System and method for determining mass fraction in test samples using wavelength dispersive X-ray fluorescence spectrometry

Abstract

This invention discloses a system, method, and computer program product for determining the mass fraction of one or more elements in a test sample based on measurements performed by a wavelength dispersive X-ray fluorescence spectrometer (WDX spectrometer), which measures the total intensity associated with the corresponding element in the test sample having a mass fraction to be determined. A mass fraction module determines the mass fraction using a calibration formula with the measured total intensity and a correspondingly calculated scattering efficiency as input. The elemental composition of the test sample is determined in either of the following ways: via an iterative module adapted to iteratively determine a mass fraction estimate of the specific elemental composition based on the measured total intensity associated with the element in the test sample; or via an EDX quantization module adapted to obtain a mass fraction estimate of the specific elemental composition based on quantization using an energy-dispersive X-ray detector.

Description

Technical Field

[0001] This invention relates generally to wavelength dispersive X-ray fluorescence spectroscopy, and more specifically to determining the mass fraction of an element in a test sample from the spectrum of a wavelength dispersive X-ray fluorescence (WDX) spectrometer. The terms "mass fraction of an element" and "concentration of an element" are used as synonyms herein. Background Technology

[0002] In wavelength dispersive X-ray fluorescence (WDX) spectroscopy, an X-ray tube produces polychromatic primary radiation, including characteristic lines from the tube material and bremsstrahlung. This primary radiation is directed onto the sample to be analyzed. The primary radiation produces X-ray fluorescence (XRF) emission characterizing the elements contained in the sample. Additionally, the primary radiation is scattered by the sample. The radiation from the sample (secondary radiation) is dispersed by a monochromator (usually a crystal) at the center of a goniometer, allowing for various diffraction angles θ. This technique is based on Bragg's law (Equation F1):

[0003] nλ = 2d sinθ, (F1)

[0004] Where n is the diffraction order, λ is the wavelength, and d is the lattice plane distance of the monochromator.

[0005] Wavelength can be converted into energy using formula F2:

[0006]

[0007] To quantify the concentration c (mass fraction) of a specific element in an unknown sample, the characteristic fluorescence intensity I of the element must be correlated with the element's concentration via a conversion factor (slope) a:

[0008] c = aI 净 (F3)

[0009] Additional corrections may be present in Equation F3, such as overlap and / or matrix corrections (known to those skilled in the art), which will not be discussed here for simplicity. In the calibration procedure, a conversion factor (and potential other correction factors) is determined, wherein a calibration sample with a known concentration (mass fraction) of the analyte is measured, and the conversion factor is adjusted such that the mass fraction calculated from the measured intensity using Equation F3 best matches the known mass fraction of the calibration sample.

[0010] However, in the spectra of an XRF spectrometer, the characteristic fluorescence intensity of an element is superimposed with other intensities known as the background. The correlated net intensity (Ig) of a specific element... 净 The intensity (I) can be measured from the peak position of the corresponding fluorescence line of the element. 峰 Subtract background (I) 背景 To determine:

[0011] I 净 =I 峰 -I 背景 (F4)

[0012] Since the background beneath the peak is not directly available, it is interpolated or extrapolated based on the intensity measured before and / or after the corresponding peak.

[0013] While spectrometers can scan a wide range of angles to produce spectra of test samples, in practical applications, it is desirable to measure only a single point to obtain good accuracy in the shortest possible time. In other words, many applications (e.g., WDX spectroscopy used in steel production) are time-critical to avoid the need to halt the production line while waiting for measurements and evaluations of product composition. However, in addition to the intensity at the peak location, the extra point of background intensity needs to be measured using existing techniques, thus increasing the total measurement time.

[0014] Another problem with existing methods when using background points is finding regions in the spectrum where the background intensity can be determined without interference, because multiple characteristic fluorescence peaks of various elements in the test sample often exist near the peak to be analyzed, thus obscuring the background intensity. To overcome this problem, existing methods typically increase the resolution of the measurement by using a different crystal (e.g., LiF220 instead of LiF200) or by using a smaller collimator that limits the angular divergence of the beam impacting the monochromator. However, both of these methods significantly reduce the overall intensity, thus again increasing the total measurement time.

[0015] Feather and Willis published an alternative prior art method to remedy this problem in 1976 in the following literature: “A simple method for background and matrix correction of spectral peaks intrace element determination by X-ray fluorescence spectrometry. X-RaySpectrom., 5: 41-48. https: / / doi.org / 10.1002 / xrs.1300050110”. This method uses the measured background intensity of a blank (a calibration sample without the analyte) and corrects for these matrix effects by calculating the mass absorption coefficient or by measuring the Compton scattering line. That is, this method calculates the sample-specific background by using a dedicated sample (a blank sample) without the analyte during calibration. Therefore, this increases the workload required during calibration and evaluation. Furthermore, it only applies when blank samples are readily available. Summary of the Invention

[0016] Therefore, there is a need for systems and methods that provide the mass fraction of one or more elements in a test sample using wavelength dispersive X-ray fluorescence spectrometry, minimizing measurement time with minimal effort during calibration and evaluation. In particular, in time-critical production processes (e.g., steel production), there is a need to reduce the measurement time for determining such mass fractions to the shortest possible time interval. This problem is addressed by the features according to the independent claim, which reduce the total measurement time required to evaluate unknown samples by eliminating the need for measuring background points. Furthermore, the invention protected by the claims allows the use of a lower-resolution WDX spectrometer, thus further allowing for higher total intensity and shorter measurement time.

[0017] In WDX spectroscopy, the background is mainly from the scattered radiation (Ix) from the X-ray tube on the sample. 散射 ):

[0018] I 背景 =bI 散射 (F5)

[0019] Where b is a scaling factor for the spectrometer's equipment parameters, taking into account the given instrument geometry.

[0020] The method disclosed herein is based on calculated scattered radiation using sample composition (i.e., the elemental composition of the sample, specified by the mass fractions of the elements contained in the sample) as the basis for calculation. The sample composition can be determined by using an iterative procedure or by measuring the sample using an additional energy-dispersive X-ray (EDX) detector, as described in further detail below.

