X-Ray and Gamma-Ray Reflection Properties from 500 X Units to Nine X Units of Unstressed and of Bent Quartz Plates for Use in the Two-Meter Curved-Crystal Focusing Gamma-Ray Spectrometer

The x-ray and gamma-ray reflection properties of the (310) planes of quartz have been investigated over the wave-length range 500 to 9 x.u. for the Laue or transmission case. The plates were inhomogeneously stressed by bending to a cylinder with a radius of 200 cm. The value of the integrated reflection coefficient was deduced from the luminosity properties of the curved-crystal spectrometer for seven different wavelengths. The data indicate that the integrated reflection coefficient R_θ for a bent crystal varies as λ² over the range of wave-lengths studied. This behavior is in accord with that of a mosaic crystal. The reflection properties of the (310) planes of an unstressed crystal plate cut from the same sample were measured over the range 700 to 120 x.u. by the two-crystal spectrometer technique. These results indicate that the unstressed quartz plates behave more nearly as perfect crystals. Data are given on the integrated reflection coefficient, the peak value of Laue reflection coefficient, and the width at half-maximum of the diffraction curve for the unstressed case.