Electron proportional gas counter for linear and elliptical Mössbauer polarimetry.
Design, characterization, and selected applications of a novel electron detector dedicated to conventional perpendicular- and low-angle-incidence conversion electron Mössbauer spectroscopy are presented. The setup is suitable for varying the incident angle and external magnetic fields on Mössbauer source and absorber. Test experiments were performed on alpha-(57)Fe films using a conventional single-line (57)Co(Rh) and magnetically split, (57)Co(alpha-Fe) Mössbauer sources. The integral "blackness effect" in conversion-electron Mössbauer spectra of (57)Fe isotope-enriched absorbers is demonstrated and shown to be pronounced at shallow angles of incidence. In order to determine the alignment and sign of the hyperfine field in an isotope-enriched absorber, the blackness effect is accounted for in a semiempirical way by using single-line source/absorber experimental relative intensities determined independently. This method works with high accuracy for linear polarimetry; however it is only a rough approximation in the case of nearly circular polarimetry.