The production of long coherence-length hard x-rays using nuclear Bragg scattering of synchrotron radiation

Recently, several experimenters have successfully observed nuclear Bragg scattering from crystals containing 57Fe. By coherently exciting the 14.4keV resonance at the Bragg condition, almost pure beams of extremely monochromatic radiation can be generated. Although the intensities observed are so far quite low, the brightness produced by these techniques exceeds that available from radioactive sources. Instrumental improvements will soon make possible interesting new experiments. Several properties of the nuclear Bragg reflection process are interesting in themselves. These include the observation of beating in the time domain among hyperfine split resonance lines, and polarization mixing produced by scattering from oriented circularly polarized oscillators. Some speculations on the potential applications of this new source of long coherence-length radiation will be presented.