8 Atomic Physics 8.3 X-ray fluorescence and Moseley's law
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X-ray fluorescence and Moseley's law with the multi channel analyser
Calibration lines of Cs-137 and Am-241
Main articles Principle The irradiation of strontinum (sulphate), cadmium, indium, iodine and barium (chloride) with soft gamma-radiations gives rise to Ka radiations characteristics of these elements. The X-rayspectra are recorded with a gamma spectrometer consisting of a scintillation counter, a pulse height analyser and a recorder. After calibration of the spectrometer, the Rydberg constant is determined from the energies of the X-ray lines, using Moseley's law. Tasks 1. Calibration of the gamma-spectrometer in the low energy range, using the Ba-resonance line 137Cs emitter (32 keV) and the gamma-line of 241Am at 59.6 keV. 2. Recording of the X-ray fluorescence spectra (Ka-lines) of different elements and determination of the corresponding energies. 3. Plotting of the measured X-ray energies according to Moseley's law against (Z-1)2 and determination of the Rydberg constant R; from the slope of the resulting lines. What you can learn about ▪ ▪ ▪ ▪ ▪ ▪
Binding energy Photoelectric eftect Shell structure of electron shells Characteristic X-ray radiation g-spectrometry X-ray spectral analysis
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Gamma detector Multi channel analyser - extended version suitable also for operation of the X-ray energy detector Radioactive source Cs-137, 37 kBq Radioactive source Am-241, 370 kBq Operating unit for gamma detector Absorption material, lead measure Software multi channel analyser High-voltage connecting cable Tin-II chloride 250 g
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13727-99 09096-01 09090-11 09101-93 09029-01 14452-61 09101-10 31991-25
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