Polarized energy dispersive X-ray fluorescence system and method

Abstract

An X-ray fluorescence system and manufacturing method are provided, including a titanium X-ray source, a focusing doubly curved lithium fluoride (LiF) crystal optic, and a detector. The titanium X-ray source includes a titanium target impinged with electrons to generate a diverging X-ray beam having a characteristic titanium-based energy. The focusing doubly curved LiF crystal optic monochromatizes and focuses the diverging X-ray beam from the titanium X-ray source to provide a monochromatized and focused X-ray excitation beam directed to impinge on a sample. The crystal optic and titanium X-ray source operate at a Bragg angle that facilitates polarization within the X-ray fluorescence system. The detector receives fluorescence from the sample induced by the X-ray excitation beam impinging thereon, the fluorescence indicating the concentration of at least one element in the sample.

Description

[Background technology]

[0001] Depending on the elements of interest in the measurement system, quantification of trace elements at the desired or required detection limits can be difficult. In one example of a measurement technique, X-ray analysis is used across many testing and monitoring applications, such as in the environmental, consumer goods, medical, pharmaceutical, and petroleum industries.

[0002] In one or more embodiments of X-ray technology, X-ray fluorescence (XRF) is used as an analytical technique, whereby a material is exposed to a beam of X-rays to determine, for example, the presence and concentration of a particular component. In XRF, at least some of the elemental components of the material exposed to the X-rays can absorb the X-ray photons and produce characteristic secondary fluorescence. These secondary X-rays are characteristic of the elemental components in the material. Upon appropriate detection and analysis, the secondary X-rays can be used to characterize and / or quantify one or more of the elemental components in a sample.

[0003] Examples of XRF technology include U.S. Patent Nos. 5,629,997 and 5,729,997, assigned to X-Ray Optical Systems, Inc., which are incorporated herein by reference in their entireties. These patents disclose monochromatic wavelength-dispersive X-ray fluorescence (MWD XRF) technology and systems for the analysis of samples, such as measuring trace levels of sulfur in petroleum products. U.S. Patent No. 5,729,997, assigned to X-Ray Optical Systems, Inc., which is incorporated herein by reference in its entirety, further discloses monochromatic excitation energy-dispersive X-ray fluorescence (ME-EDXRF) technology and systems for the analysis of samples, such as measuring trace levels of toxins in consumer goods and other materials. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 6,934,359 [Patent Document 2] U.S. Patent No. 7,072,439 [Patent Document 3] U.S. Patent No. 7,738,630 Summary of the Invention

[0005] Certain deficiencies of the prior art are overcome and additional advantages are provided by the provision of an X-ray fluorescence system in one or more embodiments. The X-ray fluorescence system includes a titanium X-ray source, a focusing doubly curved lithium fluoride (LiF) crystal optic, and a detector. The titanium X-ray source includes a titanium target upon which electrons are impinged to produce a diverging X-ray beam having a characteristic energy of the titanium base. A focusing doubly curved LiF crystal optic is included to monochromatize and focus the diverging X-ray beam from the titanium X-ray source to provide a monochromatized and focused X-ray excitation beam directed to impinge on the sample. The focusing doubly curved LiF crystal optic and the titanium X-ray source operate at a Bragg angle that facilitates polarization within the X-ray fluorescence system. The detector receives fluorescence from the sample induced by the X-ray excitation beam impinging thereon, the fluorescence indicating the concentration of at least one element in the sample.

[0006] In one or more embodiments, the focusing doubly curved lithium fluoride (LiF) crystal optics and titanium x-ray source operate at a Bragg angle in the range of 42° to 48°, which facilitates polarization within the x-ray fluorescence system.

[0007] In one or more implementations, the focusing double-curved lithium fluoride (LiF) crystal optics of the X-ray fluorescence system includes: <002> The X-ray fluorescence system includes a LiF crystal, which, together with the titanium X-ray source, operates at a Bragg angle that facilitates polarization within the system. In one embodiment, the diverging X-ray beam from the titanium X-ray source, monochromatized and focused by the focusing doubly curved LiF crystal optic, has a characteristic energy of approximately 4.5 keV. Furthermore, in one or more embodiments, the focusing doubly curved LiF crystal optic of the X-ray fluorescence system includes a logarithmic spiral doubly curved crystal or a Johann doubly curved LiF crystal.

[0008] In one or more embodiments, the focusing doubly curved lithium fluoride (LiF) crystal optics of the X-ray fluorescence system are positioned so that the X-ray excitation beam impinges on the sample at an excitation beam angle in the range of 15° to 30°. In one embodiment, the focusing doubly curved LiF crystal optics are positioned so that the excitation beam angle is in the range of 18° to 23°.

[0009] In one or more embodiments, the detector of the X-ray fluorescence system includes an energy dispersive detector, and the titanium X-ray source, doubly curved LiF crystal optics, and sample lie in a plane with the central axis of the detector at an angle in the range of 85° to 95° relative to the plane to facilitate suppression of scattering from the sample.

[0010] In one or more embodiments, the detector of the X-ray fluorescence system is positioned relative to the sample to minimize a gap between the sample and the detector such that the detector has a collection solid angle greater than 1 steradian and a transmission loss of less than 30% at 1.74 keV. In one embodiment, the minimized gap is a minimized air gap between the sample and the detector.

[0011] In one or more embodiments, the X-ray fluorescence system further includes an X-ray shield between the optics and the sample, the X-ray shield having a tapered inner chamber sized and shaped to accommodate the monochromated and focused X-ray excitation beam directed to impinge on the sample.

[0012] In one or more implementations, the at least one element in the sample includes at least one of sodium, magnesium, aluminum, silicon, phosphorus, sulfur, or chlorine.

[0013] In another aspect, a method for manufacturing an X-ray fluorescence system is provided. The method includes providing a titanium X-ray source including a titanium target impinging with electrons to generate a diverging X-ray beam having a characteristic energy of titanium. The method also includes positioning a focusing doubly curved LiF crystal optic relative to the titanium X-ray source to monochromatize and focus the diverging X-ray beam from the titanium X-ray source and provide a monochromatized and focused X-ray excitation beam directed to impinge on the sample. The focusing doubly curved LiF crystal optic and the titanium X-ray source operate at a Bragg angle that facilitates polarization within the X-ray fluorescence system. The method further includes providing a detector to receive fluorescence from the sample induced by the X-ray excitation beam impinging thereon, the fluorescence indicating a concentration of at least one element in the sample.

