1984 Volume 33 Issue 9 Pages T81-T87
Two types of gas flow propotional counters were fabricated for the use in conversion electron Mossbauer spectrometry (GEMS), and their working characteristics were investigated from the practical viewpoint. The one was a hexagonal pillar type detector, by which angular dependent (90°and 45°incident γ-ray to sample surface) CEM spectrum can be measured. The other was a thin plate type detector, which was designed to reduce the background. The variation of energy distribution of electrons reemitted from 57Fe enriched stainless steel was examined as a function of the distance between the anode wire of the detector and the sample steel surface. With the increase in the distance between γ-ray source and the detector, the FWHM of peaks became independent of the Doppler velocity and the back ground became flatter. The incident angle of γ-ray changed the electron energy distribution and the peak shape of CEM spectrum. The peak height/background ratio at 45°was larger than that at 90°. When high energy electrons were detected with the flow of Q gas, asymmetric peaks appeared in CEM spectrum due to the count loss of electrons. The phenomenon was explained by the space charge effect coupled with the scanning speed of time scaler of multichannel pulse height analyzer.
