Abstract:
A radiation detector assembly and a method for using the same are provided. The radiation detector assembly includes an aperture, a window covering the aperture, the window is configured to permit radiation to pass through, the window is configured to prevent the passage of fluids and particles through the aperture, and a protective device covers the window. The protective device includes a plurality of holes at least partially aligned with the aperture, is configured to permit at least some radiation to pass through the holes, is configured to prevent objects larger than the holes to contact the window and is configured to withstand external forces and prevent those forces from damaging the window.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of the filing date of U.S. Provisional Application No. 61/636,334 filed on Apr. 20, 2012, which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The embodiments described herein relate generally to X-ray devices that include a window through which X-rays are transmitted, and more specifically, to protecting the window from external forces. 
         [0003]    X-ray devices, for example, an X-ray source or an X-ray detector, may utilize a vacuum chamber with a window through which X-rays are transmitted. For example, a beryllium window may facilitate maintaining the vacuum within the vacuum chamber while also allowing X-rays to enter and/or leave the chamber. The transmission characteristics of the window depend on the material used to form the window and a thickness of the material. Thin windows or a film allow transmission of relatively low energy X-rays typically emitted from elements with relatively low atomic numbers. In other words, thicker windows may prevent transmission of X-rays emitted from elements with relatively low atomic numbers (e.g., Sodium). Therefore, thin windows are often desirable. However, thin windows are also more prone to breaking or being damaged by a foreign object or a sample of interest during a reading process if the foreign object or sample is permitted to contact the window. There are multiple expenses incurred by an operator of the X-ray device that are brought about by a broken window. The expenses include monetary costs associated with replacing the window and also productivity costs associated with the X-ray device not being usable while the repair is being made. 
         [0004]    Accordingly, it is desirable to have a protective device that addresses the disadvantages of the known systems described above. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0005]    In one aspect, a radiation assembly includes an aperture, a window covering the aperture, the window configured to permit radiation to pass through, the window is configured to prevent the passage of fluids and particles through the aperture, and a protective device covering the window, the protective device comprising a plurality of holes at least partially aligned with the aperture, the protective device configured to permit at least some radiation to pass through the holes, the protective device is configured to prevent objects larger than the holes to contact the window and is configured to withstand external forces and prevent those forces from damaging the window. 
         [0006]    In another aspect, a method of determining an elemental composition of a material sample includes providing a radiation source assembly including a radiation source device and a complementary radiation detector assembly including a radiation detector device wherein the radiation source assembly includes a window covering the radiation source device and the radiation detector assembly includes a window covering the radiation detector device. The method also includes covering at least one of the windows with a protective device, positioning the radiation source assembly and the radiation detector assembly proximate the material sample, and preventing the material sample from contacting the at least one of the windows using the associated protective device. 
         [0007]    In yet another aspect, a spectrometer for determining a composition of a material sample includes a first radiation assembly comprising a radiation source device configured to generate a primary beam of radiation to be directed toward the material sample, an aperture though which, a first portion of the primary beam of radiation must pass to reach the material sample, a window covering said aperture, said window configured to permit the at least a first portion of the primary beam of radiation to pass through, said window is configured to prevent the passage of fluids and particles through the aperture, and a protective device covering said window, said protective device comprising a plurality of holes at least partially aligned with the aperture, said protective device configured to permit at least a second portion of the primary beam of radiation to reach the material sample through the holes, said protective device configured to prevent objects larger than the holes to contact the window. The spectrometer also includes a second radiation assembly including a radiation detector device configured to generate a detector signal representative of a secondary beam of radiation from the material sample generated by an interaction of the second portion of the primary beam of radiation and the material sample, an aperture though which, the secondary beam of radiation must pass from the material sample to the radiation detector device, a window covering said aperture, said window configured to permit the secondary beam of radiation to pass through, said window is configured to prevent the passage of fluids and particles through the aperture, and a protective device covering said window, said protective device comprising a plurality of holes at least partially aligned with the aperture, said protective device configured to permit at least a portion of the secondary beam of radiation to reach the radiation detector device through the holes, said protective device configured to prevent objects larger than the holes to contact the window. The spectrometer also includes a processing device coupled to said radiation source device and said radiation detector device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a functional illustration of the general components of a radiation assembly  10  in accordance with an exemplary embodiment of the present disclosure. 
           [0009]      FIG. 2  is a block diagram of an exemplary radiation system in accordance with an exemplary embodiment of the present disclosure. 
