A method, system and device for precisely measuring tritium concentration in air

Abstract

This invention relates to the field of ionization concentration measurement technology, specifically to a method, system, and device for precise measurement of tritium concentration in air. The method includes: acquiring the ionization chamber current and energy spectrum; determining whether to perform ionization chamber voltage correction based on the current extreme value distribution and time interval, and analyzing the voltage correction value when correction is determined; identifying interfering nuclides based on the peak energy range of the analyte in the energy spectrum of two adjacent voltage corrections; determining the current contribution ratio of the interfering nuclides based on the energy distribution of the peak energy range in the energy spectrum; determining the correction current by combining the ionization current, tritium, and the current contribution ratios of all interfering nuclides; and calculating the tritium concentration in air based on the correction current. This application, by correcting the ionization chamber voltage, makes its capture of ion pairs more comprehensive. It also removes the interference of interfering nuclides on the ionization chamber method, resulting in higher accuracy in calculating the tritium concentration in air.

Description

Technical Field

[0001] This invention relates to the field of ionization concentration measurement technology, specifically to a method, system, and equipment for precise measurement of tritium concentration in air. Background Technology

[0002] Ionization is a common method for measuring tritium concentration in air. Its principle is based on the beta decay characteristic of tritium; the beta particles released during tritium decay ionize air molecules. The core device, the ionization chamber, is filled with air and equipped with electrodes. When tritium-containing air enters the ionization chamber, the beta particles collide with air molecules, producing ion pairs. An electric field is then applied between the electrodes to collect these ion pairs, forming a current. The magnitude of this current is related to the number of beta particles produced by tritium decay, i.e., it is related to the tritium concentration. During measurement, the ionization chamber is first calibrated using a tritium standard source with known activity to establish a calibration curve between current and tritium activity. Then, the tritium-containing air sample to be tested is injected, the current is measured, and the tritium activity is calculated based on the calibration curve. Finally, the tritium concentration is calculated by combining this with the air volume.

[0003] In related technologies, the ionization method is based on analysis using a fixed voltage. However, other nuclides in the air that undergo β decay can interfere with the measurement of tritium concentration in the ionization method, resulting in low accuracy of the tritium concentration measurement results in the air. Summary of the Invention

[0004] To address the technical problem of low accuracy in measuring tritium concentration in air due to fixed voltage analysis and interference from other nuclides in ionization methods, this invention provides a precise method, system, and device for measuring tritium concentration in air. The specific technical solution adopted is as follows:

[0005] This invention proposes a precise method for measuring tritium concentration in air, the method comprising:

[0006] Obtain the ionization chamber current and the energy spectrum of the semiconductor detector at different times;

[0007] Based on the extreme value distribution and time interval of the ionization chamber current at different times, determine the modification bias index of the ionization chamber voltage at the current time; determine whether to perform ionization chamber voltage correction at the current time based on the modification bias index, and when determining the correction, correct the voltage at the current time based on the current and voltage of the previous correction, the current and modification bias index at the current time, obtain the voltage correction value, and use the voltage correction value as the ionization chamber voltage at the current time.

[0008] In the energy spectrum of two adjacent voltage correction processes, the interfering nuclides are identified based on the peak energy range of the nuclide under test. Based on the energy distribution of different interfering nuclides in the corresponding peak energy range in the energy spectrum, the current contribution ratio of each interfering nuclide during voltage correction is determined.

[0009] By combining the ionization current at the current moment, the current contribution ratio of tritium, and the current contribution ratio of all interfering nuclides, the correction current at the current moment is determined, and the tritium concentration in the air is calculated based on the correction current.

[0010] Furthermore, based on the extreme value distribution and time interval of the ionization chamber current at different times, the modification bias index of the ionization chamber voltage at the current time is determined, including:

[0011] The ionization chamber current at different times was curve-fitted using the least squares method to obtain the current curve;

[0012] Based on the change in current at each moment in the current curve and the nearest extreme value change and time interval, determine the modification bias index of the ionization chamber voltage at the current moment.

[0013] Furthermore, based on the change in current at each moment in the current curve and the time interval between the nearest extreme values, the modification bias index for the ionization chamber voltage at the current moment is determined, including:

[0014] Determine the time interval and current difference between the current data point at the current moment and the nearest extreme point in the current curve;

[0015] The ratio of the current difference to the time interval between the two corresponding moments is used as the fitting slope for the data point at the current moment.

[0016] The ratio of the absolute value of the fitted slope of the data point at the current moment to the maximum absolute value of the fitted slope at all the times is used to obtain the current change index at the current moment.

[0017] The product of the current change index and the time interval is calculated and normalized to serve as the modification bias index for the ionization chamber voltage at the current moment.

[0018] Furthermore, based on the modified bias index, it is determined whether to perform ionization chamber voltage correction at the current moment, including:

[0019] If the modified bias index exceeds the preset modification index threshold, the ionization chamber voltage will be corrected; otherwise, no correction will be made.

