The influence of different tempers on the composition of pottery
The modification of the raw clay by the potter to produce a paste suitable for the intended purposes adds a layer of obfuscation to the problem of provenancing the original clay source by chemical fingerprinting. By preparing different pastes from the same commercially available raw clay and their chemical analysis by Instrumental Neutron Activation Analysis, an experiment under controlled conditions (tempers, mixing ratios, firing temperatures and sampling methods) sheds light on the influence of different tempers. The results show that two different sampling procedures (drilling and grinding) have almost no influence on the chemical fingerprint with the exception of the elemental concentrations of As, Zr, and Hf. This may be due to the volatility of the compounds (As) or the presence of zircon crystals (containing Zr and Hf) which are partly lost during drilling. Three different firing temperatures show no significant influence as well. The application of the modified Mahalanobis distance introduced by Beier and Mommsen in 1995 as a statistical filter and the introduction of a ‘dilution factor’ to the raw data show that the influence of quartz-dominated tempers can be filtered out of the data, resolving the underlying chemical fingerprint of the original clay source. At the same time, by mathematically removing the additional spread introduced by dilution, even subtle differences between similar pastes can be resolved by standard multivariate statistical means.
The Past and the Future of the TRIGA Reactor in Vienna
During the past five decades, the TRIGA reactor Vienna has reached a top place in utilization among low power research reactors. This paper discussed the highlights of the major neutron physics experiments in the field of neutron interferometry and ultra-small angle neutron scattering as well as in the field of radiochemistry, education and training and research in the field of nuclear safeguards and nuclear security. Potential further directions of research are outlined where the Atominstitut of Vienna might concentrate in future.
Size, shape and orientation of grains in sands and sandstones—image analysis applied to rock thin-sections
Abstract A computer based image-analysis system is used to determine the grain-size distribution, grain shape and grain orientation from rock thin-sections. A Monte Carlo simulation allows correction of the grain-size distribution for the corpuscle effect (grains cut marginally in the thin-section plane have smaller apparent diameters). Thin-section-derived grain-size distributions of modern and ancient samples have been compared with distributions obtained from sieving of the same samples. Different grain shape parameters have been compared with the Wadell formula. The grain orientation can be easily and reliably measured in thin-sections from different cuts of a sample. Grain orientation data can help to determine paleocurrent directions.