A HIGH-TEMPERATURE BONSE-HART ULTRASMALL-ANGLE X-RAY-SCATTERING INSTRUMENT

A Bonse-Hart ultrasmall-angle x-ray scattering (USAXS) instrument has been designed, constructed, and tested employing a synchrotron x-ray source. The instrument permits experiments ranging from below 0-degrees-C up to about 400-degrees-C, as well as temperature scanning, jumping, quenching, and annealing experiments. The mechanical elements used Super Invar as the basic building material in order to minimize the thermal expansion effect. As the synchrotron beam after the beamline optics is already somewhat collimated and monochromatized, a very fine tuning of the first crystal was necessary. The high-temperature Bonse-Hart instrument increased the performance by a factor of about 10 when compared with our earlier room-temperature Bonse-Hart instrument using the same set of channel-cut germanium crystals. The instrument was tested by using a suspension of polystyrene latex spheres and by combining the USAXS measurement, for the first time, with measurements of the same latex suspension by means of laser light scattering.