[0020] Furthermore, based on the previous corrected current and voltage, the current at the current moment, and the modified bias index, the voltage at the current moment is corrected to obtain the voltage correction value. The corresponding calculation formula is as follows:

[0021] V j =V j-1 ×(1+sig{(I j -I j-1 )×Q i}); where V j-1The voltage value after the (j-1)th voltage correction; I j I j-1 These represent the current magnitudes at the j-th and (j-1)-th corrections, respectively; Q i Let be the modification bias index at time i in the j-th voltage correction; sig{} represents the sigmoid function.

[0022] Furthermore, based on the analysis of the peak energy range of the nuclide to be measured, interfering nuclides were identified, including:

[0023] Obtain the peak energy range in the energy spectrum when different nuclides undergo decay;

[0024] The energy spectrum at the current moment is smoothed by SG, and the maximum points in the smoothed energy spectrum are obtained by differentiation.

[0025] The interfering nuclide is determined by comparing the energy location of the maximum point with the peak energy range of all the nuclides to be tested.

[0026] Furthermore, based on the energy distribution of different interfering nuclides within the corresponding peak energy range in the energy spectrum, the current contribution ratio of each interfering nuclide during voltage correction is determined, including:

[0027] The presence ratio of each interfering nuclide is determined based on the energy value of the interfering nuclide at the maximum count rate within the corresponding peak energy range, and the sum of all count rates of the interfering nuclide within the corresponding peak energy range.

[0028] Based on the proportion of all interfering nuclides present and the energy value at which the maximum count rate of the interfering nuclides is located in the peak energy range, determine the current contribution of each interfering nuclide during voltage correction.

[0029] The method for determining the proportion of each interfering nuclide includes:

[0030] The energy value of the interfering nuclide at the maximum count rate within the corresponding peak energy range is taken as the analytical energy value of the interfering nuclide.

[0031] The difference between the analytical energy value of any interfering nuclide and the minimum analytical energy value of all interfering nuclides is taken as the peak difference;

[0032] The negative of the peak difference is calculated and normalized to obtain the count rate weight;

[0033] The product of the sum of all count rates of the interfering nuclide within the corresponding peak energy range and the count rate weight is used as the proportion of the interfering nuclide's presence.

[0034] The method for determining the proportion of ionization current contribution of each interfering nuclide during voltage correction includes:

[0035] The ratio of the analytical energy value of any interfering nuclide to the maximum analytical energy value of all interfering nuclides is taken as the energy percentage.

[0036] The product of the presence ratio of the interfering nuclide and its energy percentage is used as the additional contribution coefficient; the sum of the additional contribution coefficient and the presence ratio is calculated and normalized to obtain the current contribution ratio.

[0037] Furthermore, by combining the current ionization current, the current contribution ratio of tritium, and the current contribution ratios of all interfering nuclides, the correction current at the current moment is determined, including:

[0038] Calculate the current contribution ratio of tritium and the sum of the current contribution ratios of all interfering nuclides, and use the ratio of the sum to the current contribution ratio of tritium as the current adjustment coefficient.

[0039] The product of the current adjustment factor and the ionization current at the current moment is used as the correction current.

[0040] Secondly, the present invention also provides a precision measurement system for tritium concentration in air, the system including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the aforementioned precision measurement methods for tritium concentration in air.

[0041] Thirdly, the present invention also provides a precision measuring device for tritium concentration in air, comprising:

[0042] The acquisition module is used to acquire the ionization chamber current and the energy spectrum of the semiconductor detector at different times.

[0043] The voltage correction module is used to determine the modification bias index of the ionization chamber voltage at the current moment based on the extreme value distribution and time interval of the ionization chamber current at different times; it determines whether to perform ionization chamber voltage correction at the current moment based on the modification bias index; when determining correction, it corrects the voltage at the current moment based on the current and voltage of the previous correction, the current moment's current and modification bias index, obtains the voltage correction value, and uses the voltage correction value as the ionization chamber voltage at the current moment.

[0044] The current contribution analysis module is used to identify interfering nuclides by analyzing the peak energy range of the nuclide under test in the energy spectrum of two adjacent voltage correction processes; and to determine the current contribution ratio of each interfering nuclide during voltage correction by analyzing the energy distribution of the corresponding peak energy range of different interfering nuclides in the energy spectrum.

[0045] The concentration measurement module is used to determine the correction current at the current moment by combining the ionization current, the current contribution ratio of tritium, and the current contribution ratio of all interfering nuclides, and to calculate the tritium concentration in the air based on the correction current.

