Browsing by Author "Williams, A"

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    The ANTARES AMS facility at ANSTO
    (Elsevier, 2004-08) Fink, D; Hotchkis, MAC; Hua, Q; Jacobsen, GE; Smith, AM; Zoppi, U; Child, DP; Mifsud, C; van der Gaast, H; Williams, A; Williams, M
    This paper presents an overview of ANTARES operations, describing (1) technical upgrades that now allow routine 0.3–0.4% 14C precision for 1 mg carbon samples and 1% precision for 100 micrograms, (2) proficiency at 236U measurements in environmental samples, (3) new developments in AMS of platinum group elements and (4), some major application projects undertaken over the period of the past three years. Importantly, the facility is poised to enter into a new phase of expansion with the recent delivery of a 2 MV 14C tandem accelerator system from High Voltage Engineering (HVE) and a stable isotope ratio mass spectrometer from Micromass Inc. for combustion of organic samples and isotopic analysis. © 2004 Elsevier B.V.
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    Characterization and ongoing development of the ANSTO AMS radiocarbon small mass H2/Fe graphitization lines
    (20th International Radiocarbon Conference, 2009-06-01) Williams, A; Varley, S
    The ANSTO AMS radiocarbon graphitization laboratory was originally established with a set of 8 graphitization lines, using Zn/Fe and having volumes around 10 to 13 mL. As the demand for smaller sample masses increased, 12 smaller volume (~3.5 mL) H2/Fe graphitization lines were developed. These lines proved to be versatile, as the operating volume could be varied by changing the volume of a removable cold finger, allowing small mass samples of <100 μg C up to ~3 mg C to be graphitized reliably. Following the success of these lines, the original Zn/Fe lines were replaced in 2004 with a second set of 12 H2/Fe lines. In 2006, following the serial failure of the original gauges used for the 3.5-mL lines we had the opportunity to decrease the reaction volume further and thus reduce the graphitization mass limit. This poster will describe the smaller volume (~2.5 mL) versions, of the original H2/Fe graphitization lines; these new lines were developed using stainless steel diaphragm pressure sensors. This development was successful in extending our lower working mass limit down to ~10 μg C at ~50% graphitization efficiency, while still retaining the flexibility to graphitize up to ~3 mg C reliably. We will present the efficiency data and the characterization tests that these lines underwent, following their rebuilding as ~2.5-mL lines. In addition, we will present the development of new graphitization lines, which are in the process of construction. These comprise 3 very small volume (~0.9 mL) H2/Fe graphitization lines (using ceramic diaphragm pressure sensors), with the primary objective of minimizing, and stabilizing, the absolute mass of added extraneous carbon and stabilizing its pMC value. To assist in this objective, we are also developing revised methods for our sample combustion and transfer procedures, and the development of a modified transfer line. Preliminary results from this work will be presented.
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    The new AMS Centre for Accelerator Science at ANSTO – a vision to the future
    (AMS 13 , Aix-en-Provence, 2014-08-24) Fink, D; Hotchkis, MAC; Wilcken, KM; Child, DP; Fujioka, T; Jacobsen, GE; Williams, A; Levchenko, VA; Charles, M
    In 2009, the Australian Federal Government approved funding for the construction of a state-of-the-art AMS and IBA centre for applied accelerator science at ANSTO. The final design includes a 1 MV dedicated AMS system (14C, 26Al, 10Be, 129I, Pu, U), a 6MV shared IBA and AMS system (10Be, 26Al, 36Cl, 129I), a gas-filled-magnet beam line and a dedicated AMS sample preparation building. The NEC accelerators are housed in a new 1500 m2 building interconnected with the existing ANTARES AMS Facility. The 1200 m2 chemistry building was designed as a multipurpose laboratory which provides dedicated and separated lab space for sample preparation for cosmogenic 10Be, 26Al and 36Cl, meteoric 10Be, low-level actinides (Pu,U) and an ice-core freezer storage facility for 14CH4 and 10Be work. An independent Uranium series laboratory (for carbonates, water, quartz) is available with allocated labs for an ICP-MC and IRMS units. The 1MV AMS accelerator was delivered in October 2013. Large beam-optical acceptance and high-mass resolution analysers, coupled to a novel fast coupled HE and LE isotope switching system, enables high quality radiocarbon and actinide analyses. The 6MV AMS System has 3 ion-sources (alphatross, muoplasmatron, MC-SNICS), a high-mass resolution injector, and 3 AMS beam lines. Construction of all facilities has been completed, and delivery of the NEC 6MV accelerator is scheduled for mid-2014. The 1 MV AMS is operational and first results are presented in a companion conference paper. The gas-filled magnet beam line has been assembled and tested with stable beams. The AMS sample chemistry building is operational and commissioned. The cosmogenic lab covers an area of 250 m2, and allows parallel sample processing.
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    Stratigraphy and age-dating of the Kiriwina Formation,Woodlark Island, Papua New Guinea
    (Australian Geosciences Council, 2012-08) McGeeney, D; Graham, IT; Cohen, DD; Spencer, L; Jacobsen, GE; Williams, A
    The Upper-Pleistocene Kiriwina Formation (KFm) of Woodlark Island, Papua New Guinea, is a complex, largely transitional shallow marine to near-shore terrestrial sedimentary unit. This study provides the first detailed analysis of the KFm on any KFm hosting island of the Solomon Sea. Highly elevated Au contents (up to 10 ppm) occur within various sub-units. The KFm covers most of the island’s surface, has a thickness of 0–90m, and unconformably overlies the mid-Miocene Okiduse Volcanics that host carbonate-base metal-Au epithermal mineralization. The formation has undergone rapid horizontal and vertical changes in the sedimentary environment and style; individual units and subunits occur as repeated lenses of conglomerates, gritstones, beach sands, silts, lagoonal clays, and mixed clays/carbonates. The KFm is capped by porous and permeable shallow marine limestones, which in places have undergone karst development. Detailed mapping indicates previously unknown near-shore terrestrial subunits that may comprise a large part of the sequence. Andesitic fragments are widely dispersed throughout each member and subunit. The main clay in the Talpos Marine Clay Member is nontronite, an Fe-rich smectite. New C14 radiometric age-dating has determined the KFm to be 47,130–60,300 yrs BP at Kulumadau and > 70,000 yrs BP at Busai. These ages were used as a basis to determine an average uplift rate of 1.06m/1000 years.