Accurate measurements of intrinsic scattering from window materials by use of a vacuum camera

The intrinsic scattering from eight window materials commonly used at synchrotron facilities has been evaluated in the range 0.07 < q < 4 nm^-1 by the use of a vacuum camera. Poly(oxydiphenylene- pyromellitimide) film, a polyimide film widely used as a window material for vacuum chambers, gave rise to two peaks at q = 0.8 and 4 nm^-1. Poly(ether-ether-ketone) gave no Bragg peaks, although the background scattering was relatively high over the entire q range. When natural mica, synthetic mica, quartz glass, beryllium, silicon nitride and silicon carbide were compared, synthetic mica showed the lowest scattering in the range 0.6 < q < 5 nm^-1, indicating that it is the most suitable window material for this q range.