           [0010]      FIG. 3  is a cross-sectional view of a portion of a known radiation system. 
           [0011]      FIG. 4  is a cross-sectional view of an exemplary protective device that may be used to protect the radiation window in accordance with an exemplary embodiment of the present disclosure. 
           [0012]      FIG. 5  is a perspective view of the protective device shown in  FIG. 4 . 
           [0013]      FIG. 6  is a perspective view of a first alternative embodiment of the protective device shown in  FIGS. 4 and 5  a portion of which is shown in  FIG. 7 . 
           [0014]      FIG. 7  is a top view of the portion shown in  FIG. 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0015]    The methods and apparatus described herein facilitate protecting an X-ray device window. X-ray device windows are typically fragile and costly to replace if damaged. One cause of damage to X-ray device windows comes from contact with a foreign object or a sample being tested. For example, the foreign object or sample being tested may be jagged and any contact with the X-ray device window could damage or destroy the window. However, it is undesirable to increase the distance from the surface of the sample to the detector in order to prevent contact between the sample and the X-ray device window. In an example of an X-ray fluorescence (XRF) analyzer, increasing the distance from the surface of the sample to the detector causes a loss of intensity of secondary radiation emitted by the sample that is proportional to the square of the distance increase. The methods and apparatus described herein protect the X-ray device window while maintaining the sample within a predefined distance of the detector. 
         [0016]      FIG. 1  is a functional illustration of the general components of a radiation assembly  10 , for example, but not limited to, an X-ray fluorescence (XRF) spectrometer. XRF spectrometers detect secondary radiation emitted from a sample of material that has been excited by radiation applied to the sample material by the spectrometer. A wavelength distribution of the emitted radiation is characteristic of the elements present in the sample, while the intensity distribution gives information about the relative abundance of the elements in the sample. By means of a spectrum obtained in this manner, a user typically is able to determine the components, and quantitative proportions of those components, within the examined test sample. In the illustrated embodiment, radiation assembly  10  includes a radiation source device  12 , a radiation detector device  14 , an analyzer  16 , and a display  19 . Radiation source device  12  may include an X-ray tube that projects a primary beam of X-rays  18  towards a sample  32  that is to be tested. In another exemplary embodiment, radiation source device  12  is a radioactive isotope, which projects a primary beam of gamma rays toward the sample  32 . In yet another exemplary embodiment, radiation source device  12  is an electron beam source that projects a primary beam of electrons towards the sample  32 . Any suitable radiation source, or plurality of sources, that allow radiation assembly  10  to function as described herein may be used as radiation source device  12 . 
         [0017]    Sample  32  becomes excited after being exposed to primary beam  18 . This excitation causes sample  32  to emit a secondary (i.e., characteristic or fluorescent) radiation  21 . Secondary radiation  21  is collected by radiation detector device  14 . Radiation detector device  14  includes electronic circuitry, which is sometimes referred to as a preamplifier, that converts collected secondary radiation to a detector signal  24  (i.e., a voltage signal or an electronic signal) and provides the detector signal  24  to analyzer  16 . In at least one embodiment, analyzer  16  includes a digital pulse processor or multi-channel analyzer. 
         [0018]      FIG. 2  is a block diagram of radiation assembly  10  in accordance with an exemplary embodiment of the present disclosure. In the exemplary embodiment, radiation assembly  10  includes radiation source device  12 , radiation detector device  14 , and analyzer  16 , which in the exemplary embodiment includes a readout electronics  17 , a processor  20 , and a memory device  22 . Radiation assembly  10  may also include a display  19  and/or a filter  26 . 
         [0019]    The terms processor or processing device, as used herein, refer to central processing units, microprocessors, microcontrollers, reduced instruction set circuits (RISC), application specific integrated circuits (ASIC), logic circuits, and any other circuit or processor capable of executing the functions described herein. 
         [0020]    It should be noted that embodiments of the invention are not limited to any particular processor for performing the processing tasks of the invention. The terms “processor” or “processing device,” as those terms are used herein, is intended to denote any machine capable of performing the calculations, or computations, necessary to perform the tasks of the invention. The terms “processor” or “processing device” also are intended to denote any machine that is capable of accepting a structured input and of processing the input in accordance with prescribed rules to produce an output. It should also be noted that the phrase “configured to” as used herein means that the processor is equipped with a combination of hardware and software for performing the tasks of embodiments of the invention, as will be understood by those skilled in the art. 