[0046] The present invention has the following beneficial effects:

[0047] This invention acquires the ionization chamber current and the energy spectrum of a semiconductor detector. Then, based on the extreme value distribution and time interval of the ionization chamber current, it performs voltage correction bias analysis to achieve voltage correction. Since the voltage magnitude directly affects the generated current magnitude, and thus the tritium concentration detection, this application uses voltage correction for adaptive voltage adjustment. Subsequently, based on the proportion of different nuclides in the energy spectrum obtained at voltage correction intervals, the current obtained in the ionization chamber is adjusted to obtain the most accurate tritium concentration. Specifically, by analyzing the interfering nuclides and based on the peak energy distribution corresponding to the interfering nuclides and the energy fluctuations in the actually measured energy spectrum, the current contribution ratio is analyzed. By analyzing the numerical distribution of the current contribution ratio of tritium and different interfering nuclides, the correction current affected by the tritium concentration at the current moment is determined, and the tritium concentration in the air is calculated based on the correction current. This application corrects the ionization chamber voltage by feedback changes in the ionization chamber current, making its capture of ion pairs more comprehensive. The current obtained in the ionization chamber is adjusted by using the proportion of different nuclides in the energy spectrum obtained by voltage correction interval to remove the interference of interfering nuclides on the ionization chamber method, so that the calculated tritium concentration in the air is more accurate. Attached Figure Description

[0048] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 A flowchart illustrating a method for precise determination of tritium concentration in air, provided as an embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of an ionization chamber model provided in one embodiment of the present invention;

[0051] Figure 3 This is a schematic diagram of a semiconductor detector structure provided in one embodiment of the present invention. Detailed Implementation

[0052] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of a method, system, and apparatus for precise determination of tritium concentration in air according to the present invention. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0053] 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 invention pertains.

[0054] The following description, in conjunction with the accompanying drawings, details the specific scheme of the method for precise determination of tritium concentration in air provided by the present invention.

[0055] Please see Figure 1 The diagram illustrates a flowchart of a method for precise determination of tritium concentration in air according to an embodiment of the present invention. The method includes:

[0056] S101: Obtain the ionization chamber current and the energy spectrum of the semiconductor detector at different times.

[0057] Ionization is a common method for measuring tritium concentration in air. Its principle is based on the beta decay characteristic of tritium; the beta particles released during tritium decay ionize air molecules. The core device, the ionization chamber, is filled with air and equipped with electrodes. When tritium-containing air enters the ionization chamber, the beta particles collide with air molecules, producing ion pairs. An electric field is then applied between the electrodes to collect these ion pairs, forming a current. The magnitude of this current is related to the number of beta particles produced by tritium decay, i.e., it is related to the tritium concentration.

[0058] During measurement, the ionization chamber is first calibrated using a tritium standard source with known activity to establish a calibration curve between current and tritium concentration. Then, the tritium-containing air sample to be tested is injected, the current is measured, and the tritium activity is calculated based on the calibration curve. Finally, the tritium concentration is calculated by combining this with the air volume. This invention determines the actual tritium concentration in the air by adjusting the ionization voltage and combining the ionization method with energy dispersive spectroscopy.

[0059] Connect the two electrodes of the ionization chamber to a sensitive current measurement circuit. Control the temperature of the ionization chamber at 20±5℃, while monitoring the air pressure to maintain it in a stable state close to standard atmospheric pressure.

[0060] The required air is placed into the ionization chamber, a voltage is applied to the ionization chamber, and the real-time current is monitored by a current measuring instrument to obtain the ionization chamber current at different times. It should be noted that the time in the embodiments of the present invention specifically refers to the periodic sampling time, that is, the current value of the sampling time can be set at fixed intervals, such as 0.01 seconds, and there is no limitation thereto. For the sake of simplicity, it will be referred to as "time" below.

[0061] See Figure 2 This is a schematic diagram of an ionization chamber model provided in an embodiment of the present invention. The ionization chamber includes a sealed cavity, with an inlet and an outlet on one side to achieve vacuuming of the sealed cavity and injection of the gas to be tested. The other side of the ionization chamber is provided with a lead end for connecting to the controller. A fixing frame is provided inside the ionization chamber near the lead end, and an electrode connected to the lead end is provided on the fixing frame. The motor transmits power through an external high-voltage device to electrolyze the gas in the sealed cavity, and the charge after electrolysis is detected by an electrometer connected to the lead end inside the ionization chamber and fed back to the controller.

[0062] To ensure the stability of the motor and the impact of possible electric arcing at the wiring terminals on charge detection, the mounting bracket includes a mounting plate and a support. The electrode is mounted on the mounting plate, which is equipped with a shield that can cover the electrode wiring terminals. The electrometer is positioned near the electrode end to ensure the accuracy of the detection. To ensure the safety of the ionization chamber, an insulating layer is provided between the support and the inner wall of the sealed cavity.