[0021] For a given incident intensity (I) 入射 The intensity of the scattered radiation can be calculated using the following formula, considering the energy (E) and sample composition (c):

[0022] I 散射 =I 入射 s(c, E) (F6)

[0023] Where s represents a function for calculating scattering efficiency, which is defined as the ratio between the incident intensity and the scattered intensity for a given sample composition and energy (given instrument geometry).

[0024] The mass fraction c of a specific element i is determined using the calibration formula F3 described above. i Conclusion:

[0025] c i =a i I 净，i =a i (I 峰，i -I背景，i )

[0026] =a i (I 峰，i -b i I 散射，i )

[0027] =a i (I 峰，i -b i I 入射，i s(c, E) i (F7)

[0028] Because of I 入射，i Independent of sample composition, it can be compared with calibration parameter b i Combine to form:

[0029] c i =a i (I 峰i -d i s(c, E)) (F8)

[0030] Where d i =b i I 入射，i Therefore, c i Indicates the relationship with fluorescence intensity I 净，i The concentration (mass fraction) of the associated single element i, while c represents the concentration of all elements in the sample.

[0031] The calibration parameters for Formula F8 are determined during the calibration process, which is performed before the mass fraction in the test samples is determined. During the calibration process, the scattering efficiency s for each calibration sample is calculated, and an additional correction parameter (d) is adjusted along with other correction parameters. i In other words, the calibration parameters are adjusted to ultimately determine calibration formula F8. In the example above, parameter a is adjusted. i and d i Perform the adjustment. For calibration, use a sample with known sample properties. These properties primarily reflect the concentration (mass fraction) of the elemental composition of the calibration sample, but other properties such as sample geometry and density can also be useful. Then, during the evaluation of the test sample, the mass fraction of the test sample is determined using calibration formula F8 with fixed parameters.

[0032] It should be noted that Equation F8 shows a simplified model formula, in which only two relevant parameters, a and d, are shown. However, in practice, such model formulas for X-ray fluorescence (XRF) are usually much more complex.

[0033] c i =a i (I净，i +∑ j o ij c j )(1+∑ j α ij c j (F9)

[0034] Among them o ij It is the concentration-based overlap correction factor of element j on element i, α ij These are the Lachance-Traill matrix correction coefficients of element j on element i. These corrections can also be calculated based on the intensities of other elements or from the sample composition. The method disclosed herein is applicable to all standard-based models and / or empirical models of XRF using net intensity. The prior art calibration formula is described in the chapter "APPLICATION OF THE ALGORITHM OF STANDARD COMPARISON TOSEVERAL STANDARD SAMPLES" of Broll et al.'s paper "Matrix correction in x-ray fluorescence analysis by the effective coefficient method" (January / February 1992, https: / / doi.org / 10.1002 / xrs.1300210111).

[0035] In one embodiment, a computer-implemented method is provided for determining the mass fraction of one or more elements in a test sample based on measurements performed by a wavelength dispersive x-ray fluorescence (WDX) spectrometer. This method can be performed by a computer system implementation having modules configured to perform the steps of the computer-implemented method. This is achieved by a computer program product implementation having computer-readable instructions that, when loaded into the memory of a computer system and executed by at least one processor of the computer system, cause the computer system to perform the computer-implemented method disclosed herein. In other words, the computer program product defines the functionality performed by the corresponding modules of the computer system.

[0036] A WDX spectrometer measures one or more total intensities associated with one or more elements in a test sample having one or more mass fractions to be determined. In practical applications, the number of mass fractions to be determined can vary significantly. In some applications, it is necessary to determine the entire elemental composition of the test sample (e.g., all elements including trace elements). In other applications, it is sufficient to determine the concentration of a single specific element or subset of elements in the test sample. The WDX measurements are then received by a computer system for sample evaluation. The computer system can be implemented as an integrated component of the WDX spectrometer, or it can be communicatively coupled to the WDX spectrometer, allowing the measurements to be received via standard data communication devices.

[0037] The computer system then determines each of one or more mass fractions to be determined by using a calibration formula with the corresponding measured total intensity and the corresponding calculated scattering efficiency as input. The calibration formula has a set of calibration parameters obtained from a previous calibration step using one or more calibration samples with known elemental compositions. The calculated scattering efficiency depends on the energy of the fluorescence line of the corresponding element and the specific elemental composition of the test sample. The calibration formula correlates the net intensity of the characteristic fluorescence line of the sample element with the corresponding mass fraction, as shown in the exemplary formula F9. Thus, the net intensity of a specific peak is obtained by subtracting the corresponding calculated scattering efficiency time d from the measured total intensity of the specific peak. i The specific elemental composition of the test sample used to calculate the scattering efficiency can be determined by the system's elemental composition module using an alternative implementation of the following alternative embodiments.

[0038] In a first alternative embodiment, the iterative module is used to iteratively determine a mass fraction estimate of a particular elemental composition based on the measured total intensity associated with elements in the test sample.

[0039] Initialize the current mass fraction estimate of the element in the test sample with any value. For example, such an initial value for the corresponding concentration could be set to... Where i = 1...n. Then, for each total intensity associated with the mass fraction to be determined, the iterative module uses the current mass fraction estimate to calculate the energy of the fluorescence line of the corresponding element to calculate the corresponding scattering efficiency.

[0040] The iterative module then uses the calibration formula (by keeping the calibration parameters constant) to calculate one or more undetermined mass fractions as estimates of the current mass fraction. For example, when using calibration formula F9, d i a i o ij and α ij Keep it fixed.

[0041] The calculation step is repeated if the difference between one or more quality scores to be determined in the most recent iteration and the corresponding one or more quality scores to be determined in the previous iteration exceeds a predefined threshold. In other words, after each iteration, the iterative module checks whether the quality score value calculated in the most recent iteration shows a change relative to the previous iteration that is greater than the predefined threshold. Therefore, the same threshold can be used for all quality scores. Alternatively, element-specific thresholds can be used. As long as the deviation still exceeds the threshold, the iterative module performs another iteration. Otherwise, the iteration stops, and one or more quality scores from the most recent iteration are provided as elements of the test sample.

