A camera for divergent x-ray beam diagrams

Kossel lines can be obtained with a simple apparatus using a conventional x-ray tube, a specimen chamber with a pinhole, and a photographic plate. Inside the chamber, a target irradiated by the primary x-ray beam generates a fluorescent radiation collimated by the pinhole; then, the divergent characteristic x-ray beam passes through the specimen. The main features of the apparatus described here are the following: (i) the chamber is temperature controlled at +- 0.020C; (ii) the rotating target can be composed of sectors of different materials, offering a great choice of wavelengths. With exposure times not exceeding eight hours, crystal parameters of cubic crystals can be measured with a relative accuracy better than 10-5. (author)