[0063] A semiconductor detector is placed next to the ionization chamber, and the signal acquisition system is activated for measurement. During the measurement, a multichannel pulse amplitude analyzer automatically records the count rate of different energy signals. After the measurement, these data are exported from the multichannel pulse amplitude analyzer by computer software, and an energy spectrum is plotted with energy as the x-axis and count rate as the y-axis. The semiconductor detector has two electrodes, with a certain bias voltage applied. When an incident particle enters the sensitive region of the semiconductor detector, an electron-hole pair is generated. After a voltage is applied to the electrodes, charge carriers drift towards the electrodes, inducing charges on the collecting electrodes, thus forming a signal pulse in the external circuit. See also Figure 3 , Figure 3 This is a schematic diagram of a semiconductor detector structure provided in one embodiment of the present invention.

[0064] S102: Based on the extreme value distribution and time interval of the ionization chamber current at different times, determine the modification bias index of the ionization chamber voltage at the current time; determine whether to perform ionization chamber voltage correction at the current time based on the modification bias index, and when determining the correction, correct the voltage at the current time based on the current and voltage of the previous correction, the current and modification bias index at the current time, obtain the voltage correction value, and use the voltage correction value as the ionization chamber voltage at the current time.

[0065] The basic working principle of an ionization chamber is based on the ionization of gas by radiation. When tritium undergoes beta decay and releases beta particles, these particles collide with gas molecules within the ionization chamber, causing the gas molecules to ionize and produce ion pairs (positive and negative ions). When a voltage is applied between the two electrodes of the ionization chamber, the ion pairs move towards the electrodes under the influence of the electric field, thus forming an ionization current.

[0066] The voltage level affects the collection efficiency of ion pairs. At lower voltages, ion pairs move slowly under the influence of the electric field, and some ion pairs may recombine during their movement, resulting in fewer collected ion pairs than actually generated, thus lowering the measured ionization current. If the voltage is too high, exceeding the saturation region, the electric field strength within the ionization chamber becomes extremely high, leading to gas amplification. In this case, ions gain sufficient energy to collide with and ionize other gas molecules, generating more ion pairs, causing the ionization current to no longer be proportional to the tritium concentration. The measured ionization current then increases abnormally due to gas amplification, resulting in an inaccurate measurement of tritium concentration. Therefore, to ensure a more accurate reflection of tritium concentration by the ionization chamber, the voltage should be corrected based on the real-time current conditions.

[0067] Furthermore, in some embodiments of the present invention, the modification bias index of the ionization chamber voltage at the current moment is determined based on the extreme value distribution and time interval of the ionization chamber current at different times, including: performing curve fitting on the ionization chamber current at different times based on the least squares method to obtain the current curve; and determining the modification bias index of the ionization chamber voltage at the current moment based on the change and time interval between the current and the nearest extreme value at each moment in the current curve.

[0068] In this embodiment of the invention, the least squares method is a well-known algorithm in the art, and curve fitting can be performed based on the least squares method. Further limitations and elaborations are not provided. It should be noted that in other embodiments of the invention, the currently acquired current curve can be smoothed using the SG smoothing algorithm to facilitate subsequent data analysis based on the current curve. For signals with a certain degree of smoothness and continuity, such as spectral data and chromatographic data, the SG smoothing algorithm typically achieves good smoothing results.

[0069] After determining the current curve, we can analyze the extreme values ​​in the current curve and obtain the extreme points of the smoothed curve by taking the derivative. That is, the greater the change in extreme values, the more necessary the corresponding modifications are to achieve a stabilizing effect.

[0070] Therefore, in some other embodiments of the present invention, the modification bias index of the ionization chamber voltage at the current moment is determined based on the change in current at each moment and the nearest extreme value and the time interval in the current curve. This includes: determining the time interval and current difference between the data point at the current moment and the nearest extreme value in the current curve; using the ratio of the current difference to the time interval between the corresponding two moments as the fitting slope of the data point at the current moment; calculating the ratio of the absolute value of the fitting slope of the data point at the current moment to the maximum absolute value of the fitting slope corresponding to all moments to obtain the current change index at the current moment; and calculating the product of the current change index and the time interval, and normalizing it as the modification bias index of the ionization chamber voltage at the current moment.

[0071] The current difference can be specifically defined as the difference between the current value at the current moment and the current value at the extreme point. The bias modification index represents the bias modification; that is, the larger the value of the bias modification index, the more voltage correction is needed at the current moment. In this embodiment of the invention, current difference analysis can be achieved through slope changes, and the corresponding calculation formula can be, for example, as follows:

[0072]

[0073] Where max{|k|} is the maximum absolute value of the fitted slope obtained at all times, |k i | represents the absolute value of the fitted slope at the current time i, t i The time interval between the data point at time i and the nearest extreme point is represented by norm, where norm represents linear normalization, and Q represents the time interval between the data point at time i and the nearest extreme point. i This indicates the bias index for modifying the voltage of ionization chamber i at the current moment.

[0074] In the formula, A larger value indicates a greater change in current, meaning a more significant increase or decrease in the number of ion pairs produced by the β decay of the gas in the ionization chamber. i The larger the value, the longer the trend of increasing or decreasing gas current is maintained. In order to ensure that the voltage of the ionization chamber is appropriate to capture the current generated by the current β decay, the voltage of the ionization chamber should be corrected in time. Therefore, the larger the value of the bias index, the more normalized it is by norm, so that it has the same dimension and is convenient for subsequent analysis.

