PIXE (Particle Induced X-ray Emission)

PIXE spectrum example with a X-ray Ketek detector

Being PIXE perhaps the most straightforward IBA technique, all the CMAM measuring spots are equipped with at least a PIXE detector. However the best measuring point so far for PIXE is the external microbeam line. The beam (normally 3 MeV protons) is extracted through a 200 nanometers thick Si₃N₄ window (surface 1 mm2) and delivered to the samples 3-5 mm downstream. X-ray spectra are collected, quite conventionally, by two Si(Li) detectors. The first one (angle 45deg, active surface 10 mm2, depth 2 mm, window 8 micron duraberillium resolution 133eV @ Mn K-alpha) looks at the sample through a small solid angle and a helium atmosphere, to enhance the response to low energy X-rays. The second one (angle 45 deg, active surface 80 mm2, depth 4.4 mm, window 12 micron duraberillium resolution 148 eV @ Mn K-alpha) looks at the sample through a larger solid angle and a filter that can be aluminium (e.g. 50 microns) polyethilene (e.g. 500 microns), cobalt (e.g. 50 microns), etc… to make predominant the response to high energy X-rays.

The PIXE schematic principles