Progress report on a novel in situ 14C extraction scheme at the University of Cologne

• Published in: Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms Beam interactions with materials and atoms, 2015-10, Vol.361, p.20-24
• Main Authors: Fülöp, R.-H., Wacker, L., Dunai, T.J.
• Format: Article
• Language: English
• Subjects: ANNEALING PROCESSES; Blanks; CATALYSTS; CLEANING; Cologne; Copper; Extraction; EXTRACTIVE METALLURGY; QUARTZ; VACUUM ANNEALING
• ISSN: 0168-583X
• DOI: 10.1016/j.nimb.2015.02.023

We present initial results of in situ 14C system blank and calibration sample measurements obtained using the in situ 14C extraction scheme developed at the University of Cologne. The 14C extraction scheme specifically exploits the phase transformation of quartz to cristobalite in order to quantitatively extract the carbon as CO2 and follows a scheme that is different to that of existing extraction systems. Features are offline furnace extraction, single pass catalytic oxidation using mixed copper (I,II) oxide as catalyst, the use of UHV-compatible components and of vacuum annealed copper tubing. The design allows a relatively rapid sample throughput - two samples per day as opposed to the current 2days per sample that can be done on other lines - and can accommodate samples ranging between 0.5 and 4g of clean quartz. Following extraction and cleaning, the CO2 gas is measured using the gas ion source of the MICADAS AMS facility at ETH Zurich. The extraction system yields low systems blanks (10 +16/-10 103 atoms 14C, plus or minus 1 sigma ) and the initial results indicate that further improvements are achievable. Measurements of the CRONUS-A standard sample show a good reproducibility and results are consistent with published values. We also present the first in situ 14C results for the CRONUS-R standard material.