@article {2994,
	title = {14C Blank Corrections for 25{\textendash}100 μg Samples at the National Ocean Sciences AMS Laboratory},
	journal = {Radiocarbon},
	volume = {61},
	year = {2019},
	month = {10/2019},
	pages = {1403 - 1411},
	abstract = {Replicate radiocarbon (14C) measurements of organic and inorganic control samples, with known Fraction Modern values in the range Fm = 0{\textendash}1.5 and mass range 6 μg{\textendash}2 mg carbon, are used to determine both the mass and radiocarbon content of the blank carbon introduced during sample processing and measurement in our laboratory. These data are used to model, separately for organic and inorganic samples, the blank contribution and subsequently {\textquotedblleft}blank correct{\textquotedblright} measured unknowns in the mass range 25{\textendash}100 μg. Data, formulas, and an assessment of the precision and accuracy of the blank correction are presented.},
	keywords = {AMS, AMS dating, blank corrections},
	isbn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2019.74},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/14c-blank-corrections-for-25100-g-samples-at-the-national-ocean-sciences-ams-laboratory/494B9CF72445198570213B4A2CC303D0},
	author = {Roberts, M. L. and Elder, K. L. and Jenkins, W. J. and Gagnon, A. R. and Xu, L. and Hlavenka, J. D. and Longworth, B. E.}
}
@article {551,
	title = {A gas-accepting ion source for Accelerator Mass Spectrometry: Progress and applications},
	journal = {Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms},
	volume = {294},
	year = {2013},
	note = {id: 2161},
	month = {Jan},
	pages = {296-299},
	abstract = {The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility at the Woods Hole Oceanographic Institution has developed an Accelerator Mass Spectrometry (AMS) system designed specifically for the analysis of 14C in a continuously flowing stream of carrier gas. A key part of the system is a gas-accepting microwave ion source. Recently, substantial progress has been made in the development of this source, having achieved ion currents rivaling that of a traditional graphite source (albeit at relatively low efficiency). Details and present performance of the gas source are given. Additionally, representative results obtained from coupling the source to both a gas chromatograph and gas bench are presented.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2011.10.016},
	author = {Roberts, M. L. and von Reden, K. F. and Burton, J. R. and McIntyre, C. P. and Beaupre, S. R.}
}
@article {2463,
	title = {Optimizing a microwave gas ion source for continuous-flow accelerator mass spectrometry},
	journal = {Review of Scientific Instruments},
	volume = {835240},
	year = {2012},
	month = {Jan-02-2012},
	pages = {02B304},
	abstract = {A 2.45 GHz microwave ion source coupled with a magnesium charge exchange canal (C {\texttimes} C) has been successfully adapted to a large acceptance radiocarbon accelerator mass spectrometry system at the National Ocean Sciences Accelerator Mass Spectrometry (AMS) Facility, Woods Hole Oceanographic Institution. CO2 samples from various preparation sources are injected into the source through a glass capillary at 370 μl/min. Routine system parameters are about 120{\textendash}140 μA of negative 12C current after the C {\texttimes} C, leading to about 400 14C counts per second for a modern sample and implying a system efficiency of 0.2\%. While these parameters already allow us to perform high-quality AMS analyses on large samples, we are working on ways to improve the output of the ion source regarding emittance and efficiency. Modeling calculations suggest modifications in the extraction triode geometry, shape, and size of the plasma chamber could improve emittance and, hence, ion transport efficiency. Results of experimental tests of these modifications are presented.},
	issn = {0034-6748},
	doi = {10.1063/1.3656408},
	url = {http://aip.scitation.org/doi/10.1063/1.3656408http://aip.scitation.org/doi/pdf/10.1063/1.3656408},
	author = {von Reden, K. F. and Roberts, M. L. and Burton, J. R. and {\'e}, S. R.}
}
@article {1829,
	title = {Age and Growth Rate Dynamics of an Old African Baobab Determined by Radiocarbon Dating},
	journal = {Radiocarbon},
	volume = {52},
	year = {2010},
	note = {Sp. Iss. 1696jn
