H. D. Rüter

Nuclear Bragg Diffraction of Synchrotron Radiation at the 8.41 keV Resonance of Thulium

For the first time nuclear Bragg diffraction of synchrotron radiation at the 8.41 keV resonance of 169Tm was observed. Time differential measurements were performed with the pure nuclear (424) reflection of a thulium iron garnet single crystal. The dynamical theory of Mossbauer optics is applied to evaluate the time spectra. The measurements reveal information about the hyperfine fields which has not been accessible before by conventional Mossbauer spectroscopy with polycrystalline samples.

Broad-Band Nuclear Resonant Filters for Synchrotron Radiation: a New Source for Nuclear Diffraction Experiments

A grazing incidence antireflection film (GIAR film) containing 57Fe has been used as a broad-band filter in a nuclear-diffraction experiment with synchrotron radiation. A band of 0.5 μeV width has been reflected by the GIAR film consisting of a 57Fe5B4C-layer on a Ta-backing. The electronic reflectivity was reduced to 0.04. The diffracted beam was analysed by the (333) pure nuclear reflection of 57FeBO3. A counting rate of delayed quanta of 8 Hz was obtained. The experiment proves that coherent excitation of hyperfine split nuclear levels took place after a GIAR film reflection.

Nuclear diffraction experiments with grazing incidence antireflection films

The energy dependent reflectivity of grazing incidence antireflection (GIAR) films containing the Mößbauer isotope57Fe has been measured with recoilless 14.4 keV radiation from a radioactive source. The reflectivity is influenced by oxide layers on the surface. Assisted by Mößbauer spectroscopy in transmission geometry and X-ray reflectivity measurements the hyperfine interaction parameters in the layers could be determined. In a nuclear diffraction experiment with synchrotron radiation a GIAR-film has been used as a filter. The diffracted beam was analysed by the (002) reflection of Yttrium Iron Garnet (YIG). The evaluation of the observed quantum beat pattern yielded the energy differential reflectivity of the GIAR-film in agreement with the results from the Mößbauer measurements.

A high resolution spectrometer using nuclear Bragg diffraction

A high resolution spectrometer for synchrotron radiation using nuclear Bragg diffraction has been constructed at a DORIS beamline (DESY, Hamburg). This spectrometer provides a γ-ray beam for hyperfine spectroscopy and for other application which need high resolution in energy and/or time.

A single line linearly polarized source of 14.4 keV radiation by means of resonant absorption

Abstract A single line linear polarized source of 14.4 keV is realized in a conventional Mossbauer setup. In combination with the dichroism of a magnetized 57FeBO3 or α-57Fe absorber a single line unpolarized 57Co Cr - or 57Co Pt -source delivers ⩾90% linear polarized radiation and about 25% of its primary intensity. The optimal value of the internal magnetic field of each absorber is selected by temperature adjustment. Calculations and measurements are in good agreement.

Nuclear Bragg diffraction using synchrotron radiation A new method for hyperfine spectroscopy

Abstract Nuclear Bragg diffraction with synchrotron radiation as source will become a powerful new X-ray source in the A region. The brilliance of conventional Mossbauer sources is already exceeded; giving hyperfine spectroscopy a further impulse. As examples applications to yttrium iron garnet (YIG) and iron borate will be discussed.

Nuclear orientation of105Rh and95Tc in iron

AbstractThe temperature-dependent anisotropy of γ-rays following the decay of oriented95Tc and105Rh nuclei was studied with a Ge(Li) detector. Mixing coefficients of some γ-and preceding β-transitions, the spins of two intermediate levels, and the magnetic hyperfine splitting of the95Tc and105Rh ground states in an Fe host were measured. From the known hyperfine fields the following magnetic moments were deduced:

The183Re ground state dipole moment and nuclear spin-lattice relaxation of Re in Fe

\begin{gathered} \mu \left( {^{105} Rh,\tfrac{{7 + }}{2}} \right) = 4.34\left( {12} \right) n.m.; \hfill \\ \mu \left( {^{95} Tc,\tfrac{{9 + }}{2}} \right) = 5.82\left( {12} \right)n.m. \hfill \\ \end{gathered}