         [0021]    Moreover, aspects of the invention transform a general-purpose computer into a special-purpose computing device when configured to execute the instructions described herein. 
         [0022]    In the exemplary embodiment, radiation source device  12  is a radiation source that projects a primary beam of radiation toward a sample material  32  that is selected to be analyzed. For example, radiation source device  12  may include an X-ray tube that projects primary beam of X-rays  18  toward sample  32 . In an alternative embodiment, radiation source device  12  is a radioactive isotope, which projects a primary beam of gamma rays toward sample  32 . In yet another alternative embodiment, radiation source device  12  is an electron beam source that projects a primary beam of electrons towards the sample  32 . Any suitable beam source, or plurality of sources, known in the art can be used as radiation source device  12 . As used herein, sample  32  includes irregular-shaped objects, relatively small object, such as, but not limited to powders, particulates, and shavings, and objects that include protrusions and pointed extensions. 
         [0023]    In the exemplary embodiment, filter  26  is positioned between radiation source device  12  and sample  32 . For example, filter  26  may be a selectable filter coupled to processing device  20 . Processing device  20  may be configured to select one or more of a plurality of filters that may be applied by filter  26 . Processing device  20  may also be configured to select that no filter be applied to primary beam  18 . More specifically, filter  26  may include a first filter  34  that modifies characteristics of primary beam  18  in a first manner and a second filter  36  that modifies characteristics of primary beam  18  in a second manner. Examples of materials included within first filter  34  and/or second filter  36  include, but are not limited to, copper, aluminum, and titanium. Although described as including two filters, filter  26  may include any number of filters that allows radiation assembly  10  to function as described herein. 
         [0024]    Sample  32  becomes excited after being exposed to primary beam  18 . This excitation causes sample  32  to emit a secondary (i.e. characteristic fluorescent) radiation  38 . Secondary radiation  38  is impinged upon radiation detector device  14 . Radiation detector device  14  converts the secondary radiation to a detector signal  24 , for example, a voltage signal or an electronic signal that is representative of the secondary radiation. Radiation detector device  14  provides detector signal  24  to readout electronics  17 , which determine an energy spectrum of the collected secondary radiation  38 . Readout electronics  17  provide this energy spectrum to processing device  20 . Although described herein as radiation detector device  14  providing detector signal  24  to readout electronics  17  and readout electronics  17  providing the energy spectrum to processing device  20 , it is contemplated that readout electronics  17  and/or processing device  20  may take action to receive detector signal  24  and/or the energy spectrum (e.g., may perform polling or a retrieve function in order to receive the signal and/or spectrum). Processing device  20  determines the unique elemental composition of the sample. Processing device  20  may also be referred to as an analyzer and may include a digital pulse processor. 
         [0025]    Display  19  allows an operator to view results provided to display  19  by processing device  20 , for example, an operator may view the energy spectrum or a derived elemental composition and a final analytical result, such as an alloy identification of sample  32 . Display  19  may be built into a handheld enclosure or it may be in the form of a small handheld computer or personal digital assistant (PDA) that is communicatively coupled to processing device  20 . 
         [0026]    In the exemplary embodiment, radiation assembly  10  determines measurement conditions to be applied during an analysis of a sample, for example, sample  32 . As described above, processing device  20  controls operation of radiation assembly  10 , and more specifically, controls operation of radiation source device  12 . In the exemplary embodiment, processing device  20  operates radiation source device  12  in accordance with at least one predefined measurement condition to perform a first elemental analysis of sample  32 . For example, processing device  20  may be configured to operate radiation source device  12  in accordance with a first measurement condition or a first set of measurement conditions. The measurement condition includes, but is not limited to, a length of time the measurement is taken, a level of voltage applied to radiation source device  12 , a level of current applied to radiation source device  12 , and/or a type of filter used. In the exemplary embodiment, a first predefined level of voltage is applied to radiation source device  12  for a first predefined length of time to perform the first elemental analysis of sample  32 . The first elemental analysis may also be referred to as an initial analysis of sample  32  that provides an initial determination of an alloy grade of sample  32 . The first elemental analysis is not stringent enough to determine, to a predefined level of certainty, that sample  32  is composed of the initial determination of the alloy grade. The first set of measurement conditions may be stored in a memory device, for example, memory device  22 . In a specific example, an aluminum/titanium (Al/Ti) filter is positioned between sample  32  and radiation detector device  14 , and power having 40 kV and 10 microamps is applied to radiation source device  12  for five seconds. 