[0014] Additional features and advantages are realized by the techniques described herein. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed aspects.

[0015] One or more aspects of the present invention are particularly pointed out and distinctly claimed by way of example in the claims at the end of this specification. The foregoing and other objects, features, and advantages of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a functional block diagram of elements of an exemplary X-ray fluorescence system, including an exemplary polarized energy dispersive X-ray fluorescence system, in accordance with one or more embodiments of the present invention. [Figure 2] FIG. 1 is a schematic diagram of an exemplary MWD XRF X-ray engine. [Figure 3] FIG. 1 is a schematic diagram of an exemplary ME-EDXRF X-ray engine that may be enhanced in accordance with one or more aspects of the present invention. [Figure 4A] 1 illustrates one embodiment of a point-focusing, double-curved, monochromating crystal optical system for an X-ray fluorescence system, in accordance with one or more aspects of the present invention. [Figure 4B] 4B is a cross-sectional elevation view taken along line 4B-4B of the optical system of FIG. 4A, in accordance with one or more embodiments of the present invention. [Figure 5A] FIG. 1 is a partial view of one embodiment of a polarized energy dispersive X-ray fluorescence system in accordance with one or more aspects of the present invention. [Figure 5B] FIG. 5B is an elevational view of the X-ray fluorescence system of FIG. 5A in accordance with one or more embodiments of the present invention. [Figure 5C] 5C is a partial cross-sectional elevation view of the X-ray fluorescence system of FIG. 5B taken along line 5C-5C, in accordance with one or more embodiments of the present invention. [Figure 5D] 5D is a partial enlarged view of the X-ray fluorescence system of FIG. 5C taken within line 5D, in accordance with one or more embodiments of the present invention. [Figure 6A] FIG. 5B is a partial view of the X-ray fluorescence system of FIGS. 5A-5D highlighting the substantially 90° reflection of the diverging X-ray beam into a monochromatized and focused X-ray excitation beam directed by the optical system toward the sample, in accordance with one or more embodiments of the present invention. [Figure 6B] 1 illustrates a schematic representation of a logarithmic spiral of a 4.51 keV focusing lithium fluoride (LiF) crystal optic that may be used in the geometry of a polarized X-ray fluorescence system according to one or more embodiments of the present invention. [Figure 6C] 5A-6A , showing the close coupling of X-ray shielding provided around the X-ray path from the X-ray source output to the optics and then to the sample, in accordance with one or more embodiments of the present invention. [Figure 7A] 5A-6C illustrate one assembled embodiment of an X-ray fluorescence system, according to one or more aspects of the present invention. [Figure 7B] FIG. 7B is an elevational view of the X-ray fluorescence system of FIG. 7A in accordance with one or more embodiments of the present invention. [Figure 7C] 7C is a partial cross-sectional elevation view of the X-ray fluorescence system of FIG. 7B taken along line 7C-7C, illustrating close coupling of the detector to the sample, in accordance with one or more embodiments of the present invention. [Figure 7D]7D is a partial enlarged view of the cross-sectional elevation of FIG. 7C taken within line 7D, in accordance with one or more embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0017] Disclosed herein is an improved X-ray analytical measurement technique that is particularly advantageous for detecting certain "light elements," including, for example, sodium, magnesium, aluminum, silicon, phosphorus, sulfur, and chlorine, within an X-ray fluorescence system. In one or more embodiments, improved measurement performance is obtained by providing a unique polarized energy dispersive X-ray fluorescence (polarized EDXRF) system that provides detection levels similar to other analytical techniques (e.g., WD XRF, ICP, ...), while maintaining the low cost and ease of use advantages of energy dispersive X-ray fluorescence (EDXRF) technology.

[0018] 1 is a high-level functional block diagram of an exemplary XRF system or analyzer 100 (including an exemplary polarized energy dispersive X-ray fluorescence system according to one or more aspects of the present invention) used to expose a sample to X-ray radiation to generate fluorescent radiation that can then be detected and analyzed to determine the sample's characteristic elements. In one or more embodiments, the analyzer includes an X-ray source 110, an X-ray focusing device 112, a test sample 114 in a sample chamber, an optional X-ray focusing device 116, an X-ray detector 118, and one or more analyzer components 132 for providing analytical results.

[0019] During operation, the X-ray source 110 (e.g., an X-ray tube) generates X-rays 122, which may be diffracted or focused by one or more X-ray focusing optics 112, as discussed herein, into an excitation beam 124. Upon illumination by the excitation beam 124, one or more constituent elements of a sample, such as the sample 114 in the sample chamber, are excited in such a manner that the constituent elements fluoresce, i.e., generate a secondary source of X-rays 126 due to excitation by the X-ray excitation beam 124. In one or more embodiments, the X-rays 126 are a diverging beam of X-rays, which may optionally be focused by the X-ray focusing optics 116, for example, to help direct focused X-rays 128 toward the X-ray detector 118 (in one embodiment). In one or more other embodiments, the X-ray focusing device 116 is omitted, and the X-ray detector 118 is, for example, an energy dispersive X-ray detector.

[0020] Depending on the implementation, the X-ray detector 118 may be a proportional counter-type or semiconductor-type X-ray detector (e.g., a silicon drift detector (SDD)), or any other suitable type of X-ray fluorescence detector known to those skilled in the art. In one particular embodiment, for a polarized energy dispersive X-ray fluorescence (EDXRF) system as disclosed herein, the detector may be, for example, a carbon-coated graphene SDD detector. In one or more embodiments, the X-ray detector 118 generates an electrical signal 130 containing one or more characteristics of the detected X-rays, which is transferred to an analyzer component 132 for analysis, printout, or other display. The analyzer component 132 may include, for example, one or more non-transitory computer-readable storage media 134 for storing computer-readable program code and / or a computer program product including a processor / logic circuitry 133 for providing and facilitating one or more aspects of the present invention.

