Energy straggling induced errors in heavy-ion PIXE analysis

Construction of a high energy resolution crystal X‐ray spectrometer to be used for wavelength‐dispersive X‐ray emission spectroscopy (WDXRS) may result in different geometrical aberrations, such as systematic X‐ray line shifts and changes of the X‐ray line shape. Most of these aberrations can be reduced by careful design of a crystal spectrometer, keeping the efficiency of the spectrometer as high as possible. The availability of high‐resolution position‐sensitive detectors and small excitation beam sizes, and therefore a possible downsized Wavelength‐dispersive X‐ray (WDX) spectrometer, increase the need for reliable simulation of aberrations involved in WDXRS. Since the experimental investigation of the impact that WDX spectrometer design has on a particular aberration is rather time‐consuming, a numerical X‐ray tracing procedure, XTRACE, has been developed and applied for this purpose. Results are given in the form of virtual X‐ray energy spectra that have been affected by the most important aberrations. Copyright © 2009 John Wiley & Sons, Ltd.

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X‐ray tracing study of crystal spectrometers for WDXRS application

Tadić

Jakšić

Božičević

2009

X-Ray Spectrometry

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The status of theoretical K‐shell ionization cross sections by protons

Lapicki

2005

X-Ray Spectrometry

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The accuracy of PIXE analysis depends on inner-shell ionization cross sections that are often calculated in the ECPSSR theory which accounts with analytical functions for the energy (E) loss and Coulomb (C) deflection of the projectile plus for the perturbed-stationary state (PSS) and relativistic (R) nature of the target's inner shell. Although the ECPSSR is within 10% overall agreement with the K-shell data -as the proton energy falls below 0.1 to 1 MeV, respectively, in ionization of light-to heavy-target atoms -the ECPSSR increasingly overestimates the empirical database of Paul and Sacher (1989). Except for an enhancement of this overestimate at low energies, a modified ECPSSR based on the Chen-Crasemann (1985, 1989) plane wave Born approximation -evaluated with the exact limits for the momentum transfers and the Dirac-Hartree-Slater wavefunctions -yields cross sections that remain within 10% of the data and the ECPSSR theory. Codes that use only the exact limits instead of the energy-loss function are confirmed to be improper for evaluation of the ECPSSR. Further enhancement of the cross sections at the low energies is limited to light target atoms after the function derived in the separated atom approach to account for the PSS effect is joined with an expression obtained in the united atom limit. An empirical database, updated with cross sections from post-1989 publications, is normalized to the modified ECPSSR theory and various forms of the Coulomb deflection factor are revisited.

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A novel micro-machining method for the fabrication of thick-film SU-8 embedded micro-channels

Tay

Kan

Watt

et al. 2000

J. Micromech. Microeng.

124

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In this paper, a novel method to realize embedded micro-channels is presented. The presented technology is based on a direct write technique using proton beams to pattern thick-film SU-8. This proton micro-machining method allows the production of high aspect ratio and complex three-dimensional micro-structures in polymers with aspect ratios of over 100 and 20 using poly(methylmethacrylate) (PMMA) and SU-8 respectively. As the SU-8 is used as a structural material, its mechanical properties have to be characterized. For a start, the Young's modulus of the proton beam exposed SU-8 is determined using a stylus-type load-deflection method. The second part of this paper describes the underlying theory and method used by the author to determine the Young's modulus of the proton beam exposed SU-8. Measurements of the SU-8 micro-structures show that the Young's modulus is dependent on the proton beam exposure dose. An exposure dose of 9.5 nC mm −2 results in an average Young's modulus value of 4.254 GPa.

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Energy straggling induced errors in heavy-ion PIXE analysis

Cited by 3 publications

References 16 publications

X‐ray tracing study of crystal spectrometers for WDXRS application

X‐ray tracing study of crystal spectrometers for WDXRS application

The status of theoretical K‐shell ionization cross sections by protons

A novel micro-machining method for the fabrication of thick-film SU-8 embedded micro-channels

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