         [0027]      FIG. 3  is a cross-sectional view of a portion of a known radiation assembly  10 . In the illustrated embodiment, radiation assembly  10  is included within, for example, an X-ray florescence (XRF) analyzer. More specifically, radiation assembly  10  may include an X-ray assembly  213 , which may include an X-ray source assembly or an X-ray detector assembly. An X-ray source assembly includes radiation source device  12  and a base  202  enclosing a chamber  214  having a controlled atmosphere. In an embodiment, chamber  214  is evacuated such that a vacuum within chamber  214 . In various embodiments, chamber  214  may be filled or partially-filled with a fluid, such as an inert gas. Chamber  214  may be maintained at a vacuum or be pressurized with respect to a pressure external to chamber  214 . An X-ray detector assembly includes radiation detector device  14  and chamber  214 . Base  202  includes a radiation window assembly  218  through which radiation and/or electrons may pass, while the controlled atmosphere condition within chamber  214  is maintained. Although described with respect to an X-ray source assembly or an X-ray detector assembly, the methods and apparatus described herein may be applied to other types of sources/detectors, including, but not limited to, ionized radiation sources, electron emitting sources, silicon pin detectors, silicon drift detectors, and/or proportional counters. Although described herein with respect to an XRF analyzer configured to determine an elemental composition of a sample  32 , radiation assembly  10  may be included within other devices. 
         [0028]    In the illustrated embodiment, radiation window assembly  218  includes a radiation window support  222  with an opening  224  defined therein. Window support  222  includes at least one wall that may form a portion of chamber  214 . In the illustrated embodiment, chamber  214  is substantially cylindrically shaped, however, chamber  214  may have any shape that allows radiation assembly  10  to function as described herein. Furthermore, opening  224  is illustrated as substantially cylindrically shaped, however, opening  224  may have any suitable shape that allows radiation assembly  10  to function as described herein, for example, but not limited to, round, rectangular, a slot, and/or multiple openings having various shapes. Moreover, radiation window assembly  218  includes a window  226  coupled to window support  222  and extending across opening  224 . Window  226  is configured to maintain the controlled atmosphere on the inside of chamber  214  while allowing transmission of radiation and/or electrons in or out of chamber  214 . Window  226  may be formed of a film or a wafer of metallic or non-metallic material, for example, window  226  may be formed from beryllium and/or any other element(s) that allow radiation window assembly  218  to function as described herein. 
         [0029]    Radiation window support  222  includes an inner side  230  (i.e., a controlled atmosphere side) and an outer side  232  (i.e., an ambient side). Opening  224  allows for the transmission of radiation in or out of chamber  214 . Window  226  is sealed against window support  222 , for example, using an adhesive  234 . Window  226  covers opening  224  to prevent gases from entering chamber  214 , thus maintaining the controlled atmosphere condition within chamber  214 . Typically, a thickness  236  of window  226  is determined that allows transmission of a desired radiation while the controlled atmosphere is maintained within chamber  214 . A thin window  226  is desirable for transmission capabilities, however, a thin window  226  is more susceptible to damage than a thicker window  226 . 
         [0030]      FIG. 4  is a cross-sectional view of an exemplary protective device  350  that may be used to protect a radiation window, for example, radiation window assembly  218  (shown in  FIG. 3 ). More specifically, protection device  350  is configured to protect window  226  included within radiation window assembly  218  (shown in  FIG. 3 ).  FIG. 5  is a perspective view of protective device  350 . In the exemplary embodiment, protective device  350  includes a device support  360  that includes a first plurality of radiation path openings  362  defined therein. In the exemplary embodiment, protective device  350  is removably coupled to radiation assembly  10 . For example, protective device  350  may be added to radiation assembly  10  to protect radiation window assembly  218 . In an alternative embodiment, protective device  350  is included in radiation assembly  10 . 
         [0031]    In the exemplary embodiment, device support  360  includes an inner surface  364  and an outer surface  366 . Device support  360  is configured to extend around at least a portion of window support  222 . For example, device support  360  may be configured such that, when assembled, inner surface  364  is positioned around outer side  232  of window support  222 . Furthermore, in the exemplary embodiment, device support  360  is configured such that protective device  350  is maintained in position around window support  222  by a press fit, an interference fit, and/or a friction fit. Alternatively, protective device  350  may be secured to radiation assembly  10  using an adhesive, a clamp, and/or any other suitable means of coupling protective device  350  to radiation assembly  10 . 
