Effects of random surface roughness in pixe analysis of thick targets

Ion Beam Analysis of Microcrystalline Quartz Artifacts from the Reed Mound Site, Delaware County, Oklahoma

“…Nevertheless, it must be accepted that sample preparation will be forbidden for many archaeological materials, and steps must be taken to account for uncertainties arising from surface contamination. The efficacy and efficiency of data acquisition could also potentially be optimized by (1) experimenting with other projectiles such as alpha particles and deuterons (to reduce X-ray bremsstrahlung background for example), (2) using multiple beam energies, multiple high energy and low energy X-ray detectors, and various filters and absorbers in order to maximize detection of as many elements as possible, (3) reducing the turnover rate of analysis by analyzing samples in air using an external beam, thereby increasing analytical efficiency (by increasing the speed and maneuverability of analysis) and eliminating charge build-up on samples, and lastly (4) correcting X-ray attenuation caused by surface roughness (perhaps this could be achieved by analyzing the sample surface using an interferometer, and subsequently applying the straightforward procedure outlined by Campbell et al [32] for correcting X-ray attenuation caused by surface roughness in PIXE analysis).…”

“…Using variables and experimental parameters defined by the PIXE yield equation [32], elemental concentrations can be obtained from the X-ray yields acquired from the experiments. When quantifying the PIXE spectra, the total charge accumulated on each artifact was scaled to account for variations in the solid angle of the X-ray detector since the sample-detector distance could not be kept constant due to varying sample heights.…”

Non-invasive quantitative micro-PIXE–RBS/EBS/EBS imaging reveals the lost polychromy and gilding of the Neo-Assyrian ivories from the Louvre collection

“…The proportions of the sediment constituents Al, Si and Fe are enhanced in the carved areas (up to 5 wt% Al 2 O 3 , 21 wt% SiO 2 and 2 wt% Fe 2 O 3 ): the eye of the stag and the carved lines of the wave frieze and of the birth of Horus tablet. However, the absolute values of light elements have to be considered with caution because of the roughness of these zones [23,24]. The eye of the stag is particularly deep (between 1 and 2 mm) ( Table 1).…”

MSL-APXS titanium observation tray measurements: Laboratory experiments and results for the Rocknest fines at theCuriosityfield site in Gale Crater, Mars

“…The Na, Mg, and Al signals also drop more than predicted for a reduction in areal coverage (Figure ). This could arise from two causes: (1) the particulate dusted on the Ti has a different composition than the aliquot used for the bulk measurement and (2) the rough surface of the thin particulate coating caused a drop in signal relative to the pressed, smooth surface of the pellet used for the bulk measurement [ Campbell et al ., ]. That Na, Mg, and Al drop the same amount for all three samples (Figure b) is evidence that the particulate has the same elemental composition in all Ti‐tray samples, and that the dusting process likely did not physically sort the mineral grains, causing compositional changes.…”

“…Exposed o-tray in the FOV results in a prominent Ti peak and elevated background (shelf) at lower energy (< 5 keV) stemming from incomplete charge collection of the Ti peak in the detector [e.g., Gellert et al, 2006]. Dropping the sample from CHIMRA also results in a rough, uneven surface that introduces uncertainty to APXS interpretations [Campbell and Cookson, 1984;Campbell et al, 1985].The two main objectives of this study are to (1) develop a practical method for interpreting MSL-APXS measurements of samples on the o-tray and (2) present and interpret results from the MSL-APXS measurement of fines scooped, processed, and delivered to the o-tray at the Rocknest sampling site in October and November 2012. To assess the o-tray challenges discussed above, we conducted laboratory experiments with the Flight Equivalent APXS Unit (FEU-APXS).…”