[0042] In a second alternative embodiment, an EDX quantization module is also used to obtain one or more mass fractions to be determined based on quantization using an energy-dispersive X-ray (EDX) detector other than the WDX detector of the WDX spectrometer. In this embodiment, the elemental composition required to calculate the scattering efficiency can be derived from EDX measurements and evaluations. Thus, measurements of the test sample using the EDX detector can be performed before, in parallel with (simultaneously with), or after measurements using the WDX spectrometer. Simultaneous measurements are possible because radiation emitted by the sample is emitted in all directions. Therefore, the monochromator of the WDX spectrometer and the EDX detector can be located in different positions. Typically, there are two different exit holes in the vacuum chamber where the test sample is placed. Radiation directed to the monochromator exits through one of these holes, and radiation directed to the EDX detector exits through the other hole. The quantization options for XRF are described in detail in "Handbook of X-Ray Spectrometry, 2nd Edition, ISBN: 978-0824706005, November 27, 2001, CRC Press", Chapter 4 (Spectrum Evaluation) and Chapter 5 (Quantification of Infinitely Thick Specimens by XRF Analysis).

[0043] It should be noted that the first alternative embodiment may also use an additional EDX detector to measure the total intensity of the sample. However, when using the first alternative embodiment, a WDX spectrometer is sufficient to iteratively determine one or more mass fractions to be determined.

[0044] Other aspects of the invention will be realized and obtained by means of the elements and combinations particularly described in the appended claims. It should be understood that the foregoing general description and the following detailed description are merely exemplary and illustrative, and not intended to limit the invention as described. Attached Figure Description

[0045] Figure 1 A block diagram of an exemplary embodiment of a computer system for determining the mass fraction of one or more elements in a test sample based on measurements of the sample using a wavelength dispersive X-ray fluorescence spectrometer;

[0046] Figure 2 This is a simplified flowchart of a computer-implemented method for determining the mass fraction of one or more elements in a test sample, according to the implementation plan.

[0047] Figure 3 The net intensity of the peaks in the WDX spectrum is shown;

[0048] Figure 4 A schematic WDX spectrum with peak and background positions is shown;

[0049] Figure 5 The overlapping peaks of an exemplary WDX spectrum with the background hidden are shown;

[0050] Figure 6A The deviation of the Sc quality score for the re-evaluated standard sample is shown;

[0051] Figure 6B The deviation of the Pb quality score for the re-evaluated standard sample is shown; and

[0052] Figure 7 This is a diagram illustrating examples of general-purpose computer devices and general-purpose mobile computer devices that can be used with the technologies described herein. Detailed Implementation

[0053] Figure 1 A block diagram of an exemplary embodiment of a computer system 100 is included, which is used to determine the mass fraction of one or more elements in a test sample 202 based on measurements taken using a wavelength dispersive X-ray fluorescence spectrometer 200. The method is described in the context of a simplified flowchart of a computer-implemented method 1000 for determining such mass fractions. Figure 1 System 100, such as Figure 2 As shown. Therefore, the following description refers to... Figure 1 and Figure 2 The reference numerals used in the figures are as follows. System 100 is thus configured to execute method 1000 when a corresponding computer program is loaded into the system's memory and executed using the system's processing apparatus. The computer program product implements the functional modules of system 100 disclosed herein.

[0054] exist Figure 1In one exemplary embodiment, system 100 is communicatively coupled to spectrometer 200 via a suitable interface (not shown). In another embodiment, computer system 100 may be an integrated component of wavelength dispersive X-ray fluorescence spectrometer 200. In both embodiments, system 100 may receive 1100 the total intensity 212 obtained by detector 204 of spectrometer 200 via a suitable interface (not shown). The functionality of spectrometer 200 has been largely described in the background section. Generally, those skilled in the art know how spectrometer 200 is able to obtain total intensity 212 from sample 202. However, reference is made below. Figure 1 Here is a brief overview of the feature.

[0055] X-ray tube 201 generates polychromatic primary radiation 201-r, which includes characteristic lines of the tube material and bremsstrahlung, and this primary radiation is directed onto the sample 202 to be analyzed. This primary radiation produces X-ray fluorescence emission characterizing the elements contained in the sample. Additionally, the primary radiation is scattered by the sample. The radiation 202-r emitted by sample 202, including X-ray fluorescence and scattered primary radiation, is analyzed by measuring the radiation 203-r reflected by the monochromator 203 of the spectrometer at various diffraction angles θ using a goniometer (measured via WDX detector 204). In an alternative embodiment, an additional energy-dispersive X-ray (EDX) detector 206 can be integrated with the WDX spectrometer 200 to measure the radiation 202-r′ emitted by sample 202. The sample emits radiation in all directions. Therefore, exemplary beams 202-r and 202-r′ represent radiation emitted by the sample in two different directions. In one direction, the emitted radiation 202-r strikes the monochromator 203. In another direction, the emitted radiation 202-r′ impacts EDX detector 206 (in an alternative embodiment).

[0056] As described above, computer system 100 is communicatively coupled to detector 204 of the WDX spectrometer. In an alternative embodiment, system 100 is additionally coupled to EDX detector 206 via a suitable interface (not shown). The computer system receives 1100 one or more total intensities 212 associated with corresponding one or more elements, wherein the corresponding one or more mass fractions MFi to be determined in the test sample 202 are obtained from the test sample 202 by detector 204 of WDX spectrometer 200. That is, when the goniometer of WDX spectrometer 200 changes the diffraction angle θ, the energy of radiation 203-r also changes. In a WDX spectrometer, the goniometer is an instrument that allows the monochromator to rotate to a precise angular position. When detector 204 measures a peak, the energy of that peak characterizes a specific element in test sample 202. The mass fraction (concentration) of that specific element is reflected by the net intensity of the peak. However, the total intensity of the peak is measured by detector 204.

