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e2v scientific instruments x-ray products |
Distributed products (UK only) |
Site last updated 06 Jun 2008
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| PIXE (Particle Induced X-Ray Excitation) is a sensitive analytical technique utilising x-ray fluorescence but without the background often associated with electron or x-ray excitation techniques. PIXE analysis can be made with a variety of excitation particle types, but most commonly used are protons with energies of a few MeV which can be produced from a medium sized Tandem Van der Graaff accelerator. | Applications
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| The proton beam may be used for PIXE analysis either in a vacuum chamber or, by allowing the beam to exit from the beam line through a thin window, large samples may be analysed in air. Local He gas environments may also be used. |  |
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| The proton beam can be focussed to a small cross-section, and can also be deflected to produce a scan of the sample object. In this way, elemental maps can be created which can be superposed on an optical image from a microscope. | ||
| For x-ray detection a large area Si(Li) detector is typically used (80mm²), mounted at a backward angle relative to the incident beam to reduce the posibility of scattered protons entering the detector. The PIXE excitation process produces both x-rays and gamma rays. Since the x-ray spectrum is weighted heavily towards the low energy end, a so called 'funny-filter', consisting of an absorber disk with a smaller central hole, is often used to preferentially reduce the low energy transmission. | ||
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Typical 80mm² Si(Li) detector for PIXE applications. Shown mounted on a manual slide with vacuum chamber interface. The base plate is used for mounting the detector for 'in-air' analysis. |
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