected by air pressure, the calibrated count rate at time t in the (q+1)th monitoring period when affected by temperature, and the calibrated count rate at time t in the (q+1)th monitoring period when affected by humidity are obtained respectively. Thus, the calibrated data of the count rate for the three environmental factors are obtained respectively.

[0115] It should be noted that changes in environmental parameters can lead to increased errors. The closer the environmental parameters are to the corresponding standard values, the smaller the impact of the error. The standard value h0 is extracted from the historical period with the smallest error. Therefore, when environmental parameters are greater than the standard value, if a unit change in the environmental parameters results in a larger count rate within a significant period, it indicates that a unit change in the environmental parameters will lead to an increase in the count rate. In this case, the count rate needs to be reduced, and G... q,r If the count rate is greater than 0, and the count rate measurement is too low within a significant period, it indicates that a unit change in environmental parameters will lead to a decrease in the count rate. In this case, the count rate needs to be increased, and G... q,r The value is less than 0, so the count rate is calibrated in real time by observing the effect of changes in environmental parameters on the count rate. When the environmental parameters are less than or equal to the standard value, the error will be smaller, and the measurement results of the neutron detector will be more accurate, so no calibration is required.

[0116] The average of the calibrated count rates of all environmental parameters at each time point in the next monitoring cycle is taken as the calibrated count rate at each time point in the next monitoring cycle.

[0117] The ratio of the calibration count rate to the neutron fluence rate is used as the calibrated neutron fluence response at each time point in the next monitoring cycle.

[0118] Thus, real-time calibration of the neutron fluence response was completed. It should be noted that the calculation of the neutron fluence response is a well-known technique, which refers to the calculation of the ratio of the neutron detector's count rate to the neutron fluence rate. Therefore, by calibrating the count rate, the neutron fluence response is calibrated in real time, thereby improving the measurement accuracy of the neutron fluence response.

[0119] It should be understood that, although Figure 1 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figure 1 At least some of the steps in the process may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least some of the sub-steps or stages of other steps.

[0120] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solution of this application, shall fall within the protection scope of the technical solution of this application.

Claims

1. A neutron fluence response calibration method based on a neutron generator reference radiation field, characterized in that, The method includes the following steps: The count rate, neutron fluence rate, and data of each environmental parameter around the reference radiation field at each moment in each monitoring cycle are collected by the neutron detector and neutron generator. Each monitoring cycle and the multiple monitoring cycles preceding it are recorded as historical cycles. The dispersion of the count rate, the correlation between the count rate and the neutron flux rate, and the differences in the changing trends between the count rate and the neutron flux rate within each historical cycle are analyzed to determine the measurement error of each historical cycle. The measurement error of all historical periods is clustered, and the dispersion of the average level of data in different historical periods within each cluster under each environmental parameter is analyzed, as well as the correlation between the average level of data of each environmental parameter in different historical periods and the measurement error, so as to obtain the measurement interference of each environmental parameter under each monitoring period. Based on the correlation between the data and the count rate of each environmental parameter at all times in each historical period, and the difference between the data and the measurement interference, all historical periods are filtered to obtain each significant period. By analyzing the deviations of data for each environmental parameter in different significant periods and the deviations in the count rate, the scattering interference degree of each environmental parameter in each monitoring period is calculated. The count rate at each moment in the next monitoring period is then calibrated to obtain the calibrated count rate at each moment in the next monitoring period, thereby performing real-time calibration of the neutron fluence response.

2. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 1, characterized in that, The environmental parameters include temperature, humidity, and air pressure.

3. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 1, characterized in that, The determination of the measurement error degree for each historical period includes: Calculate the degree of dispersion of the count rate at all times within each historical period, and denote it as the first degree of dispersion; Calculate the correlation between the count rate and the neutron fluence rate at all times within each historical period, denoted as the first correlation degree, and perform a positive mapping on the first correlation degree; Analyze the difference between the linear trend of the count rate and the linear trend of the neutron fluence rate in each historical period, and calculate the linear deviation; calculate the product of the linear deviation and the first dispersion. The measurement error is the ratio between the product value and the result of the positive mapping.

4. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 3, characterized in that, The calculation of linear deviation includes: performing linear fitting on the count rate and neutron flux rate at all times within each historical period, calculating the slope of the fitted line and denoting it as the first slope and the second slope; and denoting the difference between the first slope and the second slope as the linear deviation.

5. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 1, characterized in that, The measurement interference degree of each environmental parameter obtained in each monitoring cycle includes: Calculate the average value of each environmental parameter at all times within each historical period; calculate the dispersion of the average value of each environmental parameter within each cluster for all historical periods, denoted as intra-cluster volatility; Calculate the coefficient of variation of the intra-cluster volatility for all clusters under each environmental parameter; The correlation between the average value of all historical periods for each environmental parameter and the measurement error degree is calculated and denoted as the second correlation degree. The measured interference degree is the normalized result of the product of the second correlation degree and the coefficient of variation.

6. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 1, characterized in that, The process for obtaining each significant period is as follows: The correlation between the data and the count rate of each environmental parameter at all times in each historical period is calculated and denoted as the third correlation. The difference between the third correlation and the measurement interference is calculated and used as the discrimination coefficient for each historical period under each environmental parameter. The historical periods corresponding to the discriminant coefficient being greater than or equal to 0 are denoted as significant periods.

7. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 1, characterized in that, The calculation of the scattering interference degree of each environmental parameter in each monitoring cycle includes: Select the historical period corresponding to the minimum measurement error before each monitoring period and record it as the standard reference period; analyze the distribution of the count rate within the standard reference period and the distribution of data for each environmental parameter within the standard reference period to determine the standard count rate and the standard value corresponding to each environmental parameter; Calculate the difference between the count rate at each time point within each significant period and the standard count rate, and record it as the first difference; Calculate the difference between the data of each environmental parameter at each time point in each significant period and the standard value, and record it as the second difference; The average of the ratios of the first difference to the second difference for each environmental parameter at all times within each significant period is denoted as the interference coefficient. The scattering interference degree is the average of the interference coefficients for all significant periods under each environmental parameter.

8. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 7, characterized in that, The determination of the standard count rate and the standard value corresponding to each environmental parameter includes: calculating the mode of the count rate at all times within the standard reference period, which is denoted as the standard count rate; and calculating the mode of the data for each environmental parameter at all times within the standard reference period, which is denoted as the standard value.

9. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 8, characterized in that, The process of obtaining the calibration count rate at each moment in the next monitoring cycle includes: No. Environmental parameters for the first Within the monitoring period, the first Count rate calibrated at time 1 The calculation formula is: ,in, For the first Within the monitoring period, the first The count rate before calibration at each time point For the first Environmental parameters in the first Within the monitoring period, the first Data at any given moment For the first Standard values ​​corresponding to various environmental parameters For the first The monitoring cycle under the first Scattering interference degree of various environmental parameters; The average of the calibrated count rates of all environmental parameters at each time point in the next monitoring cycle is taken as the calibrated count rate at each time point in the next monitoring cycle.

10. The neutron fluence response calibration method based on a neutron generator reference radiation field as described in claim 1, characterized in that, The real-time calibration of the neutron flux response includes: using the ratio of the calibration count rate to the neutron flux rate as the calibrated neutron flux response at each moment in the next monitoring cycle.

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