Project

Discipline

14C; Paleoenvironment; Paleoclimate; Compound-specific radiocarbon analysis; Radiocarbon; Accelerator mass spectrometry; MICADAS; Paleo environment; Paleo climate; Archeology; Dating; Compound-specific radiocarbon analysis (CSRA); Hyphenated systems

Lead
Radiokohlenstoff (14C) ist ein langlebiges Radionuklid mit weitreichenden Anwendungsmöglichkeiten in vielen wissenschaftlichen Gebieten wie der archäologischen Datierung, der Klimaforschung und den Lebenswissenschaften. Die Universität Bern hat eine langjährige Erfahrung an präzisen 14C-Messungen. Wegen einem stark angestiegenen Bedarf an Radiokohlenstoff-Messungen wurde ein neues 14C-Labor mit einem Beschleuniger-Massenspektrometer in Betrieb genommen.
Lay summary
Inhalt und Ziel des Forschungsprojekts Die Erfahrung mit 14C-Messungen an der Universität Bern basiert auf den Entwicklungen von speziellen Gasproportionalzählrohren von Hans Oeschger vor über 50 Jahren. Deren Einsatzfähigkeit ist heute jedoch eingeschränkt wegen der benötigen Probenmengen, der aufwendigen Probenvorbereitung zur Herstellung des Zählgases und der langen Messzeiten. In den letzten beiden Jahrzehnten erfolgte eine enorme technische Entwicklung von Beschleuniger-Massenspektrometern (accelerator mass spectrometer, AMS) mit einem Durchbruch zu kleinen Instrumenten durch das MICADAS der ETH Zürich. Dieses Gerät kann ohne weiteres mit den Zählrohren bezüglich Messgenauigkeit konkurrieren und ist dabei im Vorteil durch einen geringeren Bedarf an Probenmenge und Zeitaufwand. Daher wurde ein MICADAS-System aufgebaut, um langfristig eine Infrastruktur für Radiokohlenstoff-Analysen an der Universität Bern sicher zu stellen.   Wissenschaftlicher und gesellschaftlicher Kontext des Forschungsprojekts Die Installation des MICADAS wird die erfolgreiche Weiterführung der Radiokohlenstoff-Forschung an der Universität Bern in den Atmosphärenwissenschaften, Limnologie, Paläoklimaforschung, Paläoökologie, Agroökologie und Biogeochemie sicherstellen und das Potential für innovative zukünftige Projekte schaffen. In vielen dieser Anwendungen wird die Analyse von gesamthaften Proben unausweichlich zu Fehlinterpretationen führen, wenn sich die Proben aus Material von unterschiedlichem Alter oder Ursprung zusammensetzen. Daher wird ein besonderer Schwerpunkt gelegt auf die Untersuchung von spezifischen Unterfraktionen oder sogar auf die 14C-Messung einzelner chemischer Substanzen und auf die Kopplung von Geräten zur Probenseparation mit dem MICADAS.

Direct link to Lay Summary

Last update: 09.01.2013

Lead
Radiocarbon (14C) is a long-lived radioisotope with widespread applications in many scientific branches such as archeological dating, climate research and life sciences. The University of Bern has a long history of experience in precise 14C measurements. However, an update of the facility was urgently needed accommodating an increasing number of 14C measurements. Therefore, a new radiocarbon laboratory was established at the University of Bern based on accelerator mass spectrometry (AMS).
Lay summary
Content and aim of the research project The experience in precise 14C measurements of the University of Bern bases on the conventional counting laboratory founded by Hans Oeschger more than 50 years ago. Due to the demanding procedure involved in preparing the counting gas from the organic samples and to the long counting time to obtain reliable statistics, the throughput and required carbon mass of this technique both were the limiting factors. During the last two decades, enormous technical development on accelerator mass spectrometry (AMS) has been achieved with the breakthrough of the small instrument MICADAS by ETH Zurich. This small unit can readily compete with the conventional counting method regarding precision but is significantly superior regarding its low requirements of sample amounts and process time. Consequently, a MICADAS system was set up in order to provide the long-term infrastructure for radiocarbon analysis at the University of Bern.   Scientific and social context of the research project The installation of MICADAS will ensure the successful continuation of radiocarbon applications at the University of Bern in atmospheric sciences, limnology, paleoclimatology, paleoecology, agroecology, and biogeochemistry and create the potential for innovative future projects. In many of these applications, analysis of bulk samples inevitably results in misinterpretations, if the samples are composed of materials from different sources or ages. Therefore, special emphasis is laid upon the investigation of specified sub-fractions of samples or even compound-specific radiocarbon analysis and the coupling of devices for sample preparation with the MICADAS.

