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