Christopher T. Angell

Diffraction of γ-rays with energies of 1.17 and 1.33 MeV by a flat Si crystal

Diffraction of γ-rays by a flat Si crystal has been demonstrated using a high flux 60Co source with an intensity of 2.3 TBq. The diffraction intensities of the γ-rays with energies of 1.17 and 1.33 MeV have been measured as a function of the rotation angle of the crystal. Three peaks corresponding to the Si(440) and Si(220) diffractions for 1.17 MeV and the Si(440) diffraction for 1.33 MeV have been measured. The heights and shapes of these three peaks are well reproduced by taking into account Braggs law and the experimental geometry.

Enhanced diffraction of MeV γ-rays by mosaic crystals

The diffraction of γ-rays by mosaic Si crystals with thicknesses of 20, 40, and 80 mm and by a 2-mm-thick perfect Si crystal in a transmission Laue geometry was measured using a high-flux 60Co source with an intensity of 2.2 TBq. The measured diffraction intensities at 1.17 and 1.33 MeV using 40- and 80-mm-thick mosaic crystals were enhanced by a factor of approximately 8.6 compared with those of the perfect Si crystal. The integrated reflectivity is well described in statistical dynamical theory by taking into account γ-ray absorption inside the crystals.