Direct link to Lay Summary

Last update: 09.01.2013

Active participation

Self-organised

Number	Title	Start	Funding scheme

Precise determinations of the radionuclide 14C have widespread applications in many branches of natural sciences, ranging form geochemistry, archeology, and climate science to biomedical and pharmacological applications. In the past years, Swiss researchers funda-mentally contributed to two world-valued developments in the field of 14C analysis. First, the Laboratory of Ion Beam Physics at ETH Zurich constructed an accelerator mass spectrometer named MICADAS (Mini Carbon Dating System) that occupies a mere 2.5x3.0 m2 of floor space and uses a low acceleration voltage of only 200 kV. Repeatedly, the performance of the MICADAS system for high precision 14C measurements was demonstrated to be comparable to other commercially available instruments, whereas its operation is much more straightforward and cost-effective than for larger AMS systems. The second improvement concerns analytical developments for compound-specific radiocarbon analysis and microdating, substantially advanced at the University of Bern. Today, reliable 14C AMS analyses of very small samples containing only 2-50 µg carbon are routinely conducted. The development of separation techniques for isolation of pure sub-fractions or compounds has progressed to the point that hyphenated techniques of separation devices and AMS can be realized, aiming at automation for improvement of precision and sample throughput. The combination of these two very successful developments, which were achieved in close cooperation between the groups at ETH Zurich and the University of Bern, opens up completely new areas of research that were not thought possible a few years ago. Thus, the demand for 14C analyses has substantially increased to the point that the Ion Beam Physics group at ETH Zurich is no longer capable of performing all requested measurements.The University of Bern has a long tradition for classical 14C analysis using gas proportional counters. Furthermore, 14C dating is one of the cornerstones of climate and environmental science, for which the University of Bern has an internationally recognized expertise. This is emphasized by the establishment of the Oeschger Centre for Climate Change Research (OCCR). As a consequence, a consortium was founded comprising all interested research groups and institutions. A careful analysis of the demand for high precision 14C measurements and the potential future applications formed the justification to establish a MICADAS facility at the University of Bern. After approval of the measurement quality, it is planned that this AMS system will replace conventional counting at the University of Bern.The Laboratory of Radiochemistry and Environmental Chemistry (headed by Prof. A. Türler) at the Department of Chemistry and Biochemistry was identified as most promising for the future successful operation of the instrument. Here, PD Dr. S. Szidat, a renowned specialist in 14C AMS measurements, will supervise the operation of this instrument and contribute original own research. Other main investigators are Prof. T. Stocker and Prof. M. Leuenberger (Climate and Environmental Physics), Prof. M. Grosjean (Institute of Geography), Prof. M. Schwikowski (Department of Chemistry and Biochemistry and PSI), Prof. W. Tinner (Institute of Plant Sciences) and Prof. Ch. Schlüchter (Institute of Geological Sciences). Due to the joint appointment of Prof. Türler at the University of Bern and the Paul Scherrer Institute, further research groups from PSI have already expressed their interest for 14C analyses. In addition, a demand of continued routine 14C analysis for environmental radiation protection was clearly expressed by the Federal Office of Public Health (FOPH).In summary, we believe that a MICADAS AMS facility at the University of Bern would significantly enhance the research potential of a large number of groups and, thus, their international visibility, fostering new interdisciplinary collaborations. The instrument complements perfectly one of the core research areas of the University of Bern.