[0021] X-ray focusing devices / optics 112, 116 for advanced XRF analyzers, including those discussed herein, may include, for example, curved crystal monochromating optics such as those disclosed in commonly assigned U.S. Pat. Nos. 6,285,506, 6,317,483, 7,035,374, 7,738,629, and WO 2013 / 063253, and / or polycapillary optics such as those disclosed in commonly assigned U.S. Pat. Nos. 5,192,869, 5,175,755, 5,497,008, 5,745,547, 5,570,408, and 5,604,353. Optics / light source combinations such as those disclosed in commonly assigned U.S. Patent Nos. 7,110,506, 7,209,545, and 7,257,193 may be used depending on the particular XRF system implementation, each of which is incorporated herein by reference in its entirety.

[0022] Below is an example of an X-ray optics compatible analyzer engine.

[0023] MWD XRF X-ray analysis engine: X-Ray Optical Systems, Inc. has previously disclosed a monochromatic wavelength-dispersive X-ray fluorescence (MWD XRF) analyzer engine 200 that uses two monochromating optics sets (U.S. Pat. Nos. 6,934,359 and 7,072,439, which are incorporated herein by reference in their entireties), as shown schematically in FIG. 2. The related SINDIE (Sulfur IN DIEsel) and CLORA (chlorine) product lines for the measurement of, e.g., sulfur and chlorine in diesel fuel and other petroleum products, revolutionize XRF and offer many advantages, including: (1) improved signal-to-background (S / B) due to monochromatic excitation of the sample by DCC1 112', i.e., bremsstrahlung photons with energies below the fluorescence peak (which would normally bury the peak of interest) can reach the detector only through scattering, thus dramatically improving the S / B ratio compared to polychromatic excitation; (2) excellent energy resolution—which eliminates all common interference problems and provides a physical basis for upstream applications; (3) inherent robustness and low maintenance—the analytical engine is low-power, compact, with no moving parts or consumable gases; and (4) unprecedented dynamic range, e.g., quantification levels of 0.3 ppm to 5% of sulfur in a sample.

[0024] The MWD XRF engine 200 shown schematically in FIG. 2 includes curved monochromating optics 112′ and 116′ in the excitation and detection paths, respectively, to form a (partially) focal region or spot 201 on the sample, which is the configuration of the SINDIE sulfur analyzer described above. However, in other implementations, optics may be present in only one of these paths. For example, optics of any of the types described above may be present only in the excitation path, and the detection path may include an energy-dispersive detector. This is the configuration of an energy-dispersive X-ray fluorescence (EDXRF) system, one embodiment of which is shown in FIG. 3 and discussed below.

[0025] ME EDXRF X-ray analysis engine: In one or more embodiments, a monochromatic excitation, energy-dispersive X-ray fluorescence (ME-EDXRF) analyzer can be used for the X-ray fluorescence system according to one or more aspects of the present invention. This technology is discussed, for example, in U.S. Pat. No. 6,934,359, entitled "XRF System with Multiple Excitation Energy Bands in a Highly Aligned Package," which is incorporated herein by reference in its entirety. In one embodiment, this ME-EDXRF engine 300 includes a monochromatic excitation known as high-resolution X-ray fluorescence (HD XRF), as shown schematically in FIG. 3. HD XRF, as used herein, refers to single-beam or multi-beam excitation and generally refers to an X-ray fluorescence system with high energy and spatial resolution. FIG. 3 illustrates a multi-element analysis technique that may provide higher detection performance than conventional EDXRF or WD XRF. This technique applies advanced monochromating and focusing optics 112" that illuminate a focal region or point 201' on the sample, allowing for multiple selected energy excitation beams to efficiently excite a range of targeted elements in the sample. Monochromatic excitation dramatically reduces the scattering background below the fluorescence peak, significantly increasing elemental detection limits and precision.

[0026] Polarized EDXRF X-ray analysis engine: As a further example, certain novel polarized EDXRF systems and methods are disclosed herein (also referred to as high-resolution polarized EDXRF systems and methods) and are described below with reference to Figures 4A-7D. In the disclosed improved polarized X-ray fluorescence systems and methods, a focusing double-curved crystal optic is utilized as an X-ray focusing device to focus X-rays from a source, such as an X-ray tube source, onto a sample. As described herein, the optic is paired with a specific light source to operate at a Bragg angle that facilitates polarization of the X-ray fluorescence system. For example, in one or more embodiments, an X-ray focusing device is selected in combination with the X-ray source to achieve a Bragg angle close to 45° to achieve a 90° reflection from the focusing device. Due to the polarization of the X-ray beam, scattering from the sample is suppressed using a detector positioned so that the detector's central axis is substantially perpendicular to the plane formed by the X-ray source-optics-sample focal point. This particular arrangement of the detector relative to the plane defined by the source-optics-focal point provides a further advantage in the polarized EDXRF systems and methods disclosed herein by suppressing scattering from the sample.

[0027] In one or more implementations, the x-ray source is a titanium x-ray source, such as a titanium x-ray tube, which includes a titanium target (e.g., a titanium anode) upon which electrons are bombarded to generate or form a diverging x-ray beam having a characteristic energy of the titanium base. In one or more embodiments, the electrons bombard a layer of titanium or a solid titanium anode to generate a diverging x-ray beam having a characteristic energy of the titanium base. In one or more other embodiments, a rotating titanium target may be utilized for high power load applications.

[0028] In combination with a titanium X-ray source, a focusing double curved crystal optic is provided to monochromatize and focus the X-rays from the X-ray source to provide an X-ray excitation beam directed toward the sample. For example, in one or more embodiments, the optic comprises: <002> The present invention relates to a focusing, double-curved lithium fluoride (LiF) crystal optic, such as a LiF crystal. The target energy selected by the optic must be a strong characteristic line from the anode target material to maximize the optic's performance. Advantageously, lithium fluoride (LiF) can increase the monochromatic beam flux of the curved crystal optic using a titanium X-ray source, and the combination provides a Bragg angle close to 45° to achieve a substantially 90° reflection from the optic for polarizing the excitation beam. LiF has a broad rocking curve, allowing it to capture more photons from a larger source spot size. Therefore, the diffraction efficiency from a larger source spot size is higher than that of other crystals, such as silicon (Si) crystal. Therefore, the diffracted flux can be much greater for larger source spot sizes (e.g., greater than 500 micrometers) compared to silicon crystals. Furthermore, LiF crystal optics bend more easily than Si for the same thickness. In one or more embodiments, the LiF optic can have a Johann shape design or a logarithmic spiral design.

