AMS 14C measurement and preparative techniques at NIES-TERRA

TitleAMS 14C measurement and preparative techniques at NIES-TERRA
Publication TypeJournal Article
Year of Publication2004
AuthorsYoneda, M, Shibata, Y, Tanaka, A, Uehiro, T, Morita, M, Uchida, M, Kobayashi, T, Kobayashi, C, Suzuki, R, Miyamoto, K, Hancock, B, Dibden, C, Edmonds, JS
JournalNuclear Instruments and Methods in Physics Research B

The AMS facility at the National Institute for Environmental Studies (NIES) has now been operating for five years since 1997. This AMS-dedicated facility named NIES-TERRA (Tandem accelerator for Environmental Research and Radiocarbon Analysis) consists of a 5MV tandem Pelletron (15SDH-2), a solid ion source with sequential injection system, a gas ion source with a simultaneous injection system, and a gas ionization detector. Typical precision with 14C measurements is around 0.5% and the background level has been achieved at around 50 kBP. Our main target is radiocarbon in environmental sciences, while other cosmogenic isotopes (10Be and 26Al) have been measured. Recently we have improved our preparation laboratory to increase sample throughput. CO2 production and purification using a commercial elemental analyzer connected to cryogenic traps (EA–CT) were investigated. We used a modified elemental analyzer with a chemical trap for separation and this is expected to reduce memory effect and background in comparison with an analyzer using gas-chromatography. This newly designed EA–CT system showed high precision and accuracy. Source of background contamination was also discussed based on the analysis of various amounts of standard materials.