Noninterferometric measurement of the x-ray refractive index of beryllium

The real decrement of the x-ray refractive index of beryllium was measured for the K lines of Cu, Mo, and Ag to an accuracy 0.1% with the use of a thin-wafer monolithic Laue-Laue diffractometer of a novel design. The results are in excellent agreement with theory. A full discussion of the method is given and ways of increasing its accuracy indicated.