[0029] In one or more embodiments, depending on design parameters, a focusing doubly curved crystal optic can include multiple layers. By predetermining the crystal orientation of each layer, the diffractive properties of the overall structure can be selected and optimized. Each individual crystal layer provides a distinct diffractive effect. These diffractive effects can be modeled separately, and then their collective effect in the final optical system can be predicted and implemented according to the final design criteria.

[0030] In other embodiments, layers of different material compositions can be used in the same optical system with either the same or different crystal orientations between the layers (or mixtures thereof), and similarly, layers of similar (or identical) material compositions can be used with either the same or different crystal orientations between the layers (or mixtures thereof). In any of these embodiments, a material-on-insulator can be used, or an adhesive (e.g., epoxy) layer can be used to bond adjacent crystal layers.

[0031] The optical system can be formed into a curved monochromating optical system, including a doubly curved crystal (DCC) optical system, one embodiment of which is shown in Figures 4A and 4B and described in detail in U.S. Pat. No. 6,285,506, which is incorporated herein by reference in its entirety.

[0032] In the embodiment of Figure 4A, a doubly curved optical device is shown that includes flexible layered optics 400, thick epoxy layer 402, and backing plate 401. The structure of the illustrated embodiment is further illustrated in the cross-sectional elevation view of Figure 4B.

[0033] In this device embodiment, the epoxy layer 402 holds and constrains the flexible layer 400 to a selected geometric curvature. In one embodiment, the thickness of the epoxy layer can be greater than 20 micrometers, and the thickness of the flexible layer can be greater than 5 micrometers. Furthermore, the thickness of the epoxy layer is typically greater than the thickness of the flexible layer. The flexible layer can be one of a wide variety of materials, including those described herein, such as the LiF crystal optics embodiments described herein. The epoxy layer 402 can be 10 3 ~10 4 It can be a paste type with a viscosity on the order of poise and a pot life of 30-60 minutes. The backing plate 401 can be a solid object that bonds well with the epoxy. The surface 403 of the backing plate can be flat (FIG. 4A) or curved, and its exact shape and surface finish are not critical to the shape and surface finish of the flexible layer. The device of FIGS. 4A-4B does not require a specially prepared backing plate.

[0034] Surrounding the flexible layer can be a thin sheet of protective material 404, such as thin plastic, that can be used around the flexible layer edges (see FIG. 4A). The protective material protects the production mold so that the mold is reusable, and is not necessary for molds that are the exact size or smaller than the flexible layer, or for sacrificial molds.

[0035] The optics disclosed herein can be shaped in a variety of ways, including but not limited to, a single direction of curvature (single curved crystal - SCC), dual directions of curvature (double curved crystal - DCC), and other designs, depending on the application. Double curved optical devices, such as double curved crystal (DCC) optics, can be used in materials analysis to collect and focus x-rays from a large solid angle, increasing the usable flux from an x-ray source. Three-dimensional focusing of characteristic x-rays can be achieved by diffraction from a toroidal crystal used with a compact x-ray source.

[0036] X-rays emanating from a source and incident on a crystal surface at angles within the crystal's rocking curve are efficiently reflected to a focal point or image point. The monochromatic flux density at the focal point of a DCC-based system is several orders of magnitude greater than that of conventional systems with higher power supplies and similar source-to-object distances. This increase results in extremely high sensitivity for use in many different applications, including X-ray fluorescence, and more specifically, in polarization EDXRF systems and methods such as those disclosed herein.

[0037] It should be noted that the disclosed layered optical structure offers the following advantages: 1. The mosaic property and rocking curve of the optical system are controlled by the layered orientation design. 2. The efficiency of the optical system is increased, and each layer (with its own custom orientation) can have its own field of view, resulting in a compound field of view, which increases efficiency and allows the optical system to accommodate larger source spot sizes. Also, accommodating larger source spot sizes makes the system easier to implement. 3. The bandwidth (i.e., monochromatization) of the optical system can be controlled and advantageously increased in certain monochromatization applications.

[0038] Advantageously, X-ray fluorescence systems, and in particular EDXRF analysis systems as described herein, can be further improved by polarization and further modifications, as described below with reference to FIGS. 5A-7D.

[0039] Generally, provided herein are improved X-ray fluorescence systems and methods including a titanium X-ray source, a focusing doubly curved lithium fluoride (LiF) crystal optic, and a detector. The titanium X-ray source includes a titanium target upon which electrons are impinged to produce a diverging X-ray beam having a characteristic titanium-based energy. The focusing doubly curved LiF crystal optic monochromatizes and focuses the diverging X-ray beam from the titanium X-ray source to provide a monochromatized and focused X-ray excitation beam directed to impinge on a sample. The focusing doubly curved LiF crystal optic and titanium X-ray source operate at a Bragg angle that facilitates polarization within the X-ray fluorescence system. The detector receives fluorescence from the sample induced by the X-ray excitation beam impinging thereon, the fluorescence indicating the concentration of at least one element in the sample.

[0040] In one or more embodiments, the focusing doubly curved lithium fluoride (LiF) crystal optics and titanium x-ray source operate at a Bragg angle in the range of 42° to 48°, which facilitates polarization within the x-ray fluorescence system.

[0041] In one or more implementations, the focusing double-curved lithium fluoride (LiF) crystal optics and titanium x-ray source include: <002> The system includes a LiF crystal, which, together with a titanium X-ray source, is operated at a Bragg angle to facilitate polarization within the X-ray fluorescence system. In one embodiment, the diverging X-ray beam from the titanium X-ray source is monochromatized and focused by the focusing doubly curved LiF crystal optic, and has a characteristic energy of about 4.5 keV. In one or more embodiments, the focusing doubly curved LiF crystal optic includes a logarithmic spiral crystal, a doubly curved crystal, or a Johann doubly curved LiF crystal.

[0042] In one or more implementations described herein, the focusing doubly curved lithium fluoride (LiF) crystal optics of the X-ray fluorescence system are positioned such that the X-ray excitation beam impinges on the sample at an excitation beam angle in the range of 15° to 30°, such as in the range of 18° to 23°, and more particularly in one embodiment at about 20°.

[0043] In one or more implementations, the detector of the X-ray fluorescence system includes an energy dispersive detector, and the titanium X-ray source, doubly curved LiF crystal optics, and sample are in a plane with the central axis of the detector at an angle in the range of 85° to 95° relative to the plane to facilitate suppression of scattering from the sample.

