Anusheela Das, Chris M. Heirwegh, Ning Gao, William T. Elam, Lawrence A. Wade, Benton C. Clark, Joel A. Hurowitz, Scott J. VanBommel, Michael W. M. Jones, Abigail C. Allwood
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引用次数: 0
Abstract
In this work, we studied the x‐ray energy dependence of x‐ray beam diameter focused by polycapillary optics. A quantitative beam diameter–energy relation enables more accurate estimation of the element‐specific interrogation area of a sample using the compositional maps produced by a micro‐XRF system. This improves upon our ability to visualize individual beam‐diameter sized mineral grains and in turn directly benefits Planetary Instrument for X‐ray Lithochemistry (PIXL) analyses of martian soil in addition to benefitting other micro‐focused x‐ray fluorescence (XRF) systems. The spatial distribution of an array of characteristic XRF emission lines was measured by sampling via a knife‐edge approach with small motor stepping of the beam across target edges. Data taken as part of this effort, from the Planetary Flight Model (PFM), were limited to only seven beam energies corresponding to the elements Ni, Cu, Se, Ta, Au, Ti and Ba. Hence, we conducted additional analysis using JPL's lab‐based breadboard (LBB) micro‐XRF system, a system that emulates PIXL's functionality where we measured beam diameter corresponding to 18 elements: Na, Mg, Al, Si, Cl, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, Se, Sr and Mo. The experimental results were also compared with Monte Carlo simulations. The beam diameter (y)–energy (x) relation that we obtained for LBB was y = 185.79 exp(−0.078x) whose exponential component was then used to get a more accurate relation for the PFM even with the limited data set: y = 227.53 exp(−0.078x). The difference in the two coefficients for the PFM and LBB stems mainly from the difference in the polycapillary optic design, and this work establishes x‐ray beam diameter versus energy relation quantitatively for both the systems.
期刊介绍:
X-Ray Spectrometry is devoted to the rapid publication of papers dealing with the theory and application of x-ray spectrometry using electron, x-ray photon, proton, γ and γ-x sources.
Covering advances in techniques, methods and equipment, this established journal provides the ideal platform for the discussion of more sophisticated X-ray analytical methods.
Both wavelength and energy dispersion systems are covered together with a range of data handling methods, from the most simple to very sophisticated software programs. Papers dealing with the application of x-ray spectrometric methods for structural analysis are also featured as well as applications papers covering a wide range of areas such as environmental analysis and monitoring, art and archaelogical studies, mineralogy, forensics, geology, surface science and materials analysis, biomedical and pharmaceutical applications.