[0057] This is Figure 3 The diagram shows a portion of a schematic WDX spectrum 300. The portion of spectrum 300 shown includes a peak at position 301, the total intensity of which is measured at a specific diffraction angle θ. This peak represents fluorescence emission characterizing a specific element contained in the sample. A background intensity 320 caused by primary scattered radiation (shown as a horizontal dashed line in this example) can be measured at position 302. The background is included in the total intensity 310. The desired net intensity 330 is the difference between the total intensity 310 and the background intensity 320.

[0058] Simply go to Figure 4 The majority of the schematic WDX spectrum 400 is shown with peak positions 401 to 405, which represent fluorescence emission characterizing the elements contained in the sample (i.e., the elemental composition of the sample). Background positions 406 to 411 show the locations near the peaks that can be used as measurement points for measuring the background intensity of the corresponding peaks.

[0059] However, in actual WDX spectra 500, such as Figure 5 As shown, peaks 501 to 505 typically have overlapping regions, such that the background intensity 520 (shown by the dashed line) is lower than the total measured intensity of the peak for most of the measured WDX spectrum. In other words, in the case of such overlapping peak regions, it is impossible to find a measurement point near the peak where the corresponding background intensity could be measured. Figure 5 As shown, the background intensity also varies with energy (diffraction angle). In actual spectra, the background intensity is not a linear function, but can even include parameters such as... Figure 5 The schematic diagram illustrates a step at certain energies. Therefore, it is insufficient to measure a single background intensity value anywhere in the WDX spectrum and subtract that value from the total intensity of all measured peaks. Instead, for each peak, it would be necessary to measure the corresponding background intensity, which is entirely impossible in the exemplary spectrum 500. To mitigate this problem, prior art methods increase measurement resolution by using different crystals (e.g., LiF220 instead of LiF200) or by using a smaller collimator that limits the angular divergence of the beam impacting the monochromator. However, both prior art methods significantly reduce the total intensity and thus increase the total measurement time, which is contrary to the goal of allowing measurements in time-critical applications such as steel production. It should be noted that... Figures 3 to 5 The schematic spectrum shown illustrates continuous spectral lines. However, in practical WDX measurement applications, only... Figure 3 and Figure 4 Measurements are taken at specific energy locations indicated by solid line arrows. For simplicity, [the measurement is shown in the image]. Figure 5 The location of such specific energy is not highlighted. However, those skilled in the art will know where the measurement point will be located.

[0060] Therefore, the method disclosed herein is as follows for calculating background intensity to completely eliminate the need for background intensity measurement.

[0061] System 100 has a mass fraction module 120 adapted to determine each of 1200 or more mass fractions MFi to be determined by using calibration formula CE1 with the corresponding measured total intensity 212 and the corresponding calculated scattering efficiency 112 as inputs. As previously stated, the calculated scattering efficiency is defined as the ratio between the incident intensity and the scattered intensity of a particular elemental composition and energy (of the test sample).

[0062] Calibration formula CE1 (see Figure 1 The net intensity of the characteristic fluorescence line of a sample element is correlated with its corresponding mass fraction. Calibration formula F9:

[0063] c i =a i (I 峰，i -d i s(c, E) + ∑ j o ij c j )(1+∑ j α ij c j )

[0064] As shown, the net intensity i of a specific peak is expressed as the total intensity I measured from the specific peak. 峰，i Subtract the calculated scattering efficiency s(c, E) multiplied by the scaling factor d i This is obtained by measuring a calibration sample with a known elemental composition (standard) using a WDX spectrometer to derive the calibration formula. The concentration of the standard is then determined using other measurement techniques. Using such measurements, d can be determined empirically. i And other parameters a i o ij and α ij Meanwhile, the concentration of each standard is kept constant. For the standards, the elemental composition *c* is known. That is, during the calibration process, the scattering efficiency *s* of each standard is calculated and compared with other calibration parameters *a*. i o ij and α ij Adjust the additional correction parameter d together iIn other words, the corresponding parameters are determined based on the known properties of the standard (e.g., concentration, geometry, density). The system can store different calibration parameters for different sample types (samples with different elemental compositions) in the calibration formula module 130, where the calibration parameters in the calibration formula can have different values ​​for the corresponding sample type. For example, the system may also include a calibration module 110 configured to perform the above calibration steps based on WDX measurement data obtained from the corresponding standard.

[0065] Then, during the evaluation of test sample 202, the mass fraction of the unknown test sample is determined using calibration formula CE1 with fixed parameters. In the calibration formula, elemental composition is the input parameter for calculating scattering efficiency. On the other hand, system 100 is used to determine the mass fraction of one or more elements in the test sample. This seems contradictory, since the elemental composition to be determined for the test sample requires knowledge of said elemental composition. However, the accuracy of the mass fraction of the elements required to calculate scattering efficiency is far lower than the accuracy typically required to determine the final mass fraction of one or more elements in test sample 202. Therefore, the mass fraction of the specific elemental composition used to calculate scattering efficiency is called a mass fraction estimate. For the calculation of scattering efficiency, trace elements can be completely ignored. In other words, it is sufficient to obtain an estimate of only elements whose mass fraction exceeds a threshold characterizing the mass fraction of trace elements (e.g., only at least one percent of the mass fraction). These elements are referred to herein as relevant elements. The trace elements in the test sample are irrelevant to the calculation of scattering efficiency (and therefore background intensity).

[0066] An elemental composition estimate of the test sample with the accuracy required to calculate scattering efficiency can be obtained through two alternative embodiments of the elemental composition module 121 of system 100. In a first embodiment, the elemental composition module 121 uses an iteration module 121-1, which is adapted to perform an iterative method to estimate the elemental composition of the test sample. This iterative method is shown as follows: Figure 2The loop structure in the left branch of step 1200 is determined. Before starting loop 1240, the iterative module initializes the current mass fraction estimate of the element 1210 with arbitrary values. That is, the initial elemental composition used during the first iteration step for calculating the scattering efficiency 1220 includes arbitrary values ​​of the element concentrations in the test sample. For example, the relevant elements may have been known from the sample type of the test sample. The calculated scattering efficiency 1220 is calculated for each total intensity associated with the mass fraction to be determined. That is, in this specific implementation, the total intensity of the relevant peak in the WDX spectrum is determined via detector 204 by performing WDX measurements at the corresponding energy (i.e., at the diffraction angle corresponding to the corresponding peak position). The diffraction angle is adjusted accordingly using a goniometer with monochromator 203. Thus, the corresponding calculated scattering efficiency uses the current mass fraction estimate and the energy of the fluorescence line of the corresponding element. In other words, in the first iteration, it uses arbitrary mass fraction values ​​from the initialization.

