An Analytical Approach for Compton-Rayleigh Scatter Peak Analysis for the Mars Science Laboratory Alpha Particle X-ray Spectrometer

Tesselaar, Dustin
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University of Guelph

As part of a suite of complimentary science instruments onboard the Mars Science Laboratory rover, the alpha particle X-ray spectrometer (APXS) determines the chemical abundances of Martian rocks and soils for elements from Na to Y via particle induced X-ray emission and X-ray fluorescence. Due to attenuation effects, elements with Z < 11 cannot be directly detected. These invisible components can be quantified indirectly by the Compton-Rayleigh scatter-peaks in APXS spectra. This thesis focuses on the development of an analytical simulation program (CRAM) used to predict the Compton-Rayleigh ratio (C/R) for APXS spectra in a more timely manner than the existing Monte Carlo method (MarsGeom). The simulated C/R, when related to the experimental C/R, is used to quantify any excess or deficit of invisible components in APXS targets. The results of CRAM are compared to MarsGeom and both datasets agree, giving a limit of invisible component detection of approximately 5 wt%.

Compton Scattering, Rayleigh Scattering, Physics, APXS, Alpha Particle X-ray Spectrometer, XRF, PIXE