Max Bichler

The first use of 236U in the general environment and near a shutdown nuclear power plant

We present a first effort to investigate (236)U in the environment near a shutdown nuclear power plant far away from highly contaminated sites, by using accelerator mass spectrometry. The detection limit of about 1pg (236)U allowed us to identify a minimal increase of the (236)U/(238)U isotopic ratio correlated to a peak of (137)Cs in river sediments downstream of the nuclear power plant, and to detect anthropogenic (236)U also upstream, where it is probably not related to the power plant but to global fallout. The (236)U content shoved variations of the (236)U/(238)U isotopic ratio in relation to the chemical-physical characteristics of the sediments. This demonstrates the potential of (236)U as an environmental tracer, and as an indicator for releases from nuclear facilities.

Neutron optical beam splitter from holographically structured nanoparticle-polymer composites.

We report a breakthrough in the search for versatile diffractive elements for cold neutrons. Nanoparticles are spatially arranged by holographical means in a photopolymer. These grating structures show remarkably efficient diffraction of cold neutrons up to about 50% for effective thicknesses of only 200   μm. They open up a profound perspective for next generation neutron-optical devices with the capability to tune or modulate the neutron diffraction efficiency.

South Aegean Volcanic Glass: Separation and Analysis by INAA and EPMA

Pumice from the major volcanic sources (Milos, Nisyros, Yali, Kos and Santorini) in the South Aegean region was investigated to reveal the differences between the composition of the bulk material, which contains a certain percentage of crystallites, and the pure glass phase, which is the main constituent. The knowledge of these differences is important for the identification of vitric tephra layers found in the Eastern Mediterranean region in archacological context, in deep sea drilling cores and lake sediments. Eruption products, deposited at some distance, show not only a decrease in their grain size, but also have usually lost their crystalline fraction due to gravity separation and consist only of glass shards. Major element distributions in such layers and in pumiceous glass are not sufficient for a reliable identification of the volcanic source, as several eruptions are known to have produced chemically very similar tephra layers in this region. Trace element data, especially of the rather immobile rare earth elements (REEs), can provide greater information on tephra originating from different volcanic eruptions. Therefore, a technique has been developed to separate the glass phase from different primary pumices to reveal differences in their trace element distributions. The concentrations of the major constituents, in particular Al, Ca, Fe, Mg, Mn, Na, Si, and Ti were determined by electron probe microanalysis (EPMA), those of Al, As, Ba, Ca, Ce, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mn, Na, Nd, Rb, Sb, Sc, Sm, Ta, Th, Ti, U, V, Yb and Zr by instrumental neutron activation analysis. Subtle differences between the compositions of the glass phase and the bulk material are explained by differentiation during partial crystallization. Their applicability to the classification of tephra layers is demonstrated.

Geochemical fingerprints by activation analysis of tephra layers in Lake Van sediments, Turkey

We discuss geochemical and sedimentological characteristics of 12 tephra layers, intercalated within the finely laminated sediments of Lake Van. Within the about 15kyr long sediment record studied, volcanic activity concentrated in the periods 2.6-7.2 and 11.9-12.9kyr B.P. Concentrations of 25 elements provide the geochemical fingerprint of each tephra layer and allow comparison to literature values of potential source volcanoes such as Mts. Nemrut and Süphan. The youngest two tephra layers (and probably also the other three ashes from the 2.6-7.2kyr B.P. eruptions) originate from the Nemrut volcano. The source of the older tephra (11.9-12.9kyr B.P.), however, remains unidentified.

NAA of the “Minoan pumice” at Thera and comparison to alluvial pumice deposits in the Eastern Mediterranean region

Neutron activation analysis was used to determine up to 30 elements in the pumice layers from the “Minoan eruption” at Thera (Santorini, Greece). Mt Pilato (Lipari, Italy) and in alluvial pumice from coasts of the Eastern Mediterranean region. The morphologically well distinguishable layers of the “Minoan pumice” were found to be of nearly similar composition in respect to the elements determined and their distribution patterns could therefore be used to identify a sample as Santorinian or not. Additionally, this method was applied to pumice lumps found during archaeological excavations in the Nile delta, Egypt. The results showed that two of the three Egyptian samples are products of the Minoan eruption at Thera and therefore chronologically useful. A second group of pumices collected at Antalya (Turkey), Crete (Greece) and also in Egypt was found to have a distinctly different composition and is therefore related to another volcanic event.