[0067] In this loop, the iterative module then calculates 1230 as one or more undetermined mass fractions of the current mass fraction using the calibration formula CE1 and the separately calculated scattering efficiency. That is, the estimated value of the current mass fraction (in the first iteration: an arbitrary value from the initialization) is now rewritten by the mass fraction value obtained from calculation step 1230.

[0068] The iterative module now performs check 1235, which checks whether the mass fraction difference (MFD) between one or more mass fractions to be determined in the most recent iteration and the corresponding one or more mass fractions to be determined in the previous iteration exceeds a predefined threshold T1. In the first iteration, the mass fractions of the previous iteration correspond to any initial mass fraction values. After the first iteration, it is highly unlikely that the MFD is already less than or equal to the predefined threshold. This only occurs if the initial arbitrary mass fraction values ​​have almost perfectly matched the dominant element composition in the test sample. If the MFD is greater than T1, the iterative module performs the next iteration by repeating steps 1220 and 1230 in step 1240.

[0069] With each iteration, the calculation 1230 of the mass fraction to be determined, based on the elemental composition estimated in the previous iteration, gets closer to the actual elemental composition of the test sample. In other words, in each iteration, the determined concentration of the relevant elements in the test sample is closer to the actual real-world concentration than the concentration estimated during the previous iteration. The iterative module continues to loop 1240 until the check function 1235 finally determines that the MFD is less than or equal to a predefined threshold. Then, the termination condition of loop 1240 is met, and the estimated mass fraction value calculated in 1230 in the last iteration is provided 1250 as the mass fraction to be determined.

[0070] Since this implementation requires a WDX measurement of the total intensity of all relevant element peaks, it can be advantageously used in scenarios where a large number of mass fractions must be determined from the measured WDX spectrum anyway. This saves the measurement time required in the prior art to measure the background intensity near the relevant element peaks. Furthermore, in complex spectra with many overlaps in the relevant peaks, background intensity cannot be measured at all. However, the implementation via the iterative module still allows the determination of the mass fractions of all elements (including trace elements) in the test sample via the scattering efficiency, which can be calculated solely based on the corresponding relevant elements.

[0071] In an alternative implementation, the elemental composition module 121 uses the EDX quantization module 121-2 to determine the elemental composition of the test sample for the purpose of calculating the calculated scattering efficiency 112 of the corresponding peak. Figure 2 In this embodiment, the steps performed by the EDX quantization module 121-2 are shown in a dashed box to the right of step 1200. In this specific implementation, the EDX quantization module uses the measurement results 213 of the energy-dispersive X-ray detector 206 (EDX detector) to obtain one or more mass fractions to be determined via quantization. For the purpose of calculating the scattering efficiency at the relevant peaks, the EDX detector can be used to quickly obtain a sufficiently accurate estimate of the concentration of all relevant elements. The total intensity used to determine the mass fractions to be determined with high accuracy is still obtained by the WDX detector 204. The EDX detector is only used to accelerate the determination of the elemental composition, which is required as input for calculating the calculated scattering efficiency. The quantization 1210′ of the mass fractions measured by the EDX detector is known in the art. This quantization step 1210′ allows the elemental composition estimate to be determined separately from the WDX measurement of the total peak intensity 212.

[0072] Calculation steps 1220′ and 1230′ correspond to steps 1220 and 1230 performed in a single iteration of loop 1240. In the EDX implementation, iteration is not required because the elemental composition used to calculate the scattering intensity in step 1220′ is already known from EDX measurements. To calculate the mass fraction based on the determined net intensity of the corresponding peak, the measured total peak intensity and the calculated scattering intensity are used as inputs to calibration formula CE1. This directly results in the mass fraction value to be determined, MFi. Therefore, for MF module 120, it makes no difference whether the measurement of sample 202 by EDX detector 206 is performed before, simultaneously with, or after the measurement of the test sample by detector 204 of the WDX spectrometer. The advantage of simultaneous measurement is that no additional time loss occurs; however, when EDX and WDX measurements are subsequently performed, the time required for both measurements is needed before the calculation of the mass fraction can be performed. The mass fraction result can be provided by MF module 120 to the operator of the production system, for example, via a user interface 1250. The determined mass fraction can also be used to generate control instructions for process control of industrial processes.

[0073] Figure 6A , Figure 6B The deviations in the mass fractions of re-evaluation standard samples for two different elements are shown. The mass fractions of the standard samples are known from other measurements (input SC / PB mass fractions). These standard samples are used to determine the calibration parameters in the corresponding calibration formulas. This is determined using three different methods. Figure 6A The mass fraction of Sc in the diagram is calculated by: completely ignoring background intensity (diamond symbol: no Bkg), using measured background intensity near the corresponding element peak (+ symbol: measured Bkg), and using the method disclosed in this paper based on calculated scattering efficiency (x symbol: theoretical Bkg). Figure 6B In this study, the mass fraction of Pb was determined using only the measured Bkg(+) and theoretical Bkg(x).

[0074] Figure 6A Graph 610 shows the difference (y-axis) between the undetermined (evaluated) Sc mass fraction of the standard and the input (nominal) Sc mass fraction, relative to the input Sc mass fraction of the standard (x-axis). A good quality indicator of the calibration parameter is achieved when all differences are close to zero. A positive difference at an input Sc mass fraction of zero percent means that an evaluation sample with an actual Sc mass fraction of zero will give a positive non-zero result (false affirmative).