[0044] In one or more embodiments, the detector of the X-ray fluorescence system is positioned relative to the sample to minimize a gap between the detector and the sample such that the detector's collection solid angle is greater than 1 steradian and the transmission loss at 1.74 keV is less than 30%. In one embodiment, the gap between the detector and the sample is an air gap, and the air gap is minimized between the detector and the sample such that the detector's collection solid angle is greater than 1 steradian and the transmission loss at 1.74 keV is less than 30%.

[0045] In one or more embodiments, an x-ray shield is provided in the x-ray fluorescence system between the optics and the sample, the x-ray shield having a tapered inner chamber sized and shaped to accommodate the monochromated and focused x-ray excitation beam for impingement on the sample.

[0046] In one or more implementations, the at least one element in the sample can be at least one of sodium, magnesium, aluminum, silicon, phosphorus, sulfur, or chlorine.

[0047] 5A-5D illustrate a partial embodiment of an X-ray fluorescence system, generally designated 500, in accordance with one or more aspects of the present invention. Collectively referring to FIGS. 5A-5D, X-ray fluorescence system 500 includes X-ray source 510, which, in one or more embodiments, is a titanium X-ray source having a titanium target (e.g., an anode or film) upon which electrons impinge to generate or form a diverging X-ray beam 511 having a characteristic energy of titanium. For example, when energetic electrons impinge on the anode material, characteristic X-rays of the material are emitted. The most intense characteristic X-ray line, the K a line of titanium atoms, has an energy of 4.511 keV. The K a line is very close to the K a line and typically has an energy of 4.505 keV. In one or more implementations, both lines can be used simultaneously. In one or more embodiments, X-ray source 510 can be or include a vacuum-type X-ray tube (e.g., formed of glass or ceramic) having a transmissive window through which diverging X-ray beam 511 is provided. In one embodiment, the x-ray tube contains an electron gun positioned opposite a high voltage (HV) anode. When a voltage is applied, the electron gun emits electrons in the form of an electron stream, i.e., an electron beam (e-beam), as known in the art. The HV anode acts as a target having a source spot at which the electron stream impinges to produce x-ray radiation, i.e., x-rays 511.

[0048] By way of example, the electron gun can be held at ground potential (zero volts), while the HV anode (e.g., a titanium anode or target) is held at a high voltage potential, such as about 50 kV. As a result, the e-beam emitted from the ground potential electron gun is electrically attracted to the surface of the HV anode, thereby generating x-rays 511 from a source spot on the anode where the e-beam strikes the anode. The x-rays 511 are then directed through a transmission window in a vacuum-tight x-ray tube. The transmission window is typically formed from a material such as beryllium (Be), which allows substantially unimpeded transmission of x-rays while still maintaining the vacuum within the x-ray tube.

[0049] In one or more embodiments, a housing such as that shown in FIGS. 6C-7C may at least partially surround the X-ray tube and include an aperture aligned with the transmission window of the X-ray tube. By way of example, the housing aperture may be an open aperture in the housing or a closed aperture defining a cavity. Upon transmission through the transmission window and aperture, the diverging X-ray beam 511 is focused by optics 512. In one or more implementations, optics 512 may be centered on the housing aperture, mounted on an exterior surface of the housing, or partially located within the housing so as to reside within the aperture as needed, or even supported separately from the housing but aligned with the housing aperture.

[0050] As mentioned above, in one or more embodiments, the optics 512 can be or include a monochromating and focusing optic, such as the focusing double-curved lithium fluoride (LiF) crystal optics described herein. In Figures 5A-5D, the optics are shown as focusing elements, which are useful when the X-ray source 510 is utilized in applications requiring a high-intensity, small-diameter spot. The focusing optics 512 collect the X-ray radiation 511 and focus the radiation into a polarized X-ray excitation beam 513 of focused X-rays. As described herein, in one or more embodiments, the polarized excitation beam can be achieved by having a Bragg angle in the range of, for example, 42-48°. Lithium fluoride (LiF) <002> At 2-D spacing and characteristic Ka energy levels, the Bragg angle is approximately 43°, resulting in substantial polarization of the X-ray excitation beam. Furthermore, the monochromatic beam provides excellent signal-to-background ratio and good excitation energy for light elements to be X-ray analyzed, such as sodium, magnesium, aluminum, silicon, phosphorus, sulfur, and / or chlorine. Focusing optics are also beneficial when low-power X-ray sources are used in conjunction with X-ray fluorescence systems.

[0051] In one or more embodiments, the end of the HV anode opposite the impact surface may protrude through the body of the X-ray tube 510 and be mechanically and electrically connected to a base assembly 514. In one or more embodiments, the base assembly 514 may include a conductive disk that is electrically isolated from the base plate via, for example, a dielectric disk. One embodiment of such an anode and base assembly structure, referred to herein as an anode stack, is described in detail in U.S. Pat. No. 7,110,506, entitled "Method and Apparatus for Cooling and Electrically Insulating High-Voltage Heat-Generating Components, Such as an X-Ray Tube for Analyzing Fluid Streams."

[0052] In one or more embodiments, the conductor disk is mechanically and electrically connected to a high voltage source (not shown) via appropriate high voltage leads. As a result, a high voltage potential is supplied to the conductor disk and subsequently to the HV anode. Conversely, the base plate is held at ground potential, and the dielectric disk provides electrical insulation between the high voltage conductor disk and the grounded base plate. A heat sink, such as a plurality of thermally conductive fins, can extend from the base of the anode stack to facilitate cooling of the x-ray source during operation.

