The ANSTO - University of Wollongong in-situ 14C extraction laboratory

We present our first C-14 in-situ results for calibration and system blanks from the recently completed Australian Nuclear Science and Technology Organisation (ANSTO) University of Wollongong (UOW) in-situ C-14 extraction system. System performance parameters and quality is evidenced by low C-14 blanks and good reproducibility for multiple targets from different reference materials. The C-14 extraction scheme exploits the high temperature phase transformation of quartz to cristobalite in order to quantitatively extract the carbon as CO2. The in-situ C-14 extraction system comprises three independently operated and modular units that are used for initial in-vacuo removal of meteoric C-14, followed by offline high-temperature heating of quartz to release trapped cosmogenic in-situ C-14, and finally CO2 gas purification and mass measurement. The design allows for rapid sample throughput of about 6 samples per week with samples masses ranging between 0.5 and 4 g of clean quartz. Other features include single-pass catalytic oxidation using mixed copper (LII) oxide as catalyst, use of UHV-compatible components and of vacuum annealed copper tubing. We present results for sets of purified quartz samples prepared from CRONUS-A, CRONUS-R and CRONUS-N inter-comparison materials, with final averages consistent with published values. Following extraction and cleaning, CO2 gas aliquots for some of the samples were analysed using the ETH Zurich CO2 gas ion source at the ETH MICADAS AMS facility in addition to CO2 being graphitised using the ANSTO laser-heated graphitisation micro-furnace and then analysed on ANSTO's ANTARES AMS facility. System blanks using either CO2 or graphite ion-sources at both facilities are on the order of similar to 1 x 10(4) atoms.