[0075] The calibration formula in this example is:

[0076] c Sc =a Sc (I 净，Sc )m Sc , where aSc It is the slope, and m Sc It is matrix correction. 净，Sc Regarding "No Bkg" as I 总，Sc Regarding "measuring Bkg" as I 峰，Sc -I 背景，Sc And for "theoretical Bkg" as I 峰，Sc -d Sc s(c, E). All samples contained BaO, TiO2, and Sc2O3 fused together in different concentrations to form borate glass beads.

[0077] Table 1: Included in Figure 6A Values ​​drawn in

[0078]

[0079] No background shows a clear trend of positive differences below 4% of the Sc quality score and negative differences above 4%. This indicates the presence of systematic error, in this case, missing background correction. Using no background when the input Sc quality score is 0% results in a significant false positive.

[0080] Using the intensity near the Sc KA peak as the measurement background (measuring Bkg) has yielded better results. However, a similar trend can still be observed, and false positives are still present.

[0081] The theoretical background (theoretical Bkg) method based on the computational scattering efficiency disclosed in this paper yields state-of-the-art results without false positives. It should be emphasized that the results obtained by computational background intensity disclosed in this paper are far more accurate than those obtained by prior art methods that directly measure background intensity near the corresponding elemental peaks.

[0082] Figure 6B Graph 620 in the figure shows similar results for the Pb mass fraction in the standard sample. However, Graph 620 does not include the mass fraction values ​​determined without background because the error is too large to be depicted in Graph 620. The calibration formula in this example is:

[0083] c Pb =a Pb (I 净，Pb +o Pb )m Pb , where a Pb It's the slope, o Pb It is overlap correction, and m Pb It is matrix correction. 净，Pb Regarding "measuring Bkg" as I 峰，Pb -I 背景，Pb And for "theoretical Bkg" as I 峰，Pb -d Pbs(c, E). Very different types of standards—plastic (ABS), fused borate glass beads (fused beads), and alloys (brass and copper alloys)—are part of the calibration. All standards show substantially different background contributions.

[0084] Table 2: Included in Figure 6B Values ​​drawn in

[0085]

[0086] Using the intensity near the Pb LA peak as the measurement background shows low differences for all ABS samples, but high differences for all other sample types. This is due to the problem of finding undisturbed regions in the spectrum where the measured background intensity represents the actual background (see [link to original text]). Figure 5 The theoretical background method disclosed in this paper yields the best results, thus providing good background estimation for all different sample types.

[0087] Figure 7 This is an illustration showing examples of a general-purpose computer device 900 and a general-purpose mobile computer device 950 that can be used with the technologies described herein. In some embodiments, the computing device 900 may relate to system 100 (see...). Figure 1 As previously described, such a computer device 900 can be implemented as an integrated component of a wavelength dispersive X-ray fluorescence spectrometer. The computing device 950 is intended to represent various forms of mobile devices, such as personal digital assistants, cellular phones, smartphones, and other similar computing devices. In the context of this disclosure, the computing device 950 may provide I / O devices for user interaction with the computing device 950 (e.g., for selecting diffraction orders for sample analysis). The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the specific implementations of the invention described and / or claimed herein.

[0088] Computing device 900 includes a processor 902, a memory 904, a storage device 906, a high-speed interface 908 connected to the memory 904 and a high-speed expansion port 910, and a low-speed interface 912 connected to a low-speed bus 914 and the storage device 906. Each of components 902, 904, 906, 908, 910, and 912 is interconnected using various buses and may be mounted on a common motherboard or otherwise suitably mounted. Processor 902 can process instructions for execution within computing device 900, including instructions stored in memory 904 or on storage device 906 to display graphical information of a GUI on an external input / output device, such as a display 916 coupled to high-speed interface 908. In other embodiments, multiple processors and / or multiple buses may be suitably used in conjunction with multiple memories and various types of memory. Furthermore, multiple computing devices 900 may be connected, with each device providing a portion of the necessary operation (e.g., as a server cluster, blade server group, or multiprocessor system).

[0089] Memory 904 stores information within computing device 900. In one embodiment, memory 904 is one or more volatile memory cells. In another embodiment, memory 904 is one or more non-volatile memory cells. Memory 904 can also be another form of computer-readable medium, such as a magnetic disk or optical disk.

[0090] Storage device 906 provides large-capacity storage for computing device 900. In one embodiment, storage device 906 may be or contain computer-readable media, such as floppy disk devices, hard disk devices, optical disk devices, magnetic tape devices, flash memory or other similar solid-state storage devices, or device arrays, including devices in a storage area network or other configuration. A computer program product may be tangibly embodied in an information carrier. A computer program product may also contain instructions that, when executed, perform one or more methods (such as those described above). The information carrier is a computer or machine-readable medium, such as memory 904, storage device 906, or memory on processor 902.

[0091] High-speed controller 908 manages bandwidth-intensive operations of computing device 900, while low-speed controller 912 manages lower bandwidth-intensive operations. This functional allocation is merely exemplary. In one embodiment, high-speed controller 908 is coupled to memory 904, display 916 (e.g., via a graphics processor or accelerator), and high-speed expansion port 910 that can accept various expansion cards (not shown). In this embodiment, low-speed controller 912 is coupled to storage device 906 and low-speed expansion port 914. The low-speed expansion port, which may include various communication ports (e.g., USB, Bluetooth, Ethernet, Wireless Ethernet), may be coupled to one or more input / output devices, such as keyboards, pointing devices, scanners, or networking devices (such as switches or routers), for example, via a network adapter.

[0092] The computing device 900 can be implemented in a variety of different forms, as shown in the figure. For example, it can be implemented as a standard server 920, or multiple times in a group of such servers. It can also be implemented as part of a rack server system 924. Alternatively, it can be implemented in a personal computer such as a laptop computer 922. Alternatively, components from the computing device 900 can be combined with other components in mobile devices (not shown) (such as device 950). Each of these devices can contain one or more of the computing devices 900, 950, and the entire system can consist of multiple computing devices 900, 950 communicating with each other.

