Detection of trace elements in Detection of trace elements in meteorites using PIXEmeteorites using PIXE
Presented by:
Sasha dos-Santos
Goals
• To determine the chemical composition of several meteorites
• To estimate the concentration of chemicals in PPM (parts per million)
Particle Induced X-Ray Emission Spectrometry
• A method of determining the chemical composition of a substance
• Has been in use since the 1970s
• Used in fields such as astrophysics, medicine, and environmental science
Characteristic X-Rays
Characteristic X-Rays
Characteristic X-Rays
Characteristic X-Rays
• The energy of the X-Ray is equal to the energy difference between the two orbitals
• This energy is characteristic of the element involved
Experimental Setup
• Van de Graaff Accelerator - this is the ion beam source
Experimental Setup
• Analyzing Magnet - Selects particles based on charge and mass
Experimental Setup
• PIXE Chamber - up to five samples can be placed in the chamber at a time
Experimental Setup
• Si-Li Drifted Detector - detects X-Rays and sends input to a multichannel analyzer
RobWin
• Used for Spectral Analysis
• Mathematically models background radiation (noise)
• Finds peaks that are not clearly visible
RobWin
PIXE Spectrum
PIXE Spectrum
PIXE Spectrum
Conclusions
• The elements found in the meteorites were :
Ca Ti Cr
Fe Ni Cu
Zn Ga As
Conclusions
• Next step is to use a process called spin coating to produce thin film samples
• Then use thin film standards to determine chemical concentrations in the order of
micrograms / sq. cm.
The End
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