Vacuum Windows for Third Generation Syschrotron Radiation Beamlines

Improving the quality and intensity of the x-ray beam is an important design goal for every synchrotron installation. Although small, the effects of vacuum windows on x-ray absorption and phase contrast cannot be neglected. Synchrotron x-rays have wavelengths on the order of one Angstrom (1 x 10-10m), the same order of magnitude as inter-atomic distances. These x-rays are used to study many different types of materials. Structural details that are not easy to probe in other ways can often be understood by x-ray diffraction, x-ray spectroscopy, and x-ray fluorescence. The design of vacuum windows has not kept pace with other advances that have been made in the design of third generation synchrotron radiation beamlines. To improve the performance of the windows ADC is proposing new windows that will have improved specifications for surface finish and thicknessuniformity, but will not introduce any other spatial variation in the beam intensity. ADC's proposal outlines a technical approach to achieving a surface roughness of 0.01 ?Micrometer RMS and a peak-to-valley variation of less than0.1 ?Micrometer.