[0093] The computing device 950 includes a processor 952, a memory 964, input / output devices such as a display 954, a communication interface 966 and a transceiver 968, and other components. The device 950 may also be provided with storage devices (such as microdrives or other devices) to provide additional storage. Each of the components 950, 952, 964, 954, 966, and 968 is interconnected using various buses, and some of the components may be mounted on a common motherboard or otherwise suitably mounted.

[0094] Processor 952 can execute instructions within computing device 950, including instructions stored in memory 964. The processor can be implemented as a chipset comprising individual and multiple analog and digital processors. For example, the processor can provide coordination for other components of device 950, such as the user interface, applications running by device 950, and control of wireless communications performed by device 950.

[0095] Processor 952 can communicate with the user via control interface 958 and display interface 956 coupled to display 954. For example, display 954 can be a TFT LCD (Thin Film Transistor Liquid Crystal Display) or OLED (Organic Light Emitting Diode) display, or other suitable display technology. Display interface 956 may include appropriate circuitry for driving display 954 to present graphics and other information to the user. Control interface 958 can receive commands from the user and translate them for submission to processor 952. Furthermore, an external interface 962 can be provided to communicate with processor 952 to enable near-field communication between device 950 and other devices. External interface 962 may provide wired communication in some embodiments, or wireless communication in others, and multiple interfaces may be used.

[0096] Memory 964 stores information within computing device 950. Memory 964 can be implemented as one or more computer-readable media, one or more volatile memory cells, or one or more non-volatile memory cells. Extended memory 984 can also be provided and connected to device 950 via extended interface 982, which may include, for example, a SIMM (Single In-line Memory Module) card interface. Such extended memory 984 can provide additional storage space for device 950 or can also store applications or other information for device 950. Specifically, extended memory 984 may include instructions for performing or supplementing the above processes, and may also include security information. Thus, for example, extended memory 984 can act as a security module of device 950 and can be programmed via instructions that allow secure use of device 950. Furthermore, secure applications along with additional information, such as placing identification information on the SIMM card in a hackable manner, can be provided via a SIMM card.

[0097] For example, the memory may include flash memory and / or NVRAM memory, as discussed below. In one embodiment, the computer program product is tangibly embodied in an information carrier. The computer program product contains instructions that, when executed, perform one or more methods (such as those described above). The information carrier is a computer or machine-readable medium, such as memory 964, extended memory 984, or memory on processor 952, which may be received, for example, via transceiver 968 or external interface 962.

[0098] Device 950 can conduct wireless communication via communication interface 966, which may include digital signal processing circuitry if necessary. Communication interface 966 can provide communication under various modes or protocols (such as GSM voice calls, SMS, EMS or MMS message sending and receiving, CDMA, TDMA, PDC, WCDMA, CDMA2000, or GPRS, etc.). Such communication can be performed, for example, via radio frequency transceiver 968. Furthermore, short-range communication can be performed using transceivers such as Bluetooth, WiFi, or others (not shown). Additionally, GPS (Global Positioning System) receiver module 980 can provide device 950 with additional navigation and location-related wireless data, which can be appropriately used by applications running on device 950.

[0099] Device 950 can also use audio codec 960 for audible communication, which receives spoken information from a user and converts it into usable digital information. Audio codec 960 can also generate audible sound for the user, such as through a speaker (e.g., in the handheld device of device 950). This sound can include sounds from voice telephone calls, recorded sounds (e.g., voice messages, music files, etc.), and sounds generated by applications operating on device 950.

[0100] The computing device 950 can be implemented in many different forms, as shown in the figure. For example, it can be implemented as a cellular phone 980. It can also be implemented as a smartphone 982, a personal digital assistant, or part of other similar mobile devices.

[0101] Various specific implementations of the systems and technologies described herein can be implemented in digital electronic circuits, integrated circuits, specially designed ASICs (Application-Specific Integrated Circuits), computer hardware, firmware, software, and / or combinations thereof. These various implementations may include implementations in one or more computer programs executable and / or interpretable on a programmable system, which includes at least one programmable processor, which may be dedicated or general-purpose, coupled to receive data and instructions from a storage system, at least one input device, and at least one output device, and to transfer data and instructions to the storage system, at least one input device, and at least one output device.

[0102] These computer programs (also referred to as programs, software, software applications, or code) include machine instructions for a programmable processor and can be implemented in high-level procedural and / or object-oriented programming languages ​​and / or assembly / machine languages. As used herein, the terms "machine-readable medium" and "computer-readable medium" refer to any computer program product, apparatus, and / or device (e.g., disk, optical disk, memory, programmable logic device (PLD)) used to provide machine instructions and / or data to a programmable processor, including machine-readable media that receive machine instructions as machine-readable signals. The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0103] To provide interaction with the user, the systems and techniques described herein can be implemented on a computer having a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) and a keyboard and pointing device (e.g., a mouse or trackball) that the user can use to provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound, speech, or tactile input).

[0104] The systems and technologies described herein can be implemented in computing devices that include back-end components (e.g., as a data server), or middleware components (e.g., an application server), or front-end components (e.g., a client computer having a graphical user interface or web browser through which a user can interact with a specific implementation of the systems and technologies described herein), or any combination of such back-end, middleware, or front-end components. Components of the system can be interconnected via digital data communication (e.g., a communication network) of any form or medium. Examples of communication networks include local area networks (“LANs”), wide area networks (“WANs”), and the Internet.

[0105] Computing devices can include clients and servers. Clients and servers are typically geographically separated and interact via communication networks. The client-server relationship is established by computer programs running on the respective computers and having a client-server relationship with each other.

