@article {2750,
	title = {Sub-ice shelf sediment geochronology utilizing novel radiocarbon methodology for highly detrital sediments},
	journal = {Geochemistry, Geophysics, Geosystems},
	volume = {18},
	year = {2017},
	month = {Jan-04-2017},
	pages = {1404 - 1418},
	abstract = {Sub-ice shelf sediments near Larsen C ice shelf (LIS-C) show fine-scale rhythmic laminations that could provide a near-continuous seasonal-resolution record of regional ice mass changes. Despite the great potential of these sediments, a dependable Late Quaternary chronology is difficult to generate, rendering the record incomplete. As with many marginal Antarctic sediments, in the absence of preserved carbonate microfossils, the reliability of radiocarbon chronologies depends on presence of high proportions of autochthonous organic carbon with minimized detrital organic carbon. Consequently, acid insoluble organic (AIO) 14C dating works best where high productivity drives high sediment accumulation rates, but can be problematic in condensed sequences with high proportions of detrital organic carbon. Ramped PyrOx 14C dating has progressively been shown to improve upon AIO 14C dates, to the point of matching foraminiferal carbonate 14C dates, through differential thermochemical degradation of organic components within samples. But in highly detrital sediments, proportions of contemporaneously deposited material are too low to fully separate autochthonous organic carbon from detrital carbon in samples large enough to 14C date. We introduce two modifications of the Ramped PyrOx 14C approach applied to highly detrital sediments near LIS-C to maximize accuracy by utilizing ultra-small fractions of the highly detrital AIO material. With minimization of the uncertainty cost, these techniques allow us to generate chronologies for cores that would otherwise go undated, pushing the limits of radiocarbon dating to regions and facies with high proportions of pre-aged detritus. Wider use of these techniques will enable more coordinated a priori coring efforts to constrain regional glacial responses to rapid warming where sediments had previously been thought too difficult to date.},
	doi = {10.1002/2016GC006578},
	url = {https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GC006578},
	author = {Subt, C. and Yoon, H. I. and Yoo, K. C. and Lee, J. I. and Leventer, A. and Domack, E. W. and Rosenheim, B. E.}
}
@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 {254,
	title = {Antarctic sediment chronology by programmed-temperature pyrolysis: Methodology and data treatment},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {9},
	year = {2008},
	note = {id: 1847; 284ON Times Cited:5 Cited References Count:27Y},
	abstract = {We report a detailed programmed-temperature pyrolysis/ combustion methodology for radiocarbon (C-14) dating of Antarctic sub-ice shelf sediments. The method targets the autochthonous organic component in sediments that contain a distribution of acid-insoluble organic components from several sources of different ages. The approach has improved sediment chronology in organic-rich sediments proximal to Antarctic ice shelves by yielding maximum age constraints significantly younger than bulk radiocarbon dates from the same sediment horizons. The method proves adequate in determining isotope ratios of the pre-aged carbon end-member; however, the isotopic compositions of the low-temperature measurements indicate that no samples completely avoided mixing with some proportion of pre-aged organic material. Dating the unresolved but desired young end-member must rely on indirect methods, but a simple mixing model cannot be developed without knowledge of the sedimentation rate or comparable constraints. A mathematical approach allowing for multiple mixing components yields a maximum likelihood age, a first-order approximation of the relative proportion of the autochthonous component, and the temperature at which allochthonous carbon begins to volatilize and mix with the autochthonous component. It is likely that our estimation of the cutoff temperature will be improved with knowledge of the pyrolysis kinetics of the major components. Chronology is improved relative to bulk acid-insoluble organic material ages from nine temperature interval dates down to two, but incorporation of inherently more pre-aged carbon in the first division becomes more apparent with fewer and larger temperature intervals.},
	issn = {1525-2027},
	doi = {10.1029/2007gc001816},
	author = {Rosenheim, B. E. and Day, M. B. and Domack, E. and Schrum, H. and Benthien, A. and Hayes, J. M.}
}
@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 {461,
	title = {Caribbean sclerosponge radiocarbon measurements re-interpreted in terms of U/Th age models},
	journal = {Nuclear Instruments \& Methods in Physics Research Section B-Beam Interactions with Materials and Atoms},
	volume = {259},
	year = {2007},
	note = {id: 785; 182WV Times Cited:2 Cited References Count:30Y},
	pages = {474-478},
	abstract = {Previously unpublished AMS radiocarbon measurements of a sclerosponge from tongue of the ocean (TOTO), Bahamas, as well as preliminary data from an investigation of the radiocarbon records of sclerosponges living at different depths in the adjacent Bahamas basin, Exuma Sound, are interpreted in terms of U-series age models. The data are compared to an existing Caribbean sclerosponge radiocarbon bomb curve measured using standard gas proportional beta counting and used to interpret a Pb-210 age model. The Delta C-14 records from the sclerosponges illustrate a potential for use of radiocarbon both as a tracer of subsurface water masses or as an additional age constraint on recently sampled sclerosponges. By using an independent age model, this study lays the framework for utilizing sclerosponges from different locations in the tropics and subtropics and different depths within their wide depth range (0-250 m) to constrain changes in production of subtropical underwater in the Atlantic Ocean. This framework is significant because the proxy approach is necessary to supplement the short and coarse time series being used to constrain variability in the formation of Caribbean subtropical underwater, the return flow of a shallow circulation cell responsible for nearly 10\% of the heat transported poleward in the N. Atlantic. (c) 2007 Elsevier B.V. All rights reserved.},
	issn = {0168-583X},
	doi = {10.1016/j.nimb.2007.01.235},
	author = {Rosenheim, B. E. and Swart, P. K.}
}
@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 {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.}
}
