Experimente zum Zeitverhalten zerfallender Zust�nde

Abstract

The time dependence of the transmission through a resonating absorber and of the scattering of a resonating scatterer have been investigated using the Mossbauer effect of57Fe. This seemed useful, because the results of former measurements are not in good agreement with the theoretical prediction and, moreover, there exists a theoretical possibility that these deviations result from a non-Lorentzian energy distribution of the decaying state. The theoretical curves, which will be compared with the experimental results of this work, have been calculated adopting a Lorentzian energy distribution and regarding not only the finite target thickness but also its local variations. Two approximate models have been used for these calculations. The transmission through a thin absorber but with a large absorption cross section can be described within the experimental error of about 2% by an ansatz which accounts for these local variations. On the other hand, the transmission through a thick absorber with a relatively small absorption cross section can be explained by an ansatz made for a homogeneous absorber. In this case the variations of the thickness are small because of the large geometrical thickness of the absorbing material. The results of the time dependent scattering, too, can be described within the limits of error of about 5% by the ansatz, regarding finite variations of the thickness of the scatterer.