Mössbauer Filtration of Synchrotron Radiation

Abstract

Although the first proposal to use synchrotron radiation (SR) for the excitation of a Mössbauer transition was made by S.L. Ruby in 1974 [1], only in 1983 was a paper published [2] on successful Mössbauer investigation with the use of SR, carried out in the Soviet Union at the VEPP-3 storage ring in Novosibirsk (Institute of Nuclear Physics, Siberian branch of the Academy of Sciences of the USSR). In 1985 a similar investigation [3,4] was carried out in the Federal Republic of Germany at the SR source in Hamburg (HASYLAB). These investigations demonstrated the effectiveness of using SR in yet another promising area of research and they were milestones in a number of Mössbauer investigations with SR [4–6]. The essence of this work is that they have succeeded in extracting (filtering) out of the continuous SR spectrum an extremely highly monochromatized and tightly collimated beam of gamma radiation of rather high intensity. The physical principal underlying the filtration process is the properties of Mössbauer diffraction (i.e., discussed in Chapt. 3 as the diffraction of radiation when it is scattered resonantly by the nuclei of the crystal through the Mössbauer transition). This diffraction makes it possible to separate spatially and energetically the radiation that has undergone coherent resonance scattering. The degree of monochromatization ΔE/E and the energy E of the beam are determined by the corresponding parameters of Fe⁵⁷ Mössbauer transition used in both experiments, i.e., E = 14.4 keV and ΔE/E →~ 3.10⁻¹³.