[0053] As shown in FIGS. 5A-5D, a focused X-ray excitation beam 513 is directed onto a sample 516 within a focal region or point on the sample. In one or more embodiments, the sample resides in a sample chamber 517 of a sample carrier, such as a carrier for presenting pressurized samples to a sample focal region of an analyzer. An X-ray detector 518 is oriented and positioned relative to the sample 516 (i.e., closely coupled as described herein) to receive fluorescence from the sample induced by the impinging X-ray excitation beam 513, the fluorescence indicating the concentration of at least one element in the sample. In one or more embodiments, the detector 518 is an energy dispersive detector, such as an energy dispersive SDD detector. In one or more embodiments described herein, the detector 518 is closely coupled to the sample 516, meaning that the detector is positioned relative to the sample to minimize a gap between the detector and the sample, ensuring, for example, that the detector's collection solid angle is greater than 1 steradian and that the transmission loss at 1.74 keV is less than 30%. In one or more embodiments, the gap is an air gap between the sample and the detector. In one or more other embodiments, the gap contains and / or is filled with one or more gases (e.g., helium or hydrogen) to facilitate transmission. Furthermore, in one or more other embodiments, the gap can be a vacuum gap. In the illustrated embodiment, the detector 518 includes an aperture with a cover or lens 520 that protects the aperture. As shown in FIG. 5D , in one or more implementations, the cover or lens 520 of the detector 518 is positioned closely to or coupled to the sample 516 while still allowing the focused X-ray excitation beam 513 to impinge on the focal region or point and induce fluorescence. In one or more implementations, the central axis of the detector 518 (i.e., the detector aperture) is substantially perpendicular to the plane formed by the X-ray source, optics, and sample spot. For example, in one embodiment, the central detection axis of the detector is between 85° and 95° of the plane, which advantageously suppresses scattering from the sample.

[0054] Further details of the embodiment of the polarized energy dispersive X-ray fluorescence system of Figures 5A-5D are shown in Figures 6A-6C.

[0055] 6A, as described with reference to FIGS. 5A-5D, an X-ray source 510, such as a titanium X-ray source, provides a diverging X-ray beam 511 having a characteristic energy of titanium based, such as 4.5 keV Ti Ka X-rays, to monochromating and focusing optics 512. The X-ray source, such as a titanium X-ray tube, <001> or <002> The diverging x-ray beam is aligned with optics 512, such as a Johann focusing doubly curved lithium fluoride (LiF) crystal optic or helix shape (as shown in FIG. 6B) formed from LiF crystal. Optics 512 monochromatizes and focuses the diverging x-ray beam to produce a monochromatized and focused x-ray excitation beam 513 for impinging on sample 516. The selection of a titanium target or anode in combination with the LiF doubly curved crystal optic advantageously enhances operation by providing a Bragg angle of 43.05°, which allows the design to essentially function as a polarizer in the x-ray fluorescence system while providing other benefits of the focusing doubly curved crystal optic.

[0056] 6B, optics 512, in one embodiment, is configured as a DCC optic, logarithmic spiral, 4.51 keV focusing, lithium fluoride (LiF) crystal optic, which enables polarization geometry with focusing doubly curved LiF crystal optics and a titanium X-ray source operating at a Bragg angle ranging from 42° to 48° to facilitate beam polarization. As shown in FIGS. 6A and 6B, in one embodiment, the central axes of the diverging X-ray beam from target spot 600 to optics 512 and the central axis of the X-ray excitation beam from optics 512 to sample spot 601 define approximately 90° beam paths to and from the optics.

[0057] 6C shows a partial cross-sectional view of an assembled polarized energy dispersive X-ray fluorescence system as disclosed herein. As shown, in one embodiment, the X-ray fluorescence system includes a partial X-ray shield 610 between the optics 512 and the sample 516. The X-ray shield 610 is configured with a tapered inner chamber sized and shaped to accommodate the monochromated and focused X-ray excitation beam 513 directed from the optics 512 toward the sample 516. As shown, in one or more embodiments, the X-ray shield 610 is also configured to accommodate the diverging X-ray beam 511 between the output of the titanium X-ray source 510 and the optics 512. By sizing and shaping the inner chamber to accommodate the diverging X-ray beam 511 as well as the focused X-ray excitation beam 513, background noise is reduced. To further reduce the system background, tight apertures can be placed across both the end of the excitation beam 710 near where it hits the sample as well as the detector aperture 720, as shown in FIG. 7D, to minimize the impact of argon scattering on the system background, for example.

[0058] 7A-7D show further details of one embodiment of an assembled X-ray fluorescence system or analyzer, such as that described above in connection with FIGS. 5A-6C, in accordance with one or more aspects of the present invention. As shown, a housing 700 encloses a titanium X-ray source, the housing having an aperture aligned with the transmission window of the X-ray tube, as described above, to allow the passage of the diverging X-ray beam. According to one or more aspects of the present invention, a detector 518 is closely coupled to the sample 516. This is facilitated in one embodiment by providing an X-ray excitation beam 513 from optics 512 with a shallow impingement angle relative to the sample 516, as shown in FIGS. 7C and 7D. For example, in one or more implementations, a focusing doubly curved lithium fluoride (LiF) crystal optic is positioned such that the X-ray excitation beam 513 impinges on the sample focal spot at an excitation angle in the range of 15° to 30°, e.g., 18° to 23°. In one particular example, the X-ray excitation beam 513 may be oriented to impinge on the sample within an excitation angle of approximately 20°. This shallow window of X-ray excitation beam impingement on the sample allows the detector 518 to be positioned at a minimal distance from the sample to minimize fluorescence loss from the sample, e.g., to minimize air loss. For example, in one or more embodiments, the detector is positioned relative to the sample to minimize the gap between the detector and the sample so that the detector's collection solid angle is greater than 1 steradian and the transmission loss at 1.74 keV is less than 30%. In one or more embodiments, the gap is an air gap, and minimizing the air gap between the detector and the sample is possible due to the low incidence angle of the X-ray excitation beam impingement on the sample, as shown. Furthermore, as shown in Figures 7C-7D, the system polarization geometry is further improved by the detector being positioned at approximately 90° with respect to the plane generated by the excitation assembly (i.e., the source, optics, and sample). In one or more embodiments, the detector is an energy dispersive detector, and the central axis of the detector relative to the plane generated by the excitation assembly is at an angle in the range of 85° to 95°, such as approximately 90°, which helps suppress detection of scattering from the sample.To further reduce system background noise, for example to minimize the effect of argon scattering on the system background, tight apertures such as aperture 710 are placed at the end of the X-ray excitation beam and above the detector aperture 720.

