Detection of trace elements in metorites using PIXE用PIXE陨石中微量元素检测.pptVIP

Detection of trace elements in meteorites 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 * *