Times Cited:2
Cited References Count:21
},
	month = {2010},
	pages = {727-734},
	abstract = {In 2008, a large African baobab (Adansonia digitata L.) from Makulu Makete, South Africa, split vertically into 2 sections, revealing a large enclosed cavity. Several wood samples collected from the cavity were processed and radiocarbon dated by accelerator mass spectrometry (AMS) for determining the age and growth rate dynamics of the tree. The C-14 date of the oldest sample was found to be of 1016 +/- 22 BP, which corresponds to a calibrated age of 1000 +/- 15 yr. Thus, the Makulu Makete tree, which eventually collapsed to the ground and died, becomes the second oldest African baobab dated accurately to at least 1000 yr. The conventional growth rate of the trunk, estimated by the radial increase, declined gradually over its life cycle. However, the growth rate expressed more adequately by the cross-sectional area increase and by the volume increase accelerated up to the age of 650 yr and remained almost constant over the past 450 yr.},
	keywords = {cal kyr bp, Calibration, southern-hemisphere},
	isbn = {0033-8222},
	author = {Patrut, A. and Mayne, D. H. and von Reden, K. F. and Lowy, D. A. and Venter, S. and McNichol, A. P. and Roberts, M. L. and Margineanu, D.}
}
@article {1831,
	title = {A Continuous-Flow Gas Chromatography C-14 Accelerator Mass Spectrometry System},
	journal = {Radiocarbon},
	volume = {52},
	year = {2010},
	note = {Sp. Iss. 1696jn
Times Cited:4
Cited References Count:24
},
	month = {2010},
	pages = {295-300},
	abstract = {Gas-accepting ion sources for radiocarbon accelerator mass spectrometry (AMS) have permitted the direct analysis of CO2 gas, eliminating the need to graphitize samples. As a result, a variety of analytical instruments can be interfaced to an AMS system, processing time is decreased, and smaller samples can be analyzed (albeit with lower precision). We have coupled a gas chromatograph to a compact C-14 AMS system fitted with a microwave ion source for real-time compound-specific C-14 analysis. As an initial test of the system, we have analyzed a sample of fatty acid methyl esters and biodiesel. Peak shape and memory was better then existing systems fitted with a hybrid ion source while precision was comparable. C-14/C-12 ratios of individual components at natural abundance levels were consistent with those determined by conventional methods. Continuing refinements to the ion source are expected to improve the performance and scope of the instrument.},
	keywords = {ams system, gc-ams, negative-ion source, RADIOCARBON ANALYSIS},
	isbn = {0033-8222},
	author = {McIntyre, C. P. and Galutschek, E. and Roberts, M. L. and von Reden, K. F. and McNichol, A. P. and Jenkins, W. J.}
}
@article {1830,
	title = {Fire History of a Giant African Baobab Evinced by Radiocarbon Dating},
	journal = {Radiocarbon},
	volume = {52},
	year = {2010},
	note = {Sp. Iss. 1696jn
Times Cited:11
Cited References Count:28
},
	month = {2010},
	pages = {717-726},
	abstract = {The article reports the first radiocarbon dating of a live African baobab (Adansonia digitata L.), by investigating wood samples collected from 2 inner cavities of the very large 2-stemmed Platland tree of South Africa. Some 16 segments extracted from determined positions of the samples, which correspond to a depth of up to 15-20 cm in the wood, were processed and analyzed by accelerator mass spectrometry (AMS). Calibrated ages of segments are not correlated with their positions in the stems of the tree. Dating results indicate that the segments originate from new growth layers, with a thickness of several centimeters, which cover the original old wood. Four new growth layers were dated before the reference year AD 1950 and 2 layers were dated post-AD 1950, in the post-bomb period. Formation of these layers was triggered by major damage inside the cavities. Fire episodes are the only possible explanation for such successive major wounds over large areas or over the entire area of the inner cavities of the Platland tree, able to trigger regrowth.},
	keywords = {age calibration, bomb c-14 data, bombacaceae, cal kyr bp, southern-hemisphere, system},
	isbn = {0033-8222},
	author = {Patrut, A. and Mayne, D. H. and von Reden, K. F. and Lowy, D. A. and van Pelt, R. and McNichol, A. P. and Roberts, M. L. and Margineanu, D.}
