The X-ray diffraction station at the ADONE wiggler facility: preliminary results (including crystal perfection)

The single-crystal X-ray diffractometer installed at the PWA Laboratory in Frascati is described. The Huber four-circle goniometer is controlled by an IBM-compatible personal computer by means of a plug-in board interface based on the LSI chip Am9513. The program CS running under MS-DOS performs a wide variety of operations from random search to data collection. The angular resolution of the diffractometer is 0.0025°, while the instrumental resolution at 8 keV, with an Si(lll) monochromator, is 0.0026°. After preliminary tests, 2Zn insulin crystals were mounted on the diffractometer and reflections were measured using synchrotron radiation. The rocking curves show full widths at half-maxima (FWHM) in the range 0.013-0.031° mainly due to the mosaicity.