         [0032]    In the exemplary embodiment, openings  362  are configured to allow radiation to enter and/or exit chamber  214 . More specifically, openings  362  allow radiation, for example, radiation emitted from sample  32 , to pass through window  226  and into chamber  214 . Openings  362  also allow radiation, for example, radiation emitted by radiation source device  12 , to pass from chamber  214 , through window  226 , and to sample  32 . Openings  362  are also configured to withstand external forces and prevent those forces from damaging window  226 . In the exemplary embodiment, each of openings  362  has a substantially hexagonal shape defined within device support  360 . Furthermore, in the exemplary embodiment, protective device  350  includes eighty-nine openings  362  arranged in a substantially circular orientation having a first diameter  368 . For example, first diameter  368  may be determined based at least partially on a size of radiation source device  12  or radiation detector device  14  included within X-ray assembly  213 . 
         [0033]    In the exemplary embodiment, a space  370  is maintained between window  226  and protective device  350 . For example, protective device  350  may be maintained at a predefined distance  372  from window  226 . By maintaining space  370 , protective device  350  provides protection to window  226  by preventing contact between protective device  350  and window  226  and by preventing external materials (e.g., sample  32 ) from contacting window  226 . In the exemplary embodiment, predefined distance  372  is between 0 and 1 millimeter (mm), or more specifically, between 0.25 mm and 0.75 mm, and even more specifically, approximately 0.5 mm. Furthermore, contact can be made between protective device  350  and foreign object or sample  32  without damaging window  226 . This allows sample  32  to be positioned a predefined distance  374  from window  226 , and therefore, a predefined distance  376  from radiation source device  12  or radiation detector device  14 . 
         [0034]    In the exemplary embodiment, device support  360  includes a first portion  380  and a second portion  382 . In the exemplary embodiment, first portion  380  is manufactured from at least one metal. The material from which first portion  380  is manufactured may be any suitable material in which plurality of openings  362  may be formed and that is structurally strong enough to protect window  226 . For example, openings  362  may be formed within first portion  380  using laser machining techniques and/or any other manufacturing technique that allows protective device  350  to function as described herein. 
         [0035]    The material included in first portion  380  is selected to minimize interference with operation of radiation assembly  10 . For example, in the example of an X-ray detector assembly, the material may be selected to minimize secondary radiation impinged upon radiation detector device  14  that emanated from first portion  380  of protective device  350 . More specifically, the material may be selected to minimize an effect protective device  350  has on operation of radiation assembly  10 . The material is also selected to withstand typical external forces (i.e., withstand mechanical bending potentially caused by contact between protective device  350  and a foreign object or sample  32 ). In some embodiments, first portion  380  of protective device  350  may be at least partially coated with a material that reduces the effect protective device  350  has on operation of radiation assembly  10 . For example, first portion  380 , and more specifically, edges of first portion  380  that define openings  362 , may be coated with a first coating that absorbs unwanted X-ray energies emitted by first portion  380  and which does not interfere with an analysis performed by a device in which radiation assembly  10  is included. Moreover, a second coating may be positioned over the first coating which absorbs X-ray energies emitted by the first coating and which does not produce spectral disturbances within an analytically interesting range. First and second coatings may include, but are not limited to including, indium. 
         [0036]    In at least some embodiments, protective device  350  may include a third coating  386  covering openings  362 . Third coating  386  prevents contaminants from entering openings  362  while allowing transmission of radiation through openings  362 . Third coating  386  may include, but is not limited to including, indium, copper, silver, aluminum, and/or a polyimide film, for example, Kapton®. Kapton® is a registered trademark of DuPont™. 
         [0037]    In the exemplary embodiment, second portion  382  is manufactured from a plastic, for example, but not limited to, polyvinyl chloride (PVC). Furthermore, in the exemplary embodiment, first portion  380  is coupled to second portion  382 . For example, first portion  380  may be coupled to second portion  382  using an adhesive, a fastener, and/or any other means for coupling first portion  380  to second portion  382 . Although described as including two portions, protective device  350  may alternatively be formed from a single piece of material or a number of portions exceeding two. 
