Precise Measurement of Ag KLL Auger-Spectrum

摘要

An accurate measurement of the KLL Auger spectrum of Ag in the decay of /sup 109/Cd is performed by the use of a high-resolution, high-efficiency iron-free beta -spectrometer system. As a source of Auger electrons, /sup 109/Cd is prepared in a form of arachidic (C/sub 20/H/sub 40/O/sub 2/) Cd-salt with a thickness of two molecular layers by means of the Langmuir-Blodgett method. A /sup 169/Yb source is used to calibrate the absolute energy of the spectrometer using the M conversion lines of the 20.744 keV transition in /sup 169/Tm. These two sources are set in the position of the spectrometer interchangeably. The beta -rays analyzed by the spectrometer is detected by a 40-cell proportional counter placed on the focal plane. A focusing electric potential is applied over the source plate, and the spectrum is scanned electrostatically by changing the acceleration voltage also applied on the source, keeping the magnetic field strength constant. Auger spectra are measured by a scanning step of 2.4 eV with 18 steps in total. The energy dispersion of individual detector cells is measured by shifting the Auger spectrum with the acceleration voltage. As a result, all the nine Auger lines are clearly resolved. The resultant accuracy for the energies and intensities improved those of the previous data by 1 - 2 orders of magnitude. The result indicates a good agreement with the calculations by Larkins and by Chen et al. But some discrepancies for low-intensity lines suggest a necessity of finer theoretical investigation on the mechanism of the KLL Auger transition. (Atomindex citation 18:081814)