Research Group "Isotope Research and Nuclear Physics"
The former groups "Isotope Research" and "Nuclear Physics" have merged to form one research group within the Faculty of Physics. Until a new website is launched further research topics of this group can be found under http://kernphysik.univie.ac.at/index.php?id=902.
Accelerator Mass Spectrometry
The group for Isotope Research operates the Vienna Environmental Research Accelerator (VERA), a state-of-the-art facility for Accelerator Mass Spectrometry (AMS). Versatility across the nuclear chart is a unique feature of VERA. Radioisotopes such as 10Be, 14C, 26Al, 36Cl, 41Ca, 55Fe, 129I, 182Hf, 202Pb, 210Pb, 210mBi, 236U, 239-244Pu, 247Cm, and even superheavy elements can be measured with extremely high detection sensitivities of 10–12 to 10–16. Research projects focus on the exploration of our world by means of the “isotope language”, utilizing both natural and anthropogenic long-lived radioisotopes. We pursue fundamental physics experiments and a large variety of interdisciplinary research programs. A good balance between technical developments and challenging applications is vital. The applications touch almost every issue of our environment at large, from archaeology to climate research, and are performed in collaboration with leading experts of the respective fields. Special emphasis is put on AMS applications within physics, i.e. Astrophysics, Nuclear Physics, and Atomic and Molecular Physics. One focus of our technical developments is pushing the limits of accuracy, reliability, and sample size for the most important AMS isotope 14C. By refining conventional techniques, and also by adopting new approaches we strive to establish conditions which enable AMS of radioisotopes over the whole nuclear chart.
The probably best-known and most important application of AMS is 14C dating. Thus in the research program of the VERA laboratory the 14C method also plays a main part. Several formal and informal research projects with partners from different research disciplines are currently performed. Worth to mention is the special research program SCIEM2000 (“The Synchronisation of Civilisations in the Eastern Mediterranean in the Second Millennium BC”) funded by the Austrian Science Fund (FWF) and the Austrian Academy of Sciences, which had been completed in 2011.
A method developed to deal with μg carbon samples for 14C dating of DNA (14C produced during nuclear weapon tests in the 1950s and early 1960s) samples is also to be extended to earth and environmental sciences questions.
10Be and 26Al AMS applications
The investigation of possible refinements and improvements in the overall detection efficiency of 26Al from ice samples is pursued. The aim is the refinement of the presently used method for the determination of the 26Al/10Be ratio as a cosmogenic “clock” for dating of old (0.5 to 5 million years) ice from drill-cores from Antarctica.
A new application of 10Be determinations has been started for the assessment of the impact cratering process of the Bosumtwi crater in Ghana.
Investigation of anthropogenic 236U and Pu
VERA defines the state of the art for measuring natural and anthropogenic actinides such as 236U, and 239-244Pu. Measurements of water and sediments from the Irish Sea (affected by the Sellafield nuclear waste reprocessing plant) as well as samples taken remote from possible local contributions to investigate the global fallout from nuclear weapon tests and accidental releases have been performed.
Emphasis is put on establishing 236U as an oceanographic tracer. 236U is one of the most abundant anthropogenic radioisotopes, but only recent advances in AMS allow for the required detection sensitivity. The environmental distribution is largely unexplored and measurements at VERA are usually a first in the field.
Search for superheavy elements
VERA allows us to search for so far unknown superheavy elements at the upper end of the nuclear chart. Theoretical calculations predict a particular nuclear stability around proton number 114 and neutron number 184. We have now established upper limits for the possible existence of 37 superheavy nuclides in natural samples of Pt, Au, Pb, Bi and Th. In no case could we confirm positive claims for the existence of such isotopes.
The group participates in the nuclear astrophysics program of the n_TOF (neutron time-of-flight) collaboration at the European Laboratory for Particle Physics (CERN), where stellar neutron capture cross sections relevant for the astrophysical s-process are investigated
AMS is used to analyze deep-sea sediment cores for isotopes indicating supernova events.
Stable Isotope Mass Spectrometry
Paleodiet studies via δ13C and δ15N determinations in bone collagen are conducted by elemental analyzer - isotope ratio mass spectrometry, a “conventional” (not accelerator based) mass spectrometry technique.
Further development of the AMS method
Extending the AMS method to isotopes previously difficult or impossible to measure is an important research activity at VERA. Laser photo detachment of molecular anions which are crucial for a number of interesting AMS isotopes, e.g. 182Hf, is explored.