[0075] Determine whether to perform ionization chamber voltage correction at the current moment based on the modified bias index, including:

[0076] If the modified bias index exceeds the preset modification index threshold, the ionization chamber voltage will be corrected; otherwise, no correction will be made.

[0077] The preset modification threshold is a threshold value for modifying the bias index. Optionally, it can be 0.7. That is to say, when the modification bias index is greater than 0.7, it is determined that the ionization chamber voltage needs to be corrected, and when the modification bias index is less than or equal to 0.7, it is determined that the ionization chamber voltage does not need to be corrected.

[0078] When no correction is needed for the ionization chamber voltage, the original voltage is used directly for detection. However, when correction is required, the corrected voltage data needs to be re-analyzed.

[0079] Furthermore, in some embodiments of the present invention, the voltage at the current moment is corrected based on the previously corrected current and voltage, the current at the current moment, and the modified bias index to obtain a voltage correction value. The corresponding calculation formula is as follows:

[0080] V j =V j-1 ×(1+sig{(I j -I j-1 )×Q i});

[0081] Among them, V j-1 The voltage value after the (j-1)th voltage correction; I j I j-1 These represent the current magnitudes at the j-th and (j-1)-th corrections, respectively; Q i Let be the modification bias index at time i in the j-th voltage correction; sig{} represents the sigmoid function.

[0082] In the formula, (I j -I j-1 ), Q i A larger value indicates a greater increase in current. To avoid the ion pairs moving slowly under the influence of the electric field due to a relatively small voltage, some ions recombine during their movement, resulting in fewer collected ion pairs than actually generated, thus causing the measured ionization current to be smaller, the voltage should be increased. (I) j -I j-1 The smaller the value of Q, the better. i The larger the voltage, the greater the reduction in current. To avoid gas amplification and the formation of more ion pairs, which would affect the determination of tritium concentration, the voltage should be reduced.

[0083] Therefore, in this embodiment of the invention, a voltage correction step is defined to adaptively adjust the voltage data according to the state change, obtain the voltage correction value, and use the voltage correction value as the ionization chamber voltage at the current moment.

[0084] S103: In the energy spectrum of two adjacent voltage correction processes, the interfering nuclides are identified based on the peak energy range of the nuclide to be measured; based on the energy distribution of different interfering nuclides in the corresponding peak energy range in the energy spectrum, the current contribution ratio of each interfering nuclide during voltage correction is determined.

[0085] It is understandable that voltage correction is not required at every moment. Therefore, the data from two adjacent voltage correction processes are more reliable in terms of specific parameters and less affected by interference. Thus, two adjacent voltage correction processes are used as the statistical period for interfering nuclide analysis to reduce the impact of statistical fluctuations.

[0086] In this embodiment of the invention, the peak energy range of a known nuclide to be tested can be compared with the energy range in the energy spectrum to determine the radioactive interfering nuclides that may be present in the air at the current moment.

[0087] Furthermore, in some embodiments of the present invention, the interference nuclide is determined based on the peak energy range analysis of the nuclide to be tested, including: obtaining the peak energy range of different nuclides to be tested when they decay in the energy spectrum; performing SG smoothing on the energy spectrum at the current moment, and obtaining the maximum point in the smoothed energy spectrum based on differentiation; and determining the interference nuclide by comparing the energy position of the maximum point with the peak energy range corresponding to all nuclides to be tested.

[0088] It is understandable that when performing tritium concentration detection, the nuclides that may cause interference could be, for example, cesium-137, strontium-90, iodine-131, etc. These nuclides are all known nuclides, and the types of nuclides that may cause interference are also relatively common. Therefore, all types of nuclides that may cause interference can be directly obtained as the nuclides to be tested, and the peak energy range corresponding to each type of nuclide to be tested can be determined. This is a well-known technique and will not be elaborated on here.

[0089] The acquisition of the maximum point is well known to those skilled in the art. By comparing the energy position of the maximum point with the peak energy range of all the nuclides to be tested, the comparison process can be specifically, for example, an overlap comparison. That is, if the peak energy range of a certain nuclide to be tested coincides with the energy position corresponding to the maximum point in the energy spectrum, then the nuclide to be tested can be determined to be an interfering nuclide.

[0090] If the energy position corresponding to a certain nuclide to be tested does not coincide with the energy position corresponding to the maximum point in the energy spectrum, for example, if the energy position corresponding to the maximum point in the energy spectrum is 2 MeV, while the peak energy range of cesium-137 is 1.173 to 1.332 MeV (known), then cesium-137 is not an interfering nuclide.

[0091] After identifying the interfering nuclide, the current contribution ratio can be analyzed. Different interfering nuclides will generate corresponding current interference, meaning that the obtained current value is affected by these interfering nuclides. Therefore, the current contribution analysis is performed based on the count rate of the energy within the peak energy range corresponding to the interfering nuclide.