}
@article {246,
	title = {A High-Performance (14)c Accelerator Mass Spectrometry System},
	journal = {Radiocarbon},
	volume = {52},
	year = {2010},
	note = {id: 2095; PT: J; CT: 20th International Radiocarbon Conference; CY: MAY 31-JUN 05, 2009; CL: Big Isl, HI; SI: 1; UT: WOS:000285437800005},
	pages = {228-235},
	abstract = {A new and unique radiocarbon accelerator mass spectrometry (AMS) facility has been constructed at the Woods Hole Oceanographic Institution. The defining characteristic of the new system is its large-gap optical elements that provide a larger-than-standard beam acceptance. Such a system is ideally suited for high-throughput, high-precision measurements of (14)C. Details and performance of the new system are presented.},
	issn = {0033-8222},
	doi = {10.2458/azu_js_rc.52.3657},
	author = {Roberts, M. L. and Burton, J. R. and Elder, K. L. and Longworth, B. E. and McIntyre, C. P. and von Reden, K. F. and Han, B. X. and Rosenheim, B. E. and W. J. Jenkins and Galutschek, E. and McNichol, A. P.}
}
@article {536,
	title = {Accelerator mass spectrometry C-14 determination in CO2 produced from laser decomposition of aragonite},
	journal = {Rapid Communications in Mass Spectrometry},
	volume = {22},
	year = {2008},
	note = {id: 1891; 370OU Times Cited:1 Cited References Count:16Y},
	pages = {3443-3449},
	abstract = {The determination of C-14 in aragonite (CaCO3) decomposed thermally to CO2 using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of C-14 from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30\% of material removed into CO2 despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO2 gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO2 generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO2 Copyright (C) 2008 John Wiley \& Sons, Ltd.},
	issn = {0951-4198},
	doi = {10.1002/Rcm.3745},
	author = {Rosenheim, B. E. and Thorrold, S. R. and Roberts, M. L.}
}
@article {460,
	title = {Software development for continuous-gas-flow AMS},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {266},
	year = {2008},
	note = {id: 2091; PT: J; CT: 9th European Conference on Accelerators in Applied Research and Technology; CY: SEP 03-07, 2007; CL: Florence, ITALY; SP: Univ Florence, Dept Phys, Ist Nazl Fis Nucl; UT: WOS:000257185600033},
	pages = {2233-2237},
	abstract = {The National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Facility at Woods Hole Oceanographic institution is presently completing installation of a novel continuous-flow AMS system. A multi-year development of an AMS microwave gas ion source in collaboration with Atomic Energy Canada Limited (AECL), Chalk River, has preceded this final step of an implementation that is expected to add a new dimension to (14)C AMS. National Instruments, NIM, and CAMAC modules have been programmed with Lab-VIEW on a Windows XP platform to form the basis for data acquisition. In this paper we discuss possible applications and include simulations of expected data acquisition scenarios like real-time AMS analysis of chromatograms. Particular attention will have to be given to issues of synchronization between rapidly changing input amplitudes and signal processing cycles in hardware and software. (C) 2008 Elsevier B.V. All rights reserved.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2008.03.001},
	author = {von Reden, K. F. and Roberts, M. L. and W. J. Jenkins and Rosenheim, B. E. and McNichol, A. P. and Schneider, R. J.}
}
@article {565,
	title = {Computer simulation of MC-SNICS for performance improvements},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {261},
	year = {2007},
	note = {200swTimes Cited:8Cited References Count:8},
	month = {Aug},
	pages = {588-593},
