High-temperature proportional counter and its application to resonance–electron Mössbauer spectroscopy

Abstract

The operation of a proportional counter designed for resonance–electron Mössbauer spectroscopy measurement at high temperatures up to 900 °C has been investigated. In order to avoid insulation difficulties due to electric leakage on the surfaces of heated insulators, the counter is carefully constructed so that the sensitive volume of the counter can be warmed up while keeping the insulators at room temperature; all insulating materials between the anode and cathodes are located outside the electric furnace in the counter system. The counter operation is influenced by thermal electrons emitted from the cathode material; the maximum working temperature is about 800 °C when an a-Fe foil is mounted as a cathode while operation at 900 °C is possible without the sample. 57Fe Mössbauer spectra for surface layers (∼1000 Å) have been sucessfully obtained for samples of Fe3C, Fe2O3, and a Fe. Chemical changes of the sample surfaces have been observed at temperatures greater than 600 °C by the measurements. The high-temperature counter provides us with a new method to observe directly surface phenomena at high temperatures. Some features of the counter system are described.