Claims

1. A computer-implemented method (1000) for determining mass fractions of one or more elements in a test sample (202) based on measurements by a wavelength dispersive x-ray fluorescence spectrometer, referred to as a WDX spectrometer (200), comprising: receiving (1100), from a detector (204) of the WDX spectrometer, one or more total intensities (212) associated with a respective one or more elements in the test sample (202) having a corresponding one or more mass fractions to be determined (MFi); and the method is characterized in that comprises the steps of: determining (1200) each of the one or more mass fractions to be determined (MFi) by using a calibration equation (CE1) that relates net intensities of characteristic fluorescence emission lines of sample elements to respective mass fractions, with the net intensity of a particular peak being obtained from the measured total intensity (212) of the particular peak by subtracting the respective calculated scattering efficiency (112) multiplied by a scaling factor according to the calibration equation (CE1), with the particular elemental composition of the test sample being estimated in either of: estimating a mass fraction estimate of the particular elemental composition based on measured total intensities associated with elements in the test sample after initializing the current mass fraction estimate of the particular elemental composition by an arbitrary value; or: obtaining a mass fraction estimate of the particular elemental composition from quantification using an energy dispersive x-ray detector, referred to as an EDX detector (206).

2. The method according to claim 1, wherein the calibration equation (CE1) has a set of calibration parameters obtained from a previous calibration step using one or more calibration samples having known elemental composition.

3. The method according to claim 1 or 2, wherein iteratively determining a mass fraction estimate of the particular elemental composition comprises: calculating (1220) the respective calculated scattering efficiency using the current mass fraction estimate and the energy of a fluorescence line of the respective element for each total intensity associated with a mass fraction to be determined; calculating (1230) the one or more mass fractions to be determined as current mass fraction estimate by the calibration equation; repeating (1240) the calculation steps as long as a mass fraction difference (MFD) between the one or more mass fractions to be determined of the most recent iteration and the respective one or more mass fractions to be determined of the previous iteration exceeds a predefined threshold (T1).

4. The method according to claim 1 or 2, wherein for iteratively determining the one or more mass fractions to be determined, the total intensities are measured by the detector (204) of the WDX spectrometer or by the EDX detector (206).

5. The method of claim 1, wherein obtaining the one or more to-be-determined mass fractions using an EDX detector (206) from quantification comprises any one of: measuring the sample by the EDX detector (206) prior to measuring the test sample by the detector (204) of the WDX spectrometer, measuring the sample by the EDX detector in parallel with measuring the test sample by the detector (204) of the WDX spectrometer, and measuring the sample by the EDX detector after measuring the test sample by the detector (204) of the WDX spectrometer.

6. The method of claim 2, wherein in the previous calibration step, parameters of the calibration formula are adjusted based on known properties of the one or more calibration samples.

7. The method of any one of claims 1-2, wherein the elemental composition of the test sample used for determining the calculated scattering efficiency is limited to elements having a mass fraction in the test sample exceeding a predefined threshold.

8. A computer program product for determining mass fractions of one or more elements in a test sample (202) based on measurements by a wavelength dispersive x-ray fluorescence spectrometer, the computer program characterized in comprising computer readable instructions that, when loaded into a memory of a computing device and executed by at least one processor of the computing device, cause the computing device to perform the computer-implemented method of any one of the preceding claims.

9. A computer system (100) for determining mass fractions of one or more elements in a test sample (202) based on measurements by a wavelength dispersive X-ray fluorescence spectrometer, referred to as a WDX spectrometer, the computer system characterized in comprising: an interface adapted to receive one or more total intensities (212) associated with a respective one or more elements in the test sample (202) having a corresponding one or more to-be-determined mass fractions (MFi) obtained from the test sample (202) by a detector (204) of the WDX spectrometer (200); a mass fraction module (120) adapted to determine each of the one or more to-be-determined mass fractions (MFi) by using a calibration formula (CE1) with a respective measured total intensity (212) and a respective calculated scattering efficiency (112) as input, wherein the calculated scattering efficiency is defined as a ratio between an incident intensity and a scattered intensity for a particular elemental composition and energy, the calibration formula (CE1) relating a net intensity of a characteristic fluorescence emission line of a sample element to a respective mass fraction, wherein the net intensity of a particular peak is obtained by subtracting the respective calculated scattering efficiency (112) multiplied by a scaling factor from the measured total intensity (212) of the particular peak according to the calibration formula (CE1); an elemental composition module (121) adapted to estimate the specific elemental composition of the test sample by any of: via an iterative module (121-1) adapted to iteratively determine a mass fraction estimate of the specific elemental composition based on measured total intensities associated with elements in the test sample after initializing the current mass fraction estimate of the specific elemental composition by an arbitrary value; or: via an EDX quantification module (121-2) adapted to obtain a mass fraction estimate of the specific elemental composition from quantification using an energy dispersive X-ray detector, referred to as EDX detector (206).

10. The system of claim 9, wherein the calibration formula (CE1) has a set of calibration parameters obtained from a previous calibration step using one or more calibration samples having a known elemental composition.

11. The system of claim 9 or 10, wherein the iterative module (121-1) for iteratively determining a mass fraction estimate of the specific elemental composition is adapted to: for each total intensity associated with a mass fraction to be determined, use the current mass fraction estimate and the energy of the fluorescence line of the respective element to calculate the respective calculated scattering efficiency; calculate the one or more mass fractions to be determined as the current mass fraction estimate by the calibration formula; and repeat the calculation steps as long as the mass fraction difference (MFD) between the one or more mass fractions to be determined of the most recent iteration and the respective one or more mass fractions to be determined of the previous iteration exceeds a predefined threshold (T1).

12. The system of any of claims 9 to 10, wherein the total intensities used by the iterative module (121-1) are measured by the WDX spectrometer or by the EDX detector (206).

13. The system of claim 9, wherein the one or more mass fractions to be determined obtained via the EDX quantification module (121-2) are based on any of: measuring the sample (202) by the EDX detector (206) before measuring the test sample by the detector (204) of the WDX spectrometer, measuring the sample (202) by the EDX detector (206) in parallel to the measurement of the test sample by the detector (204) of the WDX spectrometer, and measuring the sample (202) by the EDX detector (206) after measuring the test sample by the detector (204) of the WDX spectrometer.

14. The system of claim 10, further comprising a calibration module (110) configured to perform the previous calibration step to adjust parameters of the calibration formula based on known properties of the one or more calibration samples.

15. The system of any one of claims 9-10, wherein the elemental composition of the test sample used to determine the calculated scattering efficiency is limited to elements having a mass fraction in the test sample that exceeds a predefined threshold.

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