[0059] Advantageously, disclosed herein are polarized energy dispersive X-ray fluorescence (EDXRF) systems and methods. A polarized EDXRF system is achieved in two ways. First, the excitation beam is polarized, but the divergent X-rays from the source are not. To generate a polarized beam, a 90° reflection / scattering is achieved, polarizing the beam based on electromagnetic wave properties. This condition is achieved in one or more embodiments herein using lithium fluoride (LiF) (200) reflection of titanium characteristic energy (Ka line). A Bragg angle close to 45° has a 90° reflection. In a conventional approach, a scattering target with a mechanical collimator or HOPG combined with Rh 2.6 keV (Bragg angle close to 45°) can also achieve a polarized beam. However, advantages of using a titanium X-ray source in combination with a focusing, double-curved LiF crystal optic, as described herein, include better monochromaticity; fluorescence that can travel through a 100 mm gap with minimal (or acceptable) loss (e.g., ≦10% loss); a smaller focal spot on the sample; and good excitation energy for characterizing one or more of sodium, magnesium, aluminum, silicon, phosphorus, sulfur, or chlorine, since 4.5 keV scattering from the sample is far enough away from all of these fluorescent lines of the following elements. Second, when the excitation beam is polarized, scattering from the sample can be suppressed by a detector positioned so that the central ray or axis of the detector is perpendicular to the plane of the excitation assembly, including the source, optics, and focal spot. Note that this does not mean 90° from the central axis of the excitation beam, but rather perpendicular to the plane defined by the source, optics, and focal spot on the sample. When these conditions are met, a polarized EDXRF system and method, as described herein, is achieved.

[0060] As will be appreciated by those skilled in the art, one or more aspects of the present invention may be embodied as a system, method, or computer program product. For example, one or more analysis aspects of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining software and hardware aspects, all of which may be referred to generally herein as a "circuit," "module," "analyzer," or "system." Furthermore, one or more aspects of the present invention may take the form of a computer program product embodied in one or more computer-readable medium(s) having computer-readable program code embodied thereon.

[0061] Any combination of one or more computer-readable media may also be utilized. The computer-readable medium may be a computer-readable storage medium. The computer-readable storage medium may be, for example, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples (non-exhaustive list) of computer-readable storage media include an electrical connection having one or more leads, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing. In the context of this document, a computer-readable storage medium may be any tangible medium that can contain or store a program for use by or in connection with an instruction execution system, apparatus, or device.

[0062] Referring back to FIG. 1, the analyzer 32 may include, for example, one or more non-transitory computer-readable storage media 34 for storing computer-readable program code means or a computer program product including a processor / logic circuitry 33 for providing and facilitating one or more aspects of the present invention.

[0063] The program code embodied on the computer readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, fiber optic cable, RF, etc., or any suitable combination of the foregoing.

[0064] Computer program code for carrying out operations for one or more aspects of the present invention can be written in any combination of one or more programming languages, including object-oriented programming languages such as Java, Smalltalk, C++, etc., and conventional procedural programming languages such as the "C" programming language, Assembler, or similar programming languages. The program code can run entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or can be connected to an external computer (e.g., via the Internet using an Internet Service Provider).

[0065] One or more aspects of the present invention are described herein with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that one or more blocks of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus to create a machine such that the instructions, executed by the processor of the computer or other programmable data processing apparatus, create means for performing the functions / acts identified in the flowchart and / or block diagram blocks.

[0066] These computer program instructions may also be stored on a computer-readable medium that can direct a computer, other programmable data processing apparatus, or other device to function in a particular manner, such that the instructions stored on the computer-readable medium produce an article of manufacture that includes instructions that perform the functions / acts specified in the flowchart and / or block diagram blocks.

[0067] Computer program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps executed on the computer, other programmable apparatus, or other device to produce a computer-implemented process such that the instructions executing on the computer or other programmable apparatus provide a process for performing one or more functions / operations specified in the flowchart and / or block diagram blocks.

[0068] The flowcharts and / or block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of one or more aspects of the present invention. In this regard, one or more blocks in the flowcharts or block diagrams may represent a module, segment, or portion of code, including one or more executable instructions for implementing the specified logical function(s). It should also be noted that in some alternative implementations, the functions shown in the blocks may occur out of the order shown in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently or may be executed in the reverse order, depending on the functionality involved in the blocks. It should also be noted that each block of the block diagrams and / or flowchart diagrams, and combinations of blocks in the block diagrams and / or flowchart diagrams, may be implemented by a dedicated hardware-based system that performs the specified functions or operations, or a combination of dedicated hardware and computer instructions.

[0069] In addition to the above, one or more aspects of the present invention may be provided, offered, deployed, managed, serviced, etc. by a service provider that offers management of customer environments. For example, a service provider may create, maintain, support, etc. computer code and / or computer infrastructure that implements one or more aspects of the present invention for one or more customers.

[0070] In return, the service provider may receive payments from the customer, for example, under a subscription and / or fee agreement. Additionally or alternatively, the service provider may receive payments from the sale of advertising content to one or more third parties.

[0071] In one aspect of the present invention, an application can be deployed to perform one or more aspects of the present invention. By way of example, deploying an application includes providing a computer infrastructure operable to perform one or more aspects of the present invention.

[0072] As a further aspect of the present invention, a computing infrastructure can be deployed that includes computer readable code integrated into a computing system, the code in combination with the computing system being capable of performing one or more aspects of the present invention.

[0073] As a further aspect of the present invention, there may be provided a process for integrating a computing infrastructure, comprising integrating computer-readable code into a computer system, the computer system including a computer-readable medium, the computer medium including one or more aspects of the present invention, the code being capable of performing one or more aspects of the present invention in combination with the computer system.

[0074] Although various embodiments are described above, these are merely examples. Additionally, other types of computing environments can benefit from one or more aspects of the present invention.

[0075] As a further example, a data processing system suitable for storing and / or executing program code may be used that includes at least one processor coupled directly or indirectly to memory elements via a system bus, including, for example, local memory, bulk storage, and cache memory used during the actual execution of the program code, which provide temporary storage of at least some program code to reduce the number of times that code must be retrieved from bulk storage during execution.

[0076] Input / output or I / O devices (including but not limited to keyboards, displays, pointing devices, DASDs, tapes, CDs, DVDs, thumb drives, and other memory media, etc.) may be coupled to the system either directly or through intervening I / O controllers. Network adapters may also be coupled to the system to enable the data processing system to be coupled to other data processing systems or remote printers or storage devices through intervening private or public networks. Modems, cable modems, and Ethernet cards are just a few of the available types of network adapters.