[0092] Furthermore, in some embodiments of the present invention, based on the energy distribution of different interfering nuclides in the corresponding peak energy range of the energy spectrum, the current contribution ratio of each interfering nuclide during voltage correction is determined, as shown in steps S201-S202:

[0093] S201: Determine the presence ratio of each interfering nuclide based on the energy value of the interfering nuclide at the maximum count rate within the corresponding peak energy range, and the sum of all count rates of the interfering nuclide within the corresponding peak energy range.

[0094] The method for determining the presence ratio of each interfering nuclide includes: taking the energy value of the interfering nuclide at the maximum count rate within the corresponding peak energy range as the analytical energy value of the interfering nuclide; taking the difference between the analytical energy value of any interfering nuclide and the minimum analytical energy value of all interfering nuclides as the peak difference; calculating the negative of the peak difference and normalizing it to obtain the count rate weight; and taking the product of the sum of all count rates of the interfering nuclide within the corresponding peak energy range and the count rate weight as the presence ratio of the interfering nuclide.

[0095] It is understandable that the higher the sum of the count rates of radioactive nuclides within their corresponding peak energy ranges, the greater the concentration of radioactive nuclides in the air. However, since detectors have varying detection efficiencies for different energies, they are less efficient at detecting lower-energy rays. To better represent the proportion of different radioactive nuclides in the air, the sum of the count rates of different nuclides within their peak energy ranges should be weighted by the energy value of their maximum count rate within that range. In other words, the energy value of the interfering nuclide at its maximum count rate within its corresponding peak energy range should be used as the analytical energy value for the interfering nuclide.

[0096] Then, the count rate weight is determined by the peak difference. The smaller the peak difference, the smaller the detection efficiency of the interfering nuclide corresponding to this energy, the larger the actual count rate should be, and the larger the proportion of radioactive nuclide in the air (i.e., the existence ratio). Therefore, the negative of the peak difference is calculated and normalized to obtain the count rate weight. The product of the sum of all count rates of the interfering nuclide in the corresponding peak energy range and the count rate weight is taken as the existence ratio of the interfering nuclide.

[0097] S202: Based on the presence ratio of all interfering nuclides and the energy value of the maximum count rate of the interfering nuclides in the peak energy range, determine the current contribution ratio of each interfering nuclide during voltage correction.

[0098] The method for determining the current contribution ratio of each interfering nuclide during voltage correction includes: taking the ratio of the analytical energy value of any interfering nuclide to the maximum analytical energy value of all interfering nuclides as the energy ratio; taking the product of the presence ratio of the interfering nuclide and the energy ratio as the additional contribution coefficient; calculating the sum of the additional contribution coefficient and the presence ratio, and normalizing it as the current contribution ratio.

[0099] The greater the energy of the interfering nuclide during decay, the more gas in the ionization chamber will be ionized, resulting in more ion pairs and a greater contribution to the ionization current. Therefore, when correcting the current in the ionization chamber based on the proportion of each interfering nuclide and calculating the tritium concentration, the contribution of the energy generated during the decay of different interfering nuclides to the ionization current should also be considered.

[0100] Therefore, in this embodiment of the invention, energy analysis is performed by calculating the energy ratio, and the product of the presence ratio of the interfering nuclide and the energy ratio is used as the additional contribution coefficient; the sum of the additional contribution coefficient and the presence ratio is calculated and normalized to obtain the current contribution ratio.

[0101] This current contribution ratio can accurately characterize the proportion of the influence of interfering nuclides on the current. It should be noted that this calculation process can not only calculate different interfering nuclides, but also calculate the current contribution ratio of tritium itself, so as to facilitate subsequent tritium concentration analysis based on the calculation results.

[0102] S104: Combine the current ionization current, the current contribution ratio of tritium, and the current contribution ratio of all interfering nuclides to determine the corrected current at the current moment, and calculate the tritium concentration in the air based on the corrected current.

[0103] After determining the current contribution ratios of all interfering nuclides and tritium, the correction current for the current moment can be determined by combining it with the ionization current at the current moment.

[0104] Furthermore, by combining the current ionization current, the current contribution ratio of tritium, and the current contribution ratios of all interfering nuclides, the correction current at the current moment is determined, including: calculating the sum of the current contribution ratios of tritium and all interfering nuclides, and using the ratio of the sum to the current contribution ratio of tritium as the current adjustment coefficient; and using the product of the current adjustment coefficient and the current ionization current as the correction current.

[0105] By using proportional analysis, a current adjustment coefficient contributing to the tritium generation current is determined. The product of this current adjustment coefficient and the current ionization current is then used as the correction current. This correction current represents the current generated by tritium emission, thus enabling tritium concentration analysis.

