Activation Analysis of Some Metals Sticking on a Si-Wafer

The neutron activation analysis was used to identify elements and measure quantitatively the number of metalic atoms sticked on a Si-wafer which was a single crystal of 10 mm×10 mm×0.2 mm. In order to obtain measuring effciencies and limits in the analysis, the metalic samples of V, Fe, Ni and Cu were irradiated by neutrons from a reactor. The γ-rays from the activated samples were analyzed by means of a γ-ray spectrometer connected to a data acquisition and processing system. The limits of detection obtained are 0.2μg for V;500μg, Fe;2μg， Ni;1μg, Cu. These values are valid under the condition that the elements associated with the Siwafer mentioned above are packaged in the bag made of a sheet of polyethylene with 25 mm×50 mm×0.03 mm in size. The predicted values by Currie\u27s formula for the limits of detection are fairly consistent with the experimental ones. It is also found that if the lower values of detection Iimits are desired, further care should be taken to reduce the background resulted dominantly from the γ-rays emitted from ^<24>Na and ^<41>Ar contained in the package bag of polyethylene sheet