Recent developments and ASAXS measurements at the ultra small angle X-ray scattering instrument of HASYLAB

The wiggler beamline BW4 at the synchrotron radiation facility HASYLAB (DES Y) is mainly designed for Ultra Small Angle X-ray Scattering (USAXS) and us ually operated with detector-sample distances up to 13 m and at photon ener gies between 4 and 16 keV. With a new optical design the largest observable correlation distances have now been increased up to 9 x 10(3) Angstrom. A grazing incidence set-up [P. Muller-Buschbaum et al., Europhys. Lett. 42 (5 ) (1998) 517], vapor chamber. furnace. tensile testing machine and other in struments make the USAXS beamline attractive for a variety of scattering ex periments [A. Endres et al., Rev. Sci. Instrum. 11 (1997) 68; A. Karl et al ., J. Macromolecular Sci.-Phys. B 38 (5&6) (1999) 901; S. Minko et al.. J. Macromolecular Sci., Phys. B 38 (5&6) (1999) 913]. A fully evacuated beampa th allows high quality measurements with very low background signal. A photodiode mounted in the primary beam stop registers the primary beam fl ux simultaneously to the data acquisition and thus provides a precise metho d for measuring absolute scattering intensities. Anomalous small angle X-ra y scattering (ASAXS) experiments at the K absorption edge of titanium were recently performed to investigate phase separated fluorine titania silicate glass. From these measurements we expect some new results concerning the d istribution of titanium atoms within the diffusion zone outside the phase s eparated particles. (C) 2001 Elsevier Science B.V. All rights reserved.