Jun 24th PM

We went to visit Dr. Culbertson's lab. The goal was to find out what our samples of objects are made of using PIXE (proton induced X-ray emission). A beam of protons is accelerated onto each sample that is placed in a vacuum. The proton hits an electron, the electron gets excited and jump to a higher energy shell. As the electron jumps back to a lower energy shell, it can emit X-rays. The X-ray emission spectrum is different for each element and we can identify the elements in each sample based on the emission spectrum of the sample. Samples of a bracelet, ring, pearls, silver dollars and pen cap were evaluated. The bracelet was found to contain Ca and P and we concluded that it was made of bones which is mainly Ca3(PO4)2. The 1929 silver dollar has real Ag in it but the 1971 silver dollar contains Ni and no Ag. The pearls showed a lot of Ca which is the material of pearls. The pen cap was from a gold cross pen and it contains real gold atoms as seen in the emission spectrum.