Influence of the sample radius and irradiated zone width on the defocusing phenomenon in the Schulz technique

The influence of the sample radius and irradiated zone width on the defocusing phenomenon is analysed by means of theoretical expressions which result from the convolution of a Cauchy fitting of the diffraction peak on the receiving plane. For the usual sample radius (about 12 mm) an irradiated zone width which is larger than expected may be used without any additional intensity loss. For a small sample radius (e.g. 4 mm), defocusing is less pronounced when a 6 mm irradiated zone width is used. (0002) and [10-10] pole figures of Zry-4 (a zirconium-based alloy) samples (obtained from a cladding tube of a pressurized water reactor fuel element) illustrate the results. (Auth.)