[0077] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context otherwise dictates. Furthermore, the terms "comprise" (and any of their forms, such as "comprises" and "comprising"), "have" (and any of their forms, such as "has" and "having"), "include" (and any of their forms, such as "includes" and "including"), and "contain" (and any of their forms, such as "contains" and "containing") will be understood to be open-ended linking verbs. Consequently, a method or device that "comprises," "have," "include," or "contain" one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements. Similarly, a method step or device element that "comprises," "has," "includes," or "contains" one or more features possesses those one or more features, but is not limited to possessing only those one or more features. Furthermore, a device or structure that is configured in a particular way is configured in at least that way, but may also be configured in ways not recited.

[0078] Structure, material, acts, and equivalents (where present) of all means-plus-function or step-plus-function elements in the following claims are intended to include any structure, material, or acts for performing the function that is specifically claimed in combination with other claimed elements. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the invention. The embodiments were chosen and described to best explain the principles and practical application of one or more aspects of the invention and to enable those skilled in the art to understand one or more aspects of the invention in various embodiments with various modifications suitable for the particular use contemplated.

Claims

1. 1. An X-ray fluorescence system comprising: a titanium x-ray source including a titanium target that is bombarded with electrons to produce a divergent x-ray beam having a titanium-based characteristic energy; a focusing doubly curved LiF crystal optic that monochromatizes and focuses the diverging x-ray beam from the titanium x-ray source to provide a monochromatized and focused x-ray excitation beam directed to impinge on a sample, wherein the focusing doubly curved LiF crystal optic and the titanium x-ray source operate at a Bragg angle that facilitates polarization within the x-ray fluorescence system; a detector for receiving fluorescence from the sample induced by the x-ray excitation beam impinging thereon, the fluorescence being indicative of the concentration of at least one element in the sample; An X-ray fluorescence system comprising:

2. 10. The X-ray fluorescence system of claim 1, wherein the focusing doubly curved LiF crystal optics and the titanium X-ray source operate at a Bragg angle ranging from 42° to 48° to facilitate polarization within the X-ray fluorescence system.

3. 2. The X-ray fluorescence system of claim 1, wherein the focusing doubly curved LiF crystal optics includes a <002> LiF crystal operating with the titanium X-ray source at the Bragg angle to facilitate polarization within the X-ray fluorescence system.

4. 4. The X-ray fluorescence system of claim 3, wherein the divergent X-ray beam from the titanium X-ray source monochromatized and focused by the focusing doubly curved LiF crystal optic has a characteristic energy of about 4.5 keV.

5. The X-ray fluorescence system of claim 3 , wherein the focusing doubly curved LiF crystal optic comprises a logarithmic spiral doubly curved LiF crystal, a Johann doubly curved LiF crystal, or a Johansson doubly curved crystal.

6. 10. The X-ray fluorescence system of claim 1, wherein the focusing doubly curved LiF crystal optic is positioned so that the X-ray excitation beam impinges on the sample at an excitation beam angle in the range of 15° to 30°.

7. 7. The X-ray fluorescence system of claim 6, wherein the focusing doubly curved LiF crystal optics is arranged so that the excitation beam angle is in the range of 18° to 23°.

8. 2. The X-ray fluorescence system of claim 1, wherein the detector comprises an energy dispersive detector, the titanium x-ray source, the doubly curved LiF crystal optic, and the sample lie in a plane with respect to which a central axis of the detector lies at an angle relative to the plane in the range of 85° to 95° to facilitate suppression of scattering from the sample.

9. 10. The X-ray fluorescence system of claim 1, wherein the detector is positioned relative to the sample to minimize a gap therebetween so that the detector has a collection solid angle greater than 1 steradian and a transmission loss at 1.74 keV of less than 30%.

10. The X-ray fluorescence system of claim 9 , wherein the gap between the detector and the sample is an air gap.

11. 10. The X-ray fluorescence system of claim 1, further comprising an X-ray shield between the optical system and the sample, the X-ray shield having a tapered inner chamber sized and shaped to contain the monochromated and focused X-ray excitation beam directed to impinge on the sample.

12. The X-ray fluorescence system of claim 1 , wherein the at least one element in the sample includes at least one of sodium, magnesium, aluminum, silicon, phosphorus, sulfur, or chlorine.

13. 1. A method of manufacturing an X-ray fluorescence system, comprising: providing a titanium x-ray source, the titanium x-ray source including a titanium target that is bombarded with electrons to produce a divergent x-ray beam having a titanium-based characteristic energy; positioning a focusing doubly curved LiF crystal optic relative to the X-ray source to monochromatize and focus the diverging X-ray beam from the titanium X-ray source to provide a monochromatized and focused X-ray excitation beam directed to impinge on a sample, the focusing doubly curved LiF crystal optic and the titanium X-ray source operating at a Bragg angle that facilitates polarization within the X-ray fluorescence system; providing a detector to receive fluorescence from the sample induced by the X-ray excitation beam impinging thereon, the fluorescence being indicative of a concentration of at least one element in the sample; A method comprising:

14. 14. The method of claim 13, wherein the focusing doubly curved LiF crystal optic and the titanium x-ray source operate at a Bragg angle in the range of 42° to 48° to facilitate polarization within the x-ray fluorescence system.

15. 14. The method of claim 13, wherein the focusing doubly curved LiF crystal optic comprises a <002> LiF crystal operating with the titanium x-ray source at a Bragg angle to provide polarization within the x-ray fluorescence system.

16. 14. The method of claim 13, wherein the focusing doubly curved LiF crystal optic is positioned so that the X-ray excitation beam impinges on the sample at an excitation beam angle in the range of 15° to 30°.

17. 14. The method of claim 13, wherein the detector comprises an energy dispersive detector, and wherein the titanium x-ray source, the doubly curved LiF crystal optic, and the sample lie in a plane with respect to which a central axis of the detector is at an angle in the range of 85° to 95° to facilitate suppression of scattering from the sample.

18. 14. The method of claim 13, wherein the detector is positioned relative to the sample to minimize a gap between the detector and the sample such that the detector has a collection solid angle greater than 1 steradian and a transmission loss of less than 30% at 1.74 keV.

19. 20. The method of claim 18, wherein the gap between the detector and the sample is an air gap.

20. 14. The method of claim 13, further comprising an x-ray shield between the optical system and the sample, the x-ray shield having a tapered inner chamber sized and shaped to contain the monochromated and focused x-ray excitation beam directed to impinge on the sample.

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