[0106] In the controller, the measured correction current value is substituted into the correspondence between ionization current and tritium concentration obtained during the ionization chamber calibration (i.e., the calibration curve of current and tritium concentration) to calculate the tritium concentration in the air.

[0107] This invention acquires the ionization chamber current and the energy spectrum of a semiconductor detector. Then, based on the extreme value distribution and time interval of the ionization chamber current, it performs voltage correction bias analysis to achieve voltage correction. Since the voltage magnitude directly affects the generated current magnitude, and thus the tritium concentration detection, this application uses voltage correction for adaptive voltage adjustment. Subsequently, based on the proportion of different nuclides in the energy spectrum obtained at voltage correction intervals, the current obtained in the ionization chamber is adjusted to obtain the most accurate tritium concentration. Specifically, by analyzing the interfering nuclides and based on the peak energy distribution corresponding to the interfering nuclides and the energy fluctuations in the actually measured energy spectrum, the current contribution ratio is analyzed. By analyzing the numerical distribution of the current contribution ratio of tritium and different interfering nuclides, the correction current affected by the tritium concentration at the current moment is determined, and the tritium concentration in the air is calculated based on the correction current. This application corrects the ionization chamber voltage by feedback changes in the ionization chamber current, making its capture of ion pairs more comprehensive. The current obtained in the ionization chamber is adjusted by using the proportion of different nuclides in the energy spectrum obtained by voltage correction interval to remove the interference of interfering nuclides on the ionization chamber method, so that the calculated tritium concentration in the air is more accurate.

[0108] Secondly, the present invention also provides a precision measurement system for tritium concentration in air, the system including a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the steps of any of the aforementioned precision measurement methods for tritium concentration in air.

[0109] Thirdly, the present invention also provides a precision measuring device for tritium concentration in air, comprising:

[0110] The system comprises the following modules: an acquisition module for acquiring the ionization chamber current and the energy spectrum of the semiconductor detector at different times; a voltage correction module for determining the modification bias index of the ionization chamber voltage at the current time based on the extreme value distribution and time interval of the ionization chamber current at different times; a voltage correction module for determining whether to perform ionization chamber voltage correction at the current time based on the modification bias index; a voltage correction value for the current time based on the current and voltage of the previous correction, the current time and the modification bias index; a current contribution analysis module for identifying interfering nuclides based on the peak energy range of the nuclide under test in the energy spectrum of two adjacent voltage correction processes; a current contribution ratio for each interfering nuclide during voltage correction based on the energy distribution of the corresponding peak energy range in the energy spectrum; and a concentration measurement module for determining the correction current at the current time by combining the ionization current, the current contribution ratio of tritium, and the current contribution ratio of all interfering nuclides, and calculating the tritium concentration in the air based on the correction current.

[0111] The provided device for precise measurement of tritium concentration in air is used to implement the steps of any of the aforementioned methods for precise measurement of tritium concentration in air.

[0112] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0113] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A precise method for determining the concentration of tritium in air, characterized in that, The methods include: Obtain the ionization chamber current and the energy spectrum of the semiconductor detector at different times; Based on the extreme value distribution and time interval of the ionization chamber current at different times, determine the modification bias index of the ionization chamber voltage at the current time; determine whether to perform ionization chamber voltage correction at the current time based on the modification bias index, and when determining the correction, correct the voltage at the current time based on the current and voltage of the previous correction, the current and modification bias index at the current time, obtain the voltage correction value, and use the voltage correction value as the ionization chamber voltage at the current time. Based on the analysis of the peak energy range of the nuclide to be measured in the energy spectrum of two consecutive voltage correction processes, the interfering nuclides are identified. Based on the energy distribution of different interfering nuclides in the corresponding peak energy range of the energy spectrum, determine the current contribution ratio of each interfering nuclide during voltage correction. By combining the ionization current at the current moment, the current contribution ratio of tritium, and the current contribution ratio of all interfering nuclides, the correction current at the current moment is determined, and the tritium concentration in the air is calculated based on the correction current.

2. The method for precise determination of tritium concentration in air as described in claim 1, characterized in that, Based on the extreme value distribution and time interval of the ionization chamber current at different times, determine the modification bias index of the ionization chamber voltage at the current time, including: The ionization chamber current at different times was curve-fitted using the least squares method to obtain the current curve; Based on the change in current at each moment in the current curve and the nearest extreme value change and time interval, determine the modification bias index of the ionization chamber voltage at the current moment.

3. The method for precise determination of tritium concentration in air as described in claim 2, characterized in that, Based on the change in current at each moment in the current curve and the time interval between the nearest extreme values, the modification bias index of the ionization chamber voltage at the current moment is determined, including: Determine the time interval and current difference between the current data point at the current moment and the nearest extreme point in the current curve; The ratio of the current difference to the time interval between the two corresponding moments is used as the fitting slope for the data point at the current moment. The ratio of the absolute value of the fitted slope at the current time point to the maximum absolute value of the fitted slope at all times is used to obtain the current change index at the current time point. The product of the current change index and the time interval is calculated and normalized to serve as the modification bias index for the ionization chamber voltage at the current moment.

