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Matthew Lee

Matthew Lee. Classification of counterfeit coins using multivariate analysis with X-ray diffraction (XRD) and X-ray fluorescence (XRF) method. Background . In recent years, Japanese police have seized many counterfeit coins that looked like the real coins because of their pictures and letter.

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Matthew Lee

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  1. Matthew Lee Classification of counterfeit coins using multivariate analysis with X-ray diffraction (XRD) and X-ray fluorescence (XRF) method

  2. Background • In recent years, Japanese police have seized many counterfeit coins that looked like the real coins because of their pictures and letter. • The counterfeit coins were measured by an X-ray diffraction method and X-ray fluorescence after determination of their diameter, thickness etc. Judging the difference between the counterfeit coins and the real coin with X ray diffraction and fluorescence method

  3. Overview • Two hundred and seventy seven counterfeit coins were seized in Aichi prefecture in January September 1999 from different banking institution • Counterfeit coins attached on holder with adhesive tape were examined using XRD analyzer. The measurement portion was 0.1 mm diameter on the flat surface of the coin. A copper filament was used at 40kV and 100mA. Taking 100s and the measurement range was 20 to 160 degree. The angles and the intensities of the peaks of the XRD patterns were calculated by equipment software with the apparatus. Same procedure for XRF.

  4. Finding • Typical XRD patterns of two counterfeit coins and a real one are shown in the website. • For the nickel plated coin two additional peaks appeared on the pattern at about 44 and 52 degreee. The shift in the angles of each peak increased with the content of impurities such as zinc and iron • Rapid identification was performed by XRD data and applied to CA. • XRF patterns of two kinds of counterfeit coins and it contains copper, nickel ,zinc and iron.

  5. Discussion • How to make the counterfeit coin larger and thicker in order to make it looks like real • Beside using XRD and XRF to detect counterfeit coins, what kind of product can the XRD and XRF also be able to detect it is counterfeit or not.

  6. Conclusion • By using cluster analysis (CA) and principal component analysis (PCA) for XRD peak patter, we can determine which coins is real or counterfeit. • A comparison of the morphological characteristics was useful to elucidate the similarity of the samples depending on the change in the condition during the manufacturing process.

  7. Reference • http://www.sciencedirect.com/science/article/pii/S0379073800003091

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