Applications of Parallel-Plate Avalance Counters in Mössbauer Spectroscopy

Abstract

Transmission techniques are the dominating detection techniques in Mössbauer spectroscopy. As illustrated in Fig.1 the usual set-up consists of a (moving) source emitting Mössbauer γ-radiation which is partially absorbed in a resonance absorber; the transmitted radiation is detected in a suitable γ-detector as a function of a relative velocity between source and absorber. A typical transmission-spectrum shows a resonance absorption effect of a few percent. In general this percentage cannot be increased due to Debye-Waller factors f < 1 for source and absorber and due to the necessity of thin absorbers to avoid undesired line broadening. Moreover, the effect may be decreased by additionally detected background radiation. The alternative method to measure resonantly scattered γ-radiation (γ′) or X-rays or conversion electrons emitted after resonance absorption has been applied for special problems only. Here, the background of non-resonantly scattered radiation can be kept low so that large (>1) effect-to-background ratios are obtainable for many cases. This advantage, however, is restricted by a loss in intensity due to a comparably small solid angle for the detection of the scattered radiation in conventional experimental arrangements.