	abstract = {Increasing ion source current output while keeping the beam emittance small is a key for improving measurement throughput and quality of an accelerator mass spectrometry (AMS) system. The NEC MC-SNICS ion sources have widely been used for AMS around the world. In this work, a computer simulation study on MC-SNICS ion source was carried out using the code PBGUNS. The primary Cs+ beam is simulated as space-charge limited emission from the ionizer surface. The secondary negative ion beam is simulated in the presence of the space-charge induced by both the primary and the secondary beam. Two different configurations of the MC-SNICS have been studied: the original factory version and the UC Irvine modified version. The latter has a 0.668 in. radius spherical ionizer and an immersion lens at cathode potential with the original Cs focus lens removed. Simulation showed that the modified version provides more intense and better focused Cs+ beam at the cathode target, hence higher negative ion production from the sample by sputtering. The new arrangement of Einzel-preacceleration section of the MC-SNICS at UC Irvine was also simulated and discussed. Simulation results are in good agreement with the experimental observations made at UC Irvine. Hints for selection of an immersion lens geometry have been obtained. (c) 2007 Elsevier B.V. All rights reserved.},
	issn = {0168-583x},
	doi = {10.1016/j.nimb.2007.03.060},
	author = {Han, B. X. and Southon, J. R. and Roberts, M. L. and von Reden, K. F.}
}
@article {462,
	title = {Electromagnetic field modeling and ion optics calculations for a continuous-flow AMS system},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {259},
	year = {2007},
	note = {id: 1698; 182WV Times Cited:6 Cited References Count:14},
	pages = {111-117},
	abstract = {A continuous-flow C-14 AMS (CFAMS) system is under construction at the NOSAMS facility. This system is based on a NEC Model 1.5SDH-10.5 MV Pelletron accelerator and will utilize a combination of a microwave ion source (MIS) and a charge exchange canal (CXC) to produce negative carbon ions from a continuously flowing stream Of CO2 gas. For high-efficiency transmission of the large emittance, large energy-spread beam from the ion source unit, a large-acceptance and energy-achromatic injector consisting of a 45 degrees electrostatic spherical analyzer (ESA) and a 90 degrees double-focusing magnet has been designed. The 45 degrees ESA is rotatable to accommodate a 134-sample MC-SNICS as a second ion source. The high-energy achromat (90 degrees double focusing magnet and 90 degrees ESA) has also been customized for large acceptance. Electromagnetic field modeling and ion optics calculations of the beamline were done with Infolytica MagNet, ElecNet, and Trajectory Evaluator. PBGUNS and SIMION were used for the modeling of ion source unit. (c) 2007 Elsevier B.V. All rights reserved.},
	issn = {0168-583X},
	doi = {10.1016/J.Nimb.2007.01.224},
	author = {Han, B. X. and von Reden, K. F. and Roberts, M. L. and Schneider, R. J. and Hayes, J. M. and W. J. Jenkins}
}
@article {567,
	title = {Progress on a gas-accepting ion source for continuous-flow accelerator mass spectrometry},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {259},
	year = {2007},
	note = {182wvTimes Cited:24Cited References Count:12},
	month = {Jun},
	pages = {83-87},
	abstract = {A gas-accepting microwave-plasma ion source is being developed for continuous-flow accelerator mass spectrometry (AMS). Characteristics of the ion source will be presented. Schemes for connecting a gas or liquid chromatograph to the ion source will also be discussed. (c) 2007 Ellsevier B.V. All rights reserved.},
	issn = {0168-583x},
	doi = {10.1016/j.nimb.2007.01.189},
	author = {Roberts, M. L. and Schneider, R. J. and von Reden, K. F. and Wills, J. S. C. and Han, B. X. and Hayes, J. M. and Rosenheim, B. E. and W. J. Jenkins}
}
@conference {1542,
	title = {A 2.45 GHz Ion Source for use in Accelerator Mass Spectrometry},
	booktitle = {11th International Conference on Ion Ssources},
	year = {2005},
	note = {id: 1707},
	month = {2005},
	address = {Caen, France},
	author = {von Reden, K. F. and Schneider, R. J. and Roberts, M. L. and Han, B. X. and Wills, J.}
}
@conference {1543,
	title = {3-D Electromagnetic Field Modeling and Ion Optics Calculations for a Continuous-Flow AMS System},
	booktitle = {10th International Conference on Accelerator Mass Spectrometry},
	year = {2005},
	note = {id: 1708},
	month = {2005},
	address = {Berkeley, California},
	author = {Han, B. X. and von Reden, K. F. and Roberts, M. L. and Schneider, R. J. and Hayes, J. M.}
}
@conference {1576,
	title = {Beam Profile Measurements for a MC-SNICS Source with Spherical Ionizer},
	booktitle = {10th International Conference on Accelerator Mass Spectrometry},
