Ion beam analysis methods for determining major and minor element concentrations in artefacts

Two quantitative analytical techniques, Rutherford Backscattering Spectrometry (RBS) and Proton Induced X-ray Emission (PIXE), based on MeV ion beams from a Van de Graaff accelerator have been used in an archaeometric determination of major and minor element concentrations in patinated flint artefacts and a meta! fragment found during excavation of a viking settlement. A red/ brown patination on an artefact surface that had developed subsequent to exposure by flaking 6200 years ago was demonstrated to be associated with a significantly higher Fe concentration at the surface compared to the bulk and further this Fe was concentrated in the microfissures along the grain boundaries through which ground water percolates into the flint. Another type of patination, brown and purple/red spots or so-called seaweed spots, on flint artefacts that had been excavated from a site that had been flooded by sea were found to be associated with high concentrations of manganese and in the case of a modern sample from which seaweed had been removed, also iodine. Although this does not confirm that seaweed spots are actually due to seaweed the result suggests they are due to the action of marine organisms. The composition of a meta! fragment, that was found during excavation of a viking-age settlement, and suspected of having been soldered was determined to be chiefly Fe with minor components Sn and Pb. The Pb/Sn concentration ratio of about 2 at. % corresponds to an alloy like modern tinplate which suggests the specimen might be of modern origin

The impact of glucose-insulin-potassium infusion in acute myocardial infarction on infarct size and left ventricular ejection fraction [ISRCTN56720616]

BACKGROUND: Favorable clinical outcomes have been observed with glucose-insulin-potassium infusion (GIK) in acute myocardial infarction (MI). The mechanisms of this beneficial effect have not been delineated clearly. GIK has metabolic, anti-inflammatory and profibrinolytic effects and it may preserve the ischemic myocardium. We sought to assess the effect of GIK infusion on infarct size and left ventricular function, as part of a randomized controlled trial. METHODS: Patients (n = 940) treated for acute MI by primary percutaneous coronary intervention (PCI) were randomized to GIK infusion or no infusion. Endpoints were the creatinine kinase MB-fraction (CK-MB) and left ventricular ejection fraction (LVEF). CK-MB levels were determined 0, 2, 4, 6, 24, 48, 72 and 96 hours after admission and the LVEF was measured before discharge. RESULTS: There were no differences between the two groups in the time course or magnitude of CK-MB release: the peak CK-MB level was 249 ± 228 U/L in the GIK group and 240 ± 200 U/L in the control group (NS). The mean LVEF was 43.7 ± 11.0 % in the GIK group and 42.4 ± 11.7% in the control group (P = 0.12). A LVEF ≤ 30% was observed in 18% in the controls and in 12% of the GIK group (P = 0.01). CONCLUSION: Treatment with GIK has no effect on myocardial function as determined by LVEF and by the pattern or magnitude of enzyme release. However, left ventricular function was preserved in GIK treated patients

On quantitative off-axis Scanning Transmission Ion Microscopy (STIM)

Spurred by a need to determine major (C, H, N and O) contents in biological tissue sections, a formalism for quantitative off-axis Scanning Transmission Ion Microscopy (OA-STIM) has been established. This can be used with, or without, simultaneous Elastic Backscattering Spectroscopy (EBS) to provide quantitative major element composition and thickness information. As part of the work, an empirical predictor with one free parameter for the proton-proton differential scattering cross section was implemented. The predictor values were in extremely close agreement with high accuracy literature data. For 2 MeV p(-12)C elastic scattering at forward angles <= 45 degrees an interpolation procedure was used to determine the relative deviations from the Rutherford cross sections were determined to be <= 6.4%. The interpolation was based on a Coulomb field, angular momentum quantum number and nuclear structure dependent nuclear penetration factor. Finally, the quantitative combination of simultaneous OA-STIM and EBS data is discussed

Application Specific Integrated Circuit (ASIC) Readout Technologies for Future Ion Beam Analytical Instruments

New possibilities for ion beam analysis (IBA) are afforded by recent developments in detector technology which facilitate the parallel collection of data from a large number of channels. Application specific integrated circuit (ASIC) technologies, which have been widely employed for multi-channel readout systems in nuclear and particle physics, are more net-cost effective (160 /channel for 1000 channels) and a more rational solution for readout of a large number of channels than afforded by conventional electronics. Based on results from existing and on-going chip designs, the possibilities and issues of ASIC readout technology are considered from the IBA viewpoint. Consideration is given to readout chip architecture and how the stringent resolution, linearity and stability requirements for IBA may be met. In addition the implications of the restrictions imposed by ASIC technology are discussed

Micro-Particle Induced X-ray Emission Study of Lead-Free and Lead-Based Solders and Interactions with Copper Wires

Pb-free electrical solders, such as Cu-Sn alloys, work well for reflow soldering under tightly controlled conditions. Hand soldering, however, often results in poor quality joints compared to conventional Pb-Sn solders. To investigate this under realistic workshop conditions, micro-particle induced X-ray emission (micro-PIXE) with 2 MeV protons has been employed. Commercial flux-cored Cu-Sn and Pb-Sn solder wires are studied. Solder blobs under two cooling conditions as well as tinning Restriction of Hazardous Substances (RoHS)-compliant and legacy component wires are investigated. The results show that the long heating and slow cooling of Cu-Sn solder blobs lead to formation of an acicular precipitate that can be ascribed to Cu-6 Sn-5. Pb-Sn solder under the same conditions shows phase separation with regions of high Sn and regions with high Pb. In the case of rapidly cooled blobs where a shiny surface is produced, no phase separation in either solder is observed. Tinning of RoHS-compliant and legacy Cu component wires with the two solders produce significantly different interfacial depth profiles with varying degrees of grading, indicative of intermetallic phase formation

Proton beam induced degradation of Pioloform & REG; (polyvinyl butyral (PVB)) support films used for analysis of biomedical tissue sections

Pioloform & REG;, an often used support film for ion microprobe research is a terpolymer of polyvinyl butyral (PVB) and 18 mass % polyvinyl alcohol (PVA). Simultaneous off-axis Scanning Transmission Ion Microscopy (OA-STIM) and Elastic Backscattering Spectrometry (EBS) measurements have been used to measure the evolution of the C, H and O contents for an increasing proton fluence. The results showed that the composition at zero proton-fluence was in close agreement with the theoretical atomic composition. This strongly suggests OA-STIM measurements. With increasing proton fluences preferential loss of H and O was observed from the films

Direct Current Accelerators for Industrial Applications

Abstract in Undetermined Direct current accelerators form the basis of many front-line industrial processes. They have many advantages that have kept them at the forefront of technology for many decades, such as a small and easily managed environmental footprint. In this article, the basic principles of the different subsystems (ion and electron sources, high voltage generation, control, etc.) are overviewed. Some well-known (ion implantation and polymer processing) and lesser-known (electron beam lithography and particle-induced X-ray aerosol mapping) applications are reviewed

Fundamental effects and non-linear Si detector response

Non-linearity in the energy response of a Si p-i-n charged particle detector has been studied for incident particles with Z(1) between 3 and 26, and energies between 0.1 and 0.7 MeV per nucleon. Although the data closely followed a straight line relations, fitting of the data to a third order polynomial revealed that the response exhibited a persistent curvature that acted to reduce the energy interval spanned by a channel as the energy increased. The curvature increased as Z(1) increased from 4 to 8 and then systematically decreased. The curvature is larger and has the opposite energy dependence to the stopping in a dead entrance window and the energy deposited in non-ionising processes within the active layer. The plasma recombination dependence on the average stopping along the plasma column may account for the reduction in curvature as Z(1) increases from 9 to 25 but cannot explain the net effect. The low-energy increase in energy channel span, which has also been reported by others, might be associated with electron excitation in resonant and direct classical quasi-elastic collisions for low-energy ions, or less likely, electronic non-linearity's associated with Z(1) and energy dependent time structure in the current pulse from the detector. Simple interpolation of the window-loss corrected polynomial coefficients is the best approach if the calibration for Z(1) cannot be established directly

Response of Si p-i-n diode and Au/n-Si surface barrier detector to heavy ions

Pulse height versus energy calibrations of a Si p-i-n diode and a Au-/n-Si surface barrier detector have been studied for heavy ions with atomic number (Z(1)) from 3 to 79 in a range from 0.1 to 0.8 MeV per nucleon as a function of bias voltage and detector tilting angle. The detector response is simultaneously measured using a time of flight-energy elastic recoil detection analysis set-up with recoils produced over a wide energy range from a thick target of each element. Prior to impinging on the Si detector, the individual recoil is tagged by its energy determined from the time of flight and tabulated isotopic mass. For both detectors, the pulse height-energy calibration for recoils with a given Z(1) is described well by a linear relationship with small systematic deviations. The linear-fit parameters show similar, but not identical dependence on both Z(1) and bias voltage (collecting field strength) for the surface barrier detectors and the p-i-n diode. These results suggest that the efficiency of electron-hole pair collection is markedly dependent on the different electric field configurations for the two detector structures