4. The method for precise determination of tritium concentration in air as described in claim 1, characterized in that, Determine whether to perform ionization chamber voltage correction at the current moment based on the modified bias index, including: If the modified bias index exceeds the preset modification index threshold, the ionization chamber voltage will be corrected; otherwise, no correction will be made.

5. The method for precise determination of tritium concentration in air as described in claim 1, characterized in that, Based on the previously corrected current and voltage, the current at the current moment, and the modified bias index, the voltage at the current moment is corrected to obtain the voltage correction value. The corresponding calculation formula is as follows: V j =V j-1 ×(1+sig{(I j -I j-1 )×Q i }); Among them, V j-1 The voltage value after the (j-1)th voltage correction; I j , I j-1 These represent the current magnitudes at the j-th and (j-1)-th corrections, respectively; Q i Let be the modification bias index at time i in the j-th voltage correction; sig{} represents the sigmoid function.

6. The method for precise determination of tritium concentration in air as claimed in claim 1, characterized in that, Based on the analysis of the peak energy range of the nuclide to be measured, the interfering nuclides were identified, including: Obtain the peak energy range in the energy spectrum when different nuclides undergo decay; The energy spectrum at the current moment is smoothed by SG, and the maximum points in the smoothed energy spectrum are obtained by differentiation. The interfering nuclide is determined by comparing the energy location of the maximum point with the peak energy range of all the nuclides to be tested.

7. The method for precise determination of tritium concentration in air as described in claim 1, characterized in that, Based on the energy distribution of different interfering nuclides within the corresponding peak energy range in the energy spectrum, the current contribution ratio of ionization for each interfering nuclide during voltage correction is determined, including: The presence ratio of each interfering nuclide is determined based on the energy value of the interfering nuclide at the maximum count rate within the corresponding peak energy range, and the sum of all count rates of the interfering nuclide within the corresponding peak energy range. Based on the proportion of all interfering nuclides present and the energy value at which the maximum count rate of the interfering nuclides is located in the peak energy range, determine the current contribution of each interfering nuclide during voltage correction. The method for determining the proportion of each interfering nuclide includes: The energy value of the interfering nuclide at the maximum count rate within the corresponding peak energy range is taken as the analytical energy value of the interfering nuclide. The difference between the analytical energy value of any interfering nuclide and the minimum analytical energy value of all interfering nuclides is taken as the peak difference; The negative of the peak difference is calculated and normalized to obtain the count rate weight; The product of the sum of all count rates of the interfering nuclide within the corresponding peak energy range and the count rate weight is used as the proportion of the interfering nuclide's presence. The method for determining the proportion of ionization current contribution of each interfering nuclide during voltage correction includes: The ratio of the analytical energy value of any interfering nuclide to the maximum analytical energy value of all interfering nuclides is taken as the energy percentage. The product of the presence ratio of the interfering nuclide and its energy percentage is used as the additional contribution coefficient; the sum of the additional contribution coefficient and the presence ratio is calculated and normalized to obtain the current contribution ratio.

8. The method for precise determination of tritium concentration in air as claimed in claim 1, characterized in that, Based on the current ionization current, the current contribution ratio of tritium, and the current contribution ratios of all interfering nuclides, the corrected current at the current moment is determined, including: Calculate the current contribution ratio of tritium and the sum of the current contribution ratios of all interfering nuclides, and use the ratio of the sum to the current contribution ratio of tritium as the current adjustment coefficient. The product of the current adjustment factor and the ionization current at the current moment is used as the correction current.

9. A precision measurement system for tritium concentration in air, the system comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes a computer program, it implements the steps of the method as described in any one of claims 1 to 8.

10. A precision measuring device for tritium concentration in air, characterized in that, include: The acquisition module is used to acquire the ionization chamber current and the energy spectrum of the semiconductor detector at different times. The voltage correction module is used to determine the modification bias index of the ionization chamber voltage at the current moment based on the extreme value distribution and time interval of the ionization chamber current at different times; it determines whether to perform ionization chamber voltage correction at the current moment based on the modification bias index; when determining correction, it corrects the voltage at the current moment based on the current and voltage of the previous correction, the current moment's current and modification bias index, obtains the voltage correction value, and uses the voltage correction value as the ionization chamber voltage at the current moment. The current contribution analysis module is used to identify interfering nuclides by analyzing the peak energy range of the nuclide under test in the energy spectrum of two adjacent voltage correction processes. Based on the energy distribution of different interfering nuclides in the corresponding peak energy range of the energy spectrum, determine the current contribution ratio of each interfering nuclide during voltage correction. The concentration measurement module is used to determine the correction current at the current moment by combining the ionization current, the current contribution ratio of tritium, and the current contribution ratio of all interfering nuclides, and to calculate the tritium concentration in the air based on the correction current.

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