Metalloid Contaminated Microhabitats and their Biodiversity at a Former Antimony Mining Site in Schlaining, Austria

This paper is on the biological impact of arsenic and antimony on the flora and microflora on a former Sb- mining site in Schlaining (Stadtschlaining, Burgenland, Austria). Several habitats were investigated with respect to biodi- versity and metalloid contamination in soil. Although the overburden of the mining activity had been remediated less than ten years ago, metalloid concentrations occurred in soil up to 1.4‰ As and 3.6% Sb, respectively, in some microhabitats, as determined by Instrumental Neutron Activation Analysis. These metalloids were embedded into a nonuniform minera- logical background. Metalloid mobility could not be explained by common models, indicating that predictions on the mo- bility of geogenic metalloids require additional mineralogical data. The biological effects of this contamination were vari- able. We observed that metalloid resistant strands of microorganisms appeared in the contaminated soil. In cultivation ex- periments, Sb was found to be more toxic than As. Sulphur oxidising strand were more resistant than organotrophic ones and grew even better on cultivation media spiked with 10 ppm As than on the unspiked control. The flora was only par- tially influenced: the lowest biodiversity was found in metalloid richest soils, but moderate contamination resulted in en- hanced species numbers. Only in one case, where the pH-buffering capacity of the soil was exceeded by consumption of the entire carbonate, no embryophytes occurred. This was probably due to extreme pH conditions as well as to metalloid concentrations. Our data support the hypothesis that higher plants are rather affected by extreme soil conditions, which of- ten coincide with As contaminations, than by the contamination itself. A small rivulet in this area contained 26 � g/l and thus exceeded the WHO guideline value for As in drinking water by a factor of 2.6. Indeed we observed a diminished bio- diversity in this rivulet.

The Synchronization of Civilizations in the Eastern Mediterranean in the Second Millennium BC: Natural Science Dating Attempts

This chapter reports on work undertaken during the first three years of a ten-year project which aims to synchronize a range of relative and absolute dating evidence arising from archaeological records of the civilizations of the Eastern Mediterranean in the second millennium BC. At present the team is collecting chronological information from many different geographical locations. Some of the chronological methods are covered in more detail elsewhere in this volume (e.g. tephrochronology, Chapter 8 and radiocarbon dating with Bayesian models, Chapters 1and 2) and other methods such as dendrochronology and astrochronology are explained in detail here. It is already clear that the different dating methods do not lead directly to a coherent chronological picture for the region. Consequently, one of the major issues that must be tackled by this project is the synchronization of chronological evidence from different sources. This chapter outlines the nature of the evidence available and explains some of the techniques that the project team plans to use to link together the diverse dating evidence and thus develop their final chronological understanding.

On the geochemistry of the Kyra eruption sequence of Nisyros volcano on Nisyros and Tilos, Greece

The Kyra sequence is a volcanic eruption sequence originating from the eastern flank of Nisyros volcano, Greece. Its eruptions products can be found not only on Nisyros itself but also on the nearby non-volcanic island of Tilos. In an extensive sampling campaign, outcrops of the Kyra eruption products on Nisyros were sampled and corresponding samples on Tilos were taken. The clear stratigraphical relationship between the different units within in the individual outcrops, combined with the chemical information gained by the application of instrumental neutron activation analysis (INAA) to the samples, made a detailed chemo-stratigraphy of the complete eruption sequence possible. It can be shown that the sequence is separated into eight distinguishable eruptions. Furthermore, no eruption products of the caldera-forming eruptions from Nisyros (Lower- and Upper Caldera Pumice) or from Santorin were found on Tilos.

Precise measurement of the neutron capture reaction 54Fe(n,γ)55Fe via AMS

The measurement of cross sections relevant to nuclear astrophysics has become one main research topic at the VERA (Vienna Environmental Research Accelerator) facility. The technique applied, accelerator mass spectrometry (AMS), offers excellent sensitivity for the detection of long-lived radionuclides through ultra-low isotope ratio measurements. We discuss the potential and preliminary results of ongoing precision measurements of neutron-capture cross sections of

Precise measurement of the thermal and stellar

The detection of long-lived radionuclides through ultra-sensitive single atom counting via accelerator mass spectrometry (AMS) offers opportunities for precise measurements of neutron capture cross sections, e.g. for nuclear astrophysics. The technique represents a truly complementary approach, completely independent of previous experimental methods. The potential of this technique is highlighted at the example of the