	year = {2005},
	note = {id: 1706},
	month = {2005},
	address = {Berkeley, California},
	author = {von Reden, K. F. and Griffin, V. S. and Roberts, M. L.}
}
@inbook {1457,
	title = {Computer Control},
	booktitle = {Electrostatic accelerators: fundamentals and applications},
	year = {2005},
	note = {id: 1686},
	month = {2005},
	pages = {328},
	publisher = {Springer},
	organization = {Springer},
	isbn = {3540239839},
	author = {Roberts, M. L.},
	editor = {Hellborg, R.}
}
@conference {1598,
	title = {Continuous-Flow Accelerator Mass Spectrometry},
	booktitle = {the International Symposium on Utilization of Accelerators},
	series = {IAEA-CN-115-09},
	year = {2005},
	note = {id: 767},
	month = {2005},
	address = {Dubrovnik Croatia},
	author = {Roberts, M. L. and von Reden, K. F. and Han, B. X. and Schneider, R. J. and Benthien, A. and Hayes, J. M.}
}
@conference {1759,
	title = {Progress on a Gas Ion Source for Continuous-Flow Accelerator Mass Spectrometry},
	booktitle = {10th International Conference on Accelerator Mass Spectrometry},
	year = {2005},
	note = {id: 768},
	month = {2005},
	address = {Berkeley, California},
	author = {Roberts, M. L. and Schneider, R. J. and von Reden, K. F. and Han, B. X. and Rosenheim, B. E. and Hayes, J. M.},
	editor = {Knezovich, J. and et al.}
}
@article {2023,
	title = {The 14C AMS system at the University of Georgia},
	journal = {Nuclear Instruments and Methods in Physics Research},
	volume = {B 233-224},
	year = {2004},
	note = {id: 1809},
	month = {2004},
	author = {Roberts, M. L. and Culp, R. A. and Dvoracek, D. K. and Hodgins, G. W. L. and Neary, M. P. and Noakes, J. E.}
}
@article {465,
	title = {The 14C AMS system at The University of Georgia},
	journal = {Proceedings of the Ninth International Conference on Accelerator Mass Spectrometry},
	volume = {223-224},
	year = {2004},
	note = {id: 2103},
	pages = {1-4},
	abstract = {The Center for Applied Isotope Studies at the University of Georgia has installed a compact 14C accelerator mass spectrometry (AMS) system manufactured by the National Electrostatics Corporation, Middleton, Wisconsin. The system utilizes a 134 sample ion source and a 500 kV Pelletron. In terms of cost and size, the new system is a significant advance over previous technology. Details and performance of the new system will be presented.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2004.04.004},
	author = {Roberts, M. L. and Culp, R. A. and Dvoracek, D. K. and Hodgins, G. W. L. and Neary, M. P. and Noakes, J. E.}
}
@article {2010,
	title = {Plans for Expanded 14C Analyses at the NOSAMS Facility--a status and progress report. 9th International Conference on Accelerator Mass Spectrometry, Nagoya, Japan, 9/2002},
	journal = {Nuclear Instruments and Methods in Physics Research},
	volume = {B 223-224},
	year = {2004},
	note = {id: 1810},
	month = {2004},
	pages = {50-54},
	author = {von Reden, K. and Donoghue, J. and Elder, K. and Gagnon, A. and Gerlach, D. and Griffin, V. S. and Healy, R. and Long, P. and McNichol, A. P. and Percy, D. and Roberts, M. L. and Schneider, R. J. and Xu, L. and Hayes, J.}
}
@conference {1597,
	title = {Continuous-Flow Accelerator Mass Spectrometry},
	booktitle = {International Symposium on Radiation Physics},
	year = {2003},
	note = {id: 1683},
	month = {2003},
	address = {Mexico City, Mexico},
	author = {Roberts, M. L. and Benthien, A. and Schneider, R. J. and von Reden, K. F. and Hayes, J. M.}
}
@conference {1546,
	title = {The 14C AMS system at the University of Georgia},
	booktitle = {International Conference on Accelerator Mass Spectrometry},
	year = {2002},
	note = {id: 1684},
	month = {2002},
	address = {Nagoya, Japan},
	author = {Roberts, M. L. and Culp, R. A. and Dvoracek, D. K. and Hodgins, G. W. L. and Neary, M. P. and Noakes, J. E.}
}
@conference {1744,
	title = {Plans for expanded 14C analyses at the NOSAMS facility - a status and progress report},
	booktitle = {International Conference on Accelerator Mass Spectrometry},
	year = {2002},
	note = {id: 1685},
	month = {2002},
	address = {Nagoya, Japan},
	author = {von Reden, K. F. and Donoghue, J. and Elder, K. and Gagnon, A. and Gerlach, D. and Griffin, V. and Healy, R. and Long, P. and McNichol, A. and Percy, D. and Roberts, M. L. and Schneider, R. J. and Xu, L. and Hayes, J. M.}
}