         [0038]    As described above, protective device  350  is removably coupled to radiation assembly  10 . In the exemplary embodiment, protective device  350  is configured such that a press fit, interference fit, and/or a friction fit maintains second portion  382  at least partially around a portion of radiation assembly  10 . In an alternative embodiment, second portion  382  is coupled to radiation assembly  10 , for example, using an adhesive and/or any other suitable fastening method, and first portion  380  is removably coupled to second portion  382 . In a further alternative embodiment, second portion  382  is included in radiation assembly  10  and first portion  380  is removably coupled to radiation assembly  10 . By removably coupling at least one of first portion  380  and second portion  382  to radiation assembly  10 , protection is provided to radiation window assembly  218  while access to radiation window assembly  218  and window  226  is maintained. 
         [0039]      FIG. 6  is a perspective view of a first alternative embodiment of protective device  350  (shown in  FIGS. 4 and 5 ) a portion  596  of which is shown in  FIG. 7 , and is referred to herein as protective device  590 . Protective device  590  includes a second plurality of openings  592  defined within a protective device support  594 . For example, in the illustrated embodiment, protective device  590  includes thirty-seven openings arranged within a circle  598  having first diameter  568 . In other words, openings  592  included within protective device  590  are larger than openings  362  included within protective device  350 . 
         [0040]      FIG. 7  is a top view of portion  596  (shown in  FIG. 6 ). In the exemplary embodiment, each of openings  592  is separated from other openings by a predefined distance  598 . For example, predefined distance  598  may be between 50 micrometers (nm) and 200 nm, or more specifically, between 100 nm and 150 nm, or even more specifically, approximately 146 nm. Furthermore, a diameter  600  of each of openings  592  is predetermined such that, in combination with predefined distance  598 , openings  592  comprise a predefined percentage of circle  598  (shown in  FIG. 6 ) having first diameter  568 . For example, in the illustrated embodiment, openings  592  may comprise between 48% and 70% of an area of circle  598 , or more specifically, between 50% and 65% of an area of circle  598 , or even more specifically, approximately 52% of an area of circle  598 . More specifically, in a specific embodiment, to obtain an open area within protective device  590  of approximately 52%, openings  592  are defined within device support  594  to have a diameter  600  of approximately 432 nm, spaced a distance  598  of approximately 146 nm apart, over circle  598  having diameter  568  of approximately 2160 nm. 
         [0041]    In the exemplary embodiment, a loss of signal caused by protective device  590  is directly proportional to the transmission of openings  592 . For example, in the illustrated embodiment, 48% of radiation that would have entered chamber  214  from sample  32  will be lost due to the presence of protective device  590 . The loss of signal caused by protective device  590  is also known and protective device  590  is configured such that the loss of signal is acceptable to an operator of radiation assembly  10 . Without protective device  590 , the operator may not position sample  32  as close to radiation detector device  14  to prevent damaging radiation window assembly  218 . Increasing the distance between sample  32  and radiation detector device  14  changes the spectral content of the radiation that impinges radiation detector device  14  due to photons being absorbed by air present between sample  32  and radiation detector device  14 . 
         [0042]    Described herein are exemplary methods and apparatus for protecting window  226  of radiation window assembly  218  of radiation assembly  10 . More specifically, protective device  350  described herein prevents materials external to radiation window assembly  218  (e.g., foreign objects or the sample being tested) from contacting window  226  included within radiation window assembly  218 . Furthermore, the protective device  350  reduces a risk of damaging window  226  if the operator of radiation assembly  10  should contact sample  32  with the detection system. By permitting sample  32  to contact protective device  350 , sample  32  is maintained a predefined distance from radiation source device  12  and radiation detector device  14 . Moreover, the protective devices are removably coupled to radiation window assembly  218 , which allows the protective device to be replaced if damaged, and also provides access to radiation window assembly  218  for inspection, cleaning, and/or repair. 
         [0043]    The methods and apparatus described herein facilitate efficient and economical testing of samples using an XRF device. Exemplary embodiments of methods and apparatus are described and/or illustrated herein in detail. The methods and apparatus are not limited to the specific embodiments described herein, but rather, components of each apparatus, as well as steps of each method, may be utilized independently and separately from other components and steps described herein. Each component, and each method step, can also be used in combination with other components and/or method steps. 
         [0044]    When introducing elements/components/etc. of the methods and apparatus described and/or illustrated herein, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the element(s)/component(s)/etc. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional element(s)/component(s)/etc. other than the listed element(s)/component(s)/etc. 
         [0045]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.