Analyses

At CENTA laboratory, several ion beam analysis (IBA) techniques are applied.

Conventional in-vacuum particle induced X-ray emission (PIXE) together with particle induced gamma-ray emission (PIGE) provide simultaneous elemental analysis from sodium to uranium (under specific condition even boron signal can be detected, but not quantified). The vacuum chamber is limited for small samples (a few cm) and element content can be determined from the depth of few tens of microns on the smooth surface. The sample can be bombarded by different ions (usually protons of 1-6 MeV energy, deuterons of 1-6 MeV energy or alphas of 1.5-9 MeV energy can be used), while inner shell ionization occurs followed by electron re-arrangement processes with emission of characteristics X-ray. Two X-ray detectors are available for the analysis. The first one is 70 mm² Fast SDD (Silicon Drifted Detector) with patented composite window from Amptek, with the energy resolution of 123 eV@5.9 keV, that is used for light elements up to bromine. The second one is BEGe (Broad Energy Germanium) detector with 0.5 mm Carbon window from Canberra. Since, it can register quanta from 3 keV up to 3 MeV, it is used for PIXE analysis of heavier elements (with resolution of 390 eV@5.9 keV) as well as for PIGE analysis (with resolution of 1.8 keV@1.33 MeV). The elemental sensitivity of setup is determined by several factors, it can reach the ppm range in favorable conditions. The analysis involves qualitative and quantitative determination of elements in thin (thin slices of biological materials, evaporated drops of liquid on foil, deposited material on foils etc.) as well as thick samples (from environmental samples, coins, samples of cultural heritage until meteorites).

Rutherford Backscattering Spectrometry (RBS) is another non-destructive nuclear analytical method, which was adopted in CENTA laboratory. Energy distribution and yield of scattered ions (usually high energy He²⁺ ions) are measured after interaction with surface of the sample. It is possible to analyse the depth profile from RBS spectrum, since the backscattering cross section is given for each element. Therefore, it is widely used for study of the thin layers and for study of multilayer systems with thickness from nm to µm. For this analysis, Si PIN photodiode Hamamatsu is used with the energy resolution of 16 keV